GB1587005A - Material feeding apparatus - Google Patents

Description

(54) MATERIAL FEEDING APPARATUS (71) We, R.B. ENGINEERING (MACCLESFIELD) LIMITED formerly, BAYNE BARBER SHAWCROSS & CO.

LIMITED, a British Company, (trading as R.B. ENGINEERING SERVICES) of Adelphi Mill, Grimshaw Lane, Bollington, Macclesfield, Cheshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention concerns a feeding apparatus for particulate or pulverulent material having a feed member which bears the weight of the material as it progresses through the apparatus.

It is already known to provide apparatus in which the feed member (which may be, for instance, a belt conveyor or a screw feeder, or a plate against which the material impinges) is supported so as to move or tilt about a fulcrum (provided, for example, by a knife edge or flexible pivot), transducer means (for instance in the form of a strain gauge or a hydraulic or pneumatic load cell) being provided to detect movement of or changes in downward pressure applied by the said member, arising from changes in the amount of material supported thereby, and thus to provide a signal which can be indicative of flow (or absence of flow) through or over the member, or can be used to ensure a constant throughput.

The, existing arrangements generally all have moving parts which, of course, are accompanied by inertia problems, as well as pivots or bearings which are susceptible to sticking and inaccuracies. Furthermore, the majority of the known devices are such as to incorporate an adjustable counterbalance adapted to balance off the tare weight of the feed member, and although this means that the transducer means is concerned only with the actual weight of the material progressing through or over the feed member, and not the weight of the combined weight of the feed member plus the material supported thereby, there are the added disadvantages of considerable additional inertia and mechanical complexity.

An object of the present invention is to provide apparatus for feeding particulate or pulverulent material which does not suffer the above-discussed disadvantages or in which said disadvantages are minimised, and which is particularly simple in its construction and operation.

With this object in view, the present invention provides apparatus for feeding particulate or pulverulent material and having a feed member which is adapted to support directly such material as it passes through the apparatus, the feed member being supported by a centilever beam arrangement, and transducer means being provided for sensing the weight of the feed member, and any material supported thereby, as manifested by strain in the cantilever beam arrangement and for providing a signal corresponding thereto and, therefore, to the amount of material flow at the feed member.

The transducer means may serve to supply an electrical signal to a circuit incorporating high and low alarm means serving to give respective alarms when the weight of the material supported by the feed member respectively exceeds a predetermined maximum or is less than a predetermined minimum.

The signal may, if desired, be supplied to indicator means serving to afford a visual indication of the weight of material supported by the feed memeber and, therefore, of the flow rate.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation illustrating a preferred embodiment of the material feeding device of the invention; and Figure 2 is a plan view, with certain parts removed, corresponding to Figure 1.

A preferred embodiment of apparatus for feeding particulate or pulverulent material and conforming to the invention comprises a basic housing 10 (omitted from Figure 2) accommodating control circuitry (not shown) and having control knobs and dials 11, 12 set in its front wall. The housing 10 supports from below a material supply receptacle 13 (omitted from Figure 2) for receiving pulverulent or particulate material (not visible in the drawings), this receptacle 13 having an outlet spout 14 for the said material, a screw, or other suitable device, being disposed within the spout 14 and the lower part of the receptacle 13 to ensure that the material in the latter is fed out through the spout 14.

The free end of the spout 14 is connected, by a flexible gaiter 15, to an-inlet boss 16 provided at one end of a feed member, indicated generally by the numeral 17, through which the material from the recep tacle 13 passes. The feed member 17, in the illustrated case, is in the form of a screw feeder comprising a generally cylindrical casing 18 which is substantially horizontally disposed and encloses a feed screw (not visible) whose shaft 19 protrudes through a bearing (not visible) in an end plate 20 at the inlet boss end of the casing 18 and is fitted with a pulley 21. The shaft 19 is also journalled at its other end in an end cap 22 on the corresponding end of the casing 18, this end cap 22 being removable to permit access to the interior of the casing 18 for repair and/or maintenance purposes. A removable cover 23 also permits access to the interior of the inlet boss 16.

An outlet boss 24 is provided in the underside of the casing 18 adjacent its end remote from the inlet boss 16, and it will readily be understood that rotation of the feed screw, by means of its shaft 19, will serve to progress any material supplied to the inlet boss 16 along the casing 18 to the outlet boss 24. A respective flexible gaiter 25 connects the outlet boss 24 with an outflow duct or tube 26 which. is supported stationarily below the boss 24, independently of the feed member 17, by means of a cantilever tube 27 supported by and projecting substantially horizontally from a support structure, indicated generally by the reference numeral 2 & accommodated within the basic housing 10.

The support structure 28 includes a strutted upright 29 at the upper part of which is an angle support or bracket 30 to which are clamped, each by one end, a pair of can-tilever beams 31 which extend substantially parallel to one another and under the proximal end of the casing 18 where they support a weight table -32. Cradles 33 secured to the upper surface of the table 32 serve to support the casing 18 from below so that the entire weight of the screw feeder 17, and any material therein, is supported by the cantilever beams 31.

Also supported by the beams 31, by being bolted to the weight table 32 from below, is an electric motor 34 which serves to drive the shaft 19 by way of a belt 35 extending around the pulley 21.

Strain created in the cantilever beams 31 by reason of their supporting the motor 34, the feed member 17, and any material therein, is detected by electro-mechanical transducers, in the form of strain gauges 36, which in the illustrated case are shown as being bonded to the tops and bottoms of the beams 31. Strain gauges of the type which change resistance or conductivity (or even other electrical characteristics) upon being subjected to changes in stress are well known, and any suitable such strain gauge can be used as shown. These strain gauges are, of course, appropriately connected to the control circuitry within the housing 10, and the manner of so doing may vary according to how the entire feeding device is required to operate, as will shortly become evident.

It will readily be understood that the strain gauges 36 effectively provide continuous signals which will vary in accordance with any changes in the amount of material which is present in the feed member 17 since such changes vary the aggregate weight of the material plus the feeder and motor as supported by the beams 31 and creating strain in the latter.

In a first way of utilising these signals, the control circuitry is set up so as to incorporate alarm means providing visual or audible high and low alarms which are energised respectively upon the aggregate weight (and, therefore, the weight of the material in the feed member 17) on the beams exceeding a predetermined maximum and falling below a predetermined minimum.

This arrangement accordingly serves essentially as a flow detector indicating flow of material through the feed member 17 so long as neither of the two alarms is energised. If the high alarm is energised, this provides an indication of the presence of too much material in the feed member 17 as a result, for example, of a blockage at the outlet side thereof causing build-up or of the drive to the screw shaft 19 being cut-off, or a comparable break-down. On the other hand, if the low alarm is energised, this will be indicative of insufficient material reaching the feed member 17 for example as a result of a blockage in the receptacle 13 or its spout 14 or due to absence of material in the receptacle 13.

In addition, or as an alternative to this first way of using the signals, the arrange ment may be such that the control circuit provides an analog signal which is directly proportional to the weight of material pre sent within the feed member 17, this signal being fed to a meter providing a continuous read-out of the flow rate through the feed member 17, and/or summating the flow.

Yet again, in addition or as an alternative to either or both of the foregoing possibili ties, the signals from the gauges may be converted to an analog signal which is then compared with a reference signal to deter mine any difference which is then used to control the rate at which material is applied to the feed member 17 and thereby give a constant flow therethrough.

Of course, other possibilities in the use of the signals provided by the gauges will be apparent to those skilled in the art, as also will modifications of and variations to the specific constructional details of the embo diment above described. Thus, it will readily be appreciated that it is not essential to the invention that there should be two cantilev er beams, and the arrangement may have only one said beam or more than two.

Moreover, it is not essential for each such beam to have two strain gauges, since it may be sufficient to provide only one on the or each beam, and in the case of multiple beams it may be enough to provide a gauge only on one or some of the beams.

The form of the member supported by the cantilever beam(s) need not be as shown, i.e. a screw feeder. It could, for instance, be in the form of a belt conveyor or other arrangement providing for passage of the fed material therealong and supported thereby to affect its loading. Another possi bility is that the receptacle could discharge onto a feed member in the form of an inclined plate or trough down or along which the material flows by gravity, changes in the weight of the material on the plate or trough, or the downward deflection there of as a result of impingement of a stream of the material thereon, being sensed by the transducer(s) which may be electromecha nical, electronic, pneumatic, hydraulic, or any practical combination thereof.

WHAT WE CLAIM IS: 1. Apparatus for feeding particulate or pulverulent material and having a feed member which is adapted to support directly such material at it passes through the apparatus, the feed member being sup ported by a cantilever beam arrangement, and transducer means being provided for sensing the weight of the feed member, and any material supported thereby, as manifested by strain in the cantilever beam arrangement and for providing a signal corresponding thereto and, therefore, to the amount of material flow at the feed member.

2. Apparatus as claimed in claim 1 wherein the transducer means serves to supply an electrical signal to a circuit incorporating high and low alarm means serving to give respective alarms when the weight of material supported by the feed member respectively exceeds a predetermined maximum and is less than a predetermined minimum.

3. Apparatus as claimed in claim 1-or 2 wherein the signal is supplied to indicator means serving to afford a visual indication of the weight of material supported by the feed member and, therefore, of the rate of flow through the apparatus.

4. Apparatus as claimed in claim 1, 2 or 3 wherein the signal serves to control the weight of material supplied to the feed member to provide a constant throughput of said material.

5. Apparatus as claimed in any preceding claim wherein the feed member is a belt conveyor or a screw conveyor for the material.

6. Apparatus as claimed in any of claims 1 to 4 wherein the feed member is a plate onto which the material being fed is caused to impinge.

7. Apparatus as claimed in any preceding claim wherein the cantilever beam arrangement comprises a side-by-side pair of cantilever beams each fixed by one end to a support and supporting the feed member at or adjacent its other end, each said beam having a respective strain gauge bonded thereto adjacent its fixed end.

8. Apparatus for feeding particulate or pulverulent material substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. the receptacle 13. In addition, or as an alternative to this first way of using the signals, the arrange ment may be such that the control circuit provides an analog signal which is directly proportional to the weight of material pre sent within the feed member 17, this signal being fed to a meter providing a continuous read-out of the flow rate through the feed member 17, and/or summating the flow. Yet again, in addition or as an alternative to either or both of the foregoing possibili ties, the signals from the gauges may be converted to an analog signal which is then compared with a reference signal to deter mine any difference which is then used to control the rate at which material is applied to the feed member 17 and thereby give a constant flow therethrough. Of course, other possibilities in the use of the signals provided by the gauges will be apparent to those skilled in the art, as also will modifications of and variations to the specific constructional details of the embo diment above described. Thus, it will readily be appreciated that it is not essential to the invention that there should be two cantilev er beams, and the arrangement may have only one said beam or more than two. Moreover, it is not essential for each such beam to have two strain gauges, since it may be sufficient to provide only one on the or each beam, and in the case of multiple beams it may be enough to provide a gauge only on one or some of the beams. The form of the member supported by the cantilever beam(s) need not be as shown, i.e. a screw feeder. It could, for instance, be in the form of a belt conveyor or other arrangement providing for passage of the fed material therealong and supported thereby to affect its loading. Another possi bility is that the receptacle could discharge onto a feed member in the form of an inclined plate or trough down or along which the material flows by gravity, changes in the weight of the material on the plate or trough, or the downward deflection there of as a result of impingement of a stream of the material thereon, being sensed by the transducer(s) which may be electromecha nical, electronic, pneumatic, hydraulic, or any practical combination thereof. WHAT WE CLAIM IS:

1. Apparatus for feeding particulate or pulverulent material and having a feed member which is adapted to support directly such material at it passes through the apparatus, the feed member being sup ported by a cantilever beam arrangement, and transducer means being provided for sensing the weight of the feed member, and any material supported thereby, as manifested by strain in the cantilever beam arrangement and for providing a signal corresponding thereto and, therefore, to the amount of material flow at the feed member.

2. Apparatus as claimed in claim 1 wherein the transducer means serves to supply an electrical signal to a circuit incorporating high and low alarm means serving to give respective alarms when the weight of material supported by the feed member respectively exceeds a predetermined maximum and is less than a predetermined minimum.

3. Apparatus as claimed in claim 1-or 2 wherein the signal is supplied to indicator means serving to afford a visual indication of the weight of material supported by the feed member and, therefore, of the rate of flow through the apparatus.

4. Apparatus as claimed in claim 1, 2 or 3 wherein the signal serves to control the weight of material supplied to the feed member to provide a constant throughput of said material.

5. Apparatus as claimed in any preceding claim wherein the feed member is a belt conveyor or a screw conveyor for the material.

6. Apparatus as claimed in any of claims 1 to 4 wherein the feed member is a plate onto which the material being fed is caused to impinge.

7. Apparatus as claimed in any preceding claim wherein the cantilever beam arrangement comprises a side-by-side pair of cantilever beams each fixed by one end to a support and supporting the feed member at or adjacent its other end, each said beam having a respective strain gauge bonded thereto adjacent its fixed end.

8. Apparatus for feeding particulate or pulverulent material substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.