DE10317635A1 - Nozzle for injection or extrusion machines has a nozzle head containing a filter with a cleaning bore facing the nozzle outlet and closed off by a needle - Google Patents

Abstract

The nozzle head13) fits in a nozzle tube and has a central bore housing a filter body(12) with fine radial filtering bores(19) connecting the inner chamber(24) of the filter with an annular channel between nozzle head and filter body. At the front end of the filter body(12) facing the nozzle outlet(23) there is a cleaning bore(10) which can be closed with a shut-off needle(11). The cleaning bore(10) is coaxial to the nozzle outlet(23) and the shut-off needle(11) is axially moveable coaxial to the cleaning bore(10) and filter body(12). Operation of the shut-off needle can be by mechanical, electrical or pneumatic methods. For needle closure the rear end of the latter either: a) makes positive contact with an eccentric(21) of a rotatable bolt(14) perpendicular to the central axis of the nozzle and needle or b) makes positive contact with a swivelling arm. The needle passes through a torpedo inside the nozzle tube. In an alternative design the front end of the needle has an inward tapering extension(28) which closes the nozzle outlet and the cleaning bore has a larger diameter than the nozzle outlet. In one position of the needle the nozzle outlet is opened while the cleaning bore remains closed. In a second needle position the needle is pushed backwards by pressure in the annular channel(27) so that both cleaning bore and nozzle outlet are opened.

Description

The Invention relates to a spray nozzle for injection molding or extrusion machines mentioned in the preamble of claim 1 Art. By means of such spray nozzles the melted plastic mass from the cylinder, e.g. a screw cylinder, the injection molding or extrusion machine into it Injection molding tool introduced. Because the plastic melt that from Granules, regrind or recycled material is often produced Foreign body, e.g. Residues Metal, paper, glass, wood or similar Contains particles, it is, especially when producing high-quality injection molded parts necessary to melt the plastic before injecting it into the injection mold by means of a sieve body clean.

A spray nozzle combined with a sieve body is off DE 29 04 158 C2 known. With this spray nozzle, a sieve body is inserted into the central bore of the nozzle head. This sieve body consists of a cylindrical sieve sleeve, the jacket of which has numerous fine radial sieve bores through which the plastic mass pressed into the cavity of the sieve body 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, the screen body is closed by a conical front wall. Heavy substances contained in the injection molding compound flowing into the sieve body collect in the bulge formed by the end wall, so that they cannot reach the ring channel through the sieve bores and from here into the injection molding tool.

ever depending on the degree of contamination of the plastic melt, the sieve body must be Cleaned from time to time to block the screen holes to avoid and thus a constant quality of the injection molded parts to ensure.

in the Operation quits blockage of the sieve body due to a significant increase in pressure in the injection molding machine. In this case, the sieve body removed, cleaned and reinstalled. This is only with the entire expensive production plant can be shut down. Experience has shown that you need therefor 30 to 40 minutes. The shutdown of the plant leads to considerable temperature fluctuations in the entire system, especially in the screw cylinder of the injection molding machine as well as in the cooled or heated injection molding tool, causing overheating or hypothermia of the Plastic melt leads. In order to be able to produce injection molded parts of consistent quality, brought the entire system back into thermal equilibrium become what is time consuming and because of the very interruption of production is expensive.

The The present invention is therefore based on the object the sieve body combined spray nozzle to be designed in such a way that the filter cleaning can be carried out without any significant interruption to operations can. So the goal is to clean without removing of the sieve body carried out become.

According to the present Invention becomes a solution this task with a spray nozzle proposed in the preamble of claim 1 proposed 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 Locking pin lockable is.

During the production of molded parts, the outlet bore is closed by the shut-off needle, so that the plastic melt entering the sieve body can only exit through the sieve bores, while foreign bodies contained in the melt remain in the cavity of the sieve body, as shown in 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 completely or partially blocked, what by increasing the pressure on the injection molding machine cleaning of the filter body is indicated.

To the screw cylinder of the injection molding machine must do this be separated from the injection mold, whereupon the valve pin Cleaning hole in the sieve body releases the foreign bodies that have accumulated in the sieve body to be able to spray outside with the plastic melt. This Spraying triggered at the press of a button on the machine should expediently can be repeated two to three times. Following this, the nozzle connected again with the injection mold, so that the injection process can continue.

The Filter cleaning in the spray nozzle designed according to the invention can be carried out within a maximum of one minute so that by cleaning the thermal balance of the system is not significantly disturbed and shutdown compared to conventional cleaning operations injection or extrusion machines negligible is.

The design of corresponds to Cleaning bore and shut-off needle in the sieve body according to the invention, the known hydraulic or electric needle shut-off nozzles, in which the outlet bore of the nozzle head is closed, for example in the event of a business interruption, with a needle which can be displaced axially inside the nozzle head.

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

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

In particular for mechanical Adjustment is the proposal according to claim 4, according to which the locking needle by means of a rotatably mounted in the nozzle tube Eccentric is adjustable. The proposal according to claim 5 serves here the pivot limit of the pivot pin.

To another proposal specified with claim 6, the closure needle is similar to can be controlled with a hydraulic linkage nozzle using a lifting rod.

at All variants can be adjusted mechanically, hydraulically, pneumatically or done electrically.

at A coaxial arrangement of the valve pin is a centering and floating storage by means of a so-called th torpedo according to claim 7 advantageous in a manner known per se.

This Torpedo that is both the lead the locking needle and the fixing of the sieve body within of the nozzle tube serves and seals the components against each other, is subject to wear and therefore designed as a separate, interchangeable component.

To a further proposal according to claims 8 and 9 can be designed according to the invention and arranged locking needle at the same time the closure of the Exit bore of the nozzle head serve.

To for this purpose, the closure needle according to the invention has on its the cleaning hole associated end opposite to Cross section of the valve pin tapered extension, which serves as a fastener for the Exit bore of the nozzle head serves. In this case, the cleaning hole of the screen body must be one larger cross section than the exit bore of the nozzle head have, so that the valve pin in a first position only the outlet bore of the screen body and in a second Additional position the cleaning hole of the sieve body can release.

in this connection it is according to claim 10 expedient, on nozzle tube to provide an adjustable stop, which the two mentioned Positions for defines the valve pin.

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

In the drawings demonstrate

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

2 Section of the longest line II - II in 1

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

4 Section of the longest line IV - IV in 3

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

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

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

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

9 View of a detail towards IX in 7 seen.

The structure and mode of operation of the spray nozzle according to the invention with filter cleaning are easiest to use 1 and 2 explain.

In a conventional nozzle head 13 with its threaded part 13a can be screwed into the nozzle tube (not shown) DE 29 041 58 C2 known sieve body 12 inserted. The sieve body 12 is here with its ring flange 12a set in a ring shoulder corresponding to this. The cylindrical wall of the sleeve-like sieve body 12 is from a variety of radially running screen holes 19 interspersed. These screen holes 19 connect the cylindrical cavity 24 of the sieve body 19 with the ring channel 27 which after inserting the sieve body 12 from this and the inner wall 13b the one in the nozzle head 13 provided central bore is limited. This central bore goes into the exit bore in the exit direction of the plastic melt via an exit channel which is frustoconical in longitudinal section 23 about. The total cross section of the screen holes 19 of the sieve body 12 is dimensioned larger than the cross section of the outlet bore 23 so that it is within the ring channel 27 and the outlet channel 13c an overpressure builds up in the operating state of the machine.

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

The front wall 12b has a central cleaning hole 10 on through the front end of the valve pin 11 is closed. The valve pin 11 is, as symbolized by the double arrow A, displaceable in the axial direction. She is in 1 right, is the cleaning hole 10 released so that in the cavity 24 with collecting room 24a foreign particles trapped under the effect of overpressure with the plastic melt via the outlet channel 13c and the exit hole 23 can be hosed.

The axial adjustment of the valve pin 11 serves the pivot pin 14 , at its eccentric 21 the valve pin 11 under the effect of in the ring channel 13b and outlet channel 13c prevailing overpressure is non-positively.

How in particular 2 makes the pivot pin twist 14 with its eccentric 21 that the valve pin 11 in 1 to the right under the effect of that in the ring canal 27 prevailing excess pressure is pushed back, causing the cleaning hole 10 is released.

The pivot pin 14 has a milled key surface on its laterally projecting end 20 so that it can be operated with a wrench or similar tool. In the case of automatic control in particular, the pivot pin can be controlled hydraulically, pneumatically or electrically.

Further constructive details result from the 3 to 6 , with which a complete spray nozzle designed according to the invention is shown in detail.

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

The shut-off needle arranged on the axis of symmetry of the spray nozzle 11 is through one in the nozzle tube 16 used torpedo 15 centered and guided such that it is axially floating.

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

The diameter of the pivot pin 14 off-center eccentric is smaller than the diameter of the pivot pin 14 , 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 pivot pin 14 passes through the nozzle tube 16 with a tapered spigot 14a , which at its outer end by a transverse cylinder pin 22a is enforced. Paragraph 14b on the pivot pin 14 together with the radially protruding cylindrical pin 22 for the axial securing of the pivot pin 14 , At the same time, the cylinder pin serves 22 with the cylinder pins 25 and 26 the pivot limit of the pivot pin 14 , The cylinder pins serving as a stop 25 and 26 are in a milled surface 18 of the nozzle tube used.

The one inside the nozzle tube 16 arranged torpedo 15 , which, as it is subject to wear, is designed as a separate exchange part, not only serves to support and guide the valve pin 11 but puts together with the screwed-in nozzle head 13 the sieve body 12 firmly. Being in the collection chamber 16b protruding conical projection 15a is used to guide the flow into the chamber 16b entering plastic melt.

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

As well as in the cavity 24 of the sieve body 12 has collected a sufficiently large amount of foreign bodies, the screen body must be cleaned. After removal of the spray nozzle from the tool, not shown, the valve pin is in the manner explained above 11 under the effect of the overpressure in the ring channel 27 existing melt pushed back, so that between it and the cleaning hole 10 forms a sufficiently large gap through which, under the action of the in the cavity 24 prevailing overpressure, the foreign particles can be sprayed outside together with the plastic melt. This process should be repeated two to three times before the valve pin 11 by means of the pivot pin 14 is moved back to the "closed" position.

With the 7 to 9 An embodiment of a spray nozzle is shown, in which the impact according to the invention is combined with the features known per se of a hydraulic or also electrical needle adjusting nozzle.

As in the first embodiment is in the nozzle tube 16 the nozzle head 13 screwed into the central bore of the sieve body 12 is used. According to the proposal of the invention is the cleaning hole 10 using a locking pin 11 closable. In contrast to the first exemplary embodiment, the closure needle has 11 at their the exit hole 23 end facing 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 pin 11 as a result of in the outlet channel 13c prevailing excess pressure pushed back into a middle position, gives the extension 28 the exit hole 23 free, so that plastic melt can be hosed down. Because the valve pin 11 on the lever in the middle position 30 it still closes the exit hole 10 so that in the cavity 24 or in the collection chamber 16b captured foreign particles cannot escape.

Only when the valve pin 11 in their in 7 right position is pushed back, 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 pass 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 around the axis 31 pivotable 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 a stop designed as an eccentric 29 assigned which part of a pivot pin 34 is the 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 Can assume positions indicated by dashed lines, so that the valve pin 11 alternatively can take the following positions:

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

The design of the spray nozzle according to this second embodiment makes a slight redesign of the torpedo 15 ' required like that 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 (10)

Spray nozzle for injection molding or extrusion machines, essentially consisting of a nozzle head ( 13 ) using a nozzle tube ( 16 ) can be connected to the cylinder of the injection molding or extrusion machine and one into an outlet bore ( 23 ) has a continuous central bore, as well as a sieve body inserted into the central bore ( 12 ) with numerous, fine, radial screen holes ( 19 ), which the cavity ( 24 ) of the sieve body ( 12 ) with one of sieve bodies ( 12 ) and nozzle head ( 13 ) limited ring channel ( 27 ), characterized in that the sieve body ( 12 ) on the exit hole ( 23 ) side facing a cleaning hole ( 19 ) with an adjustable locking needle ( 11 ) is lockable. Spray nozzle according to claim 1, characterized in that the cleaning bore ( 10 ) of the sieve body ( 12 ) coaxial to the outlet bore ( 23 ) of the nozzle head ( 13 ) runs and that the valve pin ( 11 ) coaxial to cleaning hole ( 10 ) and sieve body ( 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 cleaning hole ( 10 ) opposite end of the valve pin ( 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 ) rotating pivot pin ( 14 ) is non-positively. Spray nozzle according to claim 3 or 4, characterized in that to limit the rotation of the pivot pin ( 14 ) this one radially protruding pin ( 22 ), which on the nozzle tube ( 16 ) provided stop pins ( 25 . 26 ) assigned. Spray nozzle according to claim 2 or 3, characterized in that the cleaning hole ( 10 ) opposite end of the valve pin ( 11 ) rests on a lever arm pivotable by means of a lever linkage. Spray nozzle according to claim 2 to 6, characterized in that within the nozzle tube ( 16 ) one of axial bores ( 17 ) interspersed torpedo ( 15 ) is arranged, in which the axially adjustable valve pin ( 11 ) is stored. Spray nozzle according to claim 2 to 7, characterized in that the sealing needle ( 11 ) at your cleaning hole ( 10 ) of the sieve body ( 12 ) assigned end opposite the cross section of the valve pin ( 11 ) tapered extension ( 28 ), which acts as a closure for the exit bore ( 23 ) of the nozzle head ( 13 ) serves that the cleaning hole ( 10 ) a larger cross section than the outlet bore ( 23 ) and that the valve pin ( 11 ) in a first position in which the outlet bore ( 23 ) opened and the cleaning hole is still closed, and in a second position, in which outlet hole ( 23 ) and cleaning hole ( 10 ) are opened under the effect of the in the outlet channel ( 13c ) or the ring channel ( 27 ) prevailing overpressure can be pushed back. Spray nozzle according to claim 8, characterized in that the axial adjustment of the shut-off needle ( 11 ) on the nozzle tube ( 16 ) pivoted lever ( 30 ) on which the valve pin ( 11 ) is non-positively and that the pivoting range of the lever ( 30 ) with an adjustable stop ( 29 ) is adjustable. Spray nozzle according to claim 9, characterized in that the adjustable stop consists of a on the nozzle tube ( 16 ) rotatable pivot pin ( 34 ) exists at the eccentric stop ( 29 ) the valve pin ( 11 ) with its rear end is non-positively, and which is transverse to the valve pin ( 11 ) extends.