EP3427937B1 - Conical worm of a conical worm separator - Google Patents

Description

The invention relates to a screw which is used in particular in press screw separators. The auger has reinforcing elements on the auger flights. Furthermore, the invention relates to a method for producing the worm. Press screw separators are for example in DE 20 2012 011 864 U1 and DE 20 2012 008 077 U1 described. DE 42 14 217 A1 Fig. 1 shows angular reinforcing elements, referred to herein as wear elements, on the flights of the screw of a press screw separator.

EP 0 034 847 A1 shows a workpiece, such as a screw conveyor, with armor plating. The armor consists of profiles or profile sections made of a hard alloy. To produce the profiles or profile sections, the hard alloy in powder or paste form is introduced into a suitably designed mold and sintered.

DE 31 40 364 A1 discloses a screw conveyor, particularly for solid bowl centrifuges. In the area of the outer circumference of the screw flight, the conveyor screw is equipped with wear plates that are lined up seamlessly. The wear plates are provided with a groove starting from their inner edge so that they can be pushed radially onto the screw flight.

DE 39 07 817 A1 shows a device and a method for dewatering liquid manure and sewage sludge. The material to be dewatered is fed into a reducing screw. The auger is sealed off from the trough, which serves as a screen, by means of a lip seal. The reduction in pitch of the screw corresponds to the removal of liquid from the material to be dewatered.

The exemplary additive manufacturing of components made of metal shows CA 29 39 609 A1 .

It is an object of the invention to specify a worm with reinforcing elements, it being possible for the reinforcing elements to be manufactured easily and to be mounted securely on the worm blades.

This object is achieved by the features of the independent claims 1 and 6. The dependent claims relate to advantageous configurations of the invention.

Thus the invention is solved by a worm. This screw is used in particular in a press screw separator. Such a press screw separator is, for example, in DE 20 2012 011 864 U1 and DE 20 2012 008 077 U1 described.

The press screw separator includes a screen. The screw is arranged in the screen and is set in rotation by means of a drive. As an alternative to this, the auger can also be stationary and the screen rotated. A slurry, for example liquid manure, municipal waste water or industrial waste water, is fed into the press screw separator. The pulp is pressed out along the screw. Liquid components of the slurry pass radially outwards through the sieve and flow off. A plug of solid forms at the end of the screw. This slug is usually held with an expulsion regulator. In particular, the area facing the plug and the radial side of the at least one screw blade are subject to relatively high mechanical stress and corresponding wear.

The screw according to the invention comprises a core. The soul extends along a longitudinal axis. A radial direction is defined perpendicular to the longitudinal axis. A circumferential direction is defined about the longitudinal axis.

Furthermore, the worm comprises at least one worm blade. In particular, two or three screw blades can also be arranged on the core. The at least one screw blade is wound around the core in the circumferential direction and along the longitudinal axis. The worm blade can also be referred to as a worm helix.

For the description of the present invention, the following sides are defined on the screw blade: a front axial side points forward with respect to the conveying direction of the screw. Opposite the front axial side is a rear axial side. The two axial sides are connected to one another via a relatively narrow radial side. The radial side is essentially perpendicular to the radial direction. When using the screw in the press screw separator, the radial side faces the screen; the front axial side faces the exhaust regulator.

In particular, the front axial side and the radial side are subject to relatively high mechanical stress and wear. Therefore, the pamphlet shows DE 42 14 217 A1 angular wear elements covering the front axial side and the radial side.

According to the invention, at least one reinforcement element is used, preferably several of the reinforcement elements on each screw blade. For the sake of simplicity, the configuration of a single reinforcement element is described in each case. However, several of the reinforcing elements can easily be used one behind the other on a screw blade.

The single reinforcement member has a U-shaped cross section. The reinforcing member is applied to the radial side of the screw blade so that a front leg of the U-shape abuts the front axial side and a rear leg of the U-shape abuts the rear axial side of the screw blade; the part of the reinforcement element connecting the two legs of the U-shape covers the radial side of the screw blade. Due to this U-shape, the reinforcement element is fastened in a form-fitting manner in both directions perpendicularly to the axial sides of the screw blade.

The U-shape basically includes all cross-sectional shapes with two opposing, connected legs, such as a C-shape or V-shape. However, it is particularly preferred that the two legs lie parallel to one another.

Provision is particularly preferably made for the reinforcing element and the screw blade to be designed in such a way that the reinforcing element can only be screwed onto the screw blade and not pushed in the radial direction. Twisting of the reinforcing element is carried out from the end of the screw blade along the spiral of the screw blade. In this configuration, the reinforcing element is also arranged in a form-fitting manner on the screw blade with respect to the radial direction.

In particular, the geometric design of the worm blade and/or the pitch of the worm blade and/or the geometric design of the reinforcement element means that the reinforcement element can only be screwed onto the worm blade and not pushed in the radial direction.

The form-fitting connection between the reinforcement element and the screw blade with respect to the radial direction is preferably achieved in that the reinforcement element extends over a relatively large angle α. This angle α is measured about the longitudinal axis and in a plane perpendicular to the longitudinal axis. If the reinforcement element extends, for example, by half a turn of the screw blade, then the angle α is 180°.

In particular, it is provided that the angle a, over which the individual reinforcement element extends, is at least 30°, preferably at least 45°, more preferably at least 60°, particularly preferably at least 90°. Furthermore, designs are also possible in which the angle α is at least 120°, preferably at least 150°.

The two legs of the reinforcing element are particularly preferably designed in such a way that they do not undercut the screw blade. This is achieved, for example, by a cross section in which the two legs are parallel to one another or by a V shape. As a result, the positive connection in the radial direction is only achieved by the relatively large angle α described and not by an undercut between the reinforcing element and the screw blade. Thus, the receiving area for the reinforcement element on the screw blade can have a simple geometry with flat surfaces.

The individual reinforcement element is preferably manufactured in one piece. "One-piece production" is to be understood as meaning that the reinforcing element is not composed of several components. Thus, the reinforcing element is preferably manufactured from the solid by machining or by archetypes. The primary forming production is preferably carried out by casting, 3D printing or sintering.

"3D printing" includes all additive manufacturing processes, such as powder bed processes, free space processes, liquid metal processes or other layer construction processes. For sintering, the green part of the reinforcement element can be produced in a conventional manner or also with 3D printing.

Preferably, three different reinforcement elements are arranged on the individual screw flight. These reinforcement elements have substantially the same U-shaped cross-sections and preferably the angle α:
A reinforcement element is preferably designed as a transition element. This transition element is first screwed onto the screw flight. The transition element preferably has a tapered section, so that the area of the screw blade formed by the reinforcement elements merges into the non-reinforced area of the screw blade without an appreciable edge.

Furthermore, a reinforcement element is preferably designed as a closing element. This final element is screwed onto the screw blade last. The closing element preferably comprises a stop side which bears against the end of the screw blade and reinforces the screw blade in this area.

Furthermore, at least one reinforcement element is preferably designed as an intermediate element. The intermediate element is located on the screw flight between the transition element and the final element. In particular, several of the intermediate elements can also be arranged between the transition element and the final element.

According to the invention, a sleeve is pushed onto the core of the worm and fastened. The sleeve rests against the foremost reinforcement element (closing element) and thus prevents this reinforcement element from being twisted off or loosened in the circumferential direction. All other reinforcement elements are secured against twisting off or loosening in the circumferential direction by their form-fitting contact with the reinforcement element arranged further forward.

The reinforcement element is preferably made of hard metal and/or hard ceramic. In particular, the sintered reinforcement element consists of a ceramic hard material, such as tungsten carbide and a tough matrix of cobalt and nickel or iron.

The invention also includes a method for manufacturing a screw. The screw is designed in particular for use in a press screw separator. In particular, the screw already described is produced with the method. In the method, the core is provided, with at least one screw blade on the core is arranged. At least one reinforcement element is screwed onto this screw blade. The reinforcement element has the described U-shaped cross section. The untwisting takes place along the longitudinal axis and in the circumferential direction.

The advantageous configurations and subclaims presented within the scope of the screw according to the invention are correspondingly advantageously applied to the method according to the invention.

In particular, it is provided that the at least one reinforcement element is produced in one piece, preferably in a 3D print.

A green body of the reinforcement element is preferably produced first. The green compact is preferably produced using 3D printing. Subsequently, the green body is sintered to form the reinforcing member.

The green compact is particularly preferably screwed onto the screw blade as described and only then sintered on the screw blade. In particular, all the reinforcement elements used are first screwed onto the screw blade and then all the reinforcement elements are sintered together.

After the reinforcement elements have been applied to the screw blade, it is possible to machine the reinforcement elements, for example by machining.

The invention also includes a press screw separator with one of the screws described or with a screw produced by a method described here.

Figur 1

eine schematische Ansicht eines Pressschneckenseparators mit erfindungsgemäßer Schnecke gemäß dem Ausführungsbeispiel,

Figur 2

die erfindungsgemäße Schnecke gemäß dem Ausführungsbeispiel,

Figur 3

eine schematische Ansicht der Schnecke aus Figur 2 in einer zur Längsachse senkrechten Ebene,

Figur 4

eine Hülse der Schnecke aus Figur 2,

Figur 5

ein Verstärkungselement der Schnecke aus Figur 2, ausgebildet als Abschlusselement,

Figur 6

ein Verstärkungselement der Schnecke aus Figur 2, ausgebildet als Zwischenelement, und

Figur 7

ein Verstärkungselement der Schnecke aus Figur 2, ausgebildet als Übergangselement.

Further details, advantages and features of the present invention result from the following description of an exemplary embodiment with reference to the drawing. It shows:

figure 1

a schematic view of a press screw separator with a screw according to the invention according to the embodiment,

figure 2

the screw according to the invention according to the embodiment,

figure 3

a schematic view of the snail figure 2 in a plane perpendicular to the longitudinal axis,

figure 4

a shell of the snail figure 2 ,

figure 5

a reinforcement element of the screw figure 2 , designed as a final element,

figure 6

a reinforcement element of the screw figure 2 , formed as an intermediate element, and

figure 7

a reinforcement element of the screw figure 2 , designed as a transition element.

the Figures 1 to 7 show a screw 1 or details of the screw 1 of a press screw separator 100.

The press screw separator 100 according to figure 1 comprises a housing 101, which in figure 1 is shown partially broken. A drive 102 with an electric motor and a gear is flanged to the housing 101 . A cylindrical sieve 106 is located in the housing 101. The worm 1 extends through the housing 101 and the sieve 106. The worm 1 is connected to the drive 102, so that the worm 1 can be rotated.

An inlet 103 for the pulp is formed in the housing 101 at the beginning of the screw 1 . Radially outside of the screen 106 there is an outlet 105 for the liquid components of the sludge exiting through the screen 106 .

The worm 1 comprises a core 2 and two worm blades 3 wound around the core 2. A discharge regulator 104 is located on the housing 101. The core 2 has an area without a worm blade 3, which extends into this discharge regulator 104. A plug from the solids in the pulp forms at the discharge regulator 104 .

Based on Figures 1 to 7 the structure of the screw 1 is explained in more detail.

According to figure 2 the core 2 extends along a longitudinal axis 30 of the worm 1. A radial direction 31 is defined perpendicularly to the longitudinal axis 30. A circumferential direction 32 is defined around the longitudinal axis 30 . The screw blades 3 are wound along the longitudinal axis 30 and in the circumferential direction 32 . The pitch of the screw 1 results from the distance between the two screw blades 3, parallel to the longitudinal axis 30.

The two screw flights 3 each have a reinforced area which is formed by a number of reinforcing elements 4 . On each screw blade 3 there is a reinforcing element 4 designed as a closing element 10, a reinforcing element 4 designed as a transition element 15 and several reinforcing elements 4 designed as intermediate elements 14.

the Figures 5 to 7 show these three different types of reinforcement elements 4. Each of the figures shows a reinforcement element 4 of a screw blade 3 and the other screw blade 3. Den Figures 5 to 7 it can be seen that the reinforcement elements 4 each have a U-shaped cross section. This cross section is formed by a front leg 8, a rear leg 9 and an area which connects the two legs 8, 9 to one another. Each reinforcement element 4 is manufactured in one piece, for example by casting, sintering or 3D printing.

The screw blades 3 each comprise a front axial side 5 which faces the discharge regulator 104 , an opposite rear axial side 6 and a radial side 7 . The radial side 7 of the screw blades 3 faces radially outwards and thus faces the screen 106 .

The front leg 8 rests against the front axial side 5 . The rear leg 9 rests against the rear axial side 6 . The transition area between the two legs 8 , 9 covers the radial side 7 and preferably rests on the radial side 7 .

As the Figures 5 to 7 show, the two legs 8, 9 of the U-shape are arranged parallel to one another. There are no undercuts that would hold the respective reinforcement element 4 in a form-fitting manner on the screw blade 3 with respect to the radial direction 31 . In order to achieve this form fit in the radial direction 31, the reinforcing elements 4 extend over a relatively large length along the wound screw blade 3. To describe this “length” along the screw blade 3, the angle α is defined. figure 3 shows a schematic view of the screw 1 in a plane perpendicular to the longitudinal axis 30 . In this representation it can be seen that the individual reinforcement element 4, as a one-piece component, extends over the angle α. In the exemplary embodiment shown, the angle α is 90°.

Due to the relatively large design of the angle α and the U-shaped cross section of the reinforcing elements 4, it is not possible to push the reinforcing elements 4 onto the screw blade 3 from the outside, ie along the radial direction 31. The reinforcing elements 4 are therefore screwed onto the screw blade 3 in the circumferential direction 32 and along the longitudinal axis 30 .

This in figure 7 Reinforcement element 4 shown, designed as a transition element 15, has a tapered section 16. Through this tapered section 16, the reinforcing element 4 merges into the non-reinforced area of the screw blade 3 without an edge.

This in figure 5 Reinforcement element 4 shown, designed as a closing element 10, has a stop side 11. This stop side 11 covers the end of the screw blade 3. The stop side 11 preferably extends from the core 2 to the radial end of the screw blade 3.

figure 4 shows a sleeve 12 which, as shown in FIG figure 2 , onto which soul 2 is plugged. The sleeve 12 has a blocking edge 13 for each of the two screw blades 3 . This blocking edge 13 rests against the closing element 10 . The sleeve 12 is firmly connected to the core 2, for example via a press or transition fit. As a result, the sleeve 12 prevents the reinforcement elements 4 from twisting or loosening along the circumferential direction 32 .

Provision is also made for the sleeve 12 to be manufactured in one piece with the closing element 10 .

Figures 5 to 7 also show that the front leg 8 has a first leg length 33 on its outside and the rear leg 9 has a second leg length 34 on its outside. The two leg lengths 33, 34 are measured parallel to the radial direction 31. The first leg length 33 is preferably greater than the second leg length 34. As a result, the front axial side 5 is primarily reinforced.

figure 5 shows a third length 35, also parallel to the radial direction 31. Toward the stop side 11, the first leg length 33 increases up to this third length 35, so that the front leg 8 merges into the stop side 11.

In addition to the above written description of the invention, explicit reference is hereby made to the graphic representation of the invention in the figures for its supplementary disclosure.

Reference List

1

slug

2

soul

3

snail wings

4

reinforcement elements

5

front axial side

6

rear axial side

7

radial side

8th

front thigh

9

rear thigh

10

final element

11

stop side

12

sleeve

13

blocking edge

14

intermediate element

15

transition element

16

tapered section

30

longitudinal axis

31

radial direction

32

circumferential direction

33

first leg length

34

second leg length

35

third length

100

press screw separator

101

casing

102

drive

103

Intake

104

output regulator

105

procedure

106

Sieve

Claims (9)

1. A screw (1), in particular of a press screw separator (100), comprising:

   - a shaft (2) extending along a longitudinal axis (30), wherein a radial direction (31) is defined to be perpendicular to the longitudinal axis (30) and a circumferential direction (32) is defined to be around the longitudinal axis (30),

   - at least one screw blade (3) arranged on the shaft (2) and screwed in the circumferential direction (32), wherein a front axial side (5), a rear axial side (6) and a radial side (7) are defined on the screw blade (3) with respect to the longitudinal axis (30), and

   - at least one reinforcing element (4) of a U-shaped cross-section, which is applied to the radial side (7) of the screw blade (3), wherein the two legs (8, 9) of the U-shape abut against the front axial side (5) and the rear axial side (6),

   characterized in that the screw further comprises:

   - a sleeve (12) slid onto and fixed to the shaft (2) and abutting against the foremost reinforcing element (4) to block screwing off the at least one reinforcing element (4) in the circumferential direction (32).
2. The screw according to claim 1, wherein the reinforcing element (4) and the screw blade (3) are formed in such a way that the reinforcing element (4) on the screw blade (3) can only be screwed on and cannot be plugged on in the radial direction (31).
3. The screw according to any one of the preceding claims, wherein the reinforcing element (4) extends over an angle a, which is measured in a plane perpendicular to the longitudinal axis (30), wherein the angle α is at least 30°, preferably at least 45°, further preferably at least 60°, particularly preferably at least 90°.
4. The screw according to any one of the preceding claims, wherein the reinforcing element (4) is integrally manufactured.
5. The screw according to claim 4, wherein the reinforcing element (4) is manufactured via 3D printing.
6. A method of manufacturing a screw (1) according to any one of the preceding claims, comprising the following steps:

   - Providing a shaft (2) with at least one screw blade (3) arranged on the shaft (2), wherein the shaft (2) extends along a longitudinal axis (30), a radial direction (31) is defined to be perpendicular to the longitudinal axis (30), and a circumferential direction (32) is defined to be around the longitudinal axis (30),

   - screwing at least one reinforcing element (4) with a U-shaped cross-section onto the screw blade (3), wherein the screwing is carried out along the longitudinal axis (30) and in the circumferential direction (32), and

   - fixing a sleeve (12) on the shaft (2) of the screw (1).
7. The method of manufacturing a screw according to claim 6, wherein the at least one reinforcing element (4) is manufactured integrally via 3D printing.
8. The method according to claim 6 or 7, wherein a green body of the reinforcing element (4) is firstly produced, preferably via 3D printing, and subsequently, the green body is sintered to form the reinforcing element.
9. The method according to claim 8, wherein the at least one green body is screwed onto the screw blade (3) and subsequently sintered onto the screw blade (3).

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