GB2128713A - Vibrator unit and apparatus for reclaiming particulate material including such a unit - Google Patents

Abstract

Material for reclaiming is loaded into a tub 12 resiliently mounted on a base. A motor 17 rotates an out-of- balance weight assembly 15 journalled on the tub 12, so that the latter follows the resultant gyratory movement of the assembly 15. The material is thus vibrated, enabling foreign bodies to be dislodged therefrom and removed. As shown, the material to be reclaimed is foundry sand, lumps of which are broken down by the vibration to pass through coarse and fine sieves 22, 23. Bottom 24 of the tub acts as a conveyer, moving the sand under an adjustable wall 26 into a chamber 27 where airjets 31 agitate it, light particles being carried off at 33. The sand passes through a further sieve 35 to a bin 37. The out-of- balance weight assembly 15 includes sector-shaped weights each with a split clamping portion by which it is clamped to a drive shaft, (Figs 3,4, not shown). <IMAGE>

Description

SPECIFICATION Vibrator unit and apparatus for reclaiming particulate material including such a unit The present invention relates to a vibrator unit, and to apparatus including such a unitfor reclaiming particulate material from such material which is mechanically bonded together. The invention isap- plicable particularly, but not exclusively, to the breaking down offoundry sand where particles of sand are bound together by a binder material such as resin or sodium silicate.

It is known to break down foundry sand by process of crushing, heating, washing or attrition. Commercially available methods of reclaiming sand by attrition utilise a vibrator unit to vibrate a tub in which the foundry sand to be broken down is located. Large amounts ofpowerare however required to drive the vibrator unit due to the large bulk of the tub.

It is an object of the present invention to provide a vibrator unit suitable for use with material recaiming apparatus which is more economical to operate.

According to a first aspect ofthe present invention, there is provided avibrator unit comprising a motordriven shaftwhich carries at least one out-of-balance weight, a gyratory motion being imparted to the shaft by the rotation of the out-of-balance weight or weights in use.

Preferably, the motor drives the shaft by way of a drive eiement (such as a pulley) which is axially interposed between at least two such out-of-balance weights.

Conveniently, the or each out-of-balance weight comprises a sector-shaped portion and a clamping portion whereby the weight is attached to the shaft.

The sector-shaped portion may, for example, be generally semicircular. In orderto minimise induced stresses, peripheral transitions between the sectorshaped portion and the clamping portion are desirably smoothly radiussed.

In a preferred construction, the or each out-of balance weight includes a aperturethrough which the shaft is received, and the clamping portion comprises a radial projection which is slotted so asto define a pair of arms and means operative to clamp the pair of arms together, the slot in the radial projection opening into said aperture. The or each out-of-balance weight can be keyed against rotation relative to the shaft by means of a recess whiich opens into said aperture and which engages a projection on the shaft, the recess preferably opening into said aperture at a point diametrically opposed to said slot in the radial projection.

The or each out-of-balance weight can also have holes therein, by means of which additional weights can be secured thereto.

According to a second aspect ofthe present invention, there is provided apparatus for reclaiming particulate material, comprising a base, a vessel resiliently mounted on the base and adapted to receive said material therein, and a motor-driven shaft rotatablyjournalled on the vessel and carrying at least one out-of-balance weight, whereby a gyratorymo- tion is imparted to the vessel as the assembly ofthe shaft and weight orweights is rotated in use.

Advantageously, the motor is mounted on the base (preferably resiliently so) and is connected to the shaft by a flexible drive connection, such as an endless belt.

In a particular embodiment of the invention, the vessel includes a compartment in which said material is received for reclaiming, one or more screens positioned at the bottom ofthe compartmentfor grading the particles of said material, a conveyor plate extending at an angle to the horizontal upwardly from a location beneath said screen or screens, classifying means provided at an upper end of the conveyor plate for separating relatively light particles from relatively heavy ones, and discharge ports through which the relatively light and relatively heavy particles are respectively discharged. The classifying means may comprise means operative to circulate a gas (e.g. air) through said material.

The invention will now befurtherdescribed, by way ofexample only, with referencetothe accompanying drawings, in which: Figure lisa side elevational view of apparatus for reclaiming particulate material, according to the present invention; Figure 2 is a sectional side view of the apparatus shown in Figure 1; Figure 3 is a perspective view of an out-of-balance weight assembly which forms part ofthe apparatus shown in Figures 1 and 2; and Figure 4 is an axial view of an imbalance weight which forms part of the vibrator assembly shown in Figure 3.Referring first to Figure 1,the illustrated appartuscomprises a base 10formedfrom rectangular hollow section metal, to one end of which a support post 11 is fixed. A reclaim vessel or tub 121s mounted upon both the base 10 and the post 11 by means of respective resilient mounts 13. In the illustrated embodimentthe mounts 13 consist of springs: however, it is possible to use a resilient material (such as plastics or rubber) as an alternativeto this. The reclaim tub 12 is generally oftriangularconfiguration, although an outer shell thereof has flanges 14which dependfromthetubproper. Rotatablyjournalledon the flanges 14 is an out-of-balance weight assembly 15 which is driven through an endless belt 16 or the like by a motor 17 (preferably an electric motor).The motor 17 is supported on the base 10 by resilient mounts 18, such as pads or springs, and its position relative to the base 10 can be varied by means of an adjuster 19, thereby enabling the tension in the belt 16 to be adjusted.The motor 17, the endless belt 16 and the out-of-balance weight assembly 15 (which will be described in detail later on) together form a vibrator unitwhich is operable to gyrate the reclaim tub 12 relative to the base 10. Typically, the motor 17 operates at a speed of about 1420 r.p.m. and drives the weight assembly 15 at approximately 960 r.p.m. To hold the reclaim tub 12 rigid against distortion under this gyratory motion, internal stiffening members 20 are provided.

Referring now also to Figure 2, the reclaim tub 12 includes a compartment 21 in which material to be reclaimed (such as foundry sand) is received. A bottom wall ofthis compartment is formed by two superimposed screens 22 and 23 which serveto grade particles ofthe material as they pass therethrough.

The upper screen 22 is relatively coarse, and may for example have an aperture size of 2 inches (5.1 cm) while the lower screen 23 is relatively fine, typically having an aperture size of 1/4 inch (0.6 cm). A conveyor plate 24 extends obliquely upwardly from beneath the screens 22 and 23, and the gyratory motion ofthe tub 12 is such that the graded particles are conveyed upwardly along this plate. A partition 25forming a forward end wall ofthe compartment 21 has its lower edge positioned so asto define an adjustable weir26 which restricts the rate at which the particles are conveyed to the upper end ofthe plate 24.

On the opposite side ofthe partition 25to the compartment 21, the reclaim tub 12 has a classifying chamber27 to which compressed air is supplied by way of a regulator28, a pressure gauge 29, afilter 30 and a distributor 31. The distributor31 directs low pressure jets of the compressed air into the particles being conveyed upwardly along the plate 24, thereby producing aturbulent motion ofthese particles as indicated by arrows 32. Relatively light particles are carriedbytheairstream out of the chamber27 through an extraction spigot 33 as indicated by arrows 34, while relatively heavy particlesfail back onto the conveyor plate 24.

Atthe upper end ofthe conveyor plate 24,there is disposed a further screen 35 made of stainless steel wire mesh and typically having a mesh size of 3/32 inch (0.23 cm) and an aperture density of 56/sq. in.

(8.7/sq. cm). The particles falling through this screen 35 pass through an outlet 36 from the reclaim tub and into a secondary classifying chamber37where air is also passed therethrough. Any relatively light particles still remaining are conveyed bythe air stream through an extraction spigot 38, as indicated by arrows 39, while the relatively heavy particles accumulate in th e the chamber37forsubsequent re- moval.

When used to reclaim foundry sand, the apparatus described above operates in thefollowing manner.

Foundry sand to be processed is loaded into the compartment21 inthetub 12: in addition to having its particles bonded together by a material such as resin orsodium silicate, the sand will normally contain foreign bodies such as tramp iron, slivers of metallic flash, core wires and nails, paper and timber. Vibration ofthetub 12 bymeansof motor 17 andthe out-of-balance weight assembly 15 causes the bonded sandparticlesto breakdown asthey pass successively through the screens 22 and 23. Small foreign bodies will also be able to pass th rough the screens, although larger bodies will remain inthe compartment 21.

After passing through the screens 22 and 23, the vibratory motion of the tub causes the sand particles to be conveyed upwardly along the plate 24 into the classifying chamber 27, the flow rate of the particles being regulated by the weir 26. In the chamber27, the particles are agitated by the low pressure airjets, which create turbulence in this area. The fine sand particles (being relatively heavy) fall through the fine screen 35 and are discharged into the secondary classifying chamber 37 for eventual collection in a pressure vessel. The sand maythen be stored in a silo or re-used. Veryfineforeign bodies (such as resin shells which have been dislodged from the sand particles) remain in a suspended state and are carried awaythroughtheextraction spigot 33 forsubsequent filtration, collection and disposal.Dislodging of the resin shells is promoted by impingement of sand particles on the conveyor plate 24, as well as by collisions between the sand particles themselves.

Heavierforeign bodies fall onto the fine screen 35 but do not passtherethrough, being continually moved by the airjets so thatthey do not obstruct passage ofthe sand particlesthrough the screen. Periodically, these bodies can be removed by reverse operation ofthe vibrator unit, which conveys the bodies to the lower part ofthe tub 12 where they can be extracted through a door 40.Any fine foreign bodies carried over into the chamber 37 are removed through the extraction spigot38bytheairflowthrough chamber The balance of agitation, suspension and exhaust is controlled by tuning the volumeandsupply pressure of the compressed air, for example by means ofthe regulator 28 and/or by means of a blast gate coupled to the extraction spigot 33 and linked directly to fans of the filtration unit It is also desirable that, during initial setting up ofthe apparatus, the air jets are directed onto parts of the fine screen where accumulation of sand particles tends to occur.

Referring nowto Figures 3 and 4, the out-of-balance weight assembly 15 is composed of a shaft 41 whose ends are rotatablyjournalled on the above-mentioned flanges 14 on the reclaim tub 12. A pulley 42 is mounted centrally of the shaft 41 and has the endless belt 16 passed therearound (as indicated in chaindotted lines in Figure 3). A plurality of imbalance weights 43 are also mounted on the shaft 41, being disposed on opposite axial sides of the pulley 42.

Although only two such weights are shown, itwill be appreciated that a different number can be provided if desired.

As can be seen to advantage in Figure 4, each imbalance weight 43 is composed of a generally semicircularbody44having an integral clamping portion 45 by means of which the weight is secured to the shaft 41. Each clamping portion 45 is defined by a radial projection which is slotted at 46 to define a pair of opposed arms 47. These arms have aligned transverse openings 48 therein, through which a bolt orthe like can be passed to enablethe arms 47 to be clamped together. The shaft 41 is received through an opening 49 in the weight 43 onto which one end ofthe slot 46 opens, and the weight is keyed against rotation relativeto the shaft by means of a projection (now shown) on the shaftwhich locates in a recess 50 which opens onto the opening 49 at an opposed position to the slot 46. The peripheral transitions between the various parts of each weight 43 are smoothly radiussed so that a minimum of stress is induced therein during rotation. Reference number51 denotes holes through each weight 43 by means of which additional imbalance weights can be clampedthereto, for example in the manner depicted in ghost lines in Figure 3.

Claims (25)

1. Avibrator unit comprising a motor-driven shaft which carries at least one out-of-balance weight, a gyratory motion being imparted to the shaft by the rotation ofthe out-of-balance weight or weights in use.

2. Avibrator unit as claimed in claim 1,whereinthe motor drives the shaft byway of a drive element which is axially interposed between at least two such out-of-balance weights.

3. Avibrator unitas claimed in claim 1 or2, wherein the or each out-of-balanceweight comprises a sector-shaped portion and a clamping portion wherebytheweight is attached to the shaft.

4. Avibrator unit as claimed in claim 3, wherein the sector-shaped portion is generally semicircular.

5. A vibrator unit as claimed in claim 3 or 4, wherein peripheral transitions between the sectorshaped portion and the clamping portion are smoothly radiussed.

6. Avibrator unit as claimed in claim 3,4 or 5, whereinthe or each out-of-balance weight includes an aperture through which the shaft is received, and the clamping portion of said weight comprises a radial projection which is slotted so asto define a pair of arms and means operative to clamp the pair of arms together, the slot in the radial projection opening into said aperture.

7. Avibrator unit as claimed in claim 6, wherein the or each out-of-balance weight is keyed against rotation relative to the shaft by means of a recess which opens into said aperture and which engages a projection on the shaft.

8. Avibrator unit as claimed in claim 7, wherein the recess opens into said aperture at a point diametrically opposed to said slot in the radial projection.

9. Avibrator unit as claimed in any preceding claim, wherein the or each out-of-balance weight has holes therein, by means ofwhich additional weights can be secured thereto.

10. Apparatus for reclaiming particulate material comprising a base, a vessel resiliently mounted on the base and adapted to receive said material therein, and a motor-driven shaft rotatably journal led on the vessel and carrying at least one out-of-balance weight, whereby a gyratory motion is imparted to the vessel asthe assembiy ofthe shaft and weight orweights is rotated in use.

11. Apparatus as claimed in claim 10, wherein the motor is mounted on the base and is connected to the shaft by a flexible drive.

12. Apparatus as claimed in claim 11, wherein the motor is resiliently mounted on the base.

13. Apparatus as claimed in claim 11 or 12, wherein the flexible drive is an endless belt.

14. Apparatus as claimed in any one of claims lotto 13, wherein the vessel inciudes a compartment in which said material is received for reclaiming, one or more screens positioned at the bottom of the compartmentfor grading the particles of said material, a conveyor plate extending at an angletothe horizontal upwardly from a location beneath said screen or screens, classifying means provided at an upper end ofthe conveyor plate for separating relatively light particles from relatively heavy ones, and discharge ports through which the relatively light and relatively heavy particles are respectively discharged.

15. Apparatus as claimed in claim 14, wherein the classifying means comprise means operative to circulate a gas th rough said material.

16. Apparatus as claimed in any one of claims 10 to 15, wherein the motor drives the shaft byway of a drive element which is axially interposed between at least two such out-of-balance weights.

17. Apparatus as claimed in any one of claims 10 to 16, wherein the or each out-of-balance weight comprises a sector-shaped portion and a clamping portion whereby the weight is attached to the shaft.

18. Apparatus as claimed in claim 17, wherein the sector-shaped portion is generally semi-circular.

19. Apparatus as claimed in claim 17 or 18, wherein peripheral transitions between the sectorshaped portion and the clamping portion are smoothly radiussed.

20. Apparatus as claimed in claim 17, 18 or 19, wherein the or each out-of-balance weight includes an aperture through which the shaft is received, and the clamping portion of said weight comprises a radial projection which is slotted so as to define a pair of arms and means operative to clamp the pair of arms together, the slot in the radial projection opening into said aperture.

21. Apparatus as claimed in claim 20, wherein the or each out-of-balance weight is keyed against rotation relative to the shaft by means of a recess which opens into said aperture and which engages a projection on the shaft.

22. Apparatus as claimed in claim 21, wherein the recess opens into said aperture at a point diametrically opposed to said slot in the radial projection.

23. Apparatus as claimed in any one of claims 10 to 22, wherein the or each out-of-balance weight has holes therein, by means of which additional weights can be secured thereto.

24. Avibrator unit substantially as herein before described with reference to Figures 3 and 4 ofthe accompanying drawings.

25. Apparatus for reclaiming particulate material, substantially as hereinbefore described with refer encetotheaccompanying drawings.