WO1993023223A1

WO1993023223A1 - Apparatus for preparing and pumping flowable composition

Info

Publication number: WO1993023223A1
Application number: PCT/SE1993/000450
Authority: WO
Inventors: Jan Olof Cedermark
Original assignee: Abs Byggsystem Aktiebolag
Priority date: 1992-05-19
Filing date: 1993-05-19
Publication date: 1993-11-25
Also published as: SE9201569L; SE470282B; SE9201569D0; AU4099993A

Abstract

An easily dismantled, mobile mixer pump for preparing screed, stopping, plaster, mortar or like materials at local sites includes a pipe (10) which is inclined to the horizontal. The pipe has a section (10) which communicates with a dry, particulate material receiving hopper (2). The pipe section (10) includes a feed screw whose lower end is connected to an agitator in a further pipe section (11) downstream of the pipe section (10). The agitator, in turn, is connected to the rotor of a monopump, which is connected to the downstream end of the agitation chamber. A single motor (4) connected to the upper end of the pipe (1) drives the rotary elements. The mixing chamber (11) has a smaller diameter than the feed screw in the pipe section (10). The downstream wall (202) of the hopper (2) is inclined at an angle of less than 25° to the vertical.

Description

APPARATUS FOR PREPARING AND PUMPING FLOWABLE COMPOSITION

The present invention relates to apparatus for prepa¬ ring and pumping flowable material, particularly such flowable material as screed (also referred to as

"selflevelling screed") , plaster, mortar or like mate¬ rial, of the kind defined in the preamble of Claim 1.

The invention is based on known apparatus of the kind manufactured by Applicants and designated "mixer pump 855".

This known mixer pump is constructed so that it can be transported easily and comfortably to and from small working sites/user sites and so that it can be easily worked and has the lowest possible degree of complex¬ ity, in order to minimize malfunctioning risks. More specifically, the mixer pump is constructed from a number of light parts which can be dismantled so as to enable the mixer to be readily transported in a small vehicle, for instance an estate car or like vehicle, and so that it can also be transported readily in lifts, elevators or carried manually up flights of stairs.

The known mixer pump is comprised mainly of a pipe which is supported on a frame structure at an angle of about 45° to the vertical.

Mounted on the upper end of the pipe, coaxially there¬ with, is an electric motor which is fitted with a torque stepping gear and which drives a feed screw fitted in the pipe.

The upper half of the pipe is removed along the screw, so as to expose the screw to a receiving hopper which communicates with the opening thus formed and into which sacks of dry powder mixture are emptied manual- It is preferred that the upper edge of the hopper is located at a convenient height above the floor, for instance a height of about 100 cm. The hopper must be capable of accommodating about 50 litres, corresponding to the contents of about two sacks.

The pipe has a diameter of about 15 cm. Downstream of the pipe opening communicating with the hopper is a mixing chamber which includes an agitator, which is connected to the feed screw, and an adjustable water supply connection. The pipe includes downstream of the preparing chamber a pump, suitable a so-called monopump, which comprises a helical rotor which extends in a surrounding, deformable helical chamber comprised of an elastomeric material. The pump rotor is connected to the agitator. The motor drives the feed screw and thereby all rotary parts in the pipe.

The known mixer pump is primarily intended for preparing and pumping surface smoothing materials (filling and stopping materials) which contain a relatively fine particle fraction.

Certain drawbacks have been encountered with this known mixer pump. For instance, the dry particulate material emptied into the hopper tends to clog and arch in said hopper and around the screw, thereby varying the amount of material that is advanced by the screw which, in turn, causes variations in the water content and the consistency of the prepared material.

These drawbacks become even more pronounced when at- tempting to prepare with the aid of the known mixer pump materials of relatively coarse fraction, for instance in the preparation of plaster or mortar.

It is true that the aforesaid problems can be alleviated by mounting a separate motor or drive in connection with the hopper, and to provide some form of agitator, but these additional features have been found incompatible with the requirements of minimum complexir.y, ready access and high reliability of the mixer pump.

Another drawback with the known mixer pump lies in the unfavourably high and varying air content of the dry particulate material fed into the mixing chamber, which also has a detrimental effect on the moisture content, manageability and final properties of the prepared material.

The object of the present invention is to reduce the aforesaid drawbacks with a mixer pump of the kind de¬ scribed.

The object also includes the ability of the mixer pump to prepare plaster and mortar.

This object is achieved by means of the invention de¬ fined in the following Claim 1.

Embodiments of the invention are defined in the subordinate Claims.

Starting from the apparatus (the ABS mixer pump 855) described in the introduction, the invention is mainly characterized in that the free cross-sectional area of the feed screw is larger than the area of the inlet to the preparing chamber. Starting from the known mixer pump, according to one embodiment of the invention the diameter of the mixing chamber is at least 10% smaller than the screw diameter, which coincides essentially with the inner diameter of the pipe cross-section sur¬ rounding the screw. The hopper is open to the pipe along a length of, e.g., 40 cm, and the particulate material is fed by the screw to the location of the step formed by the change in diameter, where a part of the flow is forced back in an upward/rearward direction. This return flow will break-down any bridges or arches that may have formed in the particulate material immediately above the screw itself, and will also break-down any bridges and collections of particulate material that may have formed in the relatively narrow underpart of the hopper. As a result of this backflow of particulate material, the feed screw is filled more effectively, which, in turn, reduces the air content of the particulate material flow driven into the preparing chamber. Deaeration of the particulate material is also improved generally, as a result of the agitation established in the particulate material in the lower part of the hopper.

To avoid the risk of particulate material collecting on the downstream wall of the hopper, it is proposed in ac¬ cordance with an advantageous further development of the invention that this wall is inclined at a steeper angle than normal, i.e. is brought closer to the vertical plane. With regard to the necessary volume of the hopper, however, this increased steepness of the downstream hopper wall necessitates moving the connection of this wall with the pipe downwards meaning that the pipe must be lengthened in order to provide space for the mixing chamber and the pump. Consequently, it is proposed in accordance with the invention that the angle of the pipe to the horizontal plane is decreased to a value of beneath 45°, for in¬ stance to a value of about 35°, in order to be able to maintain the upper edge of the hopper at the level applicable to the known mixer pump.

The invention will now be described in more detail with re erence to an exemplifying embodiment thereof and also with reference to the accompanying drawings. in which

Figure 1 is a schematic side view of an inventive mixer pump; Figure 2 is a schematic horizontal sectional view taken on the axis of the mixer pump pipe; and Figure 3 is a schematic sectional view taken on the line III-III in Figure 2.

The mixer pump includes a pipe 1 which is inclined at an angle β to the plane of the floor 36. β is smaller than 45° and preferably about 35°. The pipe 1 includes a first pipe section 10 to which a filling hopper 2 is connected. The upper part of the first pipe section 10 is removed within the region in which the hopper 2 is connected.

Downstream of the first pipe section 10 is a second pipe section 11 which extends coaxially with the pipe section 10 and forms a preparing chamber. Downstream of the second pipe section 11 is a third pipe section 12 which extends coaxially with the second pipe section and houses a monopump to which an outlet 16 is connected. A motor 4 is connected to the upper end of the pipe 1, with the driving output shaft of the pump extending coaxially into the pipe 1. The first pipe section 10 houses a feed screw, while the second pipe section 11 houses an agitator 110. The motor 4 is connected to the shaft 101 of the feed screw 100 by means of a coupling 42, whereas the shaft 101 is, in turn, connected to the agitator 110 by means of a coupling 111. The agitator 110 is connected, in turn, to the rotor 122 of the monopump by means of a coupling 112. The motor 4 is a combination of an electric motor and a torque stepping, speed-reducing gear, drives all rotating parts of the mixer pump. The pipe 1 is distanced from the floor 36 by means of a stand structure which includes a pair of front support legs 33 which are connected to the pipe 1 by means of a coupling 37 which enables the legs to be collapsed or removed. The stand structure 3 also includes a housing 31 which houses the coupling components and connection lines for the electric motor 4. The housing 31 is connected to the upper end-part of the pipe 1 by means of a coupling 35 which enables the housing to be removed or collapsed relative to the pipe 1. The housing 31 may be supported on wheels 32, to facilitate local transportation of the apparatus. The frame parts 31, 33 may be braced by means of removable and/or collapsible braces 34.

The two walls 201, 202, 203 of the hopper are inclined at a relatively small angle to the vertical plane, while the wall 202 located downstream of the pipe 1, as seen in the transport direction, is inclined at an angle to the vertical plane in accordance with an inventive modification of the known mixer pump. The angle a is smaller than 30° and is preferably from 5- 10°, wherein an angle of 10° has been found convenient in a tested embodiment of the invention.

The remaining walls of the hopper 2 are also conveniently angled to the vertical plane at an angle smaller than 20° on average.

The motor 4 is attached to the first pipe section 10 by means of a quick-release clamping device 41, and the second and third pipe sections 11 and 12 are also

connected to the pipe section 10 by means of a quick- release clamping device 14. The fact that the apparatus can be dismantled quickly and simply also enables the apparatus to be cleaned quickly and simply, which is particularly beneficial with regard to self-curing or self-hardening materials.

The output shaft of the motor 4 may rotate at a speed of 250 rpm, for instance, wherein the pump 12 will have a commensurate outflow of about 20 litre/ in. The transport capacity of the screw 100 is much greater than the flow through the preparing chamber 11 and through the pump 12, so as to provide a feed pressure into the chamber 11.

In accordance with one important feature of the inven¬ tion, however, the diameter of the first pipe section 10, which closely surrounds the bottom part of the periphery of the screw 100, is larger than the inlet opening to the mixing chamber 11. Consequently, the peripheral layer of particulate material driven by the screw 100 towards the preparing chamber 11 will be deflected by the step 101 formed by the change in diameter between the pipe sections 10 and 11 and driven upwards and backwards. This deflected flow tends to break-down bridges and arches that form in the particulate material and also results in agitation of the material in the hopper, thereby filling the upstream parts of the screw to a better extent and improving deaeration of the particulate material flowing into the screw.

In accordance with a preferred embodiment of the invention, the first pipe section 10 has an internal diameter of 150 mm while the second pipe section 11 has an internal diameter of 125 mm, meaning that the cross-sectional area of the pipe section 11 is 70% of the cross-sectional area of the screw 100. When the particulate material lying within the screw is advanced at a uniform axial speed, the peripheral parts of the particulate material that are deflected by said shoulder 101 will represent about 40% of the flow of particulate material entering the preparing or mixing chamber 11.

The second pipe section 11 will preferably have an inner diameter which is at least 10% smaller than the inner diameter of the first pipe section 10. This diameter reduction is preferably at least 15% and more preferably at least 20%.

In the case of the illustrated embodiment, the screw 100 has a central shaft 101 which carries a helical ramp 102 whose edges extend close to the inner surface of the first pipe section 10. The shaft 101 of the illustrated embodiment is considered to have a negligible cross-sectional area.

The agitator 110 may be comprised of two mutually parallel and diametrically opposed rods located adjacent the inner wall of the second pipe section 11, and the water delivery conduit 116 includes a control valve by means of which the water content of the prepared material can be adjusted to a suitable value at the motor drive speed.

Claims

1. Apparatus for preparing and pumping pumpable material, such as screed, plaster, mortar and the like, by mixing a dry particulate composition with water, said apparatus comprising a filling hopper (2) which is intended to receive the dry particulate composition, a pipe (1) which communicates with the lower end-part of the hopper and which is inclined to the horizontal plane, wherein the pipe (l) has a pipe section (10) which is radially open to the hopper and forms the bottom thereof and which includes a feed screw (100) , a mixing chamber (11) arranged in the downstream pipe section (10) as seen in the feed direction of the screw (100), said mixing chamber including a mixing rotor having an adjustable water inlet (116) , a pump arranged downstream of the mixing chamber and functioning to pump away the prepared material, and a motor (4) mounted at the upper end of the pipe (1) and functioning to drive the feed screw (100) , the mixing rotor (110) and the rotor (122) of the pump (12) , c h a r a c t e r i z e d in that the free flow cross-sectional area of the feed screw (100) is larger than the area of the inlet to the mixing chamber (11) , so as to establish a return flow of particulate material along the screw through the hopper.

2. Apparatus according to Claim 1, c h a r a c - t e r i z e d in that the screw has an outer diameter which is at least 10%, and preferably at least 15% larger than the diameter of the inlet to the mixing chamber.

3. Apparatus according to Claim 1 or 2, c h a r a c

t e r i z e d in that the reduction in area in the material flow direction at the inlet to the mixing chamber is at least 20%, preferably at least 30%.

4. Apparatus according to any one of Claims 2-3, c h a r a c t e r i z e d in that the reduction in diameter results in a shoulder which generates a return flow of at least 20%, preferably at least 30% of the low of dry particulate material flowing into the mixing chamber (11) .

5. Apparatus according to any one of Claims 1-4, c h a r a c t e r i z e d in that the downstream wall (202) of the hopper (2) forms with the vertical an angle which is smaller than 25°, preferably smaller than 10°.

6. Apparatus according to any one of Claims 1-5, c h a r a c t e r i z e d in that the mixing chamber (11) is generally cylindrical and is coaxial with the pipe section (10) that contains the feed screw.

7. Apparatus according to any one of Claims 1-6, c h a r a c t e r i z e d in that the pump (12) is a monopump; and in that the apparatus motor (4) drives all of the mutually connected, rotary parts extending coaxially in the pipe (1), i.e. the feed screw (100), the mixing rotor (110) and the rotor (122) of the pump (12) .

8. Apparatus according to any one of Claims 1-7, c h a r a c t e r i z e d in that the pipe section (10) closely surrounds the underside of the periphery of the feed screw (100) ; and in that, seen in the feed direction of the screw, the pipe section (10) containing the feed screw has a reduced diameter at the transition from the hopper to the mixing chamber_^ (11) .