IES68082B2 - Bagging machine - Google Patents

Abstract

An automatic bagging machine includes a detector located near the open end of a bag and operable to detect the difference in density between flowing solid non-granular material entering the bag and stationary material in the bag so as to determine when the bag has been filled. The machine is particularly intended for use in bagging compost.

Description

The present invention relates to bagging machines for bagging .ion-granular bulky organic materials.

Many industries which produce granular material as an end product, for example the cereals, rice, sugar and other industries, make use of automatic bagging machines which fill successive bags with granular material so that each bag contains exactly the same quantity of material. For this purpose use is made of a weight sensor which detects when the bag has been filled with a predetermined weight of the granular material and which then stops further flow of granular material into the bag.

Turning now to the compost industry, the end product is a non-granular material which presents considerable difficulties in relation to bagging. The density, texture and moisture levels are very variable. This prevents the even filling of bags by means of a weighing mechanism.

The use of bags of compost for growing mushrooms has become increasingly widespread. The purchasers of such bags of compost require that the level of compost in each bag be consistent, that is to say require that the volume be consistent. Accordingly, use is made of bagging apparatus which requires an operative to determine by visual inspection when the level of compost in a bag has reached a predetermined level and then cuts off the flow of compost to the bag by means of a foot operated switch. This method is unreliable due to operator fatigue and operator lack of concentration, and is also expensive because of the labour costs involved.

The present invention provides a bagging machine for bagging solid non-granular material comprising a bag holding means for receiving a bag to be filled and for holding the bag in the open position, dispensing means for dispensing flowing solid non-granular material into the open bag, and a control system for determining when the bag has been filled and for cutting off the flow of material to the bag, characterised in that the control system includes a sensor to determine when the material In the bag has reached a certain level .

Preferably the bag holding means in operation suspends an open bag to be filled and the sensor is located relative to the bag holding means at a level a little below the level to which the bag is to be filled and is operable to detect the difference in density between flowing material entering the bag and stationary material within the bag and the control system cuts off the flow in response to detecting a change in the density.

Preferably the sensor employs an electromagnetic field.

Preferably the bag holding means is one of a number of such holding means arranged in a carousel and the control system is operable in response to detection of a change of density to rotate the carousel to bring another bag into line with the flow of material» The invention will now be described more particularly with reference to the accompanying drawings which show, by way of example only, one construction of bagging machine in accordance with the invention. In the drawings: - 3 Figure 1 is a perspective partially cut-away view of a part only of a carousel bagging machine, showing one bag being filled and another bag waiting to be filled; Figure 2 is a similar view, showing one bag being filled and showing the carousel mounting; Figure 3 illustrates a sensor used in the bagging machine; and Figure 4 illustrates a control circuit for the bagging machine.

Referring to Figure 1, a bagging machine comprises a first hopper 1, a second hopper 2, and four more hoppers (not shown). The six hoppers form a carousel. A first bag 3, a second bag 4 and four more bags (not shown) are attached one each to each hopper. A bag holding mechanism generally designated 5 is provided on each hopper. A single stationary conveyor 6 delivers compost to the carousel. As shown in Figure 1 the conveyor 6 is delivering compost to hopper 1 to fill bag 3. When the bag 3 has been filled to the desired level, the carousel rotates in the direction indicated by arrow A so as to bring the hopper 2 and bag 4 into position below the top of the conveyor 6. The filled bag 3 is then released and removed from the hopper 1 and is replaced by an empty bag. Release is accomplished by lifting handle 7 upwardly as indicated by arrow Bs causing handle 7 to pivot about pivot mounting 8 against the bias of spring 9 thereby moving bag-engaging bar 10 out of engagement with the bag 3. The conveyor δ continuously delivers compost, and bags are brought successively one after another into the flow path of the compost.

Referring to Figure 2, the carousel comprises a stationary central pillar 15, a drive mechanism (not shown) within the pillar, and a framework 14 which is mounted on and projects radially from the top of the pillar 15 and which supports the six hoppers and which is drivable in rotation by the drive mechanism. All the foregoing is well known in the prior art and forms no part of the invention.

Also shown in Figures 1 and 2 is a sensor 20. The sensor 20 is mounted on the stationary central pillar 15 below and facing towards 4' „ 4 the conveyor 6. In operation the sensor 20 remains stationary relative to the rotational movement of the carousel. The sensor 20 emits an electromagnetic field horizontally in a plane perpendicular to the vertically downward flow path of the compost material from the conveyor 6. As shown in Figure 1, bag 3 is being filled and compost material flows past the sensor 20 at a relatively low density. When the level of compost material in bag 3 reaches the level of the sensor 20, there is an immediate change in the density of compost material opposite the sensor 20. The electromagnetic field is able to detect this change in density. The sensor 20 then emits a signal which is sent to a control system (described below). After a short predetermined time delay which allows the remainder of bag 3 to be filled, the control system causes the carousel to automatically rotate so as to bring hopper 2 and bag 4 into position.

Referring to Figure 3, the sensor 20 is a capacitive proximity switch. The capacitive proximity switch comprises a compensation electrode 21, active electrode 22 and earth electrode 23 contained in a housing 24 and emitting an electromagnetic field 25. The capacitive proximity switch requires a 24 V alternating current power supply, and has a nominal sending range of 50 mm. The capacitive proximity switch operates on variation in the oscillation rate of the electromagnetic field generated by the capacitor when a target material enters the sensing range. As used in the bagging machine of the invention, the sensor 20 is placed in a position where the electromagnetic field does not vary until the material reaches a predetermined level in the compost bag.

As best seen in Figure 2, the position of the sensor 20 is adjustable. The sensor 20 is mounted on a horizontal telescopic arm 25 to allow for radial adjustment of the position of the sensor 20 as indicated by arrow C. The horizontal arm 25 in turn is rotatably and slidably mounted on an upright vertical shaft 27 so as to allow for vertical and angular adjustment as indicated by arrows D and E respectively.

Referring now to Figure 4, the control system consists of an electrical circuit including the sensor 20 as described, in series with a timer relay 30 which activates a switch 31 which in turn operates a motor 32 forming part of the carousel drive mechanism.

It will be appreciated that this new arrangement allows each bag to be filled to the same level, as is required by customers.

It will of course be understood that the invention is not limited to the specific details described herein which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention.

Claims (5)

1. A bagging machine for bagging solid non-granular material comprising a bag holding means for receiving a bag to be filled and for holding the bag in the open position, dispensing means for dispensing flowing solid non-granular material into the bag, and a control system for determining when the bag has been filled and for cutting off the supply of material to the bag, characterised in that the control system includes a sensor to determine when the volume of material in the bag has reached a predetermined volume.

2. A bagging machine according to claim 1 in which the bag holding means is operable to suspend an open bag to be filled and the sensor is located relative to the bag holding means a little below the level to which the bag is to be filled and is operable to detect the difference in density between the flowing material entering the bag and stationary material within the bag and the control system cuts off the flow in response to detecting a change in the density.

3. A bagging machine according to claim 1 in which the sensor employs an electromagnetic field.

4. A bagging machine according to claim 1 in which the bag holding means is one of a number of such holding means arranged in a carousel and the control system is operable in response to detection of a change of density to rotate the carousel to bring another bag into line with the flow of material.

5. A bagging machine substantially as herein described with reference to and as shown in the accompanying drawings.