US3042200A - Vibratory sorting apparatus - Google Patents

Description

y 3, 1962 H. P. NOWAK 3,042,200

VIBRATORY SORTING APPARATUS Filed Feb. 29, 1960 2 Sheets-Sheet 1 N VE/VTOR HERMAN F. NOWAK A TTORNE Y United States Patent Office 3,042,200 Patented July 3, 1962 3,042,200 VIBRATORY SURTING APPARATUS Herman P. Nowair, Salem, Mass., assiguor to Raytheon Company, Waltham, Mass., a corporation of Delaware Filed Feb. 29, 1960, Ser. No. 11,751 7 Claims. (Cl. 209-99) This invention pertains generally to apparatus for sorting articles as to their thickness or other dimension, and more particularly to an apparatus for effectively sorting extremely small and lightweight articles.

Sorting machines employing vibatory gauging elements are well known in the art, and an exemplary form of such machine includes a pair of elongate gauging rails or rods which are so positioned relative to each other as to provide a tapered space therebetween. The two rails lie in a substantially common horizontal plane, and the articles to be sorted are introduced between the rails at the narrow end of the taper. Upon vibration of the two rails as a unit, the articles to be sorted are moved along the length of the rails in the direction of increasing gauging space, and ultimately the several articles fall between the rails when the gauging space reached is sulficient to permit passage. A plurality of containers or the like are normally positioned below the rails and along the length thereof, so that articles sorted as to size are collected in separate containers for subsequent use, packaging, storage or the like.

The devices of the prior art provide satisfactory performance, generally speaking, in the sorting of such articles as ball bearings, thumb tacks and larger articles. However, none of the prior art machines are capable of sorting very small and very light articles such as chips of the semiconductor material used in the fabrication of modern transistors, semiconductor diodes and other miniature electronic circuit elements. Semiconductor chips are so small and lightweight that the vibratory sorting machines of the prior art, even if reduced in scale to an appropriate degree, are utterly useless in effecting a sorting of such chips. When it is attempted to employ the prior art devices in the sorting of semiconductor chips, the chips either fail to feed along the gauge rails (perhaps as a result of electrostatic forces or a lack of feeding friction, or both), merely bunching at the point at which they are deposited along the rails, or where feeding is accomplished it is very erratic, and the sorting accuracy is so deteriorated as to destroy the effectiveness of the device.

It is accordingly a primary object of the present invention to provide a vibratory sorting apparatus for effectively sorting very light and very small articles such as semiconductor chips.

A further object of the present invention is to provide a vibratory sorting apparatus for small, lightweight articles wherein the sorting operation is carried out with great accuracy.

An additional object of the present invention is to provide a vibratory sorting apparatus for small, lightweight articles wherein an extremely large number of articles may be sorted per unit time.

In accordance with the present invention, these and other objects are achieved by means of a vibratory sorting apparatus employing a pair of spaced-apart gauging rails as in the prior art devices, but having opposed adjacent faces of such rails provided with gauging edges of slightly rounded configuration, as well as having at least one of such opposing faces inclined at a small (relative to those of the prior art) angle with respect to a horizontal plane passing therethrough. By slightly rounding the opposing gauging edges of the two rails, it has been found that extremely good feed and accurate gauging are accomplished, apparently as a result of decreased electrostatic potentials in the immediate vicinity. Further, by employing what is referred to herein as a feeding or support face on one of the rails, the feeding action is made positive, as opposed to the relatively haphazard feed which occurs when the prior art devices are required to sort such small and lightweight articles as are contemplated in the present invention. This positive feeding action is effected by positioning the rail feed face in a small angle (on the order of, for example, 20 or 30 degrees) from the horizontal; as a result of such arrangement, the articles to be sorted are supported on the rail face in question and are positively translated along the length of the rail by the friction therewith upon appropriate vibration of the rails. It has also been found that providing the support rail with an overhanging lip aids greatly in optimizing the feeding and gauging of the semiconductor chips being processed. Where the prior art devices are applied to the performance of sorting semiconductor chips, the feeding or translation friction is erratic and of a vastly smaller magnitude, since the gauging faces of those prior art devices are both at a realtively large angle with respect to the horizontal.

With the above considerations and objects in mind, the invention itself will now be described in connection with a preferred embodiment thereof given by way of example and not of limitation, and with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an exemplary embodiment of the over-all apparatus of the present invention.

FIG. 2 is an elevation view of a portion of the apparatus shown in FIG. 1, corresponding elements being identified by like reference numerals.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2.

FIG. 4 is a sectional view taken along line 4-4 in FIG. 2.

Referring now to FIG. 1, the vibratory sorting apparatus of the present invention is shown as including a pair of gauge rails 10 and 12, at least one of which is mounted for movement relative to the support members thereof, one of which is shown at 14. Support members 14 are suitably secured to a pan 16, as by welding, which generally encloses and extends below the gauging assembly including rails 10 and 12. The pan 16 is, in turn, supported at one end thereof by being welded or otherwise secured to a support plate 18, the latter being aflixed to the top of a vibratory member 20 which supplies the vibratory motion necessary in the operation of the sorting device. The particular means enclosed within the vibratory member 20 are not a part of the inventive concept of the present invention, and many suitable devices for imparting vibratory motion are commercially available. It is preferable, however, that the vibratory member 20 be of such nature as to impart a substantially arcuate vibration in a vertical plane parallel to the length of rails 10 and 12. Suitable resilient mounting means provide an oscillating support for vibratory member 20, two of which are shOWn at 22 and 24; it will be understood that additional resilient support means will generally be necessary in order to support vibratory member 20 and the other elements mounted therein.

The gauging rails 10 and 12 are mounted for limited movement relative to each other, and this movement is controlled to a very precise degree by means of micrometer screws 26 and 28, which are respectively disposed near the opposite ends of the rails 10 and 12, and which extend through and connect with the rails in a manner which will be further described herein in connection with the description of FIG. 4. Suitable indicia (not shown) will generaly be provided in connection with micrometer screws 26 and 28 in order to provide an indication of the spacing between the rails and 12 at each such screw, with screw 28 being adjusted to provide a space between rails 10 and 12 which is equal to or slightly less than the minimum dimension intended to be sorted, and micrometer screw 26 being normally adjusted to provide a spacing between rails 1i) and 12 at the remote end corresponding to or slightly exceeding the maximum dimension intended to be sorted. The semiconductor chips or other articles 30 are fed to the space between rails 10 and 12 by means of a hopper 32, which may take any suitable form. It is sometimes found necessary to provide mechanical agitation to hopper 32 in order to obtain translation of the articles 31 therein.

A plurality of trays or other container means 34 are provided for receiving articles 30 as they pass between the gauging rails 14 and 12 in the operation of the apparatus of the invention. Containers 34 are supported by a substantially horizontal tray 36 which forms a part of the tray-supporting member 33, with the latter generally resting upon the same support surface as resilient mounts 22 and 24. It will be understood that the tray 34 and the support member 38 therefor are preferably relatively stationary in the embodiment shown in FIG. 1, with the other elements heretofor described being subjected to vibration in order to achieve the desired sorting operation.

The relationship between gauging rails 10 and 12 may be more clearly seen in the fragmentary elevation showing of FIG. 2, which shows that the rails 10 and 12 are preferably not in horizontal alignment. As shown, rail 12 is somewhat elevated in comparison with rail 10, and both rails are inclined downwardly toward the right in FIG. 2. This inclination is a common feature in devices of this type, and provides improved feeding of the articles to be sorted along the gauging rails 10 and 12 in that the motion of such articles must result from the vibration imparted to the rails instead of from the forces of gravity.

FIG. 3 shows the gauging rails 10 and 12 in cross section, with the gauging faces thereof having slightly rounded edges 40 and 42 opposing each other along the length of the rods 10 and 12 and forming the gauging aperture of the device. Rail 10 is also shown as having its lower face 65 slightly undercut from the lower edge of the bar 66 to where it meets the rounded portion 40 at point 6-7 as to provide a rounded, overhanging lip at apex 40. Near the ends of rods 10 and 12 through which micrometer screw 23 passes, the separation between edges 40 and 42 is made small, whereas the corresponding space in the vicinity of micrometer screw 26 is relatively large. It is important that each of the edges 40 and 42 be slightly rounded (for example, on a .0001 radius) in order to achieve the desired operation of the present invention. While the necessity for so rounding these edges is not fully understood at present, it is felt that the removal of sharp edges at the gauging space or aperture prevents the formation of electrostatic potentials which, if present, would cause the lightweight articles St to cling to the rails 10 and 12 and to each other, thereby failing to feed along the rails for proper sorting operation.

It has also been found that the undercutting of the apex 40 by an amount of approximately .029:.001 inch is essential in achieving a high degree of relief from wedging of the semiconductor chips, being sorted, in the space between rails 10 and 12. This undercutting of apex 40' on rail 10 is necessary since it has been found that if the rail is not undercut in the manner described any chips 30 which are tapered or have any irregularities on their surface become wedged in the space between the rails. However, when rails 30 are undercut slightly in the manner described the chips swing in a suspended fashion between the rails arid continue to move along the rails in the direction of the normal feed until the space between the rails becomes great enough to allow the chip to fall free in the receptacles 34 provided beneath the rails. Thus, undercutting of the rails allows chips having any surface irregularities or chips whose thickness varies from one end to the other to be accurately gauged as to the thickestportion of the chip without wedging occurring. It wasfound that without the relief provided by this undercutting any chips whose thickness varied became securely wedged in the space between the rails and broke the free flow and passage of the following chips. This problem was eliminated by the described undercutting.

A second important feature shown in FIG. 3 is the inclination of the support or drive face 44 of gauging rail 1%. Compared to the vibratory gauging devices of the prior art, the orientation of gauging rail 10 is such as to provide a relatively small angle between support surface 44 and a horizontal plane passing therethrough. The particular magnitude of such angle is not critical in the present invention, and satisfactory operation has been achieved with the chip-supporting surface 44 being disposed at 20 or 30 with respect to the horizontal. What is important here is that the feed or chip-supporting surface 44 should be sufficiently close to horizontal to permit the articles 30 to rest thereon with sufficient friction to per mit a positive driving action of the articles upon vibra; tion of rail 10. That is to say, if the surface 44 of rail 11 were at a relatively steep angle (say 65 degrees) with the horizontal, the semiconductor chips or other articles 3% would tend to slide laterally thereon and be supported at the edges 40 and 42. With the articles 30 being supported only at these two gauging edges, the friction between the articles 30 and the two gauging rails 10 and 12 is much less than that necessary to achieve positive feeding of the articles along the rails. In addi tion, where the weight of the article 30 is concentrated at edges 40 and 42, the articles sometimes become wedged in the gauging aperture between edges 40 and 42, and the articles therefore do not fall freely through the gauging aperture at an appropriate point. In accordance with the present invention, wherein surface 44 is at a relatively small angle with the horizontal, the articles to be sorted will lie in contact with and be supported by support face 44, as indicated by the position of article 46.

FIG. 4 shows a preferred embodiment of the microme ter screws employed in adjusting the gauging aperture between rails 10 and 12. In particular, micrometer screw 26 is shown in sectional view passing through rails 16 and 12, the screw proper being indicated at 48, and having a threaded portion 50 engaging a threaded aperture 52 in gauge rail 12, the other end of screw 48 comprising head 54. Suitable means such as a set screw 56 are provided for retaining screw 48 in a selected position with respect to gauge rail 12. A micrometer sleeve 58 passes through rail 10 and is threadedly engaged therewith as indicated at 61), the protruding end 62 of such sleeve having a rounded end surface which acts as a bearing against a similarly cupped bearing surface 64 on gauge rail 12. The relative positioning of micrometer sleeve 53 and rail 11) determines the minimum spacing between rails 19 and 12 at this point, and the screw 48, the head 54 of which may conveniently be captive within an appropriate recess in sleeve 58, holds bearing surface 64 of rail 12 in close contact with the corresponding bearing surface on the end 62 of mircorneter sleeve 58. As is evident, the cupped bearing surface 64 and its corresponding bearing surface on sleeve 58 permit the relatively pivotal motion which takes place between rails 14) and 12 upon the adjustment of the spacing between the rails to a greater amplitude at one end than at the other.

In the operation of the apparatus of the present invention, semiconductor chips 30, or other small, lightweight articles to be sorted, are fed from hopper 32 to a position between gauge rails 10 and 12 near the ends of such rails which define the smallest gauging aperture. As the chips or other articles 30 are being thus fed from the hopper 32 into the gauging device, the rails 10 and 12 are vibrated as a unit by means of the vibratory member 20. As previously stated, the preferred vibratory movement is substantially arcuate in a vertical plane, the action being such as to lift and translate a given article and then quickly drop away therefrom so as to leave such article in a new position which is slightly to the left (in FIGS. 1 and 2) of the position it formerly occupied. This incremental advance of each chip 30 is repeated, with the chips lying on and being supported by feed face 44 of rail '10, until such chip reaches a point along the length of the tapered gauging aperaure between. edges 40 and 42 of the two rails at which it can drop through the aperture and into one of the receiving trays or containers 34. The articles having the least thickness will be the first to drop between the two gauging rails, and those having greater thicknesses will pass through the gauging aperture at correspondingly advanced positions along the rails. Thus, the container 34 positioned at the left-hand end of the several containers illustrated in FIG.

1 will receive the thickest articles 30, with thinner articles being received in graded manner by the other containers 34.

The above description shows that chips of uniform thickness are readily gauged by the apparatus. However, in the case of chips 30 of varying thickness, if a chip starts to fall between the rails with its thinnest end penetrating the space between the rails and if the space between the rails is not sufficiently large enough to allow the entire chip to pass therethrough, it has been found that such an irregular chip becomes securely wedged within the space between the rails and gauging and feeding action of the device is seriously interrupted until such a chip is removed. However, by undercutting the apex 49 of rail 10 it has been found that the chips 30 continue to move along the rail 10 in the direction of feed until they reach the space in which they may fall free into the receiving trays 34.

The invention has been described above in considerable detail, and particularly with reference to its application to the sorting of semiconductor chips. However, it will be apparent to those skilled in the art that the invention is also applicable to the sorting of other articles which are either of such small dimensions or light weight as to incur the difficulties explained herein in connection with the use of the devices of the prior art. in addition, it should be understood that either or both of the opposing gauging rail faces which lie above the gauging aperture may serve as a support or drive face (being inclined at it a small angle with respect to the horizontal) for effecting translation of the articles to be sorted. Further, it is entirely within the scope of the present invention for the containers or other means which receive the sorted articles to be mounted on a common support with the vibratory gauge rails so as to be vibrated therewith. Also, it !will be evident that the structural details shown in FIG. 4 herein are merely exemplary of a preferred embodiment, and other suitable means may be employed .to achieve the desired result. Hence, the invention is not 10 be considered as limited to the particular details given, nor to the specific application to which reference has been made during the description of the apparatus, except insofar as may be required by the scope of the appended claims.

What is claimed is:

1. A device for sorting small articles according to thickness, comprising a pair of elongate gauge rails positioned substantially side by side in spaced apart relation, said rails having convergent downwardly inclined first faces extending in respective given planes, the given plane of one of said first faces being disposed at a relatively small angle with respect to a horizontal plane passing therethrough, said rails each having a second face extending in a given plane divergently downwardly and outwardly from the first face, said one of said first faces having a lip connecting the first face to the respective second face, said lip projecting beyond the plane of the second face whereby relief from wedging of said articles in the space between said rails is obtained, said lip extending longitudinally of the rail and having a rounded surface, and the rail opposite the lip having a slightly rounded edge extending longitudinally thereof and facing said lip in approximately parallel relation thereto, whereby electrostatic potential between said rails is substantially eliminated, and means for vibrating said rails simultaneously to translate articles therealong to a position where they drop through the space between the rails in accordance with their thicknesses.

2. A vibratory sorting apparatus for sorting small articles according to thickness, comprising a pair of elongate g-auge rails mounted substantially side by side in spaced-apart relationship, each of said rails having a face with a slightly rounded edge thereon extending along the length of such rail and facing such rounded edge of the other rail in approximately parallel relationship, such face of one of said rails being inclined at an angle of substantially 30 degrees with respect to a horizontal plane passing therethrough so as to provide a support surface for the articles to be supported, means for adjusting the relative positions of said rails to effect a spacing between such opposed rounded edges which is tapered along the length of said rails, means for simultaneously vibrating said gauge rails in substantially arcuate parallel paths lying in planes parallel to the length of the rails and perpendicular to such horizontal plane, and means for depositing articles to be sorted at the tapered space between said gauge rails and substantially at the narrow end of such space, whereby articles translated along such tapered space by such support surface are gauged as to thickness in accordance with the relative positions along the length of said rails at which they drop through such space.

3. A vibratory sorting apparatus for sorting small articles according to thickness, comprising a pair of elongate gauge rails mounted substantially side by side in spaced-apart relationship, each of said rails having a face with a slightly rounded edge thereon extending along the length of such rail and facing such rounded edge of the other rail in approximately parallel relationship, such face of one of said rails being inclined at an angle of substantially 40 degrees or less with respect to a horizontal plane passing therethrough so as to provide a support surface for the articles to be supported, means for adjusting the relative positions of said rails to effect a spacing between such opposed rounded edges which is tapered along the length of said rails, means for simultaneously vibrating said gauge rails in substantially arcuate parallel paths lying in planes parallel to the length of the rails and perpendicular to such horizontal plane, and means for depositing articles to be sorted at the tapered space between said gauge rails and substantially at the narrow end of such space, whereby articles translated along such tapered space by such support surface are gauged as to thickness in accordance with the relative positions along the length of said rails at which they drop through such space.

4. A vibratory sorting apparatus for sorting small articles according to thickness, comprising a pair of elongate gauge rails mounted substantially side by side in spaced-apart relationship, each of said rails having a face with a slightly rounded edge thereon extending along the length of such rail and facing such rounded edge of the other rail in approximately parallel relationship, such face of at least one of said rails being inclined at an angle of substantially 30 degrees with respect to a horizontal plane passing therethrough so as to provide support surfaces for the articles to be supported, means for adjusting the relative positions of said rails to effect a spacing between such opposed rounded edges which is tapered along the length of said rails, means for simultaneously vibrating said gauge rails in substantially arcuate parallel paths lying in planes parallel to the length of the rails and perpendicular to such horizontal plane, and

means for depositing articles to be sorted at the tapered space between said gauge rails and substantially at the narrow end of such space, whereby articles translated along such tapered space by such support surfaces are gauged as to thickness in accordance with the relative positions along the length of said rails at which they drop through such space.

5. A vibratory sorting apparatus for sorting small articles according to thickness, comprising a pair of elongate gauge rails mounted substantially side by side in spaced-apart relationship, each of said rails having a face with a slightly rounded edge thereon extending along the length of such rail and facing such rounded edge of the other rail in approximately parallel relationship, such face of at least one of said rails being inclined at an angle of substantially 40 degrees or less with respect to a horizontal plane passing therethrough so as to provide support surfaces for the articles to be supported, means for adjusting the relative positions of said rails to effect a spacing between such opposed rounded edges which is tapered along the length of said rails, means for simultaneously vibrating said gauge rails in substantially arcuate parallel paths lying in planes parallel to the length of the rails and perpendicular to such horizontal plane, and means for depositing articles to be sorted at the tapered space between said gauge rails and substantially at the narrow end of such space, whereby articles translated along such tapered space by such support surfaces are gauged as to thickness in accordance with the relative positions, along the length of said rails at which they drop through such space.

6. A vibratory sorting apparatus for sorting small articles according to thickness, comprising a pair of elongate gauge rails mounted substantially side by side in space-apart relationship, the face of one of said rails being inclined at an angle of substantially 30 degrees with respect to a horizontal plane passing therethrough so as to provide a support surface for the articles to be supported, means for adjusting the relative positions of said rails to effect a spacing between said rails which is tapered along the length of said rails, means for simultaneously vibrating said gauge rails in substantially arcuate parallel paths lying in planes parallel to the length of the rails and perpendicular to such horizontal plane, and means for depositing articles to be sorted at the tapered space be tween said gauge rails and substantially at the narrow end of such space, whereby articles translated along such tapered space by such support surface are gauged as to thickness in accordance with the relative positions along the length of said rails at which they drop through such space.

7. A vibratory sorting apparatus for sorting small articles according to the thickness, comprising a pair of elongate gauge rails mounted substantially side by side in spaced-apart relationship, the face of one of said rails being inclined at an angle a substantially 40 degrees or less with respect to a horizontal plane passing therethrough so as to provide a support surface for the articles to be supported, means for adjusting the relative positions of said rails to effect a spacing .therebetween which is tapered along the length of said rails, means for simultaneously vibrating said gauge rails in substantially arcuate parallel paths lying in planes parallel to the length of the rails and perpendicular to such horizontal plane, and means for depositing articles to be sorted at the tapered space between said gauge rails and substantially at the narrow end of such space, whereby articles translated along such tapered space by such support surface are gauged as to thickness in accordance with the relative positions along the length of said rails at which they drop through such space.

Hughes et al. Apr. 8, 1958 Reilly Sept. 2, 1958

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