FEEDING SCREW MACHINE FOR FEEDING A PROCESSING SCREW MACHINE

Abstract

A feeding screw machine for feeding a processing screw machine comprises a housing with at least two housing bores formed therein and screw shafts rotatably arranged in the at least two housing bores. The at least two housing bores and the at least two screw shafts define a free volume in a respective cross-sectional plane, which decreases monotonically at least in some regions for continuous compression of a material in a conveying direction. This enables an improved supply of material with a low bulk density.

Claims

1. A feeding screw machine for feeding a processing screw machine having a housing, at least two housing bores formed in the housing and penetrating each other, a supply opening formed in the housing for supplying material into the at least two housing bores, a feeding opening formed in the housing for feeding the material to a processing screw machine, and at least two screw shafts rotatably arranged in the at least two housing bores for conveying the material a conveying direction from the supply opening to the feeding opening, wherein the at least two housing bores and the at least two screw shafts in a respective cross-sectional plane (E(x)) define a free volume V(x)=A(x).Math.H(x), wherein A(x) describes a free cross-sectional area in the cross-sectional plane (E(x)), H(x) describes a pitch of the screw shafts on a basis of an inclination (S(x)) in the cross-section plane (E(x)), and x describes a conveying point in the conveying direction; and wherein for continuous compression of the material, the free volume V(x) decreases monotonically in the conveying direction at least in some regions.

2. The feeding screw machine according to claim 1, wherein a first free volume V(x.sub.1) is defined in a first cross-sectional plane (E(x.sub.1)) at a first conveying point x.sub.1 of the at least two screw shafts and a second free volume V(x.sub.2) is defined in a second cross-sectional plane (E(x.sub.2)) at a second conveying point x.sub.2 of the at least two screw shafts which is located downstream of the first conveying point x.sub.1 in the conveying direction, wherein: 1?V(x.sub.1)/V(x.sub.2)?20.

3. The feeding screw machine according to claim 1, wherein a screw outer diameter (D.sub.a(x)) of the at least two screw shafts decreases at least regionally in the conveying direction.

4. The feeding screw machine according to claim 1, wherein a tapering $K=\frac{{D_a\left(x_1\right)}^2}{L.Math.D_a\left(x_3\right)}$ is defined for a conical configuration of the at least two screw shafts, wherein 0.05?K?1 applies, and wherein D.sub.a(x.sub.1) describes a screw outer diameter of the at least two screw shafts at a conveying point x.sub.1 which corresponds to a screw shaft start of the at least two screw shafts, D.sub.a(x.sub.3) describes a screw outer diameter of the at least two screw shafts at a conveying point x.sub.3 which corresponds to a screw shaft end of the at least two screw shafts, and L describes a length of the at least two screw shafts.

5. The feeding screw machine according to claim 1, wherein a housing bore diameter (D.sub.G(x)) of the at least two housing bores decreases at least regionally in the conveying direction.

6. The feeding screw machine according to claim 1, wherein axes of rotation associated with the at least two screw shafts enclose an angle ?, wherein: 0<??45?.

7. The feeding screw machine according to claim 1, wherein the at least two screw shafts define in the respective cross-sectional plane (E(x)) a screw outer diameter D.sub.a(x) and a screw inner diameter D.sub.i(x), wherein: 1.55<D.sub.a(x)/D.sub.i(x)?2.5.

8. The feeding screw machine according to claim 1, wherein the at least two screw shafts in the respective cross-sectional plane (E(x)) define the pitch H(x) and a screw outer diameter D.sub.a(x), wherein: 1?H(x)/D.sub.a(x)?2.

9. The feeding screw machine according to claim 1, wherein the housing comprises at least two housing portions.

10. The feeding screw machine according to claim 1, wherein the at least two screw shafts each comprise a shaft and at least one screw element which are formed in one piece with one another.

11. The feeding screw machine according to claim 1, comprising at least one degassing device.

12. The feeding screw machine according to claim 1, wherein at least one discharge opening is formed in the housing.

13. A processing installation having a processing screw machine for processing material; and a feeding screw machine according to claim 1 for feeding the material to the processing screw machine.

14. The processing installation according to claim 13, wherein the processing screw machine has at least one treatment element shaft with an outer diameter D.sub.A, the at least two screw shafts have a screw outer diameter D.sub.a(x.sub.1) in a cross-sectional plane (E(x.sub.1)) at a conveying point x.sub.1 which corresponds to a screw shaft start. wherein: 1?D.sub.a(x.sub.1)/D.sub.A?4.

15. The processing installation according to claim 13, wherein the processing screw machine has at least one treatment element shaft with an outer diameter D.sub.A, the at least two screw shafts have a screw outer diameter D.sub.a(x.sub.3) in a cross-sectional plane (E(x.sub.3)) at a conveying point x.sub.3, which corresponds to a screw shaft end, wherein: 1?D.sub.a(x.sub.3)/D.sub.A?1.5.

16. A method for operating a processing installation, comprising the following steps: providing a processing installation, supplying material through a supply opening into at least two housing bores of a feeding screw machine, conveying the material in a conveying direction to a feeding opening and continuously compressing the material at least regionally while conveying; and feeding the compressed material to a processing screw machine.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0093] FIG. 1 shows a side view of a processing installation with a processing screw machine and a feeding screw machine according to a first embodiment,

[0094] FIG. 2 shows a top view onto the processing installation in FIG. 1,

[0095] FIG. 3 shows a side view of the feeding screw machine in FIG. 1 without the processing screw machine,

[0096] FIG. 4 shows a top view onto the feeding screw machine in FIG. 3,

[0097] FIG. 5 shows a vertical section through the processing screw machine and the feeding screw machine along the section line V-V in FIG. 2,

[0098] FIG. 6 shows a horizontal section through the processing screw machine and the feeding screw machine along the section line VI-VI in FIG. 5,

[0099] FIG. 7 shows a vertical section through the feeding screw machine along the section line VII-VII in FIG. 3 at a screw shaft start,

[0100] FIG. 8 shows a vertical section through the feeding screw machine along the section line VIII-VIII in FIG. 3 at one end of the housing,

[0101] FIG. 9 shows a diagram of a throughput of the feeding screw machine as a function of a rotational speed for different materials, and

[0102] FIG. 10 shows a vertical section in the region of an inlet hopper of a feeding screw machine according to a second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0103] A first embodiment of the invention is described below with reference to FIGS. 1 to 9. The processing installation 1 shown in FIGS. 1 and 2 comprises a processing screw machine 2, a first feeding screw machine 3 for feeding the processing screw machine 2 with a material M having a low bulk density, and a second feeding screw machine 4 for feeding additives Z to the processing screw machine 2.

[0104] The processing screw machine 2 comprises a housing 5 with a plurality of housing portions 6 to 16 arranged one after the other. The housing portions 6 to 16 are joined together to form the housing 5. The processing screw machine 2 is designed as a multi-shaft screw machine. Two housing bores 17, 18 are formed in the housing 5, which are parallel to each other and penetrate each other, and which have the shape of a horizontal figure eight in cross-section. Two treatment element shafts 19, 20 are arranged concentrically in the housing bores 17, 18, which can be driven in rotation about associated axes of rotation 22, 23 by an electric drive motor 21. A branching gear 24 is arranged between the treatment element shafts 19, 20 and the drive motor 21. A coupling 25 is then arranged between the drive motor 21 and the branching gear 24. The treatment element shafts 19, 20 are driven in the same direction by the drive motor 21, i.e. in the same directions of rotation about the axes of rotation 22, 23.

[0105] The processing screw machine 2 has, one after the other in a processing direction 26, a first intake zone 27, a plasticizing zone 28, a second intake zone 29, a homogenizing zone 30 and a discharge zone 31.

[0106] In the first intake zone 27, a base material B to be processed is supplied to the processing screw machine 2. For this purpose, a first material supply opening 32 is formed in the housing portion 6. A hopper 33 is arranged on the housing portion 6, which opens into the first material supply opening 32. The base material B is, for example, a granular plastic material. In the processing direction 26 downstream from the first material supply opening 32, the material M is supplied to the processing screw machine 2. The material M is, for example, a recycled material. For this purpose, a second material supply opening 34 is formed in the housing portion 8. The second material supply opening 34 is formed laterally. Connecting bores extend laterally from the second material supply opening 34 through the housing portion 8 and open into the housing bore 17. It is also possible to exclusively supply the material M via the second material supply opening 34 in the first intake zone 27 and not to supply any base material B via the first material supply opening 32. In this case, the first material supply opening 32 can be used for venting. The second material supply opening 34 can also be formed in the housing portion 6 or 7.

[0107] The base material B and the material M are conveyed to the plasticizing zone 28 and melted into a material melt there. The processing screw machine 2 comprises degassing units 35, 36 which are arranged in the plasticizing zone 28 on the housing portions 10, 11 and are connected to associated degassing openings in the housing portions 10, 11.

[0108] The material melt is conveyed to the second intake zone 29. In the second intake zone 29, the additives Z are supplied to the material melt. For this purpose, a third material supply opening, not shown in more detail, is formed in the housing portion 13. The third material supply opening extends laterally through the housing portion 13 and opens into the housing bore 17. The second feeding screw machine 4 has a common design and is not described in more detail. The second feeding screw machine 4 is laterally connected to or attached to the housing portion 13. In the second intake zone 29, a degassing unit 37 is arranged on the housing portion 13 which opens into a degassing opening, not shown in more detail.

[0109] The material melt is conveyed together with the additives Z into the homogenizing zone 30. In the homogenizing zone 30, the material melt is mixed with the additives Z and homogenized.

[0110] In the discharge zone 31, the material melt provided with the additives Z is discharged. A nozzle plate 38 is arranged on the last housing portion 16, which forms a discharge opening not shown in more detail.

[0111] For forming the first intake zone 27, the plasticizing zone 28, the second intake zone 29, the homogenizing zone 30 and the discharge zone 31, the treatment element shafts 19, 20 usually comprise treatment elements 39, 40 which are arranged in a rotationally fixed manner on associated shafts 41, 42. The treatment elements 39, 40 are designed as screw elements and/or kneading elements. Preferably, the kneading elements are designed as kneading disks, whereby in particular a plurality of kneading disks are connected in one piece to form a kneading block. The treatment element shafts 19, 20 have an outer diameter DA and an inner diameter DI. In particular, the following applies: 1.5?D.sub.A/D.sub.1?1.8.

[0112] The first feeding screw machine 3 is designed as a two-shaft side-feeding screw machine. The feeding screw machine 3 comprises a housing 43 which has two housing portions 44, 45. The housing portions 44, 45 are arranged one after the other in a conveying direction 46 and are connected to each other to form the housing 43. Two housing bores 47, 48 are formed in the housing 43, which penetrate each other and have the shape of a horizontal figure eight in cross-section. Two screw shafts 49, 50 are arranged in the housing bores 47, 48, which can be driven in rotation in the same direction about associated axes of rotation 53, 54 by means of an electric drive motor 52 via an angular branching gear 51.

[0113] The feeding screw machine 3 comprises a coupling housing 55 which connects the housing 43 to the angular branching gear 51. The coupling housing 55 is also referred to as the gearbox lantern. Two output shafts 56, 57 of the angular branching gear 51 extend into the coupling housing 55.

[0114] The screw shafts 49, 50 each comprise a screw element 58, 59, which is formed in one piece with an associated shaft 60, 61. Respective ends of the shafts 60, 61 extend into the coupling housing 55 and are connected to the output shafts 56, 57 by means of coupling sleeves 62, 63. For sealing the shafts 60, 61, the feeding screw machine 3 comprises packing glands 70, 71 attached to the coupling housing 55.

[0115] The feeding screw machine 3 comprises a mobile frame 64 to which the coupling housing 55 and thus the angular branching gear 51 with the drive motor 52 connected thereto and the housing 43 are attached.

[0116] The feeding screw machine 3 comprises a supply opening 65 and a feeding opening 66. The supply opening 65 is formed in the first housing portion 44. The feeding screw machine 3 includes an inlet hopper 67 which opens into the supply opening 65. The supply opening 65 is formed on an upper side of the first housing portion 44 and opens into the housing bores 47, 48 via a supply chute. The supply opening 65 has a length L.sub.Z n the conveying direction 46 and a free supply opening cross-sectional area A.sub.Z.

[0117] The feeding opening 66 is formed at an end of the second housing portion 45 facing the processing screw machine 2. The feeding opening 66 is formed and arranged congruently with the second material supply opening 34. The screw shafts 49, 50 extend beyond the feeding opening 66 and open into the second material supply opening 34. The feeding opening 66 thus serves to feed the material M into the processing screw machine 2.

[0118] A discharge opening 68 is formed in the second housing portion 45 for discharging liquid. The discharge opening 68 is arranged on an underside of the second housing portion 45. The discharge opening 68 can be closed by means of a closure element 69.

[0119] The conveying direction 46 defines an x-axis. The x-axis has its origin at a screw shaft start 72 of the screw shafts 49, 50. The origin or screw shaft start 72 is referred to below as conveying point xi. A housing end 73 of the housing 43 is hereinafter referred to as conveying point x.sub.2. Furthermore, a screw shaft end 74 of the screw shafts 49, 50 is hereafter referred to as conveying point x.sub.3. Perpendicularly to the x-axis, associated cross-sectional planes E(x) are generally defined at random conveying points x.sub.1?x?x.sub.3. The x-axis and an exemplary cross-sectional plane E(x) are illustrated in FIG. 6.

[0120] The screw shafts 49, 50 are of conical design and are conically arranged in the associated housing bores 47, 48. The axes of rotation 53, 54 enclose an angle ?, wherein: 0?<??45?, in particular 1????20?, and in particular 2????10?. The output shafts 56, 57 enclose an angle ? in a corresponding manner, wherein: ?=?.

[0121] The screw shafts 49, 50 have a number of threads N, wherein: N=2. The screw shafts 49, 50 are thus formed with two threads. In order to increase a free cross-sectional area A(x) between the housing 43 and the screw shafts 49, 50 in a respective cross-sectional plane E(x), the screw shafts 49, 50 have a thrust edge profile on a respective active flank F.sub.A and on a respective passive flank F.sub.P. The respective active flank F.sub.A has a flank angle ?.sub.A. Correspondingly, the respective passive flank F.sub.P has a flank angle ?.sub.P. The flank angle ?.sub.A and/or the flank angle ?.sub.P can be constant or change, in particular increase, in the conveying direction 46. Due to the double thread design, the screw shafts 49, 50 each have two screw flights 75, 76 in the respective cross-sectional plane E(x). Each screw flight 75, 76 has a respective inclination in the respective cross-sectional plane E(x) at a respective associated screw crest, i.e. at a screw outer diameter D.sub.a(x). The inclinations of the screw flights 75, 76 differ slightly from each other due to the angle ?. An inclination S(x) of the screw shafts 49, 50 is defined as the mean value of the inclinations of the screw flights 75, 76 in the respective cross-sectional plane E(x). The inclination S(x) decreases strictly monotonically in the conveying direction 46. The inclination S(x) is generally illustrated in FIG. 6. The inclination S(x) defines a pitch H(x) for the respective cross-sectional plane E(x). The pitch H(x) is a notional value related to the inclination S(x) in the cross-sectional plane E(x). Due to the fact that the inclination S(x) decreases strictly monotonically in the conveying direction 46, the pitch H(x) is greater than an actual pitch of the screw shafts 49, 50. The pitch H(x) is defined at one revolution with the inclination S(x).

[0122] The free cross-sectional area A(x) and the corresponding pitch H(x) define a free volume V(x) for the respective cross-sectional plane E(x), wherein: V(x)=A(x).Math.H(x). Due to the conical design and due to the pitch H(x) decreasing strictly monotonically in the conveying direction 46, the free volume V(x) decreases strictly monotonically in the conveying direction 46. Due to the fact that the free cross-sectional area A(x) and the pitch H(x) decrease strictly monotonically in the conveying direction 46, the material M is compressed in the conveying direction 46 and compressed transversely to the conveying direction 46 when being conveyed.

[0123] The screw shafts 49, 50 have a screw outer diameter D.sub.a(x) and an associated screw inner diameter D.sub.i(x) in the respective cross-sectional plane E(x), which decrease strictly monotonically in the conveying direction 46. For D.sub.a(x)/D.sub.i(x) the following in particular applies: 1.55?D.sub.a(x)/D.sub.i(x)?2.5, in particular 1.8?D.sub.a(x)/D.sub.i(x)?2.2. Preferably, D.sub.a(x)/D.sub.i(x) is constant in the conveying direction 46.

[0124] The housing bores 47, 48 have a housing bore diameter D.sub.G(x), in the respective cross-sectional plane E(x), which decreases strictly monotonically in the conveying direction 46. A relative clearance

[00009]$s\left(x\right)=\frac{D_G\left(x\right)-D_a\left(x\right)}{D_a\left(x\right)}$

is constant in the conveying direction 46 and/or increases in the conveying direction 46.

[0125] For a ratio of the pitch H(x) to the screw outer diameter D.sub.a(x), the following applies in particular: 1<H(x)/D.sub.a(x)?2, in particular 1.2?H(x)/D.sub.a(x)?1.5. The ratio H(x)/D.sub.a(x) is in particular constant in the conveying direction 46.

[0126] FIG. 3 and FIG. 6 show a cross-sectional plane E(x.sub.1) at the conveying point x.sub.1, a cross-sectional plane E(x.sub.2) at the conveying point x.sub.2 and a cross-sectional plane E(x.sub.3) at the conveying point x.sub.3. FIG. 7 shows the feeding screw machine 3 in the cross-sectional plane E(x.sub.1), whereas FIG. 8 shows the feeding screw machine 3 in the cross-sectional plane E(x.sub.2).

[0127] In the cross-sectional plane E(x.sub.1) the screw shafts 49, 50 have a screw outer diameter D.sub.a(x.sub.1) and a screw inner diameter D.sub.i(x.sub.1). A center distance of the axes of rotation 53, 54 is a(x.sub.1). The housing bores 47, 48 have a housing bore diameter D.sub.G(x.sub.1). The screw shafts 49, 50 together with the housing 43 define a free cross-sectional area A(x.sub.1) of the housing bores 47, 48.

[0128] The screw flights 75, 76 have an inclination S(x.sub.1) in the cross-sectional plane E(x.sub.1), which defines a pitch H(x.sub.1) for one revolution. With reference to the cross-sectional plane E(x.sub.1), the following applies for a first free volume V(x.sub.1): V(x.sub.1)=A(x.sub.1).Math.H(x.sub.1).

[0129] In the cross-sectional plane E(x.sub.2) at the conveying point x.sub.2 or the housing end 73, the screw shafts 49, 50 have a screw outer diameter D.sub.a(x.sub.2) and a screw inner diameter D.sub.i(x.sub.1). The axes of rotation 53, 54 have a center distance a(x.sub.2). The housing bores 47, 48 have a housing bore diameter D.sub.G(x.sub.2). The housing bores 47, 48 and the screw shafts 49, 50 define a free cross-sectional area A(x.sub.2). The screw flights 75, 76 have an inclination S(x.sub.2) in the cross-sectional plane E(x.sub.2), which defines a pitch H(x.sub.2) for one revolution. With reference to the cross-sectional plane E(x.sub.2), the following applies for a second free volume V(x.sub.2): V(x.sub.2)=A(x.sub.2).Math.H(x.sub.2).

[0130] In the cross-sectional plane E(x.sub.3) the screw shafts 49, 50 have a screw outer diameter D.sub.a(x.sub.3) and a screw inner diameter D i (x.sub.3). The screw flights 75, 76 have an inclination S(x.sub.3) in the cross-sectional plane E(x.sub.3), which defines a pitch H(x.sub.3) for one revolution. For a mean screw outer diameter D.sub.am the following applies:

[00010]$D_{\mathrm{am}}=\frac{D_a\left(x_1\right)+D_a\left(x_3\right)}{2}.$

[0131] For a compression V(x.sub.1)/V(x.sub.2) in particular: 1?V(x.sub.1)/V(x.sub.2)?20, in particular 2?V(x.sub.1)/V(x.sub.2)?15, and in particular 4?V(x.sub.1)/V(x.sub.2)?10.

[0132] For a ratio A(x.sub.1)/A(x.sub.2) in particular: 1?A(x.sub.1)/A(x.sub.2)?8, in particular 1.5?A(x.sub.1)/A(x.sub.2)?7, in particular 2?A(x.sub.1)/A(x.sub.2)?6.

[0133] For a ratio H(x.sub.1)/H(x.sub.2) in particular: 1?H(x.sub.1)/H(x.sub.2)?8, in particular 1.1?H(x.sub.1)/H(x.sub.2)?5, and in particular 1.2?H(x.sub.1)/H(x.sub.2)?3.

[0134] For a ratio

[00011]$d=\frac{D_a\left(x_1\right)/D_1\left(x_1\right)}{D_a\left(x_3\right)/D_i\left(x_3\right)},$

in particular: [0135] 0.62?d?1.22, in particular 0.82?d?1. Preferably: d=1.

[0136] For a ratio

[00012]$h=\frac{H\left(x_1\right)/D_a\left(x_1\right)}{H\left(x_3\right)/D_a\left(x_3\right)},$

in particular: [0137] 0.5?h?1.5, in particular 0.8?h?1.2, and in particular 0.9?h?1.1. Preferably: h=1.

[0138] The screw shafts 49, 50 have a length L in the conveying direction 46. For a tapering

[00013]$K=\frac{{D_a\left(x_1\right)}^2}{L.Math.D_a\left(x_3\right)},$

in particular: 0.05?K?1, in particular 0.1?K?0.9, in particular 0.15?K?0.8, in particular 0.2?K?0.7, in particular 0.25?K?0.6 and in particular 0.3?K?0.4.

[0139] For a ratio D.sub.a(x.sub.1)/D.sub.a(x.sub.3), in particular: 1?D.sub.a(x.sub.1)/D.sub.a(x.sub.3)?4, in particular 1.2?D.sub.a(x.sub.1)/D.sub.a(x.sub.3)?3, and in particular 1.3?D.sub.a(x.sub.1)/D.sub.a(x.sub.3)?2.5.

[0140] A screw inner diameter D.sub.i(x) of the at least two screw shafts is constant or monotonically decreasing or strictly monotonically decreasing at least in some regions in the conveying direction.

[0141] For a ratio of a screw inner diameter D.sub.i(x.sub.1) of the at least two screw shafts at the conveying point x.sub.1 and a screw inner diameter D.sub.1(x.sub.3) of the at least two screw shafts at the conveying point x.sub.3, the following applies in particular: 1?D.sub.i(x.sub.1)/D.sub.i(x.sub.3)?5, in particular 1.25?D.sub.i(x.sub.1)/D.sub.i(x.sub.3)?4, and in particular 1.5?D.sub.i(x.sub.1)/D.sub.i(x.sub.3)?3.

[0142] The smaller the tapering K, the greater the length L. If the length L is too great, large lever forces act on the at least two screw shafts, which places great stress on the bearings for supporting the at least two screw shafts on the housing and/or the bearings of a gearbox. Furthermore, if the length L of the at least two screw shafts is too great, the production of the feeding screw machine is uneconomical.

[0143] The greater the tapering K, the smaller the length L. If the length L is too small, the conveying efficiency of the at least two screw shafts is poor.

[0144] The length L is in particular the distance between the conveying points xi and x.sub.3. The following applies in particular to the length L: 0.3 m?L?4 m, in particular 0.5 m?L?3.5 m, in particular 0.7 m?L?3 m and in particular 0.9 m?L?2.5 m.

[0145] In an axial section, an envelope of the respective screw shaft encloses an angle with the associated axis of rotation which is in particular at least 2 degrees and at most 10 degrees, in particular at least 2.5 degrees and at most 8 degrees, and in particular at least 3 degrees and at most 6 degrees. The envelope of the respective screw shaft is defined by the screw outer diameter at the respective conveying point.

[0146] For the ratio of a housing length L.sub.G of the housing 43 to the screw outer diameter D.sub.a(x.sub.1), the following preferably applies: 2?L.sub.G/D.sub.a(x.sub.1)?15, in particular 3?L.sub.G/D.sub.a(x.sub.1)?10, and in particular 4?L.sub.G/D.sub.a(x.sub.1)?6.

[0147] For a ratio D.sub.a(x.sub.1)/D.sub.A, in particular: 1?D.sub.a(x.sub.1)/D.sub.A?4, in particular 1.5?D.sub.a(x.sub.1)/D.sub.A?3, in particular 1.8?D.sub.a(x.sub.1)/D.sub.A?2.5.

[0148] Further, for a ratio D.sub.a(x.sub.3)/D.sub.A, the following in particular applies: 1?D.sub.a(x.sub.3)/D.sub.A?1.5, in particular 1.1?D.sub.a(x.sub.3)/D.sub.A?1.4, in particular 1.2?D.sub.a(x.sub.3)/D.sub.A?1.3.

[0149] For a ratio

[00014]$D=\frac{D_a\left(x_3\right)/D_i\left(x_3\right)}{D_A/D_I},$

in particular: 0.66?D?1.61, in particular 0.94?D?1.48

[0150] The feeding screw machine 3 comprises a temperature control device 77.

[0151] The temperature control device 77 serves to heat and/or cool the housing 43. The temperature control device 77 comprises fluid channels 78 formed in the first housing portion 44. The fluid channels 78 are connected to a fluid pump not shown in more detail. The fluid channels 78 serve to receive a temperature control fluid. The temperature control fluid can be heated and/or cooled in a conventional manner by means of a temperature control unit not shown in greater detail. The temperature control fluid is, for example, water.

[0152] The feeding screw machine 3 comprises a degassing device 79. The degassing device 79 comprises three degassing inserts 80, 81, 82 which are inserted into associated degassing openings 83, 84, 85 of the first housing portion 44. The degassing device 79 is illustrated in FIG. 5.

[0153] A first degassing opening 83 is formed on an underside of the first housing portion 44 and faces the supply opening 65. A second degassing opening 84 and a third degassing opening 85 are formed in the first housing portion 44 downstream from the first degassing opening 83 in the conveying direction 46. The second degassing opening 84 is arranged on the underside, whereas the third degassing opening 85 is formed on the upper side opposite the second degassing opening 84. The degassing inserts 80, 81, 82 are connected to a suction unit 92 via a respective suction line 86, 87, 88 and via a respective valve 89, 90, 91. A volume flow in the respective suction line 86, 87, 88 can be adjusted via the valves 89, 90, 91.

[0154] The respective degassing opening 83, 84, 85 has a free degassing area A.sub.E. For a ratio of the free degassing area A.sub.E to the mean screw outer diameter Dam squared, the following applies in particular: 0.3?A.sub.E/D.sub.am.sup.2?6, in particular 0.8?A.sub.E/D.sub.am.sup.2?4.5, and in particular 1.3?A.sub.E/D.sub.am.sup.2?3.5.

[0155] Preferably, the free degassing area A.sub.E of the first degassing opening 83 is larger than the free degassing areas A.sub.E of the degassing openings 84, 85.

[0156] The following applies in particular to the length L.sub.Z of the supply opening 65: H(x.sub.1)?L.sub.Z?2.Math.H(x.sub.1), in particular 1.2.Math.H(x.sub.1)?L.sub.Z?1.5.Math.H(x.sub.1).

[0157] For the ratio of the supply opening cross-sectional area A.sub.Z to the mean screw outer diameter D.sub.am squared, the following applies in particular: 2?A.sub.Z/D.sub.am.sup.2?7, in particular 2.5?A.sub.Z/D.sub.am.sup.2?5.5, and in particular 3?A.sub.Z/D.sub.am.sup.2?4.5.

[0158] The functional principle and operation of the processing installation 1 is described below:

[0159] In the first intake zone 27, the base material B is supplied via the first material supply opening 32 and the material M is supplied via the second material supply opening 34 into the housing bores 17, 18. The base material B is, for example, in the form of granules. The material M, which is for example a recycled material, is mixed with the base material B. The material M has a bulk density ?, wherein: 5 g/dm.sup.3???600 g/dm.sup.3, in particular 10 g/dm.sup.3???250 g/dm.sup.3, in particular 15 g/dm.sup.3???200 g/dm.sup.3, and in particular 20 g/dm.sup.3???100 g/dm.sup.3. The material M is present, for example, as shreds, flakes and/or pellets. The material M has a maximum dimension a.sub.max, wherein: 1 mm?a.sub.max?50 mm, in particular 5 mm?a.sub.max?35 mm, and in particular 10 mm?a.sub.max?20 mm The material M is, for example, a foil material with a foil thickness t, wherein: 10 ?m?t?400 ?m, in particular 15 ?m?t?300 ?m, and in particular 20 ?m?t?200 ?m.

[0160] The material M is supplied to the processing screw machine 2 by means of the first feeding screw machine 3. For this purpose, the material M is supplied via the inlet hopper 67 and the supply opening 65 into the housing bores 47, 48 of the feeding screw machine 3.

[0161] The material M is conveyed in the conveying direction 46 by means of the screw shafts 49, 50. For this purpose, the screw shafts 49, 50 are driven in rotation in the same directions of rotation by means of the electric drive motor 52 via the angular branching gear 51. Due to the fact that both the free cross-sectional area A(x) and the pitch H(x) decrease strictly monotonically in the conveying direction 46, the free volume V(x) also decreases strictly monotonically in the conveying direction 46. When being conveyed, the material M is thus compressed in the conveying direction 46 as well as transversely to the conveying direction 46. Due to the fact that a local derivative of the free cross-sectional area A(x), a local derivative of the pitch H(x) and a local derivative of the free volume V(x) are continuous in the conveying direction 46, i.e. they do not jump, compression takes place continuously in a simple and reliable manner. The local course of the free cross-sectional area A(x), the pitch H(x) and the free volume V(x) is illustrated in FIG. 6.

[0162] Air escaping from the material M due to compression is sucked out via the degassing device 79. The respective volume flow in the suction lines 86, 87, 88 can be adjusted as required via the valves 89, 90, 91. Heat generated by the compression can be removed from the housing 43 by means of the temperature control device 77.

[0163] The material M is dehumidified by the compression so that liquid accumulates in the housing bores 47, 48. The liquid can be discharged via the discharge opening 68.

[0164] The compressed material M is supplied through the feeding opening 66 and through the connecting bores of the housing portion 8 into the housing bores 17, 18. The connecting holes formed in the housing portion 8 continue the course of the housing bores 47, 48 up to the screw shaft end 74 or the housing bores 17, 18.

[0165] The screw shafts 49, 50 are driven in rotation at a rotational speed n and a torque M.sub.d per screw shaft 49, 50 by means of the drive motor 52 and the angular branching gear 51. The following applies in particular to the rotational speed n: 50 rpm?n?1000 rpm, in particular 100 rpm?n?800 15 rpm, and in particular 200 rpm?n?600 rpm.

[0166] For a ratio M.sub.d/a(x.sub.1).sup.3, in particular: 0.1 Nm/cm.sup.3?M.sub.d/a(x.sub.1).sup.3?0.8 Nm/cm.sup.3, in particular 0.15 Nm/cm.sup.3?M.sub.d/a(x.sub.1).sup.3?0.5 Nm/cm.sup.3, and in particular 0.2 Nm/cm.sup.3?M.sub.d/a(x.sub.1).sup.3?0.35 Nm/cm.sup.3.

[0167] Due to the fact that the feeding screw machine 3 has a large free cross-sectional area A(x) in the region of the supply opening 65, a comparatively large amount of the material M can be supplied to the feeding screw machine 3. The material M is subsequently compressed in the described manner while being conveyed, which enables the processing screw machine 2 to easily and reliably draw in the compressed material M in the first intake zone 27. For a dimensionless throughput

[00015]$?=\frac{\stackrel{.}{v}}{n.Math.{D_a\left(x_1\right)}^3}$

of the feeding screw machine 3, the following applies in particular: 0.1???1.2, in particular 0.25???1, and in particular 0.3???0.8. {dot over (?)} denotes a volume flow of the material M supplied to the feeding screw machine 3.

[0168] The base material B and the material M are conveyed in the processing direction 26 to the plasticizing zone 28 and melted there to form a material melt. Any escaping gases can be removed via the degassing units 35, 36. In the second intake zone 29, additives Z are usually supplied to the material melt, which are homogenously mixed in the homogenizing zone 30. Any escaping gases can in turn be removed via the degassing unit 37. The material melt provided with the additives Z is then discharged in the discharge zone 31 via the nozzle opening.

[0169] FIG. 9 illustrates in a diagram a throughput y of the feeding screw machine 3 in kg/h as a function of the rotational speed n in rpm for different materials M.sub.1, M.sub.2, and M.sub.3. The material M.sub.1 has a bulk density ?.sub.1=37 g/dm.sup.3, the material M.sub.2 has a bulk density ?.sub.2=41 g/dm.sup.3 and the material M.sub.3 has a bulk density ?.sub.3=16 g/dm.sup.3. In contrast, a common feeding screw machine at a maximum rotational speed of n=600 rpm for material M.sub.1 has a maximum throughput of 100 kg/h, for material M.sub.2 has a maximum throughput of 160 kg/h and for material M.sub.3 has a maximum throughput of 70 kg/h.

[0170] A second embodiment of the invention is described below with reference to FIG. 10. In contrast to the first embodiment, the feeding screw machine 3 25 comprises an inlet hopper 67 which is divided. The inlet hopper 67 has a partition 93 so that a degassing channel 94 is formed in the inlet hopper 67. The degassing channel 94 is connected to a further degassing device 79 via a suction line 95. Air escaping during the supply of the material M can be removed directly via the suction channel 94. With regard to the further construction and the further functional principle of the processing installation 1 and the feeding screw machine 3, reference is made to the preceding embodiment example.