WO1995009690B1

WO1995009690B1 - Materials mixer

Info

Publication number: WO1995009690B1
Application number: PCT/GB1994/002141
Authority: WO
Filing date: 1994-10-03
Publication date: 1995-06-22

Abstract

A materials mixer, suitable for mixing concrete, comprises a generally cylindrical housing (10), which houses a mixing chamber (15) consisting of an upper, dry mixing chamber portion (2), a central, wet mixing chamber portion (3) and a lower, discharge chamber portion (4). The materials mixer has entrance means (20) for materials to be mixed and exit means (25) for the complete mixture, between which are a plurality of rotating members (30, 40, 50, 60) which disrupt the flow of materials through the chamber (15) causing mixing of the materials. The shape of the mixing chamber is defined by a plurality of baffle plates (11, 12, 16) which help determine the path of the materials through the chamber.

Claims

25

AMENDED CLAIMS

[received by the International Bureau on 20 April 1995 (20.04.95); original claims 1-27 replaced by amended claims 1-39 (8 pages)]

1 A concrete mixer comprising a housing containing a mixing chamber, the housing having an upper inlet for materials to be mixed, and a lower discharge outlet for mixed concrete, said chamber having an upper dry mixing chamber portion for the mixing of a plurality of substantially dry constituents of concrete, and a wet mixing chamber portion, lower than said dry mixing chamber portion, for the mixing of at least one fluid with the mixture of substantially dry constituents of concrete and said mixer including in said mixing chamber at least one rotatable mixing element positioned in the path between said inlet and said discharge outlet to effect mixing of the materials to be mixed.

2 A concrete mixer as claimed in Claim 1, wherein the wall of said wet mixing chamber portion comprises an inclined surface having an annular upwardly projecting portion extending therefrom.

3 A concrete mixer as claimed in either preceding Claim, wherein said mixing chamber includes a lower discharge chamber portion, between the wet mixing chamber portion and the discharge outlet, for controlling the motion of mixture from the wet mixing chamber portion to the discharge outlet.

4 A concrete mixer as claimed in any preceding Claim, wherein said at least one rotatable mixing element comprises a member mounted upon a rotatable shaft and extending radially away from the axis of said shaft.

5 A concrete mixer as claimed in Claim 4 , wherein there is provided at least one rotatable mixing element comprising a dry mixing disc provided to effect mixing in said dry mixing chamber portion, and at least one rotatable mixing element comprising a wet mixing disc provided to effect mixing in said wet mixing chamber portion.

6 A concrete mixer as claimed in Claim 5, wherein the boundary between the dry mixing chamber portion and the wet mixing chamber portion is defined by a rotatable mixing element comprising a second or subsequent dry mixing disc.

7 A concrete mixer as claimed in Claim 3 or in any one of Claims 4 to 6 when dependent upon Claim 3, wherein there is provided at least one rotatable element in said discharge chamber portion, said at least one rotatable element comprising a discharge member.

8 A concrete mixer as claimed in Claim 7, wherein said discharge member is coupled to said rotating shaft so as to allow said discharge member to rotate with lower angular velocity than said rotating shaft.

9 A concrete mixer as claimed in Claim 8, wherein said discharge member is coupled to said rotating shaft so as to allow a degree of slip between said discharge member and said rotating shaft.

10 A concrete mixer as claimed in any one of Claims 7 to 9 wherein said discharge member includes a substantially helical member located upon an upper surface of said discharge member.

11 A concrete mixer as claimed in any one of Claims 7 27

to 9 wherein said discharge member comprises an annular member coupled to said rotating shaft by at least one member extending between said rotating shaft and said annular member.

12 A concrete mixer as claimed in any one of Claims 4 to 6 or any of Claims 7 to 11 when dependent upon one of Claims 4 to 6, wherein the surface of at least one rotatable mixing element is provided with irregularities, apertures or projections in order to further disrupt the flow of material.

13 A concrete mixer as claimed in any one of Claims 4 to 6 or any of claims 7 to 12 when dependent upon one of Claims 4 to 6, wherein at least one of the rotatable mixing elements is non-circular.

14 A concrete mixer as claimed in any one of Claims 4 to 6 or any of Claims 7 to 13 when dependent upon one of Claims 4 to 6, wherein at least one of the rotatable mixing elements has a degree of rotational symmetry between two and ten.

15 A concrete mixer as claimed in Claim 12, wherein at least one rotatable mixing element provided to effect mixing in the dry mixing chamber portion includes at least one substantially straight elongate member, projecting upwards from the upper surface of the disc.

16 A concrete mixer as claimed in Claim 15, wherein an upper surface of the elongate member is inclined with respect to the upper surface of the rotatable mixing element, along the length of the elongate member. 28

17 A concrete mixer as claimed in either of Claims 15 or 16, wherein some part of the elongate member is orthogonal to a hypothetical line extending through the centre of the element.

18 A concrete mixer as claimed in any of Claims 15 to 17, wherein at least one surface of said elongate member extends outwardly, from the centre of said rotatable mixing element, as well as upwardly from said upper surface of said element.

19 A concrete mixer as claimed in any preceding Claim, wherein there is provided a fluid inlet to said wet mixing chamber portion, said inlet allowing fluid to enter said wet mixing chamber portion without having passed through said dry mixing chamber portion, and said inlet comprising an axial bore in said rotating shaft and a nozzle means allowing said fluid to flow out of said axial bore into said wet mixing chamber portion.

20 A concrete mixer as claimed in any preceding Claim, wherein the housing is divided axially into a plurality of sections which may be separated from each other in order to allow access to the inside of the mixing chamber.

21 A concrete mixer as claimed in Claim 20, wherein the housing comprises two sections each of which is hinged to a point fixed with respect to the mixer as a whole.

22 A concrete mixer as claimed in any preceding Claim, wherein the mixer includes at least one material feed means to transport at least one of the materials to be mixed towards the mixing chamber. 29

23 A concrete mixer as claimed in Claim 22, wherein the material feed means comprises a channel in which there is provided a first forcing means.

24 A concrete mixer as claimed in Claim 23 wherein the material feed means includes an exit means whereby transported material can exit the channel, said exit means being at or adjacent one end of the first forcing means and said material feed means also includes a second forcing means applying a force in substantially the opposite direction to that applied by the first forcing means, said exit means being positioned between the first forcing means and the second forcing means.

25 A concrete mixer as claimed in either one of Claims 23 or 24, wherein the forcing means comprise rotatable screw or auger members.

26 A concrete mixer as claimed in any one of Claims 22 to 25, wherein there is provided sensing and/or control means to sense and/or control the rate of feed of at least one of the materials to be mixed.

27 A concrete mixer as claimed in Claim 26, wherein there is provided a second control means which may be set to operate a single material feed means for any one of the materials to be mixed for a predetermined time, facilitating calibration of the transport means.

28 A materials mixer as claimed in any one of Claims 22 to 27, wherein at the entrance to the materials feed means, there is provided an anti-bridging means to prevent the material from bridging across the entrance to the channel.

29 A materials mixer as claimed in Claim 28 , wherein 30

the anti-bridging means comprises at least one oscillating flap adjacent the entrance to the channel.

30 A dry mixing disc for use in a concrete mixer as claimed in Claim 5 or any in any subsequent Claim dependent thereon.

31 A wet mixing disc for use in a concrete mixer as claimed in Claim 5 or in any subsequent Claim dependent thereon.

32 A mixing disc as claimed in either of Claims 30 or 31, wherein said disc is permanently attached to a rotatable shaft.

33 A method of mixing concrete comprising the steps of: feeding at least two substantially dry constituents of concrete, one of which is aggregate, into a mixing chamber; causing said substantially dry constituents to be mixed together by the action of a rotating dry mixing member in said mixing chamber; allowing said dry mixture to fall under gravity to a level in said mixing chamber below the level of said dry mixing member; feeding a fluid constituent of concrete into said substantially dry mixture and causing said fluid to be mixed into said dry mixture, in order to form a wet mixture, by the action of a rotating wet mixing member; allowing said wet mixture to fall under gravity to a level below the level of said wet mixing member so as to exit from said mixing chamber, said wet mixture exiting from said mixing chamber comprising mixed concrete. 31

34 A method of mixing concrete as claimed in Claim 33, wherein said step of allowing said dry mixture to fall to a level below the level of said dry mixing member consists of allowing the dry mixture to pass between the dry mixing member and a wall of the mixing chamber.

35 A method of mixing concrete as claimed in either of Claims 33 or 34, wherein said step of allowing said wet mixture to fall to a level below the wet mixing member consists of allowing the wet mixture to pass between the wet mixing member and a wall of the chamber.

36 A method of mixing concrete as claimed in Claim 35, wherein the distance between the wet mixing member and the wall of the chamber is only slightly larger than the size of the largest pieces of aggregate of the dry concrete constituents.

37 A method of mixing concrete as claimed in any preceding Claim, wherein the step of allowing the wet mixture to fall to below the level of the wet mixing member, and towards an exit of the mixing chamber includes inhibiting the descent of said wet mix by the provision of at least one upwardly extending projection on the inner surface of the wall of the chamber.

38 A method of mixing concrete as claimed in Claim 37, wherein the upwardly extending projection is annular.

39 A method of mixing concrete as claimed in any one of Claims 33 to 38, wherein the mixing process is a constant flow process, the total mass of concrete constituents fed into the mixing chamber over a given. 32

arbitrary period of mixing, being substantially equal to the mass of concrete exiting from the mixing chamber over the same period.

33

STATEMENT UNDER ARTICLE 19

Independent Claim 1 has been amended so as to be directed towards a concrete mixer, and also to include the features of a dry mixing chamber portion and a wet mixing chamber portion, which were included in Claim 3 as originally filed.

Limitation of the monopoly claimed to a concrete mixer clearly distinguishes the invention, as claimed, from the disclosure of the documents cited against the independent claim, since neither document discloses a concrete mixer.