GB2052280A

GB2052280A - Concrete-mixer

Info

Publication number: GB2052280A
Application number: GB8017802A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-06-01
Filing date: 1980-05-30
Publication date: 1981-01-28
Also published as: ES491976A0; ATA268180A; IT8022465A0; GB2052280B; DE2922447C2; ES8101459A1; DE2922447A1; AT377226B; IT1131227B

Abstract

A mixing drum (1) of a transportable concrete mixer has conveyor elements (2) and a driven bottom mixing tool (3). Water is fed into the drum through its mouth (1c) from an external supply pipe (8) which is connected to spray piping (7) through a rotary coupling (9). The spray piping (7) extends along the inner wall of the drum to the bottom end of the drum (1b) and is provided with nozzles (11,12) in addition to a nozzle (10) adjacent the drum mouth. Each nozzle (12) may comprise a stub pipe having radial bores (13) covered by a rubber cap (14) which prevents clogging and acts as a valve opening under water pressure. <IMAGE>

Description

SPECIFICATION Concrete mixer The invention relates to a concrete-mixer having a rotatable mixing drum with conveyor components on the inner wall of the drum, a driven mixing tool which projects into the drum from the bottom of the drum and which is supported from the bottom of the drum, and spray piping for water entering the drum through the mouth of the drum. Such mixers are usually transportable.

Feeding water into the mixing drum through the drum mouth is the usual way for mixing drums having conveyor components on the drum wall. In the case of a mixing drum of the kind to which the invention relates the interior of which furthermore has a mixing tool, the path for the water from the mouth of the drum to the bottom of the drum is considerably reduced. The disadvantage arises from the fact that the water sprayed is taken up first of all by the contents nearer to the drum mouth so that these contents become wet very rapidly whilst in the region of the drum bottom the constituents remain dry for a long time. Thorough and uniform mixing then demands, under certain circumstances, a long mixing time which is uneconomical. Furthermore the dry contents of the drum at the bottom can under certain circumstances lead to blocking phenomena.

It is indeed already known to feed the water in to a mixing drum through the bottom. But this demands a costly sealing system in the region of the water feed into the bottom of the drum. Furthermore this kind of feed in the case of a drum of the kind to which the invention relates is not possible since the bottom of the drum already contains the bearing for the shaft of the mixing tool or respectively its driving mechanism, so that no central water feed is possible.

The object of the invention is to develop a transportable concrete-mixer with a bottom mounted mixing tool in a simple way such that the water being fed in arrives rapidly in the bottom region of the drum and, in the whole drum, right from the start, a uniform mixing with the water is effected.

In accordance with the invention, the spray piping is connected in the region of the mouth of the drum to a rotary coupling which is arranged, in use, to be connected to an external water supply, the spray piping extending in the drum along its inner wall as far as the bottom of the drum and being provided at least adjacent to the bottom of the drum with a spray nozzle.

A spray pipe laid against the inner wall of the drum is simple to apply and carries the water positively into the bottom region of the drum. The mixing process is in this way considerably accelerated. A rotatable coupling for the external water supply is arranged in the region of the mouth of the drum. In this region as hitherto a nozzle may in addition be arranged, which sprays from the mouth into the interior of the drum. A spray pipe arranged against the wall of the drum neither becomes strained by, nor impairs, the mixing process.

The spray piping may particularly advantageously exhibit in the drum a number of nozzles arranged spaced apart. The water for the mixing process can then be sprayed positively into a number of regions of the drum simultaneously. The distribution of these nozzles can in a simple way be adapted to the spacings and directions of the conveyor components on the drum well and/or blades on the mixing tool so that an optimum rapid result of the mixing is achieved.

In the case of a preferred construction the nozzles are arranged predominantly in the bottom half of the drum. In this region of the drum is to be found the greater proportion of the dry constituents of the concrete where the most water is needed. Furthermore the nozzles are adjacent to the range of action of the mixing tool, thereby promoting its mixing effect and preventing a risk of blocking which cannot bye excluded in the case of certain concrete consistencies.

The nozzles are in a simple way made as pieces of pipe branching from the spray piping into the interior of the drum, closed at their free ends and having drilled holles arranged round their circumference in a ring. The drilled holes are thereby directed not directly into the interior of the drum; but spray onto the adjacent conveyor components which take over the further distribution of the water. Furthermore the drilled holes directed in that way are easierto protect against clogging by concrete.

This is done in an advantageously simply way by the nozzles being provided in each case with a hoodlike rubber cap to act as a valve. The water pressure is adequate to raise these valve caps far enough for the water to come out but no mixture can enter the drilleed holes against the direction of stretch of the rubber caps and against the water pressure.

A particularly rapid and thorough water feed can be made possible in a simple way by the spray piping exhibiting two or more runs of pipe arranged with approximately axial symmetry. The slight additional structural outlay saves further mixing time.

The use of the concrete-mixer thereby becomes considerably more economical.

An example of a concrete-mixer constructed in accordance with the invention is illustrated in the accompanying drawings, in which: Figure lisa diagrammatic longitudinal section through the mixing drum of the concrete-mixer; and, Figure 2 is an enlarged detail of part of the spray piping.

The mixing drum designated as a whole by 1 has conveyor components 2 on its inner wall la. They extend helically from the region of the bottom of the drum 1 b up to the region of the mouth of the drum 1c. A mixing tool 3 is supported by its driving shaft 4 in the region of the bottom of the drum. Blades 5 are arranged on the shaft 4 in the form of a star. The blade arrangement may be seen from the plan indicated in the drum in dotted line. Near to the bottom 1b of the drum the mixing drum further exhibits an assembly opening which can be closed by a cover 6a.

A spray pipe designated as a whole by 7 is coupled via a rotatable coupling 9 to a waterpipe 8 entering through the mouth of the drum. Aflexible connector 8a is arranged between the coupling 9 and the waterpipe 8. The coupling point lies on the imagin arylongitudinal centre line of the mixing drum 1. In the region of the coupling 9 the spray pipe exhibits a first spray nozzle 10 which is directed into the interior of the drum approximately in the direction of the longitudinal axis. From the connection coupling 9 an arm 7a of the spray pipe running radially to the axis of the drum extends as far as the inner wall la of the mixing drum 1 and the spray pipe 7 and runs from there steadily along against the inner wall down to the bottom lb of the drum.There it exhibits a second spray nozzle 11 which is directed approximately towards the shaft 4 of the mixing tool 3.

In the region of the bottom half of the mixing drum a number of nozzles 12 are arranged spaced apart along the spray pipe. Their construction appears from the enlarged detail drawing in Figure 2. Each nozzle 12 is made as a piece of pipe projecting from the spray pipe into the interior of the drum and closed off from the interior of the drum. At a distance from the end of the piece of pipe it is surrounded by a ring of holes 13 drilled radially, through which the water can escape. For protection against soiling and clogging by the contents of the drum each nozzle 12 exhibits a rubber cap 14 which lies against the piece of pipe and covers it over about up to the spray pipe 7. The rubber cap 14 acts as a valve: the water escaping from the drilled holes 13 raises if far enough for the water to arrive in the interior of the drum.

The number, spacing and arrangement of the nozzles may vary depending upon the remaining construction of the drum. For a particularly rapid water feed more than one spray pipe may also be arranged against the inner wall of the drum. The construction of individual nozzles may likewise vary.

The example shown in particularly simple in construction and in its manner of working. But nozzles with other outlet openings and/or protective valves may be conceived within the scope of the invention.

Claims

1. A concrete-mixer having a rotatable mixing drum with conveyor components on the inner wall of the drum, a driven mixing tool which projects into the drum from the bottom of the drum and which is supported from the bottom of the drum, and spray piping for water entering the drum through the mouth of the drum characterized in that the spray piping is connected in the region of the mouth of the drum to a rotary coupling which is arranged, in use, to be connected to an external water supply, the spray piping extending in the drum along its inner wall as far as the bottom of the drum and being provided at least adjacent to the bottom of the drum with a spray nozzle.

2. A concrete-mixer according to claim 1, characterized in that a flexible connector is connected between the coupling and a water supply.

3. A concrete-mixer according to claim 1 or claim 2, characterized in that the spray piping in the drum is provided with a number of nozzles arranged spaced apart.

4. A concrete-mixer according to claim 3, characterized in that the nozzles are arranged predominantly in the bottom half of the drum.

5. A concrete-mixer according to claim 3 or claim 4, characterized in that the nozzles are made as pieces of pipe branching from the spray piping into the interior of the drum, closed at their free ends and having a circumferential ring of drilled holes.

6. A concrete-mixer according to claim 5, characterized in that the nozzles are each provided with a hoodlike rubber cap to act as a valve.

7. A concrete-mixer according to any one of the preceding claims, characterized in that the spray piping has a number of pipelines arranged with approximately axial symmetry.

8. A concrete-mixer according to claim 1, sub stantiaily as described with reference to the accompanying drawings.