Technical Field

This invention relates to a method and apparatus for removing foreign objects from glass, and for separating glass into clear and colored pieces prior to recycling.

Background Art When glass is collected for recycling, foreign material, such as rocks, sticks, ceramics and other material, needs to be separated from the glass or the recycled glass will be contaminated. In addition, clear glass and colored glass must be separated from one another prior to recycling. Heretofore, this removal of foreign material and separation has been done by hand which is time-consuming and expensive.

Disclosure of the Invention The subject invention overcomes the foregoing problem by providing an apparatus which passes the unsorted material in a discrete array along a defined plane. An optical sensing device senses when an opaque particle passes through a first line defined in the plane and where the particle is located along the first line. A series of nozzles, which emit a jet of high velocity fluid, are located adjacent to the plane with the nozzles arranged along a second line that is parallel to and offset from the first line in the direction the particles are moving. An actuator is activated by the sensing device to cause fluid to be emitted from one of the nozzles when an opaque particle sensed by the sensing device passes through the second line and blow that particle out of the plane. A chute located behind the plane captures the particles blown out of the plane and separates them from the remainder of the particles.

In a preferred embodiment of the invention, the optical sensor is a source of high intensity light that is located on one side of the plane, and a multi-element machine vision camera that is located on the other side of the plane. The machine vision camera has a plurality of light-sensitive diodes that are aimed toward the light. The diodes generate an electrical signal and the strength of the signal of each diode varies proportional to the intensity of the light that reaches the diode. The signal from the diode is fed through a micro¬ processor, which causes the fluid to be emitted from the proper nozzle at the proper time to blow the opaque particle sensed by the diode out of the plane.

In the preferred embodiment, each nozzle is supplied fluid through one or more electrically operated valves. After sensing a reduced signal from one of the diodes, the microprocessor waits a predetermined time so that the particle drops between the first line and the second line, and then opens the valve associated with the nozzle that is most closely aligned with that diode. The nozzles are carried in a manifold , which also carries the valves and the conduits that interconnect the valves with the nozzles. The manifold can either be formed from a solid block or from a series of single nozzle-containing elements which are bolted together.

An optical filter can be placed between the particles and the camera if it is desired to sort pieces of colored glass from clear glass. The colored glass can be separated by using a filter that absorbs the wave- length of light emitted through the colored glass so that the glass particles appear opaque to the camera.

Accordingly, it is a principal objective of the subject invention to provide an apparatus which optically senses and removes opaque particles from a group of primarily transparent particles.

It is a further object of the present invention to provide such an apparatus which utilizes by a machine

vision camera and high intensity source of light which shines through the particles toward the camera to sense the opaque particles.

It is a still further object of the subject invention to provide such an apparatus which uses a jet of high velocity fluid to remove the opaque particles from the plane.

It is yet a further object of the subject invention to provide such an apparatus in which there are a plurality of nozzles through which the jet of fluid can be emitted.

It is a still further object of the subject invention to provide such an apparatus in which fluid is fed to the nozzles through remotely controlled valves. It is a further object of the subject invention to provide such an apparatus in which a microprocessor is used to open the appropriate valve at the proper time upon receiving a signal from the camera, so that a jet of fluid strikes a particular particle sensed by the camera. The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.

Brief Description of the Drawings

FIG. 1 is a foreshortened side elevation view, partially broken away to show hidden detail, of a glass cullet separator embodying the subject invention. FIG. 2 is a fragmentary sectional view taken along the line 2-2 in FIG. 1.

FIG. 3 is a sectional view, at an enlarged scale, taken along the line 3-3 of FIG. 1.

FIG. 4 is a fragmentary side elevation view, partially broken away to show hidden detail, of a portion of the manifold shown in FIG. 3.

FIG. 5 is a detail view showing the nozzle assembly in the manifold.

FIG. 6 is an exploded pictorial view of an alternate embodiment of the manifold.

Modes for Carrying Out the Invention

Referring to FIGS. 1 and 2 of the drawings, a glass cullet separator embodying the subject invention comprises a rectangular shell 10 that is supported in an elevated position by legs 12. The shell has an in-feed slot 14 that extends across its upper skin 16, and a discharge slot 18 that extends across its lower skin 20 directly below the in-feed slot. Otherwise, the shell is completely enclosed. Located above the shell is an oscillatory vibrating shaker table 22 into which the glass particles that are to be recycled are deposited. The shaker table, which is commercially available, processes material that is received in batches into a steady stream of individual particles with most of the particles being coplanar.

However, because of its oscillatory nature, the particles discharged from the table often are not lying flat and a portion of the particles are not coplanar. In order to ensure that all of the particles are coplanar and are laying flat, the particles are passed across a series of inclined ramps 24. The ramps 24 are mechanically connected to the table 22 so that they move with the table. Their movement is not as pronounced as the table, however, and is mostly horizontal. Thus, the ramps spread the particles out so that they are completely coplanar and are flat. In the embodiment illustrated there is a first ramp 26, that receives particles from the table, and a second ramp 28, that receives particles from the first ramp and discharges them into the in-feed slot 14 of the shell 10. As a result of the separation caused by the ramps, the particles drop through the shell along a vertical plane A, and they are oriented with

their smallest dimension perpendicular to that plane. The table and the ramps, and thus the plane A, have a width which is slightly less than the width of the shell 10. Located at the end of the shell containing the slots 14 and 18 and proximate the upper skin 16 is a source of high intensity light 30 that extends across the entire width of the shell and is directed across the plane A. The light source preferably is a fluorescent tube of the type used in photocopy machines. Located at the other end of the shell, at the same level as the light 30, is a commercially available machine vision camera 32 that is aimed toward the light. The machine vision camera contains a plurality of light sensitive diodes 34 that can discern various degrees of brightness. A typical machine vision camera would have approximately 1,000 separate diodes and could sense over 250 degrees of brightness. The camera provides an output signal for each diode and the strength of each signal varies according to the degree of brightness of the light source sensed by that diode. Since the diodes 34 and light 30 are at the same vertical location, the light sensed by the diodes passes through the plane A along a horizontal line B that extends across the plane. Line B is termed the image line. As can be seen in FIG. 2, the image line is optically focused onto the diodes so that each diode senses light that passes through a unique point on the image line.

Referring now also to FIGS. 3-5, located across the plane A from the light 30 is a manifold 36 that carries a plurality of the nozzles 38. The nozzles are arranged along a line that is parallel with the image line and are aimed in a direction that is perpendicular to plane A. The nozzles are located below the image line by a predetermined distance C. The manifold extends across the entire width of the plane A, and the nozzles are placed at evenly spaced intervals along the manifold.

The number of nozzles, and thus the spacing between them, is limited only by the physical size of the nozzles, and the larger the number of nozzles the better control that can be obtained. While the drawings do not indicate the number of nozzles, manifolds have been tested that contain approximately 100 nozzles and they work well for the intended purpose.

The manifold illustrated in FIGS. 1-5 is an integrated manifold that is machined from a solid block of material. The manifold not only carries the nozzles 38 but also carries the valves 40 that regulate the flow of fluid through the nozzles and the fluid conduits 41 that interconnect the valves and the nozzles. In the embodiment illustrated, there are two valves 40 for each nozzle because there are no valves on the market that are small enough to fit in the limited space available and provide the response time and air flow requirements necessary for this apparatus.

Three large air passageways 42 extend through the entire extent of the manifold. The air passageways are covered at each end by removable plates 44. Fittings 46, that fit in openings in the plates 44 at one end of the manifold, open into the air passageways. Fluid from a source of pressurized fluid (not shown) is provided to the fittings through tubes 48. One of the outside passageways 42 feeds only the even numbered nozzles, and the other outside passageway feeds only the odd numbered nozzles. The center passageway feeds both nozzles. The conduits 41 interconnect the passageways 42 with the inlet ports (not shown) of the valves 40, and the outlet ports (not shown) of the valves with the nozzles.

In the embodiment illustrated the nozzles 38 are removable. As can be seen in FIG. 5, each nozzle is a cylindrical sleeve 50 that slidably fits in a conform- ing bore 52 located in the manifold. A bolt 54, thread- edly engaged in a hole beside the bore 52, contacts the sleeve and holds it in place in the bore. A converging-

diverging nozzle is used in order to permit supersonic flow when the fluid is air. Preferably, the pressure in the manifold is such (approximately 90 psig) that the air flow at the nozzle exit will be approximately mach 2. The signals from the camera 32 are passed to a microprocessor, shown schematically at 56, through cables 58. The microprocessor in turn is connected to the valves through cables 60. The microprocessor is programmed to detect when the output of one of the diodes 34 drops below a certain value which would identify that an opaque particle has passed the image line B between the light source 14 and the particular diode. The microprocessor is programmed to delay a predetermined time, i.e., the time it takes for a particle to drop the distance C, and then open the valves that feed the nozzle that is aligned with that particular diode. After a predetermined dwell time the microprocessor causes the valves to close again. The dwell time is set to cause the jet to displace a particle from the plane A. A chute 62 mounted in the shell below the plane of the nozzles collects the particles displaced by the jets and directs them out of the apparatus to an appropriate collection device (not shown) . The remainder of the particles drop out of the discharge slot 18 into a separate collection device for recycling.

The apparatus can also be used to separate colored glass from clear glass by placing an optical filter 64 between the plane A and the camera 32. A filter is selected that absorbs light having a wavelength associated with light passing through the particular color of glass that is to be removed. Thus, colored glass appears to the camera to be opaque and will be blown out of the plane.

In an alternate embodiment of the invention shown in FIG. 6, the manifold 64 is comprised of a plurality of separable segments 66, each of which carries a single nozzle. Thus, the number of nozzles can be

changed by adding or subtracting the appropriate number of segments. Alternate segments are reversed end for end and rotated 90 degrees to provide separate passageways 68 for alternate nozzles, which is necessary to provide the required flow characteristics with available valves 70. Spacers 72 are provided at the outside ends of the segments in order to provide a flat outside face. End plates 74 cover each end of the assembly, and bolts 76 extend through the assembly to hold it together as an integral unit. This embodiment not only allows varying the number of nozzles, but does not require as difficult machining as is required in an integral manifold.

With either manifold operation of the device is straightforward. Glass cullet, including foreign mate- rial that is to be sorted out, is deposited into the shaker table 22 which spreads the material out and deposits it on the inclined ramps 24. The ramps further spread the material and cause it to lay flat, so that when the material drops from the discharge end of the second ramp 28 it falls through the shell 10 along the vertical plane A in a discrete array with the smallest axis of each particle oriented perpendicular to the plane.

As the particles pass the line B any opaque particle blocks a localized portion of the light from the light source 30 and the diode 34 that is aligned with that opaque particle senses the lower light level and its output signal is reduced. The microprocessor 56 senses this reduced signal, creates a time delay equal to the time it takes for the particle to drop the distance C, and then opens the valve 40 that is aligned with that particular diode. A jet of high velocity air is ejected from the nozzle and the opaque particle is blown out of the plane A and into the chute 62 where it is collected. The remaining transparent particles drop out of the shell through the discharge slot 18 where they are collected separately from the opaque particles.

If the cullet contains semi-transparent colored glass the collected particles must then be passed through the device again with the correct filter in place to cause the diode to sense colored pieces as opaque and remove them.

The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expres- sions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.