GB2171682A

GB2171682A - Feeding discrete objects by suction

Info

Publication number: GB2171682A
Application number: GB08529628A
Authority: GB
Inventors: William James Turner
Original assignee: Anstalt Gersan
Current assignee: Anstalt Gersan
Priority date: 1985-01-18
Filing date: 1985-12-02
Publication date: 1986-09-03
Also published as: GB2171682B; BE904046A; GB8529628D0; GB8501335D0

Abstract

In order to feed small objects, e.g. diamonds, one by one, there is a rotary bowl 2 with a highly resilient foam plastic insert 12 providing a V-shaped annular trough to which the objects are fed. There is a rotary feeder head whose axis is inclined to the axis of the bowl 2, and which carries a nozzle wheel 4 with a number of suction nozzles 47, arranged so that the nozzles 47 pick up successive objects from the bowl 2. As the nozzle wheel 4 rotates, ports 52, 53 on the nozzle wheel 4 register with stationary ports 58, 59 to which compressed air is supplied. The ports 52, 58 cause the suction to be released and the ports 53, 59 cause a blast of compressed air to be blown through an annular array of discharge openings 49. The insert 12 enables the relatively delicate nozzles 47 to be used and the porting arrangement 52, 53, 58, 59 causes precise release and ejection of the objects after pick-up. <IMAGE>

Description

SPECIFICATION Feeding discrete objects Background of the invention The invention relates to an apparatus for, and a method of, feeding discrete objects one by one.

This is a particular problem when the objects are of different shapes and sizes, as may occur for instance in the gemstone industry, and where the objects are small, for instance of a sieve (pass) size of 10 mm, 5 mm or less (a minimum sieve size possibly being 0.5 mm). Although it must be expected with all apparatus that an occasional double feed occurs, frequent double feeds are very disturbing and should be avoided. A further problem in dealing specifically with gemstones is that gemstones are very hard and cause considerable abrasion if they are jostled or slid over other surfaces, so that it is desirable to provide an apparatus that involves as little jostling or sliding movement of the gemstones as possible.

The invention The invention provides apparatus for feeding discrete objects one by one, comprising: a container for containing a number of the objects, the container having a base formed of highly resilient material; a feeder member having at least one suction nozzle, the nozzle being arranged to pass down into the container, and to pick up an object from the base of the container by suction; and means for discharging the object from the nozzle when the object has been lifted from the container.

The highly resilient base in the apparatus can prevent any jamming of the suction nozzle against the base of the container, even with a rather oversized object, and can prevent the objects being crunched against each other The invention also provides apparatus for feeding discrete objects one by one, comprising: a feeder member carrying at least one suction nozzle, the nozzle being arranged to pass down and pick up an object due to the effect of suction, the nozzle having a suction duct leading to a suction opening; suction connection means for applying suction to the nozzle suction duct; and means for breaking the nozzle suction at a discharge point and discharging the object from the nozzle, which suction breaking means comprise means for blowing a pressure fluid into the nozzle suction duct without physically closing the suction connection means.More specifically, the suction nozzle can be associated with a passage for connection to a pressure fluid supply and connected to the nozzle suction duct, and valve means can be provided for opening the pressure fluid connection when the nozzle reaches a discharge point, thereby causing the suction to be ineffective at the nozzle suction opening when the nozzle reaches the discharge point.

This apparatus avoids having to provide a valve closure in the suction ducting to the nozzles. This is of particular importance where abrasive material may be present, for instance fine diamond dust when the objects are diamonds; such abrasive material tends to be drawn into the suction nozzles. If there is a valve closure, there must be some sliding member and the abrasive material very quickly wears the sliding member and causes imperfect operation.

The invention further provides apparatus for feeding discrete objects one by one, comprising: a feeder member carrying at least one suction nozzle, the nozzle being arranged to pass down and pick up an object due to the effect of suction, the nozzle having a suction opening and annular discharge opening means around the suction opening; and valve means for connecting the annular discharge opening means to a compressed fluid supply when the nozzle reaches the discharge point, thereby blowing the object off the suction opening.

This apparatus enables the object to be discharged from the nozzle in a roughly predictable direction, which is very useful in that the apparatus receiving the object does not have to have any particular arrangement for catching the object.

Preferred embodiments the invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a plan of apparatus in accordance with the invention, the feeder member being omitted; Figure 2 is a side view of the apparatus, partly in section along the line ll-ll in Figure 1; Figure 3 is a side view looking in the direction of the arrow III in Figure 2 (the feeder member being omitted); Figure 4 is a view looking directly onto the top of the feeder member, in the direction of the arrow IV in Figure 2; Figure 5 is a view looking onto the bottom of the feeder member, in the direction of the arrow V in Figure 2, the nozzle wheel being omitted; Figure 6 is a view looking direct on the righthand side of the feeder member, in the direction of the arrow VI in Figure 2;; Figure 7 is a section along the plane VII-VII in Figure 4; Figure 8 is a section along the line VIII-VIII in Figure 2; Figure 9 is a view looking directly on the bottom of the wiper spring, in the direction of the arrow IX in Figure 2; Figure 10 is a view looking directly on the top of the nozzle wheel, in the direction of the arrow X in Figure 2; Figure ills a section along the line Xl-Xl in Figure 10, on a larger scale; Figure 12 is a view looking in the direction of the arrow XII in Figure 11; and Figure 13 is a view corresponding to Figure 2, but showing part of a different embodiment.

Figures 1 to 12 The apparatus is in two parts, namely a con tainer part 1 having an open-top container in the form of a bowl 2, and a feeder part 3 having a feeder member in the form of a nozzle wheel 4.

The bowl 2 is rotatable about a vertical axis by means of a drive belt 5 and a motor 6. The drive connection includes a collar 7 which is biassed upwards by a spring 8. The bowl 2 can slide vertically with respect to a central spindle 9 and is retained by a central screw 10 (which determines the uppermost position of the bowl 2) and by an adjusting screw 11 (which adjusts the height of the bowl 2 against the spring 8). The height of the bowl 2 is adjusted to suit the size range of the objects. The pulley on the spindle 9 has a crowned ring and is made of a low-friction plastic such as polytetrafuoroethylene or Delrin so that the pulley slips at its inside diameter if a jam occurs.

The bowl 2 is of double-cone form, providing an annular V-shaped trough for the objects being fed.

Suitable angles are chosen, for instance 30 inclination on the inner cone and 20 inclination on the outer cone. For higher speeds of rotation, steepersided bowls can be used. The bowl 2 can be made of metal or moulded in a plastics material such as melamine, but has its base formed by an annular insert 12 of highly resilient material such as polyester foam having a density of 20-23 Kg/m3 and a British Standard (BS 3667) hardness of 18-22 Kg.

The trough base in the insert 12 is nearer the inner periphery than the outer periphery of the insert 12.

The insert 12 prevents or makes very unlikely bridging or jamming between the nozzles 47 and the bowl 2, and can therefore avoid bending the nozzles 47 or damage to the objects or flipping the objects out of the bowl 2. The bowl 2 is surrounded by a close-fitting rim plate 13 located by the machine frame (not shown), and by decking 14.

A feed channel 16 is provided for feeding in this case diamonds onto the periphery of the bowl 2.

In order to sense the presence of objects in the bowl 2, there is a sensor roller 17 associated with a bowl height datum roller 18, both mounted on arms pivoted on a common pivot 19. The sensor roller 17 may be made of foam. The datum roller 18 can have a small rubber tyre, as shown. The datum roller arm carries an opto-switch 20 associated with an interrupter 21 on the sensor roller arm.

There is a sensor roller height adjusting screw 22 so that, if desired, the sensor roller 17 can be held clear of the insert 12 when the bowl 2 is empty. If the sensor roller 17 moves up too far in relation to the datum roller 18, a signai is given by the optoswitch 20, indicating that the bowl is over-full. Likewise, if the sensor roller 17 is too low in relation to the datum roller 18, the opto-switch 20 gives a signal indicating that more objects should be fed to the bowl 2. The interrupter 21 can provide simple on/off switching. The opto-switch 20 is connected to a primary feeder (not shown) such as a motorised hopper.

To ensure that the objects pass down into the base of the bowl 2 (on the insert 12), the sensor roller arm carries an inner scraper wire 23 and the datum roller arm carries an outer scraper blade 24.

The feeder part 3 is on a hinge mounting, and can be swung about an axis 25 which is behind the feeder part 3 as seen in Figure 2 and inclined to the horizontal. The angle of the axis 25 determines the angle of the axis 4' of the nozzle wheel 4. A suitable angle can be chosen, but in the present case the axis 4' is inclined at 45" to the vertical.

The axis 4' crosses the bowl axis without intersecting it with the lowest point 4" (see Figure 1) on the path of the nozzles 47 being ahead (upstream) of the vertical diametrical plane of the bowl 2 to which the nozzle wheel axis 4' is parallel - this may reduce the risk of the nozzles 47 trapping objects against the base of the bowl 2, and increased clearance is provided on the rising side of the nozzle wheel 4, which is useful if a steep-sided (high speed) bowl is used - specifically the arrangement provides more clearance on the leading side, where the nozzles 47 are carrying the objects, than on the trailing side, where there are no objects on the nozzles. The distance between said diametrical plane and the nozzle wheel axis 4' is preferably about 10% of the operating diameter (the diameter of the bowl trough base).The feeder part 3 can be swung up to change nozzle wheels 4, on depressing a locking lever 26. The locking lever 26 has a pin 27 which engages forks (not visible in Figure 2) on a head 28 of a locking rod 29. The rod 29 is spring-loaded in a rotational sense and carries a locking plate 30 (Figure 6) which has a projecting locking pin 31. The pin 31 can engage in one of two slots 32 in a latch plate 33 secured to the machine frame.

The feeder part 3 carries a stepper motor 36 connected by a drive belt 37 to the rotary feeder head 38. At one end (see Figure 7), the feeder head 38 carries an encoder disc 39. There is an opto-switch 40 which is carried on a pivot shaft 41 and whose position can be locked by a locking screw 42. The opto-switch 40 reads slots in the encoder disc 39.

At the other end, the feeder head 38 carries a mounting ring 43 with say three captive and sprung ball detents 44. These detents engage in an annular groove in a mating ring 45 on the nozzle wheel 4, thereby providing snap retention of the nozzle wheel 4. As visible in Figure 10, a radial locating pin 46 on the mounting ring 43 enters a short key-way on the ring 45. The nozzle wheel 4 is readily, i.e. quickly and easily, exchangeable to suit the nozzle sizes to the sizes of the objects.

The nozzle wheel 4 is best seen in Figures 10 and 11. It carries a number of equally-spaced, removable suction nozzles 47 which are push-fitted in radial bores in the nozzle head 4. Each nozzle 47 has a suction duct 48 leading to a suction opening at its tip. Each nozzle 47 has been machined from a cylindrical piece which had (radial) gear-type teeth cut around its periphery, as shown in Figure 12, providing an annular array of discharge or eject means in the form of openings 49 around the suction opening 48. As shown in Figures 7 and 11, the suction duct 48 is connected to a central suction plenum 50. The plenum 50 extends up the middle of the feeder head 38 and is connected to a main suction lead 51. The suction duct 48 is also connected, by a branch adjacent the tip of the nozzle 47, to a suction release port 52. The eject openings 49 are connected to an eject port 53.

As shown in Figures 5 and 7, the feeder part 3 carries a stationary part-annular (horseshoe) sealing member 54 which may be made for instance of poíytetrafluoroethylene. This member engages the ports 52, 53 and seals them, being freely suspended and held onto the top of the nozzle wheel 4 by suction - here wear by abrasive dust is not of critical importance. The feeder part 3 also carries a stationary shoe plate 55 which carries air transfer shoes 56, 57 (see Figure 11) having ports 58, 59 which form valve means and will register with the ports 52, 53. The individual shoes 56, 57 can be made of for instance polytetrafluoroethylene, being held on by air pressure.The ports 52, 53 are connected to individual compressed air lines 61, 62 (see Figure 5); the lines 61, 62 are preferably not under constant pressure, being controlled by solenoid valves indicated schematically as 63, 64, timed by the encoder disc 39, though it is considered that the eject solenoid 64 could be dispensed with, relying solely on the setting of the shoe plate 55 to set the eject timing.

As can be seen in Figure 2, each nozzle 47 will in turn pass down into the bowl 2, will pick up an object in the bowl 2 by suction and will discharge the object into a further apparatus which is merely indicated in Figure 2 as a schematic box 65. This further apparatus may for instance be an accelerator wheel or belt for the further conveyance of the object, as in GB 85 26955/. The object is discharged when the ports 52, 53 in the nozzle wheel 4 register with the stationary ports 58, 59. The release port 52 receives a pulse of air which destroys the suction at the suction opening, i.e. causes the suction to be ineffective at the tip of the nozzle 47 (though the suction connection is not physically closed).The eject port 53 connects the eject openings 49 with the compressed air supply and causes a pulse of air to pass through them, blowing the objects positively off the suction opening. As the array of discharge openings 49 surrounds the suction opening, the force applied to the objects is fairly well balanced and will be in the axial direction of the nozzle 47. The array of eject openings 49 provides a broad and more accurate jet. By having a number of openings 49, rather than a single annular opening, more even flow is obtained around the nozzle 47, preventing a predisposition to blow the object off in a certain oblique direction.

Thus fairly good control of the eject direction is achieved, and the object can be projected with reasonable accuracy into the further apparatus 65.

The timing of the pressure pulses can be adjusted by providing timing marks (not shown) on the nozzle wheel 4 and on the shoe plate 55, and adjusting the position of the nozzle wheel 4. The circumferential position of the shoe plate 55 can also be adjusted. In one example, where the nozzle wheel 4 rotates at 26.25 rpm (providing a feed of seven objects per second), the ports 52, 53 and 58, 59 can just start to overlap at 4" 48' before the discharge axis, full registration occurring as or before the eject axis is reached. Though it is convenient to have the stationary ports 58, 59 radially aligned, this is not essential. The air (suction) release is preferably initiated 4" 48' before the eject axis and the eject timing is preferably set at 3 48' before the eject axis.The arrangement should be such that the ports 52, 53 and 58, 59 should be fully in register when the respective nozzle 47 is precisely coincident with the eject axis. The release timing procedure should be such that the release solenoid 63 is energised at a precise point in advance of the respective nozzle 47 being coincident with the eject axis, to allow for solenoid operation and air velocity build-up. The 4" 48' angle allows 30 milleseconds at a feed rate of seven objects per second.

The eject blast can be applied for instance for 10 milleseconds. The suction (vacuum) can be at about 7000 Pa (two inches of mecury). The compressed air applied to the port 52 can be at about 80000 Pa (12 psi) whilst the compressed air applied to the eject port 53 can be about 35000 Pa (5 psi).

As more than one object can occasionally be picked up by a single nozzle 47, means are provided against which an object on the nozzle 47 will wipe, after pick-up, for wiping off any excess object(s). These means are in the form of a leaf spring blade 71 (see Figure 2) carried on the feeder part 3 and positioned so that any object on the nozzle 47 will engage the underside of the end of the blade 71; although all objects will contact the blade 71, in general, one object will remain on the nozzle 47 while the others will fall off. Just under the nozzle wheel 4, the decking 14 can slope up at 45" so as to return objects to the bowl 2. The blade 71 is carried on a small block 72 by means of a screw 73 and clip spring 74 and is located by a small dowel 75.The block 72 can be adjusted and set about one axis by means of a setting screw 76 and spring 77, its height can be adjusted and set by means of a setting screw 78 and a spring 79 (see Figure 8).

Although the nozzle wheel axis crosses but does not intersect the bowl axis in the apparatus described above, it is possible to have such axes intersecting, particularly because the highly resilient insert 12 is present.

The bowl 2 is arranged to rotate at such a speed that at the operating radii, the nozzles 47 are moving just slightly slower or just slightly faster than the insert 12, ensuring that all the objects can be removed from the bowl 2, a suitable differential speed being about 10%. For sorting objects the largest of which have a sieve (pass) size of about 2.5 mm, the bowl 2 may have an operating diameter (diameter of the trough base) of about 115 mm, the other dimensions being in proportion.

GB 85 01336 describes a slightly different bowl which could be used as an alternative; it also describes an alternative feeder head.

Figure 13 In Figure 2, it can be seen that the lowest and the highest points of the motion of the nozzles 47 are on the same side of the bowl axis, the highest point being radially outwards (with respect to the bowl axis) of the lowest point. However, as shown in Figure 13, the nozzle wheel 4 can effectively be positioned on the other side of the bowl axis so that, with respect to the bowl axis, the highest point of the path of the nozzles 47 is in a direction radially inwards of the lowest part, and in the case shown, on the other side of the bowl axis though this need not be necessarily so. It is considered that this provides the possibility of higher bowl speeds, say up to 100 rpm for the same radii as opposed to 20 rpm for the Figure 2 arrangement.

In Figure 13, the axis of the nozzle wheel 4 is inclined at 35 to the horizontal while the inner cone of the bowl is at 30 to the horizontal and the outer cone is at 150 to the horizontal.

Claims

1. Apparatus for feeding discrete objects one by one, comprising: a container for containing a number of the objects, the container having a base formed of highly resilient material; a feeder member having at least one suction nozzle, the nozzle being arranged to pass down into the container, and to pick up an object from the base of the container by suction; and means for discharging the object from the nozzle when the object has been lifted from the container.

2. The apparatus of Claim 1, wherein the container is an open-top container rotatable about a generally vertical axis with means for rotating the container about its axis, and the feeder member is also rotatable, with means for rotating the feeder member.

3. The apparatus of Claim 2, wherein the container comprises two conical surfaces, namely an inner surface which slopes downwards and radially outwards, and an outer surface which slopes upwards and radially outwards.

4. The apparatus of Claim 2 or 3, wherein the feeder member axis is inclined with respect to the container axis but does not intersect the container axis, the closest point on the path of the nozzle(s) to the base of the container being upstream of the diametrical plane of the container to which the feeder member axis is parallel.

5. The apparatus of any of Claims 2 to 4, wherein the feeder member axis intersects the plane of the base of the container on the same side as, and radially outwardly of (with respect to the container), the lowest point of the nozzle.

6. The apparatus of any of Claims 2 to 4, wherein the axis of the feeder member intersects the plane of the base of the container radially inwardly (with respect to the container) of the lowest point of the nozzle.

7. The apparatus of Claim 6, wherein the feeder member axis intersects the plane of the base of the container on the other side of the container axis to the lowest point of the nozzle.

8. Apparatus for feeding discrete objects one by one, comprising: a feeder member carrying at least one suction nozzle, the nozzle being arranged to pass down and pick up an object due to the effect of suction, the nozzle having a suction duct leading to a suction opening; suction connection means for applying suction to the nozzle suction duct; and means for breaking the nozzle suction at a discharge point and discharging the object from the nozzle, which suction breaking means comprise means for blowing a pressure fluid into the nozzle suction duct without physically closing the suction connection means.

9. Apparatus for feeding discrete objects one by one, comprising: a feeder member carrying at least one suction nozzle, the nozzle being arranged to pass down and pick up an object due to the effect of suction, the nozzle having a suction duct leading to a suction opening; suction connection means for applying suction to the nozzle suction duct; a passage for connection to a pressure fluid supply and connected to the nozzle suction duct; and valve means for opening the pressure fluid connection when the nozzle reaches the discharge point, thereby causing the suction to be ineffective at the nozzle suction opening when the nozzle reaches the discharge point.

10. Apparatus for feeding discrete objects one by one, comprising: a feeder member carrying at least one suction nozzle, the nozzle being arranged to pass down and pick up an object due to the effect of suction, the nozzle having a suction opening and annular discharge opening means around the suction opening; and valve means for connecting the annular discharge opening means to a compressed fluid supply when the nozzle reaches the discharge point, thereby blowing the object off the suction opening.

11. The apparatus of Claim 10, wherein there is an array of at least three discharge openings forming the annular discharge opening means.

12. The apparatus of Claim 10, wherein the or each nozzle is received in a bore in the feeder member, a duct leading from the bore to the valve means, the nozzle having therearound an annulus of radial teeth which form the annular discharge opening means.

13. The apparatus of any of Claims 10 to 12, and also in accordance with Claim 8 or 9.

14. The apparatus of any of Claims 8 to 13, and also in accordance with any of Claims 1 to 7.

15. The apparatus of any of the preceding Claims, wherein means are provided for wiping against an object on the nozzle, or against which an object on the nozzle will wipe, after pick-up, for wiping off any excess object(s) if the nozzle picks up more than one object.

16. A method of feeding discrete objects one by one, comprising using the apparatus of any of the preceding Claims.

16. Apparatus for feeding discrete objects one by one, substantially as herein described with reference to, and as shown in, Figures 1 to 12 or Figure 13 of the accompanying drawings.

17. A method of feeding discrete objects one by one, comprising using the apparatus of any one of the preceding Claims.

Amendments to the claims have been filed, and have the following effect: (A) Claims 8-10, 12-17 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows: New claims 8-10, 12-17.

8. The apparatus of any of the preceding Claims, wherein the suction nozzle has a suction duct leading to a suction opening, and is associated with suction connection means for applying suction to the nozzle suction duct and means for breaking the nozzle suction at a discharge point and discharging the object from the nozzle, which suction breaking means comprise means for blowing a pressure fluid into the nozzle suction duct without physically closing the suction connection means.

9. The apparatus of any of Claims 1 to 7, wherein the nozzle has a suction duct leading to a suction opening and is associated with suction connection means for applying suction to the nozzle suction duct, a passage for connection to a pressure fluid supply and connection to the nozzle suction duct, and valve means for opening the pressure fluid connection when the nozzle reaches a discharge point, thereby causing the suction to be ineffective at the nozzle suction opening when the nozzle reaches the discharge point.

10. The apparatus of any of the preceding Claims, wherein the nozzle has a suction opening and annular discharge opening means around the suction opening, and is associated with valve means for connecting the annular discharge opening means to a compressed fluid supply when the nozzle reaches the discharge point, thereby blowing the object off the suction opening.

12. The apparatus of Claim 10, wherein the or each nozzle is received in a bore in the feeder member, a duct leading from the bore to the valve means, and the nozzle having therearound an annulus of radial teeth which form the annular discharge opening means.

13. The apparatus of any of the preceding Claims, wherein means are provided for wiping against an object on the nozzle, or against which an object on the nozzle will wipe, after pick-up, for wiping off any excess object(s) if the nozzle picks up more than one object.

14. The apparatus of any of the preceding Claims, wherein the container is substantially as herein described with reference to, and as shown in, Figures 1 to 12 or Figure 13 of the accompanying drawings.

15. Apparatus for feeding discrete objects one by one, substantially as herein described with reference to, and as shown in, Figures 1 to 12 or Figure 13 of the accompanying drawings.