GB2305133A

GB2305133A - A blending apparatus

Info

Publication number: GB2305133A
Application number: GB9518974A
Authority: GB
Inventors: James Joseph O'callaghan
Original assignee: Vervant Ltd
Current assignee: Vervant Ltd
Priority date: 1995-09-11
Filing date: 1995-09-15
Publication date: 1997-04-02
Anticipated expiration: 2015-09-15
Also published as: IES950705A2; GB2305133A8; GB9518974D0; GB2305133B; IES66231B2

Abstract

A blending apparatus (1) has a primary additive feed hopper (4) and secondary additive feed hoppers (5, 6) suspended from load cells on a support frame (2). Additive materials are delivered from the hoppers (4, 5, 6) to a discharge chute (8) for delivery to a material processing device such as a plastics extrusion device (10). A controller associated with the blending apparatus (1) monitors the throughput of process material in the extrusion device (10) and the discharge rate of additives from the hoppers (4, 5, 6) and controls the process material throughput for controlling blending of the feed additives with the process material.

Description

2305133 "A blending apparatus" This invention relates to a blending

apparatus and method.

The invention particularly relates to a blending apparatus for controlled delivery of blend additives into a material processing device such as a plastics extruding device, or in processes requiring accurate blending of material.

It is known to provide a blender for supplying a mixture of different additives to a plastic extrusion device. one type of blender has hoppers for a number of additives, each hopper having an auger operable for delivering metered quantities of selected additives in a desired ratio to a mixing chamber in which the required mixture is formed, the mixture being subsequently delivered from the mixing chamber to the extrusion device at a desired rate. This blender is, however, of relatively complex construction making it relatively expensive to manufacture and somewhat unreliable in operation particularly where working conditions are not ideal. Uneven blending of additives can occur due to uneven mixing or separation of additives after blending or within the mixing chamber which adversely affects product quality. Further, at the end of each production run, pre-blended material within the mixing chamber may be wasted. This waste can be particularly significant where a large number of different products are being produced using different blends. Also, because of the relatively complex construction, it is difficult and time consuming to clean out the blender between different production runs with consequent losses due to downtime of the plastic extrusion device or other process or apparatus with which the blender is used.

- 2 The present invention is directed towards providing an improved blending apparatus which overcomes these problems.

According to the invention, there is provided a blending apparatus for controlled delivery of blend additives to a material processing device, comprising a primary additive feed hopper and at least one secondary additive feed hopper, an additives discharge chute having an upper inlet end and a lower outlet end, the outlet end for connection to an additive inlet of the material processing device, a primary additive feed pipe having an inlet end and an outlet end, the primary additive feed pipe mounted coaxially within the additives discharge chute with an outlet end of the primary additive feed pipe terminating within the additives discharge chute intermediate the ends of the additives discharge chute, an outlet of the primary additive feed hopper communicating with the inlet end of the primary additive feed pipe, each secondary additive feed hopper having an associated feeding means with an inlet for reception of material from the secondary additive feed hopper and an outlet communicating with the additives discharge chute for delivering material from the secondary additive feed hopper into the additives discharge chute, means being provided for sensing the throughput of material in the material processing device and means being provided for sensing discharge of additives from the feed hoppers, both said means being connected to a controller for regulating the throughput of material through the material processing device in response to the sensed discharge of material from the feed hoppers.

Preferably, the feeding means outlet communicates with the additives discharge chute at a location above the outlet end of the primary additive feed pipe for delivering material from the secondary additive feed hopper into the additives discharge chute between an exterior of the primary additive feed pipe and an interior of the additives discharge chute.

In another embodiment, the means for sensing discharge of additives from each feed hopper is a load cell mounted on a support frame, the feed hopper being hung from a cantilevered hopper carrying fork mounted on the load cell, the hopper carrying fork being U-shaped having an inner end attached to the load cell with a pair of spacedapart outwardly extending hopper support arms, each arm having a groove in an upper surface of the arm, each hopper having a pair of spaced-apart hanging plates mounted at an upper end of the hopper, each hanging plate having an out-turned flanged upper end for engagement within the groove to suspend the hopper on the arms.

Preferably, an adjustment plate is mounted on each arm by means of adjustment screws which pass through complementary adjustment slots in the arm and engage threaded holes in the adjustment plate for adjustment of the adjustment plate on the arm, an upper edge of each adjustment plate forming a support for the hopper hanging plate.

In a further embodiment, a centring plate is mounted on each arm having an inwardly extending central lug for engaging the hanging plates for positioning the hopper between the arms.

Preferably, the load cell is mounted on a bottom face of a carrier plate, a top face of the carrier plate abutting a horizontal support surface on the support frame to which the carrier plate is secured, the load cell having a fixed inner end attached to the carrier plate and a free outer 4 end on which the hopper carrying fork is mounted, a safety bolt being mounted at a free end of the load cell and housed within an associated stepped socket in the carrier plate, a head of the bolt movable vertically within the socket between the horizontal support surface and a stepped shoulder in the socket defining deflection limits for the load cell.

In another embodiment, each feeding means comprises a screw feeder having a screw shaft rotatably mounted within a cylindrical housing extending radially outwardly from the extruder supply pipe, the screw shaft having a drive head at an outer end of the screw shaft engaged by a complementary motor drive head on a drive motor for the shaft, the drive heads being releasably engageable.

Conveniently, the motor is movable between an engaged position for driving the screw shaft and a retracted disengaged position.

ideally, the motor is hingedly mounted on the housing adjacent the outer end of the screw shaft for movement between the engaged and disengaged position.

In a further embodiment, the feeding means comprises a rotatable discharge cone device, having a conical body which tapers inwardly between an inlet end and an outlet end of the body with drive means for rotation of the body, the inlet end for reception of material from the secondary additive feed hopper and the outlet end communicating with the additives discharge chute.

Preferably, the discharge cone device is mounted on the load cell together with the feed hopper.

In another aspect, the invention provides a method for delivering additives to a material processing device, comprising the steps:continuously delivering a primary additive material under gravity from a primary additive feed hopper through a feed pipe to an additives discharge chute having an outlet end connected to an additives inlet of the material processing device, the feed pipe being mounted co-axially within the additives discharge chute with an outlet end of the feed pipe terminating intermediate an inlet end and the outlet end of the additives discharge chute, continuously delivering a secondary additive material from a secondary additive feed hopper through a feeder means to the additives discharge chute, sensing the rate at which primary additive material is discharged from the primary additive feed hopper, sensing the rate at which the secondary additive material is discharged from the secondary additive feed hopper, controlling the feeder means to maintain said primary and secondary discharge rates in a preset desired ratio, sensing throughput of process material in the material handling device, and controlling the process material throughput in response to the sensed primary additive material discharge rate for controlling blending of the feed additives with the process material.

The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:- Fig. 1 is an exploded front elevational view of a blending apparatus according to the invention; Fig. 2 is a perspective view of the blending apparatus; Fig. 3 is a detail perspective view showing a hopper forming portion of the apparatus; Fig. 4 is a detail perspective view showing a load cell assembly used in the apparatus; Fig. 5 is a detail perspective view showing a feed screw portion of the apparatus; Figs. 6 and 7 are detail perspective views of portion of the apparatus; Fig. 8 is a schematic elevational view of the blending apparatus in use mounted on a plastics extrusion device; and Fig. 9 is a side elevational view of an alternative feeder device for the apparatus.

Referring to the drawings, there is illustrated a blending apparatus according to the invention and indicated generally by the reference numeral 1 the blending apparatus 1 in this case for blending three materials. The blending apparatus 1 comprises a rigid support frame 2 on which three hoppers, namely, a primary additive feed hopper 4 and two secondary additive feed hoppers 5, 6 are mounted. Materials from the feed hoppers 4, 5, 6 are fed through a vertical additives discharge chute 8 for delivery of additive materials to a material processing device such as a plastics extrusion device 10 for example (see Fig. 8) on which the blending apparatus 1 is mounted in use.

The support frame 2 is of rigid construction comprising a base 14 with upstanding side walls 15 at each end of the base 14. Upper ends of the side walls 15 are interconnected by a top panel 16. The additives discharge chute 8 extends vertically downwardly from the base 14 directly beneath the primary additive feed hopper 4 and has an upper inlet end 18 and a lower outlet end 19.

As can be seen in Fig. 8, a primary additive feed pipe 20 is vertically mounted on the base 14 having an upper inlet end 21 and a lower outlet end 22. It will be noted from Fig. 8 that the feed pipe 20 is mounted co-axially within the additives discharge chute 8 with the outlet end 22 of the feed pipe 20 terminating intermediate the ends 18, 19 of the additives discharge chute 8.

Extending radially outwardly at the inlet end 18 of the additives discharge chute 8 are feeder means in this case comprising a pair of screw feeders 25, 26 associated with the secondary feed hoppers 5, 6 respectively. Each screw feeder 25, 26 comprises a screw shaft 27 (Fig. 5) rotatably mounted within a cylindrical housing 28 having an inlet end 29 beneath an associated feed hopper 5, 6 and an outlet end 30 connected to the upper end 18 of the additives discharge chute 8. In alternative embodiments of the invention, other feeder means may be used such as 30 belt or vibration feeders.

In the drawings, only two screw feeders 25, 26 are shown mounted at opposite sides of the additives discharge chute - 8 8. However, it will be noted that either one or two additional screw feeders with associated feed hoppers may be mounted at the upper inlet end 18 of the additives discharge chute 8. These additional screw feeders can be mounted extending radially outwardly at a front and/or rear of the additives discharge chute 8 which has appropriate additional inlet openings closed by cover plates 31 when not in use. Further, it is envisaged that in some cases instead of the four-sided discharge chute 8 shown in the drawings, other multi-sided discharge chutes may be provided, having for example five, six or more sides, to allow for additional material feeders.

Referring to Figs. 5 to 7, each screw shaft 27 has a drive head 32 at an outer end of the screw shaft 27 engaged by a complementary motor drive head 33 on a drive motor 34 for the screw shaft. As can be seen in Fig. 5, the motor 34 is carried on a mounting bracket 35 which is mounted by a hinge 36 at the inlet 29 for movement of the motor 34 between a retracted disengaged position as shown in Fig. 5 and a closed engaged position as shown in Fig. 1 in which the drive heads 32, 33 interengage screw shaft 27. A quick-release catch 37 i a side of the mounting bracket 35 for mounting bracket 35 in the closed position.

to drive the s provided on securing the It will be noted that the screw shaft 27 is mounted within an associated plastics barrel which is slidably received within the cylindrical housing 28 releasably held within the housing 28 by a locknut which engages the barrel through a side wall of the housing. In this way, the screw shaft 27 can be readily easily and quickly removed for cleaning or the barrel and screw shaft changed for handling different types of additive.

The blending apparatus 1 also has identification means (not shown) which automatically senses the type of screw 9 - shaft 27 installed in each housing 28, and also means for monitoring the actual speed of rotation of the screw shaft 27, each of said means being connected to a controller for the blending apparatus 1. Furthermore, an inspection window may be provided in a side wall of the inlet 29 allowing visual monitoring of the screw shaft 27.

At a lower end of the inlet 29, a drain flap 39 is hingedly mounted to allow drainage of material from a hopper 5, 6 straight through the inlet 29 if required, at the end of an extrusion run for example, when changing over additives. The flap 39 is held in the closed position by a quickrelease catch 40 (see Fig. 1) engageable between a free end of the flap 39 and an underside of the mounting bracket 35.

Referring to Fig. 6, at an entrance to each inlet 29, a flow director 42 is preferably provided. The flow director 42 has internal walls 43 which flare outwardly and downwardly, a lower outlet end of the hoppers 5, 6 being located within the flow director 42.

Referring to Figs. 3 and 4, each hopper 4, 5, 6 is suspended from the top panel 16 of the frame 2 by means of a load cell assembly 45. The load cell assembly 45 comprises a mounting plate 46, an upper surface of which is secured against an underside of the top panel 16. A load cell 47 is mounted on an underside of the plate 46 at a downwardly stepped outer end 48 of the plate 46. A free outer end 49 of the load cell 47 has a hopper carrying fork 50 mounted thereon.

The hopper carrying fork 50 is of U-shaped construction having an inner end 51 attached to the load cell 47 with a pair of spaced-apart outwardly extending hopper support arms 52. Each arm 52 has a groove 53 in an upper surface - 10 of the arm 52. Each hopper 4, 5, 6 has a pair of upstanding spaced-apart hanging plates 55 extending upwardly of an upper end of the hopper 4, 5, 6. Each hanging plate 55 has an out-turned flanged upper end 56 for seating engagement within the groove 53 to suspend the hopper 4, 5, 6 on the arms 52.

An adjustment plate 58 is mounted on an inside face of each arm 52 by means of a pair of adjustment screws 59. The adjustment screws 59 pass through associated enlarged adjustment slots in the arm 52 and engage associated threaded holes in each plate 58 for adjustment of the plate 58 on the arm 52. An upper edge 60 of each adjustment plate 58 forms a support for the hopper hanging plate 55. The positioning of the adjustment plate 58 on the arms 52 can be adjusted to properly hang the hopper 4, 5, 6 from the arms 52 in a correctly balanced position. Mounted between the adjustment plate 58 and each arm 52 is a centring plate 62 having an inwardly extending pointed central lug 63 for centring the hopper between the arms 52. On an outside of the arm 52, a locking washer 65 is mounted between the adjustment screws 59, the locking washer 65 having locking tabs 66 which engage flat side faces of the locking adjustment screws 59 when the adjustment plate 58 has been set.

Referring to Fig. 4, a safety bolt 70 is mounted at an inner end 49 of the load cell 47 projecting upwardly therefrom freely passing through an associated hole in the carrier plate 46 and locating within a stepped socket 71 in the carrier plate 46 at an upper end of the hole. A head 72 of the bolt 70 is movable vertically within the socket 71 which is of greater depth than the bolt head 72 between the underside of the top panel 16 of the frame 2 to which the carrier plate 46 is attached and a stepped shoulder at a lower end of the socket 71 which define deflection limits for protecting the load cell 47.

Referring to Fig. 1, optionally reservoir hoppers80 containing additive materials may be mounted above each hopper 4, 5, 6 with discharge from the reservoir hoppers controlled by pinch or slide valves 81. A f urther manual slide gate 82 may also optionally be provided if desired. A control box 84 and control console 85 are mounted on opposite side walls 15 of the frame 2.

Fig. 8 shows the blending apparatus 1 in use mounted on a plastics extrusion device 10.

In use, the hoppers 4, 5, 6 are filled with additive materials. A primary additive is delivered by gravity feed from the hopper 4 through the primary additive feed pipe 20 and through the additives discharge chute 8 into the extruder 10, as shown in Fig. 8. At the same time, secondary additive materials are fed from the hoppers 5, 6, the motors 34 being controlled to regulate the quantity of secondary additive materials fed to the additives discharge chute 8. The controller for the blending apparatus 1 has means (not shown) for connection to a sensor for sensing the throughput of the extruder 10 and for regulating the throughput of material through the extruder 10 in response to the sensed discharge of material from the hoppers 4, 5, 6 to control the blend of material in the extruder 10. It will be noted from Fig. 8 that the individual additives are continuously fed directly to the material processing device, in this case the extruder 10, with blending being carried out on the extruder screw 11. It will be appreciated that in other applications, additives may be fed in similar fashion to other material processing devices such as a belt, conveyor, vibration feeder or screw feeder for example.

Accurate mixing of the additive materials can be achieved as there is no opportunity for the additive materials to separate because of the continuous dosing directly to the screw 11. Each of the load cells for the hoppers 4, 5, 6 and the motors 34 for the screw feeders 25, 26 are connected to a controller (not shown) for regulating operation of the blender 1. The hoppers 3, 4, 5 are filled as required under the direction of the controller.

It will be appreciated that the invention advantageously provides a blending apparatus of relatively simple construction for the accurate control of the supply of additives to a material processing device. The blending apparatus is ideally suited to plastics extrusion processes, and may equally well be applied to textile, pharmaceutical, food, chemical and other manufacturing processes requiring accurate blending.

Further, the simple, robust and compact design ensures operational reliability. Also, all parts of the blender are readily easily accessed to allow rapid cleaning of screw feeders and hoppers thus minimising downtime.

Advantageously, there is no opportunity for the additive materials to separate because of the continuous dosing directly to the extruder screw or other material processing device giving an accurately proportioned supply of additive materials evenly throughout the throughput of the material processing device.

Also, advantageously as the blender operates on a continuous basis, at the end of a production run there is no pre-blended material wasted as with other systems which mix the additives prior to delivery to the material processing device.

Referring to Fig. 9, an alternative feeding means is shown. This is particularly suitable for controlling relatively low feed rates of additives, for example in the order of 40 gm/hr. The feeding means comprises a rotatable discharge cone device 100 having a conical body 101 which tapers inwardly between an inlet end 102 and an outlet end 103 of the body 101 with drive means 105 for rotation of the body 101 for discharge of material from the body 101. Material is gravity fed from an additive feed hopper 106 to the inlet end 102. Material discharged from the outlet end 103 is delivered to the discharge chute 8. Feed rate from the body 101 is determined by the speed of rotation of the body 101. The discharge cone device 100 is suspended on the load cell 47 together with the feed hopper 106, weight loss being monitored and communicated to the blender controller which varies the rotational speed of the cone body 101 to maintain a desired material feed rate.

The invention is not limited to the embodiment hereinbefore described which may be varied in both construction and detail.

- 14

Claims

A blending apparatus for controlled delivery of blend additives to a material processing device, comprising a primary additive feed hopper and at least one secondary additive feed hopper, an additives discharge chute having an upper inlet end and a lower outlet end, the outlet end for connection to an additive inlet of the material processing device, a primary additive feed pipe having an inlet end and an outlet end, the primary additive feed pipe mounted co-axially within the additives discharge chute with an outlet end of the primary additive feed pipe terminating within the additives discharge chute intermediate the ends of the additives discharge chute, an outlet of the primary additive feed hopper communicating with the inlet end of the primary additive feed pipe, each secondary additive feed hopper having an associated feeding means with an inlet for reception of material from the secondary additive feed hopper and an outlet communicating with the additives discharge chute for delivering material from the secondary additive feed hopper into the additives discharge chute, means being provided for sensing the throughput of material in the material processing device and means being provided for sensing discharge of additives from the feed hoppers, both said means being connected to a controller for regulating the throughput of material through the material processing device in response to the sensed discharge of material from the feed hoppers.

2.

Apparatus as claimed in claim 1 wherein the feeding means outlet communicates with the additives discharge chute at a location above the outlet end of the primary additive feed pipe for delivering - 1 r.material from the secondary additive feed hopper into the additives discharge chute between an exterior of the primary additive feed pipe and an interior of the additives discharge chute.

3. Apparatus as claimed in claim 1 or 2, wherein the means for sensing discharge of additives from each feed hopper is a load cell mounted on a support frame, the feed hopper being hung from a cantilevered hopper carrying fork mounted on the load cell, the hopper carrying fork being U-shaped having an inner end attached to the load cell with a pair of spacedapart outwardly extending hopper support arms, each arm having a groove in an upper surface of the arm, each hopper having a pair of spaced-apart hanging plates mounted at an upper end of the hopper, each hanging plate having an out-turned flanged upper end for engagement within the groove to suspend the hopper on the arms.

Apparatus as claimed in claim 3 wherein an adjustment plate is mounted on each arm by means of adjustment screws which pass through complementary adjustment slots in the arm and engage threaded holes in the adjustment plate for adjustment of the adjustment plate on the arm, an upper edge of each adjustment plate forming a support for the hopper hanging plate.

5.

6.

Apparatus as claimed in claim 3 or claim 4 wherein a centring plate is mounted on each arm having an inwardly extending central lug for engaging the hanging plates for positioning the hopper between the arms.

Apparatus as claimed in any of claims 3 to 5, wherein the load cell is mounted on a bottom face of a carrier plate, a top face of the carrier plate abutting a horizontal support surface on the support frame to which the carrier plate is secured, the load cell having a fixed inner end attached to the carrier plate and a free outer end on which the hopper carrying fork is mounted, a safety bolt being mounted at a free end of the load cell and housed within an associated stepped socket in the carrier plate, a head of the bolt movable vertically within the socket between the horizontal support surface and a stepped shoulder in the socket defining deflection limits for the load cell.

Apparatus as claimed in any preceding claim wherein each feeding means comprises a screw feeder having a screw shaft rotatably mounted within a cylindrical housing extending radially outwardly from the extruder supply pipe, the screw shaft having a drive head at an outer end of the screw shaft engaged by a complementary motor drive head on a drive motor for the shaft, the drive heads being releasably engageable.

8. Apparatus as claimed in claim 7 wherein the motor is movable between an engaged position for driving the screw shaft and a retracted disengaged position.

9. Apparatus as claimed in claim 8 wherein the motor is hingedly mounted on the housing adjacent the outer end of the screw shaft for movement between the engaged and disengaged position.

10. Apparatus as claimed in claims 1 to 6 wherein the feeding means comprises a rotatable discharge cone device, having a conical body which tapers inwardly between an inlet end and an outlet end of the body with drive means for rotation of the body, the inlet end for reception of material from the secondary additive feed hopper and the outlet end communicating with the additives discharge chute.

11. Apparatus as claimed in claim 10 wherein the discharge cone device is mounted on the load cell together with the feed hopper.

12. A blending apparatus substantially as hereinbefore described with reference to the accompanying drawings.

13. A method for delivering additives to a material processing device, comprising the steps:- continuously delivering a primary additive material under gravity from a primary additive feed hopper through a feed pipe to an additives discharge chute having an outlet end connected to an additives inlet of the material processing device, the feed pipe being mounted co-axially within the additives discharge chute with an outlet end of the feed pipe terminating intermediate an inlet end and the outlet end of the additives discharge chute, continuously delivering a secondary additive material from a secondary additive feed hopper through a feeder means to the additives discharge chute, sensing the rate at which primary additive material is discharged from the primary additive feed hopper, sensing the rate at which the secondary additive material is discharged from the secondary additive feed hopper, controlling the feeder means to maintain said primary and secondary discharge rates in a preset desired ratio, sensing throughput of process material in the material handling device, and controlling the process material throughput in response to the sensed primary additive material discharge rate for controlling blending of the feed additives with the process material.

14. A method for delivering additives to a material processing device substantially as hereinbefore described with reference to the accompanying drawings.