GB2046608A

GB2046608A - Discharging a mixer having a rotatable drum

Info

Publication number: GB2046608A
Application number: GB8010505A
Authority: GB
Original assignee: ZYKLOS MASCHINENBAU GmbH
Current assignee: ZYKLOS MASCHINENBAU GmbH
Priority date: 1979-04-02
Filing date: 1980-03-28
Publication date: 1980-11-19
Also published as: GB2046608B; FR2452961A1; FR2452961B1; DE2913195A1

Abstract

A guide vane 17 is lowered to deflect the mixture towards a discharge aperture 19 on anti-clockwise pivotal movement of a lever 15 on which the vane is supported. A throttle 29 controls the speed at which the vane is lowered and hence the discharge speed of the mixture. <IMAGE>

Description

SPECIFICATION Mixer with a revolving tub The present invention relates to a mixer having a rotatable tub or drum, mixing vanes rotatable about an axis parallel to the rotary axis of the drum and an emptying aperture formed in the centre of the drum and closable by a bottom flap.

It is known to empty such a mixer by opening the base flap and by lowering a guide vane, which during the mixing was raised above the material being mixed, into the material being mixed so that the material contained in the revolving drum is conducted towards the base flap opening.

One has thus been content to move the base flap and guide vane from one end position into the other and to collect the outflowing mix in a transportation container and to convey it to the point of use. This arrangement led to disturbances in many cases. The outflowing quantity often varied in accordance with the flowability of the mix and fluctuated considerably - especially with a fairly solid mix. If, for example, a concrete transport container was to be filled, the quantity outflowing from the container could at times be greater than the absorbing ability of the container. The mixed material on the other hand, when it is relatively viscous, exerted a considerable resistance on the guide vane, so that the latter descended only slowly and the mixe was discharged too slowly.In mixes containing foam, non-uniform and occasionally excessive dropping out of the mix led to the foam being partially destroyed and the mix becoming undesirably wet and dense.

It is an object of the present invention to conduct the mix material with varying compositions in such a manner that whilst maintaining its consistency it is discharged from the mixer so that it may be further used without impairment, but with the operations occurring as fast as possible.

According to the present invention there is provided a mixer having a rotatable tub or drum, mixing vanes rotatable about an axis parallel to the rotary axis of the drum and an emptying aperture formed in the centre of the drum and closable by a bottom flap, wherein adjusting means are provided by means of which the emptying speed of the mixer may be regulated.

The advantage of the mixer device of the invention is that, depending upon the mixture used, action thereon may be in such a manner that the quantity outflowing in a certain time corresponds to the required use and that the outflow does not impair the quality of the mixture.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which Fig. 1 is a part cross-section through a mixer having a hydraulic circuit in simplified illustration and Fig. 2 is a plan view of the mixer of Fig. 1 partly in section along the line ll-ll of Fig. 1.

A mixer is illustrated having a drum or tub 1, which is supported on a frame 3 via ball bearing 2. A machine housing 5 is mounted on the frame 3, is pivotal about an axis 4 and has an arm 6 extending over the tub 1. Housing 5 contains a motor 7 which, via a drive belt 8, drives a shaft 9 which has four mixing vanes 10 mounted thereon. A scraper 11 is secured to the arm 6 and projects along the wall of the tub 1 almost to the base.

A double acting lifting cylinder 12 is mounted in the arm 6 and has a lever 15 connected on its piston or connecting rod 13. The lever 15 is pivotal about an axis 14 and supports a guide vane 17 on an upright arm 16.

An outlet aperture 19 is provided in the centre of the base 18 of the tub 1 and in the position shown the aperture 19 is closed by a base flap 20 which is mounted on a lever 21. The lever 21 is mounted on the frame 3 and connected to the connecting rod of the lifting cylinder 22. A hopper 23 adjoins the emptying aperture 19 and extends downwardly therefrom with its lower end being located closely above a conveyor type balance or weigher 24 which has an indicating and transmitter device 25.

Two conduits 26, 27 lead from the lift cylinder 12 to a switching valve 28. Incorporated in the conduit 27 are a variable throttle 29 and a non-return valve 30 opening in the direction towards the switching valve 28. Moreover, a pump 31 and a return 32 which leads to a container 33 are connected to the switching valve 28. A suction conduit 34 of the pump 31 emanates from the container.

When mixture 35 is charged in the tub 1 and the mixing vanes 10 rotate, the vanes engage the tub 1 via the mix and the vanes mix the mixture which accumulates in the outer region of the tub. The mixture is diverted by the scraper 11 from the wall of the tub and returns thereto, is engaged by the mixing vanes 10 and intensively circulated. During this operation additives or also foam agents may be added and the mix may, for example, be concrete, but also sand, plastics material orthe like.

When the mixing operation is terminated, the bottom flap 20 is opened by means of the lifting cylinder 22. Since the mixture 35 for a greater part circulates outside of the region of this flap, only a small quantity is conveyed by the mixing vanes 10 to the emptying aperture 19. The mixture is discharged over the inside wall surface of the hopper 23 and then onto the conveyor type weigher 24 and then to a container or to a processing position (not shown).

At the same time, the switching valve 28 is switched so that it connects the pump 31 with the conduit 27 and the conduit 26 with the return 32. The connecting rod 13 is thereby retracted, the lever 15 are pivoted in anti-clockwise direction and the guide vane 17 is lowered. The vane 17 engages the mixture 35 deflected inwardly by the scraper 11 and conducts it towards the the emptying aperture 19. The throttle 29 is so adjusted that the guide vane 17 is lowered at a predetermined speed independent of the resistance which it finds when entering the mixture. This speed is so adjusted, that the outflowing quantity is uniform and so measured as it can be removed at the conveyor type weigher. There is prevented any brief excess discharge of mixture or the falling of any heavy parts on top of one another to cause any foam mixed therein to be burst.

If the tub is empty, the loading on the conveyor type weigher 24 returns to 0. It then switches the switching valve 28 over such that the pump 31 feeds into the conduit 26 and the conduit 27 feeds into the return 32. The connecting rod 13 is thereby rapidly thrust out, the pressure medium is discharged, unthrottled through the conduit 27 via the nonreturn valve 30. The guide vane 17 is raised and thereby lifted out again. When having reached its upper dead end position, the switching valve 28 is so adjusted in known manner (not shown) that the pump 31 is connected directly to the return 32, and the conduits 26 and 27 are shut down. The bottom flap 20 has in the meantime been closed. New mixture may be charged and the working cycle repeated.

The adjustment of the throttle 29 depends upon the kind of material being mixed according to its desired consistency and possibly special conditions.

The throttle 29 may be adjusted in accordance with values experienced. By this there is achieved the discharge of the mix in a predetermined flow-stream, which, for example, is adapted to the capacity of a connected container or a conveyor device and is so gauged that the condition of the mix is not adversely affected.

It may, however, also be expedient to automatically control the throttle 29, by making such, for example, dependent upon the momentary load of the convor type weigher 24. This would permit the outflowing stream of mix to be accurately controlled.

Instead of actuating the lifting cylinder 12, controlled or regulated in the manner stated, or in addition to such actuation, the lifting cylinder 22 may be operated in the same manner. The bottom flap 20 then opens only far enough for the outflowing stream of mix having the predetermined strength and uniformity. The lifting cylinder 22 then has a hydraulic circuit corresponding to the circuit shown associated therewith. Its throttle in turn may be adjusted in accordance with values obtained through experience or be influenced by the conveyor type weigher 24 or by suitable transmitters.

Quantity regulating valves may be provided instead of throttles-especially when the conduit pressures fluctuate noticeably. The conveyor type weigher may also be replaced at the outlet by storage and conveyor means of known kind.

Claims

1. A mixer having a rotatable tub or drum, mixing vanes rotatable about an axis parallel to the rotary axis of the drum and an emptying aperture formed in the centre of the drum and closable by a bottom flap, wherein adjusting means are provided by means of which the emptying speed of the mixer may be regulated.

2. A mixer as claimed in claim 1, in which the emptying speed is adjustable in accordance with required values.

3. A mixer as claimed in claim 1, in which the emptying speed is regulatable dependent upon the measuring values, more especially the quantity of mixed material discharged per unit time.

4. A mixer as claimed in any of the claims 1 to 3, in which the bottom flap may be opended by means of a lifting cylinder, which is supplied with pressure medium via a controllable switching valve and by a variable throttle.

5. A mixer as claimed in any of the claims 1 to 4, in which a guide vane is mounted in the drum, which vane acts to conduct the mix from areas close to the edge to the emptying aperture, and in which the guide vane is vertically adjustable and connected to a double acting lifting cylinder which is supplied with pressure medium via a switching valve and a controllable throttle.

6. A mixer as claimed in claim 4 or 5, in which a balance is provided for measuring the outflowing mix and is adapted to control the throttle.

7. A mixer device substantially as herein described with reference to and as illustrated in the accompanying drawings.