GB2060910A - Weighing apparatus - Google Patents

Abstract

Apparatus for weighing predetermined amounts of material so that containers can be sequentially filled comprises a pair of balance assemblies (2, 3) with a chute (17) arranged above the assemblies (2, 3) for directing material into guide chutes (8, 9) to which the containers are releasably secured. Material is delivered into one of the containers and at the equilibrium position the balance assembly (2, 3) actuates power-operated means, conveniently a compressed air system to move the chute (17) to direct material into the container on the other balance assembly (3, 2). The filled container is removed and replaced during filling of the container on the other balance assembly (3, 2) whereby the filling operation can be repeated on a continuous basis. <IMAGE>

Description

SPECIFICATION Weighing apparatus The present invention relates to weighing apparatus.

In particular the present invention relates to weighing apparatus of the type used in the sequential filling of containers with a preselected weight of material. For this purpose, it is known to divert the flow of material from a first container to a second container when the first container has received the required amount of material and to replace with a further container while the second container is receiving material. A known weighing apparatus comprises two weighing platforms and a material feed chute to dispense material alternately into containers on the platforms. The feed chute is coupled by a mechanical linkage to the platforms whereby the chute is physically moved from one of the containers to the other of the containers when the contents of said one container reaches the predetermined amount.

This moving of the feed chute causes problems with the accurate location and fixing of the containers usually bags or sacks, thereto.

Also delays must necessarily occur whilst a filled container is released and the chute is moved to the next entrance to be filled.

The aim of the present invention is to provide an apparatus which is capable of dispensing predetermined amounts of material in a substantially continuous manner, it being possible to securely and accurately locate the containers to avoid spillage, such apparatus avoiding delays which previously occured whilst a container is detached before the chute can be moved.

According to the present invention a weighing apparatus comprises two balance assemblies operable alternately and successively to weigh predetermined amounts of material into containers, means for directing material to fall into the containers, and means for oscillating the directing means between first and second positions associated with the respective balance assemblies, such that when the predetermined amount of material is received in one container the associated balance assembly actuates switch means to thereby energise the oscillating means to move the directing means to its other position to allow material to fall into the container on the other balance assembly.

Preferably, the operation of the directing means is by a pneumatic control system.

The invention will now be further described, by way of example, with reference to the accompanying diagrammatic drawings; in which: Figure 1 is a side view, part section and part elavation, of one embodiment of a weighing apparatus according to the present invention; Figure 2 is a view in the direction of arrow A in Fig. 1; and Figure 3 is a pneumatic circuit diagram, which pneumatic circuit can control the apparatus of Figs. 1 and 2.

A weighing apparatus as illustrated in the accompanying drawings comprises a frame structure 1 to support two side-by-side and separate balance assemblies 2 and 3. Each balance assembly is arranged to pivot about a respective pivot axis 4 located in a base portion of the frame structure. Each balance assembly includes a platform 5 for supporting a container, such as a bag or sack, to be filled with a known weight of material and a platform 6 at the opposite side of the pivot axis 4 to carry a required known weight.

Each balance assembly further includes upright members 7 extending from or adjacent to the platform 5 to a funnel 8 located above the platform 5. The funnel 8 directs material to be weighed into a container on the platform 5. As mentioned the container can be a bag or sack with a filler neck at one corner therof which is adapted to fit about spout 9 of the funnel 8. A clamping means (not shown in Figs. 1 and 2) can be provided to clamp the neck of the bag about the spout 9. The platform 5 is inclined as shown in order to better support the bag thereon although it will be realised that the platform 5 can be substantially horizontal. The angle of inclination is adjustable, the platform 5 being pivotable about an axis 10 and having a clamping bracket co-operable with upright member 7.

The platform 6 for the weight can also pivot about an axis 1 2 and is maintained at all times and irrespective of the attitude of the balance assembly in a substantially horizontal plane by means of a stabiliser 1 3. The stabiliser 1 3 comprises a rod 1 4 pivotally connected at one end 1 5 to the frame structure 1. The opposite end of the stabiliser rod is pivotally connected to one end of a member 16 which is connected to the platform 6.

Material to be weighed can be fed under gravity into the bags from an overhead hopper (not shown). The material falls into an inclined chute 1 7 which is wider at its top end than at its bottom end. The chute pivots about a substantially vertical axis 1 8 whereby to direct material to fill a bag on platform 5 and then to fill another bag on the other platform 5.

During filling of a bag on one platform 5 the filled bag on the other platform 5 is removed and replaced with an empty bag. The bags are filled, removed and replaced in a continuous cycle of operation.

The material can fall through the chute 1 7 into a tray 1 9 having outlet channels 20 which extend into the mouths of the respective funnels 8.

A fine adjustment can be provided by an arm 21 carrying a weight 22. One end of the arm 21 is pivotally connected to the frame structure and the opposite end of the arm is pivotally connected to upright member 7. The weight 22 is set at a desired position on the arm 21 to compensate for any initial imbalance in the assembly.

The chute 1 7 is arranged to oscillate about its pivot in response to movements of the balance assemblies. The operation is controlled pneumatically as described with reference to Fig. 3. Each platform 5 in passing through its balance position actuates a valve to allow compressed air or gas to actuate a switch.

As the amount of material fed into a bag on the platform 5 approaches the weight on the platform 6 the balance assembly, which includes the respective funnel 8, will move and at the equilibrium position at which the contents of the bag equals the weight on the platform 6 the balance assembly actuates valve 23 mounted at a convenient position on the frame structure. A valve 23 is associated with each balance assembly. On tripping valve 23, compressed air is directed to one end of a switch 24. The switch is actuated to allow compressed air from supply line 25 to operate a so-called torque unit 26. The latter comprises a piston slidable in a cylinder to actuate a crank through a fixed degree of rotation.

Thus, linear motion of the piston under the influence of compressed air delivered through the switch 24 is converted into rotary movement about axis 18, the axis of the chute 17, as indicated by the arrows in Fig. 3. Thus the chute pivots in response to movements of the separate balance assemblies to direct material to fill successively first one bag and then a bag on the other platform 5. The bags are removed when filled and replaced with empty bags to maintain a continuous operation.

The clamping means mentioned hereinbefore for clamping the necks of the bags to the sprouts 9 can also be operated pneumatically.

Branch lines 27 (Fig. 3) supply compressed air to clamping means 28. The clamping means are actuated to alternatively clamp or release a bag by means of a manually operable valve 29 in each branch line.

Means can be provided to interrupt the supply of material in the event that filled containers occupy both of the balance assemblies. Again with reference to Fig. 3, branch lines 30 extend from the lines between the valves 23 and the switch 24 to further valves 31. The valves 31 are located in a line 32 from a pressure source 33 to a piston and cylinder assembly 34. The piston of the assembly is coupled to a closure plate which can slide across the flow path of the material to the chute 17.

Normally, the valves 31 exhaust to atmosphere thereby rendering the piston and cylinder assembly 34 inoperative. During normal filling operations the valves 31 are actuated alternately and in sequence and the assembly 34 remains inoperative as one of the valves is venting to the atmosphere at any one time.

However, if a filled container occupies each balance assembly the two valves operate to provide communication along the line 32 from the source 33 to the assembly 34. The piston is thereby actuated to slide the closure plate across the flow path of the material.

The pneumatic circuit can be replaced by an hydraulic arrangement. Alternatively, it is possible to utilise an electrical system incorporating solenoid valves and switches to control the movement of the chute in response to the weighing operations. In each case, the operation will be substantially the same as described above.

The apparatus can be used for weighing a variety of different kinds of materials. For materials which tend to stick and are difficult to flow, it is possible to include a powerassisted screw feed in the flow paths to the containers.

Claims (6)

1. A weighing apparatus comprising a pair of balance assemblies and means for dispensing material to be weighed into removable containers on said balance assemblies, said means alternately directing material from one of the containers to the other of the containers when a predetermined amount of material is received in the said one container, poweroperated means actuated by the balance assemblies when the said one container receives the predetermined amount of material to direct the dispensing means to discharge material into said other container.

2. A weighing apparatus according to claim 1, in which the power-operated means comprises a pneumatic pressure system, said system including valve means operable by the balance assemblies, switch means responsive to operation of said valve means and means for oscillating the dispensing means between the containers under the control of said switch means.

3. A weighing apparatus according the claim 2 in which said oscillating means comprises a piston and cylinder assembly and a crank movable by the piston coupled to the dispensing means, the switch means directing pressure fluid sequentially to opposite ends of the cylinder to effect reciprocable movement of piston thereby causing the crank to oscillate and move the dispensing means through the fixed arc.

4. A weighing apparatus according to claim 2, including pneumatically operable clamping means for releasably securing containers on the balance assemblies.

5. A weighing apparatus according to claim 2, in which the pressure fluid system incorporates means for interrupting flow of material when the container on each of the balance assemblies receives the predetermined amount of material.

6. A weighing apparatus constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.