DE3502437A1 - Pin-lined barrel screw extruder - Google Patents

Abstract

The invention relates to a pin-lined barrel screw extruder, the pins of which are provided with a blind hole in which a transmitter controlling a switch-off device is accommodated. The object of the invention is, in the case of high pin loading, not to allow the pins to break off but rather shut down the machine. In one embodiment the invention consists in making the pins of a flexible material and accommodating in the blind hole a small tube which is filled with pressurised gas or pressurised liquid, is closed at the end projecting into the blind hole and provided at the other end with a pressure sensor or pressure switch and is made of a material which breaks under flexural loading. Another embodiment of the invention consists in making the mixing pins of a flexible material and having a pin of conductive material or a contact or proximity transmitter projecting contact-free into the blind hole as transmitter.

Description

Pin barrel screw extruder

The invention relates to a pin cylinder screw extruder, the Pins are provided with a blind hole in which a disconnection device controlling encoder is housed.

Such pin cylinder screw extruders are from DE-PS 32 21 472 and from DE-OS 32 25 512 known.

In the case of a pin-barrel screw extruder, the same in the professional world referred to as a cross-flow Nisch screw extruder, protrude into the interior of the screw cylinder Pins into it, past which the liquid to be plasticized is conveyed by the screw is, these pens represent iderstäuide of a special kind, which the flastification and mixing of the extrudate in special tracks. This strong plasticizing and mixing effect, high loads occur on the pins. Hence these Pins made of a very hard steel to prevent the pins from breaking off. Breaking off the pins could never be avoided during operation. Because even if the pins are to be plasticized and to be mixed Resist material, have foreign bodies inadvertently getting into the material led to broken pins.

The D-PS 32 21 472 shows as known a broken pen display with equipped with a shut-off device for the drive of the pin-barrel screw extruder is. If a foreign body gets into the screw extruder, the broken pin indicator switches the drive of the screw extruder via the cut-off device. That moment of shutdown however lies far too late. Because once a pen is broken, so judge He causes considerable damage within the screw extruder. This damage is all the more larger if the pin break is caused by a foreign object: the from Foreign bodies driven by the screw flanks have broken off the pin Wedging occur between auger, foreign body and pin, leading to damage of the cylinder and the screw leads. Is due to the occurrence of this wedging Deformations of the cylinder torn, the whole screw cylinder with its Cooling devices are scrapped. But also the dismantling of the screw for removal the foreign body and the broken pin is caused by such wedging made extremely difficult, if not impossible.

To avoid these disadvantages, the DS-OS 32 25 512 already suggests switch off the drive of the screw extruder before a break if significant Deformations occur on the pin. For this purpose, the pins are provided with a blind hole, in which electrical or optical conductors are housed as a transmitter a severe deformation of the pen body should be interrupted by tearing. It is proposed here to insert a glass body into the blind hole in the pin to use in which there is a conductor wire loop, which should break the glass rod rips.

There is a break in the usual pins made of hard steel of the pin takes place even with slight deflections, those housed in the glass rod are sufficient metallic conductors are not enough to tear off so early that the machine is in front a broken pin can be stopped.

It is therefore proposed to use graphite or instead of metallic conductors Melting carbon in thread form in the glass pen because graphite and carbon are brittle and, like metals, are not drawn over a certain length without tearing off can be. Melting graphite or carbon threads in glass pens but is associated with extraordinary difficulties.

But even if this succeeds, and if it succeeds in reducing the carbon or to tear graphite thread immediately when deformed are in the Machine mostly still so considerable inertial forces that the shutdown is not in time occurs and the pin breaks. A broken pin makes it necessary that the screw is removed to end the broken pin from the screw extruder take out. This always results in longer production stoppages.

The present invention avoids the disadvantages of the prior art Technology. It is the object of the invention to avoid high pin loads the pins break off, but the machine may come to a standstill allow.

The invention consists in that the pins are made of a flexible material Material are made and that in the blind hole with a pressurized gas or hydraulic fluid filled, closed at the end protruding into the blind hole, at the other end with a pressure transmitter or pressure switch provided tube a material that breaks under bending stress is accommodated.

In contrast to the prior art, in which the pens always come from a very hard material are used in the pin cylinder of the invention the pins are made of a flexible material. That generally requires Pins of a slightly larger diameter, but has the advantage that the pins do not break off, but allow foreign bodies in the worm gear to pass through. An in The small tube located in the blind hole made of material that breaks under bending stress but will break if the pin is bent. This causes a Pressure relief at the pressure transmitter and the pressure switch open, as pressurized gas or hydraulic fluid emerges from the tube into the blind hole. This is by means of the pressure transmitter or a pressure switch controlled disconnection device, the machine is shut down. At the disconnection device is also provided with a display device which shows which pin the tube was broken in. It is then easy to use this pen remove and replace with an undeformed replacement pin. It is also It is possible without any difficulty to remove the worm and get one into the worm gear Remove any foreign bodies that have entered, because they do not become wedged with the pin could. However, it is often not necessary to remove the screw, because you already have the deformation of the pin shows whether the deformation is under overload came about as a result of incorrect operation of the screw extruder or whether the deformation of the pin caused by a foreign body in the worm gear came about. An expansion of a single pen naturally requires a lot Much less interruption in production than removing a screw, self if it is not wedged by a broken end of the pin and a foreign object is.

The pins are expediently made of resilient types of steel or made of relatively easily plastically deformable types of steel. The tube is expediently made of a very brittle material.

Brittle metals as well as ceramics and glass are suitable for this.

It is useful if the tube is a closed and an open one Has end and when the open end is clamped in a holder on the pin is attached and has a bore that is a pressure transmitter or pressure switch leading channel forms. Such a holder makes it possible to hold pens that have deformed elastically after replacing the broken tube with a to continue using the new tube.

It is also advantageous if a device for adjusting the Length of the protrusion of the tube into the pin is provided. With such a device it becomes possible to break a tube with more or less strong deformations to break the pen.

It can also be advantageous if tubes of different lengths are built into the pins so that the machine does not come to a standstill, when the loading device more closely adjacent pins flexed more are considered to be pins further from the loader.

Another embodiment of the invention is to # ate the mixing pens are made of flexible material and that in the blind hole as a donor contact a pin made of conductive material or a contact or proximity sensor protrudes.

The timely shutdown is extremely high in this embodiment easily achieved in that a pin made of conductive in the blind hole Material or a contact or proximity sensor protrudes. Because with a strong one Bending of the mixing pen touches the inner wall of the SiskleEhEs or the pen comes so close to the Berürrungs- or proximity sensor that the shutdown process is initiated. There are many ways to set this encoder so that it initiates the shutdown process at certain deflections. Through this achieved with certainty that the mixing pins do not tear off, but only bend.

Both elastic steels are used as the material for the mixing pens as well as plastically deformable steels. Is a screw extruder through the Deformation of a mixing pen triggered brought to a standstill, can be done on a The display device can see which mixing pen has disconnected. here you unscrew the mixing pen and see on the mixing pen whether the deformation under excessive loads due to improper operation of the extruder has come about or whether a foreign body has penetrated the worm gear is and has made the deformation of the pin.

In the former case, the screw does not need to be removed. If an elastic steel has been used, the same pin can continue to be used If the pen has undergone a plastic deformation, it will turn against you replaced new pen. The resulting production interruptions are very short compared to the otherwise usual production interruptions in the state of the art.

In an advantageous embodiment, the blind hole is with a Well conductive coating lined - it can be the surface of the blind hole here galvanically hit fine, highly conductive metal, or it can be in the blind hole has a socket, possibly insulated, made of a highly conductive material, wherein the pin is also made of a highly conductive material and with the lining of the blind hole forms a touch switch. That is a very simple embodiment that switches particularly reliably and also extremely simple built-up shut-off device safely operated. You have the inner wall of the blind hole covered with a thin layer of gold and the pen also with a thin layer of gold has been proven, reliable contact is possible even after decades of operation guaranteed.

The proximity sensor can, for example, be an electrical inductor be that on a measuring device for measuring the change in inductance as a component of the shutdown circuit is switched, you can greed the shutdown process extremely sensitively Adjust certain deflections.

It is advantageous if a blind hole tightly closes the blind hole on the mixing pin Arranged holder for the conductive writing or the contact or proximity sensor is.

This ensures that even after decades of operation no contamination can enter the blind hole and cause a shutdown without the mixing pen being bent.

It is also advantageous if the holder is provided with a device for adjusting the length of the protrusion of the pin into the blind hole is. This allows the sensitivity of the shutdown to different deflection values to adjust.

The essence of the invention is shown below with reference to in the drawing schematically illustrated embodiments explained in more detail. They show: Fig. 1 shows a cross section through a pin with a short tube, FIG. 2 shows a section through a pen with a longer tube.

3 shows a mixing pen with a transmitter in the form of a conductive one Pen, in section, Fig. 4 a mixing pen with an inductive contact sensor on average.

The one for screwing into a pin barrel screw extruder provided pin has two length sections 1,2. The length section 1 of the The pin protrudes into the interior of the cylinder, the length section 2 with the Thread 3 is used for screwing into the cylinder, not shown, of the not shown Screw extruder. The pin 1, 2 has a blind hole 4. This blind hole is 4 by a screwed-in holder 5 with possible application not shown Sealing rings closed, the holder 5 is used to hold a tube 6, the is closed at its end facing away from the holder 5. This tube 6 is filled with a hydraulic fluid or a compressed gas or compressed air, which through the valve 7 can be filled. The one connecting the pressure tube 6 to the valve 7 Channel 8 has a branch channel 9 which leads to a pressure switch 10, the Pole 11 via electrical lines with the disconnection device for disconnection of the drive of the screw extruder.

The tube 6 is at its end facing the holder 5 by means a nut 12 which has an axial bore and which has a flange-like design end of the tube presses against a sealing ring 13.

If the tube 6 is to protrude deeper into the blind hole, will between the nut 12 and the seal 13 in the holder 5 with an external thread Intermediate or extension piece provided at one end and internal thread at the other end 14 (Fig. 2) installed. The tube mounted by means of this intermediate piece 14 protrudes 6 deeper into the blind hole 4, it occurs even with lower bending loads of the pin 1 comes into contact with this and breaks.

In the exemplary embodiment in FIG. 3, too, the pin 1, 2 consists of two Length parts, of which the length part 1 in the interior of the barrel of the screw extruder protrudes, while the part 2, which carries the external thread 3, in the not shown The cylinder of the screw extruder, not shown, is screwed in as a pin holder is. Inside the pin 1, 2 there is a blind hole 4. In this blind hole a pin 15 protrudes into it. If the mixing pin 4 is bent, it bends Pin 15 not because it protrudes freely into the blind hole 4 and Xa only from Surrounded by air or gas.

This pin 15 is carried by a holder 16, which means a thread 17 is screwed into a bore in the end face of the pin 1,2 which forms the blind hole 4 in its extension. In this holder 16 the conductive pin 5 is mounted by means of an insulation 18. On the one from the Mixing pin 1,2 protruding end of the conductive pin 5 is a terminal 19 for clamping a line leading to the disconnection device, not shown arranged.

The holder 16 then has a further clamp for clamping a further line leading to the cut-off device. This terminal 20 is in conductive connection with the inner wall of the blind hole 4.

When the inner wall of the blind hole 4 comes into contact with the pin 15 a conductive connection between terminals 19 and 20.

There are a number of ways to get a touch between the conductive pin 20 and the inner wall of the blind hole 4 at different deflections of the mixing pen 1,2: You can put a crown 21 different on the pen 15 Diameter z, B, put on by screwing, so that the distance between the The outer edge of this crown and the inner wall of the blind hole 4 is reduced. Man can let the pin 15 protrude differently far into the blind hole 4.

For this purpose, a screwable adjusting device can be attached to the bracket 22 can be provided with which the pin 15 can be pushed into the blind hole at different depths and is detectable. Pins 15 of different lengths can also be used be.

In the exemplary embodiment of FIG. 4, a tube 23 becomes an inductive one Transmitter 24 is carried, the two supply lines 25 of which are passed through the tube 23 and are led out of the holder 16. With a screwable adjustment device 22, the tube can also be pushed into the blind hole 4 at different depths here.

Claims (9)

A n s p r e c h e: 1. Pin-barrel screw extruder, its pins are provided with a blind hole in which a shutdown device controlling Encoder is housed, characterized in that the pins are made of a bendable Material are made, and that in the blind hole (4) with a pressurized gas or hydraulic fluid filled, closed at the end protruding into the blind hole (4), at the other End with a pressure transducer or pressure switch (lo) provided tube (6) from a breaking material is accommodated in the event of bending stress. 2. Pin-cylinder screw extruder according to .Anspruch 1, characterized in that that the tube (6) has a closed and an open end, and that the open end is clamped in a holder (5) which is attached to the pin (1, 2) and a bore (8, 9) which has a to the pressure transmitter or pressure switch (lo) leading channel forms. 3. Support cylinder screw extruder according to im.spruch 1, characterized in that that a device for adjusting the length of the insertion of the tube (6) is provided in the pin (1, 2). 4. pin cylinder screw extruder according to claim 1, characterized in that that tubes (6) of different lengths are built into different pins (1). 5. Pin-barrel screw extruder, the mixing pins with a Blind holes are provided in which a switch-off device controlling a transmitter is housed, characterized in that the mixing pins (1,2) made of flexible Material are made, and that in the blind hole (4) as a transmitter without contact a pin (15) made of conductive material or a touch or proximity sensor (24) protrudes. 6. pin cylinder screw extruder according to claim 5, characterized in that that the blind hole (4) is lined with a highly conductive notice, the forms a touch switch with the pin (15) made of conductive material. 7. Pin-barrel screw extruder according to Claim 5, characterized in that that the proximity sensor (24) is an electrical inductance that is attached to a measuring device is switched to measure inductance changes in the shutdown circuit. 8. pin-cylinder screw extruder according to claim 5, characterized thereby, that aw mixing pen (1,2) a holder (16) that firmly closes the blind hole (4) arranged for the conductive pin (15) or, the proximity or touch sensor (24) is. 9. pin cylinder screw extruder according to claim 6, characterized in that that the holder (16) with a device (22) for adjustment the length of the protrusion of the pin (15) or the carrier (23) of the contact or Proximity sensor is equipped in the blind hole (4).