ROTOR SHAFT COMPRISING A HELIX FOR A DYNAMIC MIXER FOR MIXING LOW- TO HIGH-VISCOSITY COMPONENTS

Abstract

The invention relates to a rotor shaft for a dynamic mixer, in particular a dental dynamic mixer, for mixing low to high viscous components, comprising a mixing area and a connection geometry adjoining the mixing area, the mixing area comprising a central shaft having a distal end and a proximal end abutting the connection geometry, and having at least one worm thread, in particular the rotor shaft has at least two mixing sections, a first mixing section comprising at least two mixing blades radially oriented on the surface of the central shaft and a second mixing section comprising at least one worm thread having spirally running thread flanks, the spirally running thread flanks peripherally entwining the surface of the central shaft. Furthermore, the invention relates to a dynamic mixer, in particular a dental dynamic mixer, comprising the rotor shaft, as well as its use for mixing low to high viscous components.

Claims

1. Rotor shaft (1) for a dynamic mixer (0) for mixing low to high viscous components, comprising a mixing area (2) and a connection geometry (3) adjoining the mixing area (2), the mixing area (2) comprising a central shaft (20) having a distal end (20.1) and a proximal end (20.2) abutting the connection geometry (3), the mixing area (2) has at least two mixing sections (21, 22) along the central shaft (20), a first mixing section (21) at the distal end (20.1) of the central shaft (20) comprising at least two mixing blades (210, 211) radially oriented on the surface of the central shaft (20) and a second mixing section (22) at the proximal end (20.2) of the central shaft (20) comprising at least one worm thread (220) having spirally running thread flanks, the spirally running thread flanks peripherally entwining the surface of the central shaft (20), wherein the rotor shaft is made of polyoxymethylene.

2. Rotor shaft (1) according to claim 1, wherein in that the spirally running thread flanks of the worm thread (220) in the second mixing section (22) are spaced from the at least two mixing blades (210, 211) in the first mixing section (21).

3. Rotor shaft (1) according to claim 1, wherein in that the ratio of the length of the second mixing section (22) to the length of the first mixing section (21) is in the range interval of 1:4 to 10:1, preferably in the range interval of 1:3 to 5:1, particularly preferably of 1:2.5 to 2.5:1.

4. Rotor shaft (1) according to claim 1, wherein in that a) the blade diameter F of the mixing blades (210, 211) of the first mixing section (21) amounts to greater than or equal to 10 mm to less than or equal to 20 mm, in particular greater than or equal to 11 mm to less than or equal to 15 mm, and/or b) the worm diameter D of the worm thread (220) of the second mixing section (22) amounts to greater than or equal to 10 mm to less than or equal to 20 mm, in particular greater than or equal to 14 mm to less than or equal to 18 mm, wherein preferably the diameter d of the central shaft (20) amounting to greater than or equal to 1 mm to less than or equal to 10 mm, in particular greater than or equal to 4 mm to less than or equal to 8 mm.

5. Rotor shaft (1) according to claim 1, wherein in that a) the blade width G of the mixing blades (210, 211) of the first mixing section (21) amounts to greater than or equal to 1 mm to less than or equal to 10 mm, in particular greater than or equal to 2 mm to less than or equal to 4 mm, and/or b) the web width E of the worm thread (220) of the second mixing section (22) amounts to greater than or equal to 0.1 mm to less than or equal to 5 mm, in particular greater than or equal to 0.5 mm to less than or equal to 2 mm.

6. Rotor shaft (1) according to claim 1, wherein in that the thread flanks entwine the surface of the central shaft (20) helically having a uniform thread angle .

7. Rotor shaft (1) according to claim 6, wherein in that (i) the thread width B as related to the worm diameter D amounts to greater than or equal to 0.1D to less than or equal to 4D, in particular greater than or equal to 0.3D to less than or equal to 1.1D, and/or (ii) the thread height T as related to the worm diameter D amounts to greater than or equal to 0.25D to less than or equal to 4.5D, in particular greater than or equal to 0.5D to less than or equal to 1.5D.

8. Rotor shaft (1) according to claim 6, wherein in that the thread depth H amounts to greater than or equal to 1 mm to less than or equal to 10 mm, in particular greater than or equal to 4.5 mm to less than or equal to 7.5 mm.

9. Rotor shaft (1) according to claim 1, wherein in that the surface of the thread flanks of the worm thread (220) has a roughness R.sub.a of less than or equal to 2.5 m, in particular a roughness R.sub.a of less than or equal to 1.6 m.

10. Rotor shaft (1) according to claim 1, wherein in that the at least two mixing blades 210, 211) radially oriented in the first mixing section (21) on the surface of the central shaft (20) are composed each of at least three mixing blade segments, the at least three mixing blade segments being turned relative to each other on the surface of the central shaft (20) by respectively 60 to 120, in particular by approx. 90.

11. Rotor shaft (1) according to claim 1, wherein in that a plane circular plate (23) is formed between the mixing area (2), in particular the second mixing section (22), and the connection geometry (3), which circularly encloses the proximal end (20.2) of the central shaft (20) and the connection geometry (3) adjoining thereto.

12. Rotor shaft (1) according to claim 11, wherein in that the plane circular plate (23) is spaced from the spirally running thread flanks of the worm thread (220) in the second mixing section (22).

13. Rotor shaft (1) according to claim 1, wherein in that the rotor shaft (1), in particular the mixing area (2) and/or the connection geometry (3), is an injection-molded part or has been produced in a generative material-adding process.

14. Dynamic mixer (0), in particular dental dynamic mixer, for mixing low to high viscous components comprising a rotor shaft (1) according to claim 1, the dynamic mixer (0) comprising a housing (10) comprising a housing body (11) having at least one outlet opening (11A) and a cover (12) closing the housing body (11) having at least two inlet openings (12A, 12B) for insertion of the components to be mixed, as well as a rotor opening (12.1), the rotor shaft (1) with its mixing area (2) being rotatably arranged within the housing (10) and the rotor opening (12.1) being provided to receive the connection geometry (3) of the rotor shaft (1).

15. Dynamic mixer (0) according to claim 14, wherein in that the housing (10) comprises at least one main mixing chamber (110) arranged in the housing body (11) as well as at least one pre-mixing chamber (111) arranged in the housing body and/or in the cover (12), the first mixing section (21) of the rotor shaft (1) being arranged within the main mixing chamber (110) and the second mixing section (22) of the rotor shaft (1) being arranged within the pre-mixing chamber (111).

16. Dynamic mixer (0) according to claim 15, wherein in that the ratio of the volume of the pre-mixing chamber to the volume of the main mixing chamber is in the range of 1:2 to 2:1, preferably in the range of 2:3 to 3:2, particularly preferably at about 1:1.

17. Dynamic mixer (0) according to claim 14, wherein in that the housing (10) comprises at least one pre-chamber (112) arranged in the housing body (11) and/or in the cover (12) the proximal end (20.2) of the central shaft (20) being arranged within which.

18. Dynamic mixer (0) according to claim 17, wherein in that the pre-chamber (112) is arranged between the at least two inlet openings (12A, 12B) and the at least one pre-mixing chamber (111).

19. Dynamic mixer (0) according to claim 15, wherein in that the worm clearance between the worm thread (220) of the second mixing section (22) and the inner walling of the pre-mixing chamber (111) amounts to greater than or equal to 0.01 mm to less than or equal to 1 mm.

20. Use of a dynamic mixer (0) according to claim 15 for mixing at least two low to high viscous components, in particular at least two low to high viscous dental materials.

Description

[0067] The invention is explained in more detail with the aid of the figures without limiting the invention to the exemplary embodiments. They show:

[0068] FIG. 1a,b,c: each a rotor shaft 1 according to the invention having a mixing area 2 and a connection geometry 3

[0069] FIG. 2: a rotor shaft 1 according to the invention having a first mixing section 21 and a second mixing section 22

[0070] FIG. 3: a dynamic mixer 0 according to the invention for mixing low to high viscous components in exterior view

[0071] FIG. 4: a sectional view of a dynamic mixer 0 according to the invention comprising the rotor shaft 1 according to the invention

[0072] FIGS. 1a, 1b and 1c respectively show a rotor shaft 1 according to the invention for a dynamic mixer for mixing low to high viscous components.

[0073] FIG. 1a represents lateral total view of a first embodiment of the rotor shaft 1 according to the invention. The rotor shaft 1 is divided into a mixing area 2, which comprises a worm thread having six spirally running thread flanks, and a connection geometry 3 adjoining the mixing area 2. The mixing area 2 comprises a central shaft 20 having a conically tapering distal end 20.1 and a proximal end 20.2 abutting the connection geometry 3. A plane circular plate 23 is formed between the mixing area 2 and the connection geometry 3.

[0074] FIG. 1b represents a lateral total view of a further embodiment of the rotor shaft 1 according to the invention. The rotor shaft 1 is divided into a mixing area 2 and a connection geometry 3 adjoining the mixing area 2. The mixing area 2 comprises a central shaft 20 having a conically tapering distal end 20.1 and a proximal end 20.2 abutting the connection geometry 3. In addition, the mixing area has two different mixing sections 21 and 22, the first mixing section 21 comprising a mixing blade radially oriented on the surface of the central shaft 20 and the second mixing section 22 comprising a worm thread having five spirally running thread flanks. A plane circular plate 23 is formed between the second mixing section 22 and the connection geometry 3.

[0075] FIG. 1c represents a lateral total view of a particularly preferred embodiment of the rotor shaft 1 according to the invention. The rotor shaft 1 is divided into a mixing area 2 and connection geometry 3 adjoining the mixing area 2, which is provided for coupling to a mixer drive shaft. The mixing area 2 comprises a central shaft 20 having a conically tapering distal end 20.1 and a proximal end 20.2 abutting the connection geometry 3. In addition, the mixing area has two different mixing sections 21 and 22 spaced from each other, the first mixing section 21 being arranged in the direction of the proximal end 20.1 of the central shaft 20 and the second mixing section 22 being arranged in the direction of the distal end 20.2 of the central shaft 20. A plane circular plate 23 is formed between the second mixing section 22 and the connection geometry 3, which circularly enclosed the proximal end 20.2 of the central shaft 20 and the connection geometry 3 adjoining thereto.

[0076] The first mixing section 21 comprises in total five mixing blades radially oriented on the surface of the central shaft 20, the first mixing blade 210 of which being arranged at the proximal end 20.1 of the central shaft 20 and the second mixing blade 211 being arranged behind it in relation to the longitudinal axis of the central shaft 20. Each of the mixing blades comprises four mixing blade segments (not shown), which are turned relative to each other by respectively 90 C. and are arranged radially offset in such a way that the free passages between the mixing blade segments of one mixing blade are respectively covered by the passage-free parts, i.e. the respective mixing blade segments, of the subsequent mixing blade. Whereas the second mixing blade 211 as well as the remaining mixing blades arranged thereafter have a uniform layer thickness, the first mixing blade 210 is thicker and trapezoidally tapers in the direction of the distal end 20.1 of the central shaft 20.

[0077] The second mixing section 22 comprises a worm thread 220 having two spirally running thread flanks, which peripherally entwine the surface of the central shaft 20. The worm thread 220 is spaced from the last mixing blade of the first mixing section 21 and twines as right-handed helix in the direction of the proximal end 20.2 of the central shaft 20, where it adjoins the circular plate 23. When rotating the rotor shaft 1, the low to high viscous components to be mixed are inserted into the cavity formed by the first spirally running thread flank laterally along the side of the circular plate 23 and are transported further from there through the worm thread 220.

[0078] FIG. 2 represents an extract of the total vie of the rotor shaft 1 shown in FIG. 1c focusing on the first mixing section 21 and the second mixing section 22. The first mixing section 21 comprises in total five mixing blades (first mixing blade 210, second mixing blade 211) radially oriented on the surface of the central shaft 20 and the second mixing section 22 comprises a worm thread 220 having two spirally running thread flanks, which peripherally entwine the surface of the central shaft 20.

[0079] The diameter d of the central shaft 20 represents the core diameter of the worm thread 220 at once. It is uniformly chosen in the first mixing section 21 and the second mixing section 22 and amounts to approx. 6 mm.

[0080] The diameter D is the worm diameter of the worm thread 220 of the second mixing section 22 and corresponds the diameter of a fictive cylinder which would come into existence by rotation of the peripheric edges of the spirally running thread flanks of the worm thread 220. It amounts to approx. 16 mm. Half the difference of the worm diameter D and the diameter d of the central shaft 20 makes the thread depth H, which amounts to approx. 5 mm. The layer thickness of the respective thread flanks is indicated as web width E and amounts to approx. 1 mm. In addition, the worm thread 220 of the second mixing section 22 is characterised by the thread height T, which indicates the way of full turn of the thread flanks along the longitudinal axis of the central shaft 20 and amounts to approx. 5 mm, as well as the thread angle , which corresponds to the helix angle of the thread flanks in relation to the longitudinal axis of the central shaft 20 and amounts to approx. 9. Finally, the thread width B is made by the difference of thread height T and the web width E and amounts to approx. 5 mm.

[0081] The diameter F is the blade diameter of the mixing blades (first mixing blade 210, second mixing blade 211) of the first mixing section 21 and corresponds to the diameter of a fictive cylinder which would come into existence by rotation of the peripheric edges of the mixing blades. It amounts to approx. 13 mm. The layer thickness of the respective mixing blades is indicated as blade width G and amounts to approx. 3.7 mm for the first mixing blade 210 and approx. 2.5 mm for the second mixing blade 211 as also for the remaining mixing blades of the first mixing section 21. The single mixing blades have a distance to each other of approx. 2.5 mm auf.

[0082] FIG. 3 shows an exterior view of a dynamic mixer 0 according to the invention in a view from below, wherein the position of the rotor shaft situated in the interior is merely adumbrated. The dynamic mixer 0 comprises a housing 10 having a housing body 11 and a cover 12 sealingly closing the housing body 11.

[0083] The cylindrical cover 12 has a circular base plate having a centrical rotor opening 12.1, the internal hexagonal geometry of which being provided to receive the connection geometry of the rotor shaft. The rotor opening 12.1 is surrounded at the outside by a cylindrical seat having a slightly larger internal diameter. Furthermore, two inlet openings 12A and 12B being opposite each other beside the rotor opening 12.1 are located in the base plate of the cover 12 for insertion of the low to high viscous components to be mixed. The inlet openings 12A and 12B are differently sized in order to be able to provide one component with a larger volume amount (inlet opening 12A) and one component with a smaller volume amount (inlet opening 12B) when inserting the components to be mixed. Each of the inlet openings 12A and 12B is encircled at the outside by a cylindrical seat for fixing the cartridge(s) containing the respective components. In doing so, the seat of the larger inlet opening 12A is slightly larger and the seat of the smaller inlet opening 12B is significantly larger as their respective diameter. Besides, the cover 12 comprises at its outside a guiding rail provided for precentering the cartridge(s) containing the respective components.

[0084] A cylindrical outlet opening 11A for discharging the now mixed low to high viscous components that have been inserted via the inlet openings 12A and 12B is formed at the distal end of the housing 11.

[0085] FIG. 4 shows a cross section through a dynamic mixer 0 according to the invention having a rotor shaft 1 mounted rotatably therein.

[0086] The dynamic mixer 0 comprises a housing body 11, which is sealingly closable at its proximal end by a cover 12. In doing so, a cylindrical sealing lip of the housing body 11 engages into a corresponding groove of the cover 12, while housing body 11 and cover 12 join in with each other in a positive-locking manner. A conically tapering transition section adjoins behind the sealing lip of the housing body 11, which ends up in an axially running short cylinder section. The internal space circumscribed by the inner walling of the transition section as well as of the short cylinder section of the housing body 11 forms a pre-mixing chamber 111, which is provided for pre-mixing the components to be mixed regarding a global homogenization of the mixture. A long cylinder section of the housing body 11 having a smaller internal diameter adjoins behind the short cylinder section after short conical tapering, the inner walling of which circumscribing an internal space, which corresponds to a main mixing chamber 110 and is provided for intermixing the components on local level. Finally, a cylindrical outlet opening 11A is arranged at the distal end of the housing body 11 after a further conical tapering

[0087] The rotor shaft 1 is arranged in the interior of the dynamic mixer 0, wherein the distal end of the central shaft 20 is located in the region of the outlet opening 11A of the housing body 11 and the connection geometry 3, which is provided for coupling to a mixer drive shaft (not shown), protrudes through the rotor opening 12.1 as well as the related seat of the cover 12. The mixing area 2 of the rotor shaft 1 is arranged in the housing body 11 of the dynamic mixer 0 in such a way that the first mixing section 21 of the mixing area 2 is situated within the main mixing chamber 110 and the second mixing section 22 of the mixing area 2 is situated within the pre-mixing chamber 11. In doing so, neither the mixing blades in the first mixing section 21 nor the thread flanks of the worm thread in the second mixing section 22 touch the inner walling of the pre-mixing chamber 111 and the main mixing chamber 110.

[0088] During the mixing process, the component having a larger volume amount is pressed through the lager inlet opening 12A and the component having the smaller volume amount is pressed through the smaller inlet opening 12B into the pre-mixing chamber 111. In this context, the circular plate 23, which is arranged in the transition region between the cover 12 and the housing body 1, serves for concentration control and pre-mixing of the components by, first, keeping the proximally inserted components from the worm thread and, subsequently, axially inserting them in the first into the cavity formed by the first spirally running thread flank of the worm thread in the second mixing section 22 laterally along the side of the circular plate 23. The components are then transported further by the thread flanks of the worm thread in the second mixing section 22, wherein it is provided for the pre-mixing chamber 111 to be almost completely filled with the inserted components before they arrive in the main mixing chamber 110. Thus, the components are prevented from too quick traverse by the worm thread of the second mixing section 22 which increases the dynamic pressure and results in global homogenization of the mixture. In the same time, an axial transport movement into the first mixing section 21 situated in the main mixing chamber 110 is supported by the rotation movement of the thread flanks of the worm thread. The mixing blades in the first mixing section 21 in the main mixing chamber 110 serves for further turbulence of the pre-mixed components, wherein the arrangement radially offset of the single mixing blade segments of the mixing blades ensure that a part of the components possibly not collected by one mixing blade is collected by the following mixing blade, sheared and subsequently intermixed with the remaining part of the components. Besides, the mixing blades of the first mixing section 21 achieve a forwarding pf the mixed components in the direction of the outlet opening 11A of the housing body 11, where the now globally and locally homogenized mixture can leak out.

REFERENCE NUMERALS

[0089] 0 dynamic mixer [0090] 1 rotor shaft [0091] 10 housing of the dynamic mixer 0 [0092] 11 housing body [0093] 11A outlet opening in the housing body 11 [0094] 110 main mixing chamber inside the housing body 11 [0095] 111 pre-mixing chamber inside the housing body 11 [0096] 112 pre-chamber inside the housing body 11 [0097] 12 cover that closes the housing body 11 [0098] 12A, 12B inlet openings in the cover 12 [0099] 12.1 rotor opening [0100] 2 mixing area of the rotor shaft 1 [0101] 20 central shaft of the mixing area 2 [0102] 20.1, 20.2 distal end or proximal end, respectively, of the central shaft 20 [0103] 21 first mixing section [0104] 210, 211 mixing blades in the first mixing section 21 [0105] 22 second mixing section [0106] 220 worm thread having thread flanks in the second mixing section 22 [0107] 23 circular plate [0108] 3 connection geometry of the rotor shaft 1 [0109] d diameter of the central shaft 20, corresponds to the core diameter of the worm thread 220 [0110] B thread width of the worm thread 220 (axial distance between two thread flanks of the worm thread 220) [0111] D worm diameter of the worm thread 220 (diameter of a fictive cylinder, created by rotation of the peripheric edges of the thread flanks of the worm thread 220) [0112] E web width of the worm thread 220 (layer thickness of the thread flanks of the worm thread 220) [0113] H thread depth of the worm thread 220 (half the difference of worm diameter Ddiameter d of the central shaft 20) [0114] T thread height of the worm thread 220 (sum of thread width B+web width E) [0115] thread angle of the worm thread 220 (equal to arctan T/2d) [0116] F blade diameter of the mixing blades 210, 211 (diameter of a fictive cylinder, created by rotation of the peripheric edges of the mixing blades 210, 211) [0117] G blade width of the mixing blades 210, 211 (layer thickness of the mixing blades 210, 211)