DE102014003760A1 - Apparatus and method for feeding screw conveyors with pourable bulk material - Google Patents

Abstract

The invention relates to a device (1) for feeding processing machines (2) with pourable bulk material, comprising a stuffing device (9) which has at least one inlet (10) and one outlet (11) which is connected to a filling area (6) of the processing machine (2) is connected. It is proposed that in the Stopfwerk (9) a continuous conveyor element (12) is arranged, which continuously transported by the at least one inlet (10) bulk material in the direction of the outlet (11) transported so that the necessary pressure for stuffing only directly in the region of the transition of the bulk material from the conveying element (12) to the screw threads (8) of the processing machine (2) is constructed.

Description

The invention relates to a device for feeding processing machines, in particular screw conveyors with free-flowing bulk material, comprising a Stopfwerk, which has at least one inlet and an outlet, which is connected to a filling region of the processing machine. However, the invention also relates to a method for feeding processing machines with said device.

Such processing machines, such. B. injection molding machines, extruders, or the like, with free-flowing bulk material, such as. As pellets, chips, granules, powders, flakes, grains, flour or the like. Such a processing machine has a screw-like conveying element in the form of a worm, which is arranged in a cylindrical housing. The screw, so the extruder screw and the cylindrical housing form the so-called plasticizing, in which the free-flowing bulk material, in particular plastic is melted. In the known from practice processing machines, from which the invention proceeds, and which are particularly suitable for processing plastics, the screw has the task to collect the plastic in the cylinder to promote it, melt and homogenize. Likewise, a pressure must be built up so that the molten plastic can flow through a tool which may be provided at one end of the conveying path of the screw. So z. B. plastic can be regranulated in a suitable manner during recycling. However, it is also possible to create objects with very different designs with regard to color appearance, material composition (including various components) and dimension.

So that the processing machines can always be supplied with the required bulk material, the Stopfwerk is provided. This is usually funnel-shaped, with the funnel tapering conically from its inlet towards its outlet. In this respect, the Stopfwerk also serves as a material storage in which there is always enough bulk material to supply the processing machine accordingly. Designed as a compression screw, the screw of the Stopfwerkes forces a better filling of the screw in the inlet of the plasticizing unit of the following machine. Gravity is simply used to fill the flights, which is a very energy efficient method.

A disadvantage of filling the screw by gravity alone is that the screw threads of the extruder can not be sufficiently filled. Although a complete filling of the flights can be achieved by means of additionally arranged in the Stopfwerk, discontinuous conveying devices, such as stuffing pistons, conical plug screws or the like, however, such stuffing plants are usually built complicated and correspondingly expensive to manufacture and purchase. The main disadvantage inherent in the stuffing plants, that is to say also the stuffing machines with discontinuous conveying devices, is that they cause the plastic to be filled to become a stuffing material on the bulk material particles due to the resulting friction, and a considerable, undesirable one even between the bulk material particles themselves in this important feeding region Exposure to heat (frictional heat). The clumps which usually occur as a result of partially melting plastic particles bring the production to a standstill.

The known stuffing plants thus do not permit pure solids to be conveyed in the transition zone of the intake zone. The pressure necessary for filling the screw flights of the extruder screw already leads to plasticizing phenomena even before the purpose of filling in the cavities is achieved, whereby obstructions due to clumping occur. However, solids transport is essential in this area for optimal loading of the plasticizing screw.

It can therefore be seen that mixing ratios of the flowable bulk materials previously set by gravity and by means of a stuffing machine can be influenced and adversely changed even before entry into the screw. This can even lead to failures of the entire batch to be produced, which can mean a significant qualitative impairment and thus economic loss.

The supply of free-flowing bulk materials to processing machines, in particular to plastic extruders thus offers quite some room for significant improvements.

Therefore, the invention has for its object to improve a device for feeding a processing machine with pourable bulk material with simple means so that the screw threads of the further processing machine are always filled as completely as possible, in addition, a disturbing heating in the filling should be avoided as possible. So it should also be ensured that the set mixing ratios of the introduced bulk material are neither influenced nor changed. The invention is also based on the object, a method for feeding a processing machine with to provide a device that allows considerable improvement in this regard.

This demanding object can be achieved according to the invention with a device according to claim 1. The procedural part of the object is achieved by a method having the features of claim 9.

Accordingly, a device for feeding processing machines, in particular screw conveyors, so z. B. of extruders with free-flowing bulk material, comprising a Stopfwerk, which has at least one inlet and an outlet which is connected to a filling region of the processing machine proposed. According to the invention, a continuous conveyor element is arranged in the stuffer, which continuously transports the bulk material introduced through the at least one inlet towards the outlet so that the pressure required for the stoppers is built up only directly in the region of the transition of the bulk material from the conveyor element to the screw flights of the processing machine , Target is when the continuous conveyor element is designed as a screw conveyor, as dosing and stuffing screw. The screw conveyor is preferably regulated in terms of process so that forces such. As pressure and compression, occur only in the area of the screw tip.

With the invention, a trouble-free and low-friction supply in a continuous forced conveying the bulk material in different, but suitable mixing ratios to the actual processing machine, ie z. B. to an extruder, which is conveniently achieved with the screw conveyor, ie with the dosing and screwing screw.

Among other things, it is important in the processing of plastics to produce as homogeneously mixed end products as possible. It was recognized that the catchment area of the extruder screw, that is to say the screw of the plasticizing unit, is of great importance. This is where the invention comes in, because the more homogeneously the mixtures are introduced there, the less homogenization effort the extruder screw has to make. In the process, segregation on the way from the feed to the entrainment of the mixtures by the extruder screw has hitherto been taking place. Preferably, therefore, the mixing process is placed as close as possible to the screw inlet of the extruder.

In order to be able to effect the forced guidance of the screw conveyor in the stuffing mechanism, it is favorable for the purposes of the invention if the stuffing mechanism has a hollow body which is hollow in its interior, preferably has a hollow-cylindrical basic body or jacket which can be connected to the processing machine at its foot region, that the outlet of the stuffing box is aligned with the filling area, ie with its filling opening, so that disturbing edges or obstacles are avoided. It is also objective if the stuffing mechanism has a drive element for driving the continuous conveyor element, ie for driving the conveyor screw, on its head region opposite the foot side. In this respect, the Stopfwerk is designed as a hollow cylindrical body in which the screw feeds the introduced bulk material forcibly transported towards the outlet, the drive of the continuous conveyor element arranged directly to the Stopfwerk and fastened in a suitable manner, ie z. B. is screwed to this.

It is expedient if the continuous conveying element, ie the screw conveyor with its end, so protrudes with its screw tip into the filling, ie in the filling, so that the non-pressurized forced delivery in the filling preferably up to the filling to be filled screw of the processing machine, ie the plasticizing remains. Thus, inter alia, an adverse effect on set mixing ratios of the introduced bulk material is also avoided along the filling area.

In order to introduce the free-flowing bulk material in the Stopfwerk, ie in the hollow cylindrical body, is provided in a favorable embodiment, to arrange the inlet as a separate nozzle at the Stopfwerk. This is also advantageous because the drive unit for the continuous conveyor element, ie for the screw conveyor in the stuffing plant is arranged at the head area. In this respect, the inlet is arranged as an inlet nozzle below the head area at the Stopfwerk. The inlet is about a trickling stream of flowable bulk material, so z. B. granular to pulverulent material chargeable.

In addition, it is also possible not only to provide an inlet to the stuffing mechanism, but a plurality of different components can be introduced through each inlet in the conveying region of the continuous conveyor element, wherein the desired mixing ratio is set and maintained within the Stopfwerks. Of course, however, only a single inlet can be provided, through which free-flowing bulk material can also be introduced in the desired mixing ratio. In an expedient embodiment, it is provided to arrange the at least one inlet, that is to say the inlet connection with its central axis, at an angle to the center axis of the stuffing mechanism, that is to say of the hollow cylindrical body. It is preferred if the inlet with its central axis at an acute angle, more preferably at an angle of 45 ° is arranged to the middle ash of Stopfwerks. This embodiment meets the needs of the mixing process, are sought in the circumstances in which flowable material flows meet in flight. Thus, the free-flowing bulk material can be produced virtually quiescent and homogeneous and can be introduced into the interior of the stuffing plant, and passed without forced demixing up to the extruder screw. Pressure is to be exerted only when it reaches the extruder screw, with no space change in the sense of segregation taking place any more.

Targeting within the meaning of the invention is also when a cooling of the components, which is provided with the contents, so come into contact with the flowable bulk material, so that the Stopfwerk and / or the continuous conveyor element cooling liquid, ie coolant for optional cooling of said Components can be fed. Coolants can also be cryogenic media.

In this case, a coolant connection can be arranged at least in the foot region of the stuffing mechanism. Thus, coolant may cool at least the foot region of the stuffing box by creating a coolant jacket which at least cools the foot region. It is favorable if for a cooling element is arranged on the foot area, which can be designed as a cooling nozzle, but also in the wall of the foot area corresponding cooling channels can be introduced, which are in communication with the coolant connection. Thus, the Stopfwerk is in his foot with circulating liquid, alternatively also with cryogens coolable, which has an advantageous effect on the set goals in terms of avoidable heating in the filling, which would lead to homogeneity losses due to melting of components, stickiness and clumping.

In addition, a coolant connection can also be provided for cooling the continuous conveying element, it being possible for coolant to be conducted into the interior of the continuous conveying element, so that the filling region, ie also its filling opening, can be cooled from the inside. For this purpose, the shaft of the screw conveyor is carried out expediently hollow, with a coolant connection for supplying the coolant and a cooling connection for discharging the optionally heated coolant is provided. A rotary feedthrough arranged on the head allows inlet and outlet of the coolant. Thus, the entire conveyor element is coolable with its screw turns, which is why the free-flowing bulk material along the conveying path of the screw conveyor does not stick. Of course, a coolant circuit with corresponding lines, cooler and pump can also be provided. It is expedient for the purposes of the invention if both the cooling of the continuous conveyor element, but especially the foot of the stuffing box is summarized in a common coolant circuit. Again, could be provided as coolant cryogenic media. The purpose of the cooling is to cool the machine parts that are touched by the plastic and not the plastic.

In the method according to the invention for feeding the processing machine, it is provided that the bulk material is fed to the stuffing plant through at least one inlet, wherein the bulk material is forcibly conveyed continuously in the direction of the outlet by means of a continuous conveying element. The forced delivery is preferably effected with a continuous conveyor element designed as a screw conveyor, wherein the stuffing unit is designed as a hollow cylindrical base body. It is useful if the continuous conveyor element with its end in the filling z. B. of the extruder, that protrudes into the filling opening, so that the bulk material only immediately in the filling area upon impact with the extruder screw generates the pressure that is necessary to fill the screw space. This is achieved at the same time that the extruder screw is pressed only with a minimum of force against the plasticizing, where the generation of frictional heat is no longer harmful. Targeting within the meaning of the invention is also when the continuous conveyor element from the inside and / or the stuffing is cooled at least in his foot from the outside.

With the invention, it is also possible to process multicomponent materials which, among other things, consist, for example, of plastic and wood components.

Further details and advantages will be described below in conjunction with the drawing for a preferred embodiment. In it shows the only one

1 a device for feeding a processing machine with free-flowing bulk material in a longitudinal section.

1 shows a device 1 for loading a processing machine 2 from which in 1 only their plasticizing unit 3 is shown. The plasticizing unit 3 is made of a hollow cylindrical housing 4 formed in which an extruder screw 5 is arranged. In the case 4 is a filling area 6 with its filling opening 7 arranged, so that flowable bulk material in the screw flights 8th the extruder screw 5 can be introduced. This is the device of the invention 1 intended.

The device 1 has a darning plant 9 on which at least one inlet 10 and an outlet 11 Has. The outlet 11 stands with the filling area 6 So with its filling opening 7 in connection. In the stuffing 9 is a continuous conveyor element 12 arranged, which through the inlet 10 introduced bulk material towards the outlet 11 , and thus in the extruder screw 5 promotes. The introduction of the bulk material is by means of the inlet 10 assigned arrow shown in principle.

The continuous conveyor element 12 is as recognizable as screw conveyor 12 executed and will be referred to below as a screw conveyor 12 designated.

The stuffing 9 has a hollow body inside it 13 so hollow coat 13 on which one foot area 14 and a head area opposite thereto 15 Has.

The foot area 14 has a foot flange at the end 16 so the stuffing 9 with the filling area 6 is connectable. This is indicated by the filling area 6 a recess 17 on, in which the filling opening 7 empties. The stuffing 9 is with his foot flange 16 into the recess 17 used, and suitable with the housing 4 connected, z. B. screwed. The stuffing 9 is with its central axis perpendicular to the central axis of the plasticizing unit 3 arranged. The outlet 11 As can be seen, preferably one to the filling opening 7 identical diameter.

The screw conveyor 12 extends through the stuffing plant 9 , and towers over this foot. The feed screw extends on the foot side 12 in the filling area 6 , ie until the end of the filling opening 7 , so that the forced conveyance of the bulk material by means of the screw conveyor 12 along the filling area 6 , ie within the entire filling opening 7 is maintained.

For driving the screw conveyor 12 is a driving element 18 provided, which head on the Stopfwerk 9 is arranged. This is the header area 15 extended flange, so that a sufficient support surface for the drive element 18 is created. The drive element 18 can be designed as a geared motor.

The geometry of the screw conveyor 12 and their operating speed according to the invention ensure that the compression space is limited to the space in which the screw tip 27 is arranged. The geometry of the screw conveyor and its operating speed are variable within the meaning of the invention and can be adapted to each other.

The inlet 10 is preferably as inlet nozzle 19 at the hollow cylindrical Stopfwerk 9 arranged. As can be seen, the central axis of the inlet 10 angled to the center axis of the stuffing plant 9 arranged, wherein both axes are preferably arranged at an acute angle (> 0 ° and less than 90 °), more preferably at an angle of 45 ° to each other.

In 1 is only a single inlet 10 recognizable. It is within the meaning of the invention, several inlets 10 at the hollow cylindrical Stopfwerk 9 to arrange. Through the inlet 10 the pourable bulk material gets into the interior of the hollow cylindrical stuffing plant 9 introduced, which of the screw conveyor 12 to the outlet 11 and thus into the filling opening 7 passing to the extruder screw 5 is transported so that the screw threads are completely fillable.

In 1 are also still coolant connections 20 . 21 . 22 and 23 recognizable.

The coolant connections 20 and 21 are the foot side of the hollow cylindrical Stopfwerks 9 arranged and stand with a cooling element 24 connected to the foot area 14 of the darning plant 9 is arranged. The cooling element 24 can be designed as a cooling nozzle, which is conceivable to introduce cooling channels in the Fußbereichswand. The coolant connection 20 directs the coolant as a coolant inlet 20 to the cooling element 24 , wherein the coolant connection 21 the coolant as coolant outlet 21 away from this. Both coolant connections 20 and 21 are associated with appropriate coolant lines, so that at least the foot area 14 of the hollow cylindrical stuffing plant 9 flows around coolant. This is the hollow cylindrical stuffing plant 9 Can be cooled from the outside, so that sticking or lumping of the material located in the corresponding cooling region can be avoided. In principle, a coolant circuit may be provided which also has a cooler and a pump. Of course, the entire body can also 13 So the whole stuffing 9 as well as the inlet 10 be cooled.

Furthermore, it is still planned, the screw conveyor 12 to cool. These are the coolant connections 22 and 23 as recognizable above the drive element 18 arranged. The coolant connection 22 stands as a coolant inlet 22 with a hollow drive shaft 25 of the drive element 18 in communication with the coolant through the drive shaft 25 in the inside hollow screw conveyor 12 is directed. The coolant connection 23 stands as a coolant outlet 23 with a hollow cooling lance 26 in conjunction, which is characterized both by the drive shaft 25 as well as through the inside hollow screw conveyor 12 up to its end area 27 So just before the tip of the screw 27 extending. So coolant is the drive shaft 25 passing to the end area 27 So up to the point of the screw 27 the screw conveyor 12 from where the coolant passes through the cooling lance 25 is discharged. This ensures that the auger 12 being cooled from the inside, being also the snail tip 27 which extends to the end of the filling opening 7 extends, is coolable, so that sticking or lumping of the material located in the corresponding cooling area can be avoided. Of course, a coolant circuit as previously mentioned is also conceivable. Of course, the respective flow direction of the coolant can also be reversed, the cooling connections 21 and 23 then be designed as a coolant inlet.

To the rotational movements of the drive shaft 25 from the coolant connections 22 and 23 decoupling is a decoupling element 28 in the exemplary embodiment as a rotary feedthrough 28 intended.

It is within the meaning of the invention, if for cooling the screw conveyor 12 from the inside and for cooling the hollow cylindrical stuffing plant 9 are provided from the outside a common radiator and a common pump, so that a common coolant circuit is possible. The respective exemplary coolant flow is by means of the coolant connections 20 . 21 . 22 and 23 Removable flow arrows removed.

LIST OF REFERENCE NUMBERS

1

contraption

2

processing machine

3

plasticizing

4

casing

5

extruder screw

6

filling area

7

fill opening

8th

screw flights

9

stuffing unit

10

inlet

11

outlet

12

Continuous conveyor element / screw conveyor

13

Body / shell

14

footer

15

head area

16

base flange

17

recess

18

Driving element / gearmotor

19

flowguide

20

Coolant connection / coolant inlet

21

Coolant connection / coolant outlet

22

Coolant connection / coolant inlet

23

Coolant connection / coolant outlet

24

cooling element

25

drive shaft

26

cooling lance

27

End area v. 12 / Screw tip

28

Decoupling element / rotary union

Claims (9)

Device for loading processing machines ( 2 ) with pourable bulk material, comprising a stuffing plant ( 9 ), which has at least one inlet ( 10 ) and an outlet ( 11 ), which with a filling area ( 6 ) of the processing machine ( 2 ), characterized in that in the stuffing plant ( 9 ) a continuous conveying element ( 12 ) arranged by the at least one inlet ( 10 ) introduced bulk material continuously towards the outlet ( 11 ). Apparatus according to claim 1, characterized in that the continuous conveying element ( 12 ) as screw conveyor ( 12 ), preferably designed as a dosing and stuffing screw. Apparatus according to claim 1 or 2, characterized in that the Stopfwerk ( 9 ) a hollow body inside ( 13 ), which at its foot region with the processing machine ( 2 ) is connectable. Device according to one of the preceding claims, characterized in that on the head side of the stuffing plant ( 9 ) a drive element ( 18 ) is arranged. Device according to one of the preceding claims, characterized in that the continuous conveying element ( 12 ) with its end in the filling area ( 6 ) protrudes. Device according to one of the preceding claims, characterized in that the at least one inlet ( 10 ) as inlet nozzle ( 19 ) at the stuffing plant ( 9 ), wherein the inlet ( 10 ) with its central axis at an angle to the center axis of the stuffing box ( 9 ), preferably at an acute angle, more preferably at an angle of 45 °. Device according to one of the preceding claims, characterized in that at least one coolant connection ( 20 . 21 . 22 . 23 ) is provided so that the Stopfwerk ( 9 ) at least in regions from the outside liquid or cryogen cooling and / or the continuous conveyor element ( 12 ) is internally liquid or cryogen cooling. Device according to one of the preceding claims, characterized by a cooling element ( 24 ), which at a foot area ( 14 ) of the stuffing plant ( 9 ) is arranged. Method for loading processing machines ( 2 ) with pourable bulk material, in particular with a device ( 1 ) according to one of the preceding claims, comprising a stuffing mechanism ( 9 ), which has at least one inlet ( 10 ) and an outlet ( 11 ), which with a filling area ( 6 ) of the processing machine ( 2 ), whereby bulk material belongs to the stuffing plant ( 9 ) through the at least one inlet ( 10 ), and wherein the bulk material by means of a in the Stopfwerk ( 9 ), continuous conveying element ( 12 ) continuously towards the outlet ( 11 ) is transported.

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