GB2283437A - Mixer drum for concrete - Google Patents

Abstract

The drum 1 for concrete for a concrete mixer, is moulded from plastics material and has integral ribs 12 on the cylindrical internal wall which are inclined in the direction of rotation of the drum (arrow 14). The ribs can be straight or curved (12', Figure 4). The drum is mounted on a plate 7 by bolts (8, Figure 3) which allow for its detachment from the drum. A boss 9 in the centre of the plate receives a drive spindle of a mixer. Exchange of the plate 7 for a different one suits the drum to a different mixer. <IMAGE>

Description

MIXER DRUM This invention relates to mixer drums, for example for use in the mixing of mortar, concrete and other building materials.

Known drums include those which form part of concrete mixers. These usually consist of a generallycylindrical drum which is mounted on a framework which includes a motor and drive means arranged to cause rotation of the drum about an axis extending longitudinally of the cylinder. The drum is usually pivotable about a transverse axis, to allow emptying of its contents after mixing.

The known drums however suffer from disadvantages. The efficiency of mixing is not very good and the drums tend to be difficult to empty.

There have also been problems associated with the mounting of the drum on the framework and coupling it to the drive means.

The present invention provides a mixer drum of generally cylindrical shape having an open mouth at one end and a closed floor at the other, the drum being mountable on a support means and having means for engagement with a drive means for causing the drum to rotate about an axis extending longitudinally of the drum.

According to a first aspect of the invention, the drum has on its cylindrical internal wall a plurality of internal ribs which extend rectilinearly or curvilinearly along lines inclined to the rotational axis of the drum.

The ribs are preferably equidistantly spaced around its internal wall. Any convenient number can be provided, for example five.

The direction in which the ribs are inclined is preferably the direction in which the drum rotates, in other words the ends of the ribs distant from the drum floor are preferably displaced in the direction of drum rotation relative to the ends adjacent the floor.

The ribs may be rectilinear and extend along straight lines, or may be curvilinear and extend on a right-hand or a left-hand curve from their ends adjacent the floor towards their ends distant therefrom. In either case the distant ends are preferably displaced in the direction mentioned above.

Advantageously, the ribs have a transverse section which presents a curved, preferably substantially semi-circular, outer surface to the interior of the drum.

The ribs are preferably formed integrally with the drum.

The drum is conveniently moulded from plastics material.

According to another aspect of the invention, the floor of the drum comprises a reinforcing element which extends over substantially the entire floor area externally of the drum and has in a central region thereof the means for engagement with the drive means.

The reinforcing element is preferably substantially planar, for example in the form of a circular or square plate.

The reinforcing element can be attached to the drum floor by releasable fastening means, for example a set of bolts.

If releasable from the drum, one plate can simply be exchanged for another having a different drive means suited to a different model of mixer. In this way the drum can be suited to virtually any model of mixer.

The central region of the drum floor is advantageously shaped to form a cavity which receives the engagement means.

An embodiment of the invention will now be described by way of example with reference to the drawing, in which: Figure 1 is a longitudinal sectional view of a mixer drum, Figure 2 is a transverse section on the line A-A of Figure 1, Figure 3 shows the drum of Figure 1 when viewed in the direction of arrow B, and Figure 4 shows a modification of the drum of Figure 1.

The drum 1 shown in Figure 1 has a circular floor 2 from which extends a cylindrical side wall 3 consisting of a straight section 4 and a frusto-conical section 5. The drum has a circular mouth 6. The drum is moulded from a suitable plastics material. This assists in cleaning and emptying the drum when material has solidified inside.

A reinforcing plate 7 is secured to the outer surface of the floor 2 by eight bolts 8 which are shown in Figure 3. The bolts 8 have nuts or engage threaded sockets to allow the plate 7 to be detached from the floor 2.

At its centre the plate 7 has a boss 9 which is internally threaded to accept a threaded drive spindle of a mixer in which the drum 1 is to be mounted. The floor of the drum has a central dome 10 which forms a cavity to receive the boss 9. The plate 7 can be removed by releasing the bolts 8. It can be replaced by one having a different boss, suited to a different mixer.

The drum 1 is moulded with five internal ribs 12 which are curved in section, as can be seen in Figure 2. The ribs 12 are inclined to the rotational axis 13 of the drum, in the direction of rotation of the drum as represented by the arrow 14.

In other embodiments, there may be another number of ribs. Five is just an example.

The ribs may be curved instead of straight, for example as shown in Figure 4 where the ribs 12' are curved along a left-hand curve from their ends adjacent the floor 2 to their ends nearer the drum mouth 6.

Tne inclination of the ribs works two-fold: it increases the efficiency of mixing and helps to make emptying of the drum more easy.

Claims (12)

1. A mixer drum of generally cylindrical shape having an open mouth at one end and a closed floor at the other, the drum being mountable on a support means, having means for engagement with a drive means for causing the drum to rotate about an axis extending longitudinally of the drum, and having on its cylindrical internal wall a plurality of internal ribs which extend rectilinearly or curvilinearly along lines inclined to the rotational axis of the drum.

2. A mixer drum according to claim 1, in which the ribs are inclined in the direction in which the drum rotates.

3. A mixer drum according to claim 1 or 2, in which the ribs are curvilinear and extend on a righthand or left-hand curve from their ends adjacent the drum floor to their ends distant therefrom.

4. A mixer drum according to any preceding claim, in which each rib has a transverse section which presents a curved outer surface to the interior of the drum.

5. A mixer drum according to claim 5, in which the outer surface is substantially semi-circular.

6. A mixer drum according to any preceding claim, in which the ribs are formed integrally with the drum.

7. A mixer drum according to any preceding claim, moulded from plastics material.

8. A mixer drum of generally cylindrical shape having an open mouth at one end and a closed floor at the other, the drum being mountable on a support means and having means for engagement with a drive means for causing the drum to rotate about an axis extending longitudinally of the drum, the floor of the drum comprising a reinforcing element which extends over substantially the entire floor area externally of the drum and has in a central region thereof the means for engagement with the drive means.

9. A mixer drum according to claim 8, in which the reinforcing element is substantially planar.

10. A mixer drum according to claim 8 or 9, having releasable fastening means for attachment of the reinforcing element to the drum floor.

11. A mixer drum according to claim 10, in which the central region of the drum floor is shaped to form a cavity which receives the engagement means.

12. A mixer drum substantially as hereinbefore described with reference to the drawings.