A bucket mixer for mixing solid aggregates and delivering the mixture

Abstract

 The bucket mixer comprises a mixing screw (11) extending substantially throughout the whole bucket mixer and counter-current mixing blades (13) carried by the peripheral part of the mixing screw and radially extending from the edge thereof to near the inner wall of the vessel (10). The blades are oriented at a winding direction opposite to that of the mixing screw (11), and are rigidly and entirely fixed (14) in releasable manner to supports (15) welded to the peripheral part of the mixing screw.

Description

[0001] The present invention refers to a bucket mixer for mixing solid aggregates and delivering the mixture. More particularly, the invention relates to a bucket mixer for mixing solid aggregates such as concrete aggregates, of the kind comprising a vessel and an inner mixing screw rotating about an axis parallel to the longitudinal axis of the vessel.

[0002] Furthermore, the bucket mixer of this invention is of the kind providing a plurality of blades mounted to the peripheral part of the mixing screw so as to extend radially as far as near to the edge of the vessel, the blades being oriented at a winding direction opposite to that of the mixing screw so as to attain the double effect of cleaning or scraping the vessel walls and urge the material in the opposite direction of that imparted by the mixing screw during operation of the bucket mixer.

[0003] U.S. patent No. 4,223,996 discloses an apparatus of the above discussed kind and suggests that the blades can be welded or otherwise secured in a rigid manner, permanently or removably, to the peripheral part of the mixing screw. According to this document, fixing is accomplished by restraining the inner edge of the blade in a recess obtained in the mixing screw. This solution first of all weakens the mixing screw at the points where the recesses are. Further, it makes it difficult to provide a system for releasably securing the blade to the peripheral part of the mixing screw, as these two members are substantially at a right angle with respect to each other in a point where they undergo considerably high torsion stresses. Finally, for the same reasons also the blade tends to deform rapidly. Replacing the blade may become difficult or impossible due to the manner in which it is coupled to the mixing screw.

[0004] Italian patent No. 1,210,783 discloses a bucket mixer of this kind wherein each blade is pivotally mounted to a support welded to the mixing screw, in order to rotate from a retracted position near the axis of the mixing screw to an extended position in proximity of the vessel.

[0005] Practice has shown that with time, if thorough and cleaning is not carried out continuously, concrete or any other material being mixed solidifies in the interstices between the blade and the support, thereby locking the blade in a position. This cancels any benefit that pivotal mounting of the blade could involve. Further, should locking occur when the blade is retracted, the bottom of the vessel can no longer be scraped and cleared. Finally, replacing the blades is an extremely difficult and complex operation.

[0006] It has also been found that it is not necessary that the blades rotate to contact the walls of the vessel to attain efficient and complete cleaning. As the blades wear out with time, some provision should instead be made to allow for replacing the blades rapidly in absence of binding systems to the mixing screw which weaken either members.

[0007] These and further objects which will be more apparent hereinafter are attained according to the present invention by the provision of a bucket mixer for mixing solid aggregates and delivering the mixture, comprising counter-current mixing means of mixing screw-like kind extending substantially throughout the whole bucket mixer and blade-like mixing means carried by the peripheral part of the mixing screw and radially extending from the edge thereof to near the inner wall of the vessel, the blades being oriented at a winding direction opposite to that of the mixing screw, characterised in that the blades are rigidly and entirely fixed in releasable manner to supports welded to the peripheral part of the mixing screw.

[0008] For a better understanding of the present invention, reference is made to the following detailed description of various exemplary embodiments considered in combination with the accompanying drawings in which:

FIG. 1

is a substantially front view of a bucket mixer in accordance with the present invention;

FIGS. 2, 4 and 6

are views of mixing blades according to the present invention in three different arrangements; and

FIGS. 3, 5 and 7

are views of the blades of the previous figures as seen in the directions of arrows A, B and C, respectively.

[0009] A bucket mixer of known kind provides a vessel 10 for containing the products to be mixed. Within vessel 10 there is mounted a mixing screw 11 rotating about a central longitudinal axle consisting of a shaft 12.

[0010] Still in known manner, along the peripheral part of mixing screw 11 there are mounted blades 13 forming preset angles therebetween. The blades 13 are oriented perpendicular to the mixing screw 11 and directed towards the inner wall of the vessel 10, so as to provide counter-current mixing with respect to mixing screw 11 and clear the inside of vessel 10 during mixing.

[0011] According to the present invention, the blades 13 are rigidly fixed, for example by means of bolts 14, directly or indirectly, to a support 15 welded to the peripheral part of the mixing screw 11.

[0012] As depicted in the drawings, in the solution of FIGS. 2 and 3 the support 15 is a flat base. Interposed between the flat support 15 and the flat blade 13 there is an L-shaped bracket 16 connected by bolts to either members 13 and 15 (as shown in FIGS. 2 and 3) or only one of them.

[0013] In the embodiment of FIGS. 4 and 5, the support 15 is L-shaped and there are no intermediate brackets as there are bolts connecting the blade to the longer portion of support 15.

[0014] Finally, in the solution of FIGS. 6 and 7 the blade 13 is L-shaped so that its shorter portion is the one welded in 14 to support 15.

[0015] In all the disclosed embodiments, the blade is rigidly fixed to the mixing screw but in such way as not to cause deformation in either bodies and be easily replaced when worn or in case of failure. In addition, no blades maintenance (washing) is required as there are no parts reciprocally moving during operation.

Claims

1. A bucket mixer for mixing solid aggregates and delivering the mixture, comprising counter-current mixing means (11) of mixing screw-like kind extending substantially throughout the whole bucket mixer and blade-like mixing means carried by the peripheral part of the mixing screw and radially extending from the edge thereof to near the inner wall of the vessel (10), the blades being oriented at a winding direction opposite to that of the mixing screw (11), characterised in that the blades (13) are rigidly and entirely fixed (14) in releasable manner to supports (15) welded to the peripheral part of the mixing screw (11).

2. A bucket mixer as claimed in claim 1, characterised in that the blades (13) are directly fixed to the corresponding supports (15).

3. A bucket mixer as claimed in claim 1, characterised in that the blades (13) are fixed to the corresponding supports (15) through an intermediate bracket (16) releasable from the blade or the support (15) or both.

4. A bucket mixer as claimed in claim 3, characterised in that the intermediate bracket (16) is L-shaped.

5. A bucket mixer as claimed in claims 1 and 2, characterised in that the blades (13) are L-shaped.

6. A bucket mixer as claimed in claims 1 and 2, characterised in that the supports (15) are L-shaped.

7. A bucket mixer as claimed in the previous claims, characterised in that the releasable fixing members are bolts (14).

Drawing