GB2169885A

GB2169885A - Feeding objects one by one

Info

Publication number: GB2169885A
Application number: GB08501336A
Authority: GB
Inventors: Timothy James Osgood
Original assignee: Anstalt Gersan
Current assignee: Anstalt Gersan
Priority date: 1985-01-18
Filing date: 1985-01-18
Publication date: 1986-07-23
Also published as: GB8501336D0; BE904045A; IL77553A; GB2169885B

Abstract

In order to feed small objects one by one there is a rotary bowl 1 with a highly resilient foam plastic insert 2, providing a V-shaped annular trough from which the objects are fed. There is a rotary, vertical axis feeder assembly which has a nozzle head 10 carrying a number of vertically-movable suction nozzles 12 actuated by a double lift cam 20 and return springs 18. There are suction connections 9,24,25,26 so that the nozzles 12 pick up successive objects from the bowl 1, and there is a short pressure branch 27 which registers with a compressed air supply 29 at an eject point, causing the respective object to be discharged from the nozzle 12. In this way, precise control of the feed of the object can be obtained and the object can be ejected through a relatively small viewing area 21. <IMAGE>

Description

SPECIFICATION Feeding objects one by one 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 (retention) 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 as set forth in Claims 1 or 15 and a method as set forth in Claim 16. The remaining Claims set forth preferred features of the invention.

Using the invention, a very precisely positioned feed can be provided. The apparatus is particularly useful where the assembly is rotatable about a vertical axis and the nozzles are directed vertically downwards. The apparatus can be used to lift objects up over the side of a bowl containing a pool of the objects and to drop the objects off from a precise position just above a viewing area in which the objects are examined in quick succession.

Preferred Embodiment The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a vertical section through apparatus in accordance with the invention, taken on the line I-I in Figure 2; Figure 2 is a top view of the nozzle wheel, the nozzle holders not being shown; and Figure 3 is a side view on the arrow Ill in Figure 2.

The apparatus has two main parts, namely an open-top container for the objects in the form of a V-section bowl 1, and a feeder.

The bowl 1 has an annular trough defined between an inner conical surface and an outer conical surface. Though any suitable angle can be chosen, the inner surface may slope at 30 to the horizontal and the outer surface at 20 to the horizontal. The base of the trough is formed by an annular insert 2 of highly resilient material such as a polyester foam having a density of 20-23 Kg/m3 and a British Standard (BS 3667) hardness of- 18-22 Kg. The remainder of the bowl can be formed of say aluminium or a plastics material such as melamine. The bowl 1 is rotated about a vertical axis at constant speed in the direction indicated by the arrow.

More details of a bowl similar to tht described above are given in a GB patent application filed today by the same Applicants with the title "Feeding Discrete Objects".

The feeder incorporates an assembly which is rotatable about a vertical axis spaced from that of the bowl 1 in the direction indicated by the arrow. The assembly has a hollow shaft 3 whose upper end carries a drive pulley 4 and an encoder disc 5. The drive pulley 4 is connected by a timing belt 6 to a stepping motor 7 (for instance a 200 step motor). The encoder disc 5 actuates an opto-switch 8.

The top end of the shaft 3 is sealed to a stationary vacuum (suction) connection 9, say at about 7000 Pa (two inches of mercury).

The lower end of the shaft 3 carries a nozzle head 10 which in turn carries a number (for instance 12) of nozzle holders 11 each with a suction nozzle 12-the nozzle holders 11 are equispaced around the axis of the assembly.

It has been found necessary to use a variety of nozzle sizes to cater for objects of different sizes. To this end, the nozzle head 10 is readily, i.e. quickly and easily, exchangeable for another. The nozzle head 10 is a sliding fit over the lower end of the shaft 3 and is keyed thereto by a dowel pin 13 which engages in an slot 14 in the nozzle head 10; in addition, the lower end of the shaft 3 is closed by a screw-in plug 15 which is locked in position (by means not shown) and a wing screw 1 6 holds the nozzle head 10 against the bottom of the shaft 3.

Each of the nozzle holders 11 is reciprocable in a vertical direction (i.e. parallel to the axis). Vented bellows 17 are provided to prevent the ingress of dirt and particularly abrasive dust. The nozzle holders 11 are biassed upwardly by springs 18 and at their upper ends, they carry cam follower wheels 1 9 which engage a stationary, annular, double lift cam 20 secured to the feeder body. The arrangement is such that the nozzle head 10 can be removed and replaced without difficulty. Figure 1 shows the two lowermost positions of the nozzles 12, namely immediately over the bowl 1 and at 1800 to such a position, over for instance a viewing area 21. In between these two positions, the nozzles 12 must be lifted up over the side of the bowl 1.

It will be seen that the nozzle holders 11, which are of generally cylindrical shape, slide in self-lubricating bearings (bushes) 22 which are a force fit in the head 10, and have their strokes limited by screw dowels 23 which extend into longitudinal slots in the holders 11.

In this way, the holders 11 remain captive in the head 10.

To provide suction at the nozzles 12, radial suction bores 24 are drilled in the lower end of the shaft 3 and register with radial suction bores 25 in the head 10; the outer end of each bore 25 is connected by an individual flexible tube 26, for instance formed of silicon rubber, to a small vacuum connection adjacent the nozzle 12. In this way, the nozzle 12 is in permanent physical connection with the interior of the shaft 3 and hence with the suction connection 9.

Adjacent the periphery of the head 10, there is a short branch bore for each nozzle 12, which forms a port 27 on the upper face of the head 10 (see Figure 2). Above the path of the ports 27, there is a fixed shoe 28 (for instance formed of polytetrafluoroethyleneì which is connected to a compressed air line 29 and which contains a port which will register with successive ports 27, forming valve means. The shoe 28 is carried in a shoe support block 30. Around the remainder of the outside of the upper face of the head 10, a horseshoe seal 31, for instance also of polytetrafluoroethylene, seals off the ports 27; it is found that this seal 3 1 can just lie by gravity, and the suction draws it down against the upper face of the head 10; though the seal 31 will be worn, it is not of critical importance.It will be seen that at the eject or discharge point, the vacuum is broken by a compressed air blast. It is preferred to incorporate a solenoid valve 32 (shown schematically in Figure 3) in the compressed air line 29, the valve 32 being controlled by the encoder disc 5 so that it opens just sufficiently before the eject position of the nozzle 12 to provide a pulse of compressed air. A suitable compressed air pressure is about 80000 Pa (12 psi). The arrangement is such that there is slight positive pressure at the nozzle 12 when this occurs.

The object will then drop down or be ejected down through the viewing area 21. The velocity of the ejected object may be controlled by the amount of positive pressure and the rise of the cam 20.

The arrangement of the vacuum connections and of the compressed air connections is such that they do not interfere with the ready removability of the head 10.

In one example, the head 10 had an overall diameter of about 130 mm. This was suitable for a feeder which would pick up 0.04 to 0.2 carat gemstones such as diamonds (sieve pass size roughly 1.5 to 2.5 mm) and pass them through a viewing area 21 defined by a sphere 10 mm in diameter at a speed of 5 to 20 objects per second with a tolerance of less than 3 milleseconds. At 20 objects per second, the speed of the shaft 3 is 100 rpm, and the speed of rotation of the bowl 1 can be about 10% less.

The apparatus is specifically for small objects, say for a sieve (pass) size of 4 mm down to a sieve (retention) size of 0.5 mm.

The apparatus is capable of ynchronisation with a rotary dispense system, the positional information being provided from the encoder disc 5.

Claims

1. Apparatus for feeding objects one by one, comprising a feeder assembly which is rotatable about an axis and has: means for rotating the assembly about the axis; a number of suction nozzles positioned around the axis; means for lowering successive nozzles with respect to the feeder assembly at a pick-up zone, for picking up successive objects; and discharge means for discharging the objects from the successive nozzles at a discharge zone.

2. The apparatus of Claim 1, wherein said axis is vertical.

3. The apparatus of Claim 1 or 2, wherein the lowering motion of the nozzles is a rectilinear motion.

4. The apparatus of Claim 3, wherein the motion of each of the nozzles is parallel to said axis.

5. The apparatus of Claim 3 or 4, and comprising a stationary cam, engaged by followers on ends of reciprocable nozzle holders which mount the nozzles at their other ends, the nozzle holders being spring biassed against the cam.

6. The apparatus of any of Claims 3 to 5, wherein each nozzle is on a nozzle holder mounted for reciprocatory motion with respect to a mounting member which mounts all the nozzle holders, the mounting member having at least one suction duct and each nozzle being connected to the suction duct by an individual flexible tube.

7. The apparatus of any of the preceding Claims, wherein each nozzle is mounted on a mounting member which is secured to the end of a drive shaft rotatable about said axis, which shaft is hollow with its interior connected to a main suction connection of the assembly and also connected to the nozzles.

8. The apparatus of any of the preceding Claims, wherein the discharge means do not physically close the suction connection to the respective nozzle.

9. The apparatus of Claim 8, wherein each nozzle has a suction duct provided with a branch duct leading via valve means to a pressure fluid supply, the valve means being for supplying the pressure fluid to the suction duct and thereby causing the suction to be ineffective at the nozzle.

10. The apparatus of Claim 9, wherein there is a stationary pressure duct in the assembly, leading to a pressure port, each nozzle being mounted on a mounting member which has an annular array of ports leading to a suction duct for each nozzle, said ports providing said valve means.

11. The apparatus of Claim 9 or 10, wherein the valve means is electrically actuated and controlled by an encoder disc which rotates with the mounting member.

11. -The apparatus of any of the preceding Claims, wherein each of the nozzles is mounted on a readily exchangeable mounting member.

12. The apparatus of any of the preceding Claims, and further comprising a rotary, opentop container from which the nozzles will pick up the objects.

13. The apparatus of Claim 12, wherein the container comprises a V-shaped annular groove.

14. The apparatus of any of the preceding Claims, and comprising a container having a highly resilient base, from which the nozzles will pick up the objects.

15. Apparatus for feeding objects one by one, substantially as herein described with reference to, and as shown in, the accompanying drawings.

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

CLAIMS Amendments to the claims have been filed, and have the following effect.

Claims 1, 5, 6, 7, 10, 11 above have been deleted or textually amended.

New or textually amended claims have been filed as follows:

1. Apparatus for feeding objects one by one, comprising a feeder assembly which is rotatable about an axis and has: means for rotating the assembly about the axis; a number of suction nozzles positioned around the axis the nozzles being mounted on a readily exchangeable mounting member; means for lowering successive nozzles with respect to the feeder assembly at a pick-up zone, for picking up successive objects; and discharge means for discharging the objects from the successive nozzles at a discharge zone.

5. The apparatus of any of the preceding Claims, and comprising a stationary cam, engaged by followers which rotate with the mounting member and cause the lowering movement of the nozzles, the followers being spring biassed against the cam.

6. The apparatus of any of Claims 3 to 5, wherein each nozzle is on a nozzle holder mounted for reciprocatory motion with respect to the mounting member, the mounting mem ber having at least one suction duct and each nozzle being connected to the suction duct by an individual flexible tube.

7. The apparatus of any of the preceding Claims, wherein the mounting member which is secured to the end of a drive shaft rotata ble about said axis, which shaft is hollow with its interior connected to a main suction con nection of the assembly and also connected to the nozzles.

10. The apparatus of Claim 9, wherein there is a stationary pressure duct in the assembly, leading to a pressure port, the mounting member having an annular array of ports leading to a suction duct for each nozzle, said ports providing said valve means.