GB2071343A - Automatic feed weighers - Google Patents

Abstract

Plant for delivering measured quantities of wet concrete to moulds 66 has a storage hopper 2 supplied, when the load in the hopper falls below a predetermined amount, from mixing plant 4. The storage hopper 2 has a vibrated outlet 10 discharging to a tray vibrator 12 and a weigh hopper 20. When a predetermined load of concrete has been discharged to the weigh hopper, a gate plate 30 is moved to allow the concrete to fall through an adjustable cross-section delivery chute 48 into moulds 66 on a conveyor belt 68, sequentially indexed to register with the chute. <IMAGE>

Description

SPECIFICATION Improvements in measured delivery means This invention relates to measured delivery means for a slurry material and, more particularly, to means adapted to deliver a variable but predetermined, load of wet concrete to a mould.

According to the present invention there is provided a measured delivery means for a slurry material including a storage hopper having an outlet supplying an independently supported vibratory feed means discharging to an independently supported weigh hopper, a gate controlled outlet from the weigh hopper discharging to a chute having front, rear and side walls adjustable in position to vary the chute discharge cross-section, load sensing means positioned to provide a signal indicative of the load of slurry within the weigh hopper, control circuitry arranged to compare the value of the signal from the load sensing means with a variable, pre-set value such that when the load signal is equivalent to the pre-set value actuation of the gate controlling the outlet from the weigh hopper is effected to permit the discharge of a load of slurry material.

The invention will now be described, by way of example, with reference to the accompanying, partly diagrammatic, drawings, in which: Figure 1 is a side elevation of a plant for the delivery of wet concrete to moulds on a conveyor belt; Figure 2 is a portion of Figure 1 to an enlarged scale; Figure 3 is a front elevation corresponding to Figure 2; and Figure 4 is a plan view corresponding to Figure 2.

As shown in Figure 1, a wet storage concrete hopper 2 is positioned below a concrete mixer outlet 4 and is pivotably supported on a framework 6 with a part of the reaction being taken on an electric load cell 8 giving an indication of the load of concrete in the hopper.

An outlet 10 from the hopper discharges to an electric tray vibrator feeder 12 resiliently mounted on a tubular frame 14 depending, through an adjustable connection 1 6 and a support frame 18, from the framework 6. The electric tray vibrator 12 feeds wet concrete at a controlled rate to a weigh hopper 20 resiliently mounted through torsion type electronic load cells 22 on a second tubular frame 24 depending, through an adjustable connection, from a support frame 26 on the framework 6. A pneumatic vibrator 28 is provided adjacent the storage hopper outlet, and the weigh hopper outlet is controlled by a pneumatically operated, sliding gate plate 30, with the pneumatic circuits interconnected such that the vibrator 28 operates only when the gate plate 30 is in an open position.

The gate plate 30 is carried on collars 32 sliding on guide rods 34 mounted on a pair of bracket plates 36 bolted to the weigh hopper adjacent the outlet. Each bracket plate carries a double acting pneumatic cylinder 38 having a lug 40 secured to an output shaft 42 bolted to one of the collars 32 connected to the gate plate 30, such that actuation of the pneumatic cylinders causes the gate plate to move between open and closed positions.

A pair of plates 44 are bolted to the inner faces of the bracket plates 36 and carry a short guide chute 46, of downwardly decreasing, rectangular horizontal cross-section, in register with the outlet from the weigh hopper. Subjacent the guide chute 46 is provided a rectangular cross-section delivery chute 48 formed by two pairs of co-acting chute plates 50, 52 each carried on a pair of threaded spindles 54, 56 welded to upper edges thereof.

The spindles 56 pass through the side plates 50 and the spindles 54 pass through front and rear extension plates 52, to permit the chute plates to pivot on horizontal axes. The threaded spindles 54, 56 are provided with short lever arms 58, 60 to facilitate pivoting of the chute plates, and lock nuts 62, 64 to fix the spindles in position once a required configuration of discharge cross-section has been attained. It will be appreciated that the chute plates may be interchanged to suit varying mould cross-sections as necessary.

Once set to an appropriate discharge crosssection configuration, the chute plates 50, 52 ensure an even discharge of concrete into an associated concrete mould 66 indexed into registration therewith on a conveyor belt 68 beneath the hopper.

The conveyor belt 68 is formed with projections 70, to position the moulds 66 longitudinally of the belt, and provided with adjustable guide plates 72, to position the moulds laterally of the belt. Drive to the belt is through a pneumatic cylinder 74 acting on an arm 76 attached through a ratchet device 78 to the conveyor drive shaft. A ram 80 is positioned to an unloading station to push filled moulds laterally from the conveyor belt and along a vibratory table to a stacking station, where baseboards are interposed to assist assembly of a stack. After about 24 hours the set concrete is removed from the moulds which are then washed and returned for delivery to the conveyor.

In operation, the chute plates 50, 52 of the chute are adjusted to conform to the form of a series of identical moulds 66 on the conveyor belt 68 and a control circuit receiving a signal from the torsional type electronic load cells 22 on the weigh hopper 20 is set to initiate discharge from the weigh hopper upon a pre-set loading appropriate to the moulds. Upon a mould being indexed in register with the weigh hopper outlet, the electric tray vibrator 12 and the pneumatic vibrator 28 are energised and wet concrete discharged from the storage hopper 2 to the weigh hopper 20.Upon the load in the weigh hopper reaching the predetermined value, the electric tray vibratory feeder 12 and the pneumatic vibrator 28 are de-energised (which effectively halts discharge from the storage hopper) and the gate plate 30 of the hopper is moved to the open position to discharge the concrete load to the mould. Upon the concrete load being discharged from the weigh hopper, the weigh hopper gate plate 30 is moved to the closed position, the conveyor belt is operated to index an empty mould to below the weigh hopper, the electric tray vibratory feeder is re-energised to recharge the weigh hopper and the sequence is repeated.

The filled mould is carried along on the conveyor belt 68 to the unloading station where it is moved laterally onto the vibratory table and thence to the stack.

The concrete load in the storage hopper is sensed by the load cell such that when a value corresponding to a pre-set minimum is reached a mixing and batching plant is put into operation to re-stock the storage hopper.

It will be appreciated that whilst an arrangement having but a singie weigh hopper has been described, a pair of weigh hoppers may be provided fed from a corresponding pair of electric tray vibratory feeders receiving concrete from dual outlets from the storage hopper and delivering concrete to moulds arranged in pairs on the conveyor. Similarly, more than one vibratory table may be utilised.

Further, where relatively small loads of concrete are required, with a correspondingly low rate of concrete feed, the operation of the electric tray vibratory feeder or feeders may be continuous, an allowance for the continuing feed to the weigh hopper during discharge being made in determining the pre-set value set on the control circuit.

Surfaces having reduced friction properties may be utilised to facilitate movement of the moulds and, indeed, the conveyor belt carrying the moulds into operation subjacent the weigh hopper and to the unloading station may be replaced by such surfaces together with pusher means to effect indexing and transfer of the moulds.

Claims (7)

1. A measured delivery means for a slurry material including a storage hopper having an outlet supplying an independently supported vibratory feed means discharging to an independently supported weigh hopper, a gate controlled outlet from the weigh hopper discharging to a chute having front, rear and side walls adjustable in position to vary the chute discharge cross-section, load sensing means positioned to provide a signal indicative of the load of slurry within the weigh hopper, control circuitry arranged to compare the value of the signal from the load sensing means with a variable, pre-set value such that when the load signal is equivalent to the pre-set value actuation of the gate controlling the outlet from the weigh hopper is effected to permit the discharge of a load of slurry material.

2. A measured delivery means as claimed in Claim 1 wherein a second control circuit is provided to compare a signal indicative of the load of slurry material in the storage hopper with a preset minimum value and upon the signal becoming equivalent to the value to originate a signal initiating replenishment of the storage hopper.

3. A measured delivery means as claimed in Claim 1 or Claim 2, wherein the storage hopper has dual outlets supplying a pair of vibratory feed means discharging to a pair of weigh hoppers, each having associated control circuitry and adjustable discharge cross-section chutes.

4. A measured delivery means as claimed in any preceding claim, wherein the storage hopper is provided with vibratory means adjacent the outlet thereof energisable during discharge of slurry material from the weigh hopper.

5. A measured delivery means as claimed in any preceding claim, wherein means are provided sequentially to index moulds into register subjacent the chute to receive a measured delivery of slurry and to transfer filled moulds to a vibratory table.

6. A measured delivery means as claimed in Claim 5, wherein a conveyor belt having longitudinal positioning stops for the moulds is arranged sequentially to index moulds past lateral positioning guides and into register subjacent the chute and from thence to a location at which lateral transfer of the moulds to the vibratory table is effected.

7. A measured delivery means arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.