Feeder module in planetary roller extruder design

Abstract

A planetary roller extruder section forms a feed part of an extruder. The planetary roller extruder has an internally toothed housing and an externally toothed central spindle disposed centrally within and at a distance from the housing. Planetary spindles are arranged to rotate in a void between the central spindle and the housing. Each planetary spindle has an external toothing meshing with both the housing and the central spindle. At least one planetary spindle has two axially spaced areas with less than a full set of teeth. Those axially spaced areas include a first area having a first number of teeth and a second area having a second number of teeth. The second number of teeth is less than a full set of teeth and more than the first number of teeth.

Claims

1. A planetary roller extruder section forming a feed part of an extruder, comprising: an internally toothed housing; an inlet opening extending through the internally toothed housing; an externally toothed central spindle disposed centrally within and at a distance from the housing; and planetary spindles arranged to rotate in a void between the central spindle and the housing, each planetary spindle having an external toothing meshing with both the housing and the central spindle, wherein at least one planetary spindle comprises at least two axially spaced areas including a first area having a first number of teeth, the first number of teeth being less than a full set of teeth, and a second area having a second number of teeth, the second number of teeth being less than a full set of teeth and more than the first number of teeth, and wherein the first area of the at least one planetary spindle is arranged at an axial osition of the inlet opening.

2. The planetary roller extruder section as in claim 1, wherein the first area and the second area have the same length.

3. The planetary roller extruder section as in claim 1, wherein the first area and the second area have different lengths.

4. The planetary roller extruder section as in claim 1, comprising a transition area between the first area and the second area in which teeth that are present in the second area and not present in the first area gradually taper off from their total depth, a length of the transition area being at least 0.5 times the depth of the teeth.

5. The planetary roller extruder section as in claim 4, wherein the length of the transition area is at least equal to the depth of the teeth.

6. The planetary roller extruder section as in claim 1, wherein the at least one planetary spindle has a drive-side guiding area with full toothing disposed at an end of the planetary roller extruder section proximal to a drive.

7. The planetary roller extruder section as in claim 6, wherein the drive-side guiding area has an axial length which is at least equal to an external diameter of the planetary spindles.

8. The planetary roller extruder section as in claim 6, wherein the at least one planetary spindle has a further guiding area disposed at an opposite end of the drive-side guiding area, a length of the further guiding area being between 0.2 times and 0.7 times an axial length of the drive-side guiding area.

9. The planetary roller extruder section as in claim 6, wherein the at least one planetary spindle has a further guiding area disposed at an opposite end of the drive-side guiding area, a length of the further guiding area being between 0.3 times and 0.4 times an axial length of the drive-side guiding area.

10. The planetary roller extruder section as in claim 1, wherein the internally toothed housing comprises an internally toothed liner disposed within the housing.

11. The planetary roller extruder section as in claim 1, wherein the at least one planetary spindle has a drive-side guiding area with full toothing disposed at an end of the planetary roller extruder section proximal to a drive and a further guiding area with full toothing disposed at an opposite end of the drive-side guiding area.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic illustration of an extruder having multiple sections.

(2) FIG. 2 is a schematic illustration of a planetary spindle having two toothing sections.

(3) FIG. 3 is a schematic illustration of a planetary spindle having a first type of toothing.

(4) FIG. 4 is a schematic illustration of a planetary spindle having a second type of toothing.

(5) FIG. 5 is a schematic illustration of an alternative extruder having multiple sections.

(6) FIG. 6 is a schematic side view of a planetary spindle.

(7) FIG. 7 is a cross sectional view A-A of the planetary spindle as shown in in FIG. 7.

(8) FIG. 8 shows an example of a planetary spindle.

(9) FIG. 9 shows another example of a planetary spindle.

(10) FIG. 10 shows yet another example of a planetary spindle.

(11) FIG. 11 is a cross sectional view of a feed part in form of a planetary extruder module.

(12) FIG. 12 is a perspective view of a feed part in form of a planetary extruder module.

(13) FIG. 13 is a partially cut away view of a feed part in form of a planetary extruder module.

(14) FIG. 14 is a cross sectional view of a planetary extruder module with an inlet opening.

(15) FIG. 15 is a partially cut away view of a planetary extruder module with an inlet opening.

(16) FIG. 16 is schematic illustration of different teeth depths.

(17) FIG. 17 shows a cross section through a planetary roller extruder section with supply for solid matters.

(18) FIG. 18 shows a planetary roller extruder module used as a feed part and a single-screw extruder module used as a further feed part.

(19) FIG. 19 is a side view of a planetary spindle with multiple stages.

(20) FIG. 20 is a cross sectional view A-A of the spindle shown in FIG. 19.

(21) FIG. 21 is a cross sectional view B-B of the spindle shown in FIG. 19.

(22) FIG. 22 is a cross sectional view C-C of the spindle shown in FIG. 19.

DETAILED DESCRIPTION

(23) FIG. 1 shows an extruder with a drive 1, a feed supply 2, a plurality of planetary roller extruder sections 3.1, 3.2, 3.3, 4 and a discharge die 6. Into the feed supply 2 leads into a dosing 8. From the container 8 a dosing pipe leads into the feed supply 2.

(24) The dosing is filled in a not shown form with fine-grained raw material for its processing and closed.

(25) The raw material arrives in the feed supply 2 and is conveyed from there in extrusion direction. In the drawing, the extrusion direction points from left to right.

(26) The feed supply 2 is designed in modular design. This module has the design of a planetary roller extruder.

(27) In the feed supply 2, a first heating takes place. For the heating of the raw material, a heating-cooling circuit 15 is provided. The heating-cooling circuit 15 interacts with the housing shell of the module. Via the housing shell, the heat is transferred to the supplied raw material. In addition, the screw rotating in the module 2 generates a heating of the raw material.

(28) In the execution example, the raw material, at its preheated temperature, enters the next extruder section/module 3.1. The extruder section/module 3.1 is followed by extruder sections/modules 3.2 and 3.3, 4. The modules 3.1 to 4 have the construction design of planetary roller extruders. The modules 2, 3.1, 3.2 and 3.3, 4 have coordinated housings and not depicted connection flanges at which they are connected with each other. The connection is a screw connection.

(29) In the planetary extruder roller sections/modules 3.1, 3.2 and 3.3, 4, the raw material is kneaded multiple times between the rotating planetary spindles, the central spindle, and the internally toothed extruder housing so that always new surfaces are created which can be used for the heat transfer. Thereby, the heat from the housing shell can be transferred to the raw material or detracted from the raw material and dissipated via the housing shell. Like in module 2, the modules 3.1, 3.2 and 3.3 as well as 4 are equipped with heating-cooling circles 16, 17, 19, 20.

(30) In the extruder sections/modules 3.1, 3.2 and 3.3, the raw material is brought to melt temperature and homogenized and in the extruder section/module 4 cooled to discharge temperature. The heating-cooling circuits 16, 17, 19, 20 secure the maintenance of the desired temperature. Thereby, heat is introduced into the raw material by the deformation work of the extruder sections/modules. In case that the heat supply is insufficient to achieve the desired temperature, the missing heat is transferred from the heating-cooling circuits via the corresponding housing shell of the module to the raw material. As far as the heat quantity generated by the deformation work exceeds the desired temperature of the required heat quantity, the excess quantity is dissipated via the heating-cooling circuits.

(31) In addition, in the execution example is provided a supply of liquid process agents for the processing of the raw material. The supply takes place via an injection ring 21. The injection ring 21 is provided between the modules 3.1 and 3.2. The injection ring 21 is connected via a line to a pump and an oil reservoir.

(32) In the execution example, the injection ring 21 forms the stop ring for the rotating planetary spindles of the module 3.1. Furthermore, openings are provided on the injection 21 in which pressure measuring devices and temperature measuring devices are located. These devices are integrated in the control of the heating-cooling circuits. Concerning the details of the injection ring 21 and its arrangement in the housing reference is made to the DE19720916B4. Stop rings 22 and 23 are also provided on the modules 3.2 and 3.3 by which pressure measurements and temperature measurements can be carried out as on the module 3.1.

(33) The raw material is discharged from the extrusion line at a certain exit temperature. For this, the module 4 is provided on the outlet side with a round die 24 with a diameter of 20 mm. The discharged raw material is cooled between cooling rolls 25.

(34) The execution example according to FIG. 5 differs from the execution example according to FIG. 1 by a degassing 27 and by an additional dosing 28. The degassing 27 consists of a laterally flanged twin-screw extruder with which the melt discharge can be avoided, but an outgassing is admitted. The outgassing is effected by an induced draft adjacent to the twin-screw extruder.

(35) The additional dosing 28 is used for mixing in an additive.

(36) FIG. 3 schematically shows conventional planetary spindles 321 for planetary roller extruders. These planetary spindles 321 form multi-flight screws which extend over the entire length of the spindle with constant inclination. The screw flights are depicted in the drawing by lines running obliquely to the longitudinal axis of the spindle.

(37) In the side view right, the screw flights run from right, clockwise. The screws have a toothing on the outside. The corresponding mirror-image toothing is located on the central spindle of the planetary roller extruder section and the internally toothed surrounding housing so that the planetary spindles 321 can mesh with both the toothing of the housing and the central spindle.

(38) FIG. 4 shows known planetary spindles 322, which on the one hand have the same screw flights as the screws/spindles according to FIG. 3. On the other hand, the spindles have at the same time left-handed grooves which cross the right-handed running screw flights. The left-handed grooves are depicted with lines in the FIG. 4 which are crossing rectangularly the screw flights known from FIG. 3. This is depicted with crossing lines. Due to the crossing grooves, the lads of screw between the screw flights, forming in the cross section the teeth of the toothing, are interrupted. The teeth remaining between two interruptions form a spiky/nap-like tooth. The many side by side occurring spikes/naps lead to the name nap toothing. In the following, the interruptions are referred to as tooth gaps.

(39) FIG. 2 shows further planetary spindles 323 with a part 325, which is replicated of the toothing according to FIG. 3, and with a part 324, which is replicated of the toothing according to FIG. 4.

(40) FIGS. 6 to 8 show a planetary spindle 60 for the use of a planetary roller extruder in a drying station of a processing line. The planetary spindle 60 consists of two parts 61 and 62. The part 61 corresponds to a conventional planetary spindle with full tooth set. In the execution example, it is a planetary spindle with a pitch diameter of 34 mm, with an outside diameter of 42 mm and a diameter of 26 mm at the tooth root of the tooth set. In the execution example, the part 61 has a length of 200 mm. The total length of the planetary spindle 60 amounts to 1000 mm.

(41) This results in a length of 800 mm for the part 62. The part 62 defines a range of the design of the planetary spindle, part 61 defines the remaining area. In part 61, the spindle has 7 teeth 64, which are similar to threads, but with a very large pitch at the outside of the planetary spindle. This is depicted in FIG. 8.

(42) In part 62 three teeth 64 have been milled off. This is done before a surface hardening of the teeth 64. The distribution of the remaining teeth is shown in FIG. 7. Thereby, still two teeth 64 are adjoining. To the remaining teeth there is a tooth gap.

(43) The planetary spindles according to FIGS. 6 to 8 are called transport spindles because they have—in contrast to the nap spindles—a greater transport effect. However, it has also become apparent, that the deformation work done by the transport spindles is surprisingly low. The energy input into the raw material is correspondingly low. This makes it easier to comply with the temperature control needed for the raw material.

(44) The execution examples according to FIGS. 1 and 5 refer to an extruder with 70 mm housing diameter (based on the pitch diameter of the internal toothing of the housing). The maximum number of planetary spindles for the set of the modules 3.1, 3.2, 3.3 and 4 amounts to 7. There are 6 planetary spindles each of the design according to the FIGS. 6 and 8 provided for the processing of raw material in each module. In other execution examples are in the different modules different planetary spindles provided. Thereby, the differences can be related to the “missing” teeth. The differences can also result from the combination with spindles of another design. The differences can also result from the combination of different toothings at individual or all planetary spindles. At least, one planetary spindle designed partly as transport spindle is provided in the extrusion line.

(45) FIG. 9 shows a planetary spindle with a conventional toothing 80 at one end, then a range 81 with a nap toothing, and a range 82 with a reduced toothing as described above.

(46) FIG. 10 shows a planetary spindle with a conventional toothing 85 at one end, then a range 86 with a nap toothing, then a range 87 with a reduced toothing and again a conventional toothing at the other end of the spindle.

(47) In the execution examples, the length of the modules amounts to 400 mm. in the execution example, the planetary spindles have a shorter length, partly a different length.

(48) According to FIGS. 11 and 12 is the feed supply 2 designed as planetary roller extruder module. The planetary roller extruder includes a housing too, that at every end is equipped with a flange 101. Moreover, the housing has a liner 109, which is equipped with an internal toothing 110. Outside, heating-cooling channels 108 are incorporated into the liner. In the assembled state, the heating-cooling channels 108 are externally closed by the housing. At the ends of the heating-cooling channels 108 there are provided feed lines/discharge lines for a heating-cooling agent. In FIG. 12 is a connection depicted of the two feed lines/discharge lines.

(49) Centrically in the housing too there is arranged a central spindle 107. At the drive side the central spindle 107 is designed as spine shaft 105, in order to correspond with a gear motor.

(50) Between der internal toothing 110 and the central spindle 107 there are intended planetary spindles 106. The planetary spindles 106 mesh with the toothing of the central spindle 107 and the internal toothing 110. In the drawing, the planetary spindles 106 show a conventional/standard toothing like the central spindle and the liner 109. Other than depicted, these are transport spindles.

(51) Moreover, at the top of the housing too, a flange 102 is provided with an inlet opening 104 for the raw material intended for extrusion. A feed hopper is attached to the flange 102.

(52) FIG. 13 shows the feeder with an opened shell so that the view onto the transport spindles 106 is unobstructed.

(53) In operation, the extrusion material/raw material from the feed hopper, not depicted, runs without pressure into the inlet opening 104 of the shell 100. Without pressure means that no pressure is exerted in direction of the inlet opening on the material except the weight of the material column standing over the inlet opening 104. The extrusion material enters between the transport spindles 106 and is caught by the transport spindles and brought extremely gently to blend and conveyed in the direction of the other planetary roller extruder sections/modules in order to be further processed there.

(54) FIGS. 14 and 15 show a further execution example. The further execution example according to FIG. 14 differs from the execution example according to FIGS. 11 to 13 by another housing shell 119. The housing shell 119 also has an inlet opening 120 for the raw material. Moreover, the housing shell 119 is equipped with an internal toothing 121, which is suitable like the internal toothing according to FIGS. 11 to 13 to interact with the planetary spindles 106. In contrast to the internal toothing of the housing according to FIGS. 11 to 13, the internal toothing 121 flattened in the area 122 joining the inlet opening 120 and which extends in direction of rotation of the central spindle. In the depiction according to FIG. 14, the direction of rotation of the central spindle runs clockwise.

(55) At the end adjacent the inlet opening, the teeth are reduced by ¾ of their depth due to the flattening. In the execution example, this flattening 133 decreases in the direction of rotation of the central spindle. Thereby, the flattening 133 in the execution example extends over 1/10 of the circumference of the pitch circle belonging to the internal toothing of the housing. In other execution examples, the area may extend over at least ¼ of the circumference of the pitch circle or at least ½ of the circumference of the pitch circle or at least ¾ of the circumference of the pitch circle. Thereby, the dimension of extent of the area 122 is determined from the point at which the area 122 in the depiction according to FIG. 14 with a cut through the middle of the inlet opening being circular in the transversal section adjoins the inlet opening.

(56) The direction of extent of the area 122 extends in the depiction according to FIG. 14 solely in the circumferential direction. In other execution examples, the direction of extent shown in FIG. 14 can also run in circumferential direction and at the same time inclined to the longitudinal direction of the housing.

(57) FIG. 15 shows that the flattening 133 extends in the execution example over the entire opening width of the inlet opening. In other execution examples, the flattening extends at most over 90% of the opening width of the inlet opening, in still further execution examples over at most 80% of the opening width of the inlet opening and in still other execution examples over at most 70% of the opening width of the inlet opening.

(58) In still further executions, the flattening 133 can extend over the width depicted in FIG. 15 also beyond the opening width of the inlet opening, for example, by at most further 10% of the openings width or by at most further 20% of the opening width or by at most 30% of the opening width.

(59) The flattening shown in FIGS. 14 and 15 forms a feed hopper which facilitates the supply of the raw material into the extrusion line.

(60) FIG. 16 shows an original tooth 136 between tooth gaps 135. The depiction includes a section of the internal toothing of a housing. By spark erosion a dash-dotted depicted tooth 137 is shown with lower depth, round head and tooth flanks, which have a lower inclination towards the pitch diameter of the internal toothing than the tooth flanks of the original tooth 136.

(61) FIG. 17 shows a cross section through a planetary roller extruder section with supply for solid matters 202. The cross section shows a housing 201 with an internal toothing 205. A central spindle 204 and planetary spindles 203 are rotating in the housing 201.

(62) The supply for solid matters 202 has a non-depicted hopper with a cylindrical outlet which is flanged to the housing 201. The hopper with the cylindrical outlet is—with regard to the center of the central spindle 204—arranged eccentrically. That means, the center axis 208 of the feed 202 passes by in a distance at the center axis of the central spindle. The distance of both axes is in the execution example slightly larger than a quarter of the pitch diameter of the internal toothing of the housing 205, but essentially smaller than half the pitch diameter of the internal toothing of the housing 205. Consequently, the central axis 208 points into an area of the movement path of the planetary spindles 203, in which the planetary spindles 203 move down significantly after having reached the highest positions in the view according to FIG. 17. On the way, the material is much better fed into the planetary roller extruder module than in the conventional arrangement of material supply above the planetary roller extruder module, where the central axis of the material supply is perpendicular to the central axis of the planetary roller extruder module. The material is depicted schematically with particles 206 in the view according to FIG. 17.

(63) As a result of the dimensions of the supply 202, the supply at the eccentric arrangement of the supply 202 protrudes in the vertical projection on a horizontal level in which the center axis of planetary roller extruder module is located compared to the planetary roller extruder module. In order to guide the solid particles 206 well into the planetary roller extruder module, a tapered transition 207 is intended from the material supply into the planetary roller extruder module. In the execution example, the transition forms a bevel. The bevel proceeds at an angle of 60 degrees to the horizontal.

(64) FIG. 18 shows a planetary roller extruder module 220 used as a feed part and a single-screw extruder module 221 used as a further feed part. To the planetary roller extruder module 220 belong planetary spindles 226 and a material supply as depicted in FIG. 17. To the single-screw module 221 belong a feed screw 227 and a material supply 228. The material supply 228 serves to supply non-adhesive material, the material supply 225 to supply material that tends to stick/adhere.

(65) FIGS. 19 to 22 show a planetary spindle for the use in feed parts of planetary roller extruder modules as depicted in FIGS. 11 to 15 and 17, 18. Depicted is a staged transport spindle.

(66) Traditional transport spindles are depicted and described in FIGS. 6 and 7. The planetary spindle as shown in FIG. 19, in contrast, is a transport spindle with three different areas 251, 252 and 253. All areas 251, 252 and 253 have the same axial length in the execution example. The area 251 shows a tooth reduction to one tooth 255, the area 252 a tooth reduction to two teeth 255, 257 and the area 253 a tooth reduction to three teeth 255, 256, 257.

(67) The tooth reduction in the area 251 is, according to FIG. 22, depicted in one cut along the line C-C; the tooth reduction in the area 252 is, according to FIG. 21, depicted in one cut along the line B-B and the tooth reduction in the area 253 in one cut along the line A-A.

(68) At both ends of the planetary spindle 249 there are guiding areas 250 and 254. The guiding area 250 has three times the guide length in relation to the guide length of the guiding area 254. The guiding area 250 is located at the drive-side end of the planetary spindle. Drive-side means: at the end facing the extruder drive. All guiding areas have full toothing/conventional toothing. The full toothing is characterized by a full number of teeth.