GB2453543A

GB2453543A - Cement mixer with removable mixing blade

Info

Publication number: GB2453543A
Application number: GB0719601A
Authority: GB
Inventors: Leonard John Ash; Peter Dennis
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-10-08
Filing date: 2007-10-08
Publication date: 2009-04-15
Also published as: GB0719601D0

Abstract

A cement mixer drum 60 comprises at least one mixing blade 10 and a mounting arrangement 18 for mounting the mixing blade to the drum and inside it, so that in use the mixing blade moves with the drum and promotes mixing of its contents, wherein the mounting arrangement is releasable, enabling the mixing blade to be removed from the drum for cleaning, and to be subsequently re-mounted ready for use. The present invention also relates to a mixing blade for use in a cement mixer. Preferably the mounting arrangement comprises complementary mating features of the mixing drum and the blade; this may include a male tongue, or hook portion, and a female slot to receive the tongue. Two spatially separated mounting means may be provided and the second mounting means may comprise openings on the drum and blade to receive a releasable fastener such as a pin or bolt 22.

Description

DESCRIPTION

CEMENT MIXER

The present invention relates to an improved cement mixer.

Cement mixers usually comprise a rotatable open ended drum having a number mixing blades mounted within the drum to rotate along with it. A drawback of these mixers is that it is difficult to clean the interior of the drum after use. The blades, which are typically welded in place inside the drum, hamper the use of a spade to remove excess cement prior to washing the drum.

Whilst a trowel can be used to scrape the excess cement from between the blades, this often results in damage to both the trowel and an individual's knuckles.

After prolonged use of the mixer, hardened concrete builds up between the blades and the interior of the drum which further hinders cleaning and reduces the efficiency of the mixer. Methods commonly used to reduce this build up, such as hammering the outside of the drum or placing bricks in the drum whilst it is rotating so as to chip off the hardened concrete, result in damage to both the drum and the mixing blades.

US 5,934,800 discloses a portable mixer which has a removable mixing container held inside a rotatable drum. The removable mixing container has a number of keyway grooves which secure the removable mixing container within the rotatable drum and also serve as mixer blades. Whilst the removable container can be removed from the mixer, slurry and unmixed cement can still accumulate in the spaces between the "mixer blades" and the interior surface of the container.

It is an object of the present invention to provide a cement mixer which can be easily cleaned.

In accordance with the present invention, there is provided a cement mixer drum provided with at least one mixing blade and with a mounting arrangement for mounting the mixing blade to the drum and inside it, so that in use the mixing blade moves with the drum and promotes mixing of its contents, wherein the mounting arrangement is releasable, enabling the mixing blade to be removed from the drum for cleaning, and to be subsequently re-mounted ready for use.

The present invention provides for mixers which are relatively easy to clean as the mixing blades can be detached and washed separately from the drum.

Preferably, the mounting arrangement comprises complementary mating features of the mixing blade and of the drum which are shaped to releasably interengage, and further comprises a releasable fastener, so that mounting the mixing blade involves positioning the mixing blade such as to engage the mating features, and then securing the mixing blade in this position with the fastener, thereby maintaining the mating features in engagement. Such an arrangement allows for rapid mounting and removal ofthe mixing blades. The mating features may for example comprise a male feature insertable in a female feature. The male feature may be a tongue and the female feature a slot. Preferably the male feature comprises a hooked portion.

The releasable fastener may take the form of a pin or bolt for insertion in alignable openings of the drum and the mixing blades.

In a further preferred embodiment, the mounting means provides two spatially separated points of attachment of the mixing blade to the drum. A rigid and secure mounting can consequently be provided.

Preferably, the drum has a base wall and a cylindrical side wall, and one of the points of attachment is at the base of the drum and the other is at its side wall.

Still more preferably, the point of attachment at the base of the drum comprises a male part insertable in a female part, and the point of attachment at the drum's side wall comprises alignable openings for receiving a releasable fastener.

In a further preferred embodiment, the mixing blade comprises an elongate blade member and a laterally projecting portion securable to the drum to stabilise the blade member in a position in which it stands up from the drum's interior surface.

The cement mixer drum itself is preferably a cylindrical hollow metal body having an open mouth and an inwardly tapering portion leading to the mouth.

In accordance with a further aspect of the present invention, there is IS provided a mixing blade for use in a cement mixer drum, comprising a mating feature which is complementary to a mating feature of the drum to allow releasable interengagement of the blade to the drum, the blade further comprising a releasable fastener to allow the blade to be secured to the drum and thereby maintain the mating features in engagement.

The mating feature may comprise a male feature which is insertable in a female feature of the drum. The male feature may be a tongue and the female feature may be a slot to receive the tongue. Preferably, the male feature comprises a hooked portion. -4-.

The blade may have an opening which can be aligned with an opening on the drum to receive a releasable fastener in the form of a pin or bolt. The mating feature and the releasable fastener may be provided in two spatially separated points of the blade.

S Preferably, the mixing blade comprises an elongate blade member and a laterally projecting portion which is securable to the drum to stabilise the blade member in a position in which it stands up from the drum's interior surface Preferably, the mixer blade is formed from stainless steel. This will not only prolong the life of the blade, but also allow for the blade to be easily cleaned.

Alternative materials may be used where appropriate, such as plastics, metals and alloys thereof.

A specific embodiment of the present invention will now be described, by way of example only, with reference to the following figures in which: Figure 1 is a perspective view of a detachable mixing blade according to the present invention; Figure 2 is a perspective view of a cement mixer incorporating the mixing blade shown in Figure 1; Figure 3 is a cross-sectional view of the drum of the cement mixer shown in Figure 2; and Figure 4 is a perspective view of a detachable blade having a different construction to the blade shown in Figure 1 In Figure 1 there is shown a detachable mixing blade 10 for use in a drum of a cement mixer. The blade 10 is formed from an elongate, generally rectangular piece of stainless steel having a thickness of approximately 3mm.

One of the ends of the blade terminates with a tab 12 which has a smaller width than the rest of the blade. The tab 12 terminates with a curved lug 14 which takes the form of a partial cylinder. Towards the other end of the blade 10, there is a diagonal cut-away 16 in thc bottom corner which allows the blade to follow the contours of the interior of the drum. Just before the diagonal cut-out, a bracket 18 extends downwardly towards a point which is substantially level with a lower edge of the rectangular blade and incorporates a bolt aperture 20. The bolt aperture 20 can receive a bolt 22 which has a ring hole 24 located at an end distal to a bolt head.

The blade 10 is bent in the middle at a slight angle (in the region of 20°), so as to form a crease 30 which divides the blade into a first half 26 and a second half 28. The first half 26 incorporates the tab 12, whereas the second half incorporates the bracket 18. Each half incorporates respective vents 32,34 which are rectangular shaped apertures cut out of the blade to assist in mixing.

Figure 2 shows a cement mixer 50 with a tubular frame 52 forming a stand 56 and handles 58, and carrying two wheels 54 on which the cement mixer 50 can be trundled from one place to another. A steel drum 60 is rotatably mounted on the frame 52 and is arranged to be driven by a motor 62 located to the rear of the frame. The drum is ofa generally cylindrical shape and tapers inwardly at a frusto-conical lip 64 toward its open end. The interior of the drum 60 houses the detachable mixing blades 10, which protrude inwardly towards the centre of the drum 60. Whilst only one mixing blade 10 can be seen in Figure 2, there are in fact Ibur detachable blades at circumferential intervals around the interior of the drum. Other embodiments may have a different number of blades.

Figure 3 shows the assembly of the drum 60 and blades 10 in cross section. A cog 74 at the base 72 of the dnim 60 is part of a gear train coupling the drum to the motor 62.

On the base of the drum 60, there are provided slots 76. To mount one of the blades 10, its curved lug 14 is inserted into one of the slots 76, the blade 10 resting within the drum 60 such that it extends inwardly from the interior surface of the drum. The bracket 18 rests against the interior of the drum 60, its aperture lining up with an aperture 66 in the drum 60. The bolt 22 is inserted through the apertures, its distal end (which includes the ring aperture 24) protruding from the exterior of the drum 60. In order to finally secure the blade to the drum, a lock ring 68 is inserted through the ring aperture 24. As the lock ring 68 abuts the exterior surface of the drum, it prevents movement of the blade. In order to remove the blade, the reverse of the above procedure is employed.

Figure 4 shows a blade 80 which is of a similar construction to the one illustrated in Figure 1 and similar features are denoted with the same reference number prime (). In order to enhance the mixing effect of the blades, the first and second halves 26' and 28' have upper edges 82 and 84 which extend upwardly in the general shape of an isosceles trapezium.

Whilst the blades in the figures are shown to extend parallel to the longitudinal axis of the drum, they may instead extend along a helical path.

After use, the blades 10 can easily be removed from the drum 60 and washed. As the blades 10 are manufactured from stainless steel, the use of water will not result in the blades rusting. With the blades removed, the drum 60 can also be cleaned easily, excess slurry being removed with a spade or trowel and the drum then being washed with water. With the blades removed, build up of hardened concrete between the blades and the interior of the drum is prevented. If required, an additional drainage hole (not shown) can be included on the drum, so as to allow the water to drain easily.

Existing drums/cement mixers could be adapted to receive the detachable mixing blades if desired.

Claims

I. A cement mixer drum provided with at least one mixing blade and with a mounting arrangement for mounting the mixing blade to the drum and inside it, so that in use the mixing blade moves with the drum and promotes mixing of its contents, wherein the mounting arrangement is releasable, enabling the mixing blade to be removed from the drum for cleaning, and to be subsequently re-mounted ready for use.
2. A cement mixer drum as claimed in claim I in which the mounting arrangement comprises complementary mating features of the mixing blade and of the drum which are shaped to releasably interengage, and further comprises a releasable fastener, so that mounting the mixing blade involves positioning the mixing blade such as to engage the mating features, and then securing the mixing blade in this position with the fastener, thereby maintaining the mating features in engagement.
3. A cement mixer drum as claimed in claim 2 in which the mating features comprise a male feature insertable in a female feature.
4. A cement mixer drum as claimed in claim 3 in which the male feature is a tongue and the female feature is a slot to receive the tongue.
5. A cement mixer drum as claimed in claim 3 or claim 4 in which the male feature comprises a hooked portion.
6. A cement mixer drum as claimed in any of claims 2 to 5 in which the drum and s the mixing blade have alignable openings to receive a releasable fastener in the form of a pin or bolt.
7. A cement mixer drum as claimed in claim 1 in which the mounting means provides two spatially separated points of attachment of the mixing blade to the drum.
8. A cement mixer drum as claimed in claim 7 in which the drum has a base wall and a cylindrical side wall, and in which one of the points of attachment is at the base of the drum and the other is at its side wall.
9. A cement mixer drum as claimed in claim 8 in which the point of attachment at the base of the drum comprises a male part insertable in a female part, and the point of attachment at the drum's side wall comprises alignable openings for receiving a releasable fastener.
10. A cement mixer drum as claimed in any preceding claim in which the mixing blade comprises an elongate blade member and a laterally projecting portion securable to the drum to stabilise the blade member in a position in which it stands up from the drum's interior surface.
11. A cement mixer drum as claimed in any preceding claim which is a cylindrical hollow metal body having an open mouth and an inwardly tapering portion leading to the mouth.
12. A cement mixer comprising a drum as claimed in any preceding claim.
13. A cement mixer further comprising a stand upon which the dnim is rotatably mountable, and a powered drive for rotating the drum.
14. A mixing blade for use in a cement mixer drum comprising a mating feature which is complementary to a mating feature of the drum to allow releasable interengagement of the blade to the drum, the blade further comprising a releasable fastener to allow the blade to be secured to the drum and thereby maintain the mating features in engagement.
15. A mixing blade as claimed in claim 14 in which the mating feature comprises a male feature which is insertable in a female feature of the drum.
16. A mixing blade as claimed in claim 15 in which the male feature is a tongue and the female feature is a slot to receive the tongue.
17. A mixing blade as claimed in claim 16 in which the male feature comprises a hooked portion.
18. A mixing blade as claimed in any one of claims 15 to 17 in which the blade has an opening which can be aligned with an opening on the drum to receive a releasable fastener in the form of a pin or bolt.

S
19. A mixing blade as claimed in claim 15 in which the mating feature and the releasable fastener are provided in two spatially separated points of the blade.
20. A mixing blade as claimed in any one of claims 15 to 19 in which the mixing blade comprises an elongate blade member and a laterally projecting portion which is securable to the drum to stabilise the blade member in a position in which it stands up from the drum's interior surface.
21. A cement mixer drum substantially as herein described with reference to, and as illustrated in, the accompanying drawings.
22. A cement mixer substantially as herein described with reference to, and as illustrated in, the accompanying drawings.
23. A mixing blade substantially as herein described with reference to, and as illustrated in, the accompanying drawings.