US3680694A - Method and apparatus for separating objects having different resiliencies - Google Patents

Abstract

A method and apparatus for separating objects having different resiliencies according to the modulus of elasticity thereof. The objects are passed through a zone and are transversely vibrated at a selected frequency and amplitude to eject those objects having the higher natural frequencies of vibration.

Description

United States Patent Hamann [4 Aug. 1, 1972 [54] METHOD AND APPARATUS FOR [5 6] References Cited SEPARATING OBJECTS HAVING DIFFERENT RESILIENCIES Um I ED STATES PATENTS 3,473,657 10/1969 Grafetal ..209/117 [72] 2,370,539 2/1945 l-lodecker ..209/106 [73] Assignee: Research Corporation, New York,

N.Y. Primary Examiner-Allen N. Knowles Assistant Examiner-Gene A. Church [22] Filed May 1970 Att0rneyStowell and Stowell [2]] App]. No.: 40,919

[57] ABSTRACT [52] U.S. Cl ..209/l19 A method and apparatus for separating objects having [51] Int. Cl. ..B07b 13/10 different resiliencies according to the modulus of [58] Field of Search ..209/1l5, 116, 117, 118, 106, elasticity thereof. The objects are passed through a 209/119 zone and are transversely vibrated at a selected frequency and amplitude to eject those objects having the higher natural frequencies of vibration.

4 Claims, 4 Drawing Figures PATENTEDAuc 1 m2 Bob H300 FIG. 3

1N1 EA TOR I DONALD D HAM IMV A TTORNEYS METHOD AND APPARATUS FOR SEPARATING OBJECTS HAVING DIFFERENT RESILIENCIES BACKGROUND OF THE INVENTION This invention relates generally to sorters and more particularly to separaters for objects having different resiliencies or moduli of elasticity.

There exists, in the art, a need to classify objects of many kinds according to various factors such as type, size, weight, ripeness, quality and the like. One property which can be indicative in the determination of factors, such as quality and ripeness of fruits and vegetables, is the resiliency or natural frequency of vibration of the object. In the case of ripeness of fruits, for example, a decrease in the natural frequency of vibration of the fruit correlates with an increase in soluble solids and a decrease in total acid content which are recognized indicators of ripeness.

In the prior art, there have been few means for separating objects according to resiliency on a high volume basis. There are, extant, for example, devices which sort objects by bounce technique wherein the objects are dropped onto a surface and categorized according to the distance of their bounce or rebound. Such devices are not as accurate as the method to be described and also have the disadvantage of subjecting the material to be sorted to much higher force levels than desired and therefor possible damage.

OF THE INVENTION This invention provides means for sorting objects having varied resiliency which avoids the disadvantages of the prior art by furnishing a method and apparatus for separating the objects, according to the natural frequencies of vibration thereof, in a continuous, high volume manner.

The invention further provides an apparatus which continuously separates objects according to their natural modulus of elasticity by applying a transverse, con trolled vibration to a stream of objects to eject those of higher natural frequency from the stream.

In the preferred embodiment, the invention provides a separator for materials of varied firmness comprising means to channel a stream of objects to be separated through a separating zone; vibrator means to vibrate objects in the zone transversely of the flow of the objects at a controlled amplitude and frequency and selectively eject therefrom objects having the higher natural frequencies; first receiving means adjacent the zone for collecting objects ejected therefrom; and second receiving means communicating with the zone for collecting the residual objects.

These and other objects and many of the attendant advantages of the invention will become better understood by reference to the following detailed description when viewed in light of the accompanying drawings wherein like numerals indicate like components throughout the figures thereof and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a device in accordance with the invention;

FIG. 2 is an end view of the device of FIG. 1;

FIG. 3 is a plan view of another device in accordance with the invention; and

FIG. 4 is an end view of yet another device in accordance with the invention.

DESCRIPTION OF THE PREFERRED ENBODIMENTS Although the invention is specifically described hereinafter as applied to the sorting of fruits or vegetables according to ripeness, it should be understood that the invention may be applied to the separation of objects of any kind and for any purpose according to the resiliency modulus of elasticity or viscoelastic modulus as is exhibited by the natural frequency thereof.

In fruits and vegetables, the firmness thereof decreases with increasing maturity and generally corresponds with an increasing content of soluble solids and decreasing total acid. As the firmness or modulus of the material decreases, the natural frequency or sensitivity to higher frequencies of vibration thereof decreases.

As a result of the above, firmer objects will react or be bounced by the higher frequency imposed vibration while the softer objects will not react. When applied to a mass of objects having varied natural frequencies then, the frequency of imposed vibration can be selected to cause a portion of the objects having desired higher natural frequencies to react or bounce while the remaining objects do not react or react to a lesser degree. By proper selection of the amplitude and direction of vibration, then, the reacting objects can be bounced from the mass of objects and thereby be separated therefrom.

The invention is applicable to objects of any shape, however, objects having a relatively consistent shape throughout the mass are more predictable in their reaction. The direction of reaction is more controllable in objects having regular shapes such as those approximately spheroidal or elliptical, for example, golf balls, ping pong balls, fruits, vegetables and the like. Mixed objects of different kinds can also be separated according to the natural frequencies thereof. For example, small hard spheres have a frequency band, the high side of which is on the order of 1,000 cps or more, in contrast to which apples have a band, the high side of which is on the order of cps. Cherries, blueberries, plums and other intermediate size objects have a band, the high side of which is between that of the hard spheres and the apples. Very soft, overmature, damaged or partly decomposed materials dissipate most of the vibrational energy imposed thereon in the form of heat with the result that the low end of the band thereof can be extended to zero. Blueberries, for example, would then extend from 400 cps to zero for a wide variety of maturity and decomposition.

In FIG. 1, a separating device, particularly adapted for sorting spheroidal or ellipsoidal objects adapted to be conveyed by gravity along inclined troughs, is illustrated in perspective. The device comprises a feed trough 10 which feeds into a separating trough l2 defining a separating zone. The trough I2 is resiliently mounted, such as by springs indicated schematically at 14, and disposed beneath the feed end of the feed trough 10 to receive the discharge therefrom. A vibrator 16 is affixed to the side wall 18 of the trough 12 to impart vibrations thereto transversely of the length of the trough and normal to the plane of the side wall 18. The vibrator 16 may be of any type known in the art,

such as an eccentric rotary weight vibrator; however, an electromagnetic vibrator has been found to be particularly suitable for the purposes of this invention in that the required degree of control of both amplitude and frequency of vibration can readily be achieved. For this purpose the vibrator 16 is connected to a source of electrical energy 20 through a control 22, which control provides, as is known in the art, means for individually varying the frequency and amplitude of vibration imparted to the trough 12.

The trough 12 discharges, at the lower end thereof to a container 24. The discharge can alsobe fed into other conveyer means if the requirements of the process, plant or equipment so dictate.

:As-is best seen in FIG. 2, a receiving trough 26 is disposed beneath the trough l2 and laterally displaced therefrom in a direction away from the wall 18. This trough may comprise astationary container or second conveyor means as is desired. In the embodiment illustrated, the trough 26 is an inclined conveyer which discharges at the lower end thereof into a container 28.

In operation, relatively unripe berries 30a and ripe berries 30!; are introduced into the separating zone in the trough 12 through the feed trough 10. The vibrator 16 is energized and the frequency and amplitude thereof are adjusted by the control 22 until the desired separation of berries a and 30b occurs. At a certain frequency and amplitude the berries 30a, due to their higher natural frequency as discussed above, will react ripeness is disposed therein and the vibrator 16 is adjusted to induce a high frequency at a low amplitude. Fruit ejected from the trough under these conditions is collected. The vibrator frequency is then lowered and the amplitude raised in steps, with fruit ejected at each step collected separately. The ripeness of the fruit in each sample can then be determined, as a function of total soluble solids as set forth above, and the proper conditions for desired separations for that particular type of fruit are thereby established.

For example, with a test sample of Muscadine grapes of the Aberrnarle variety, the following data were established where total soluble solids represent the ripeness of grapes ejected at the given frequency and amplitude, the amount of solids increasing with increasing maturity in the grapes:

Ejection Ejection Total Soluble Frequency Amplitude Solid Content Step C.P.S. Inches Of Grapes l 200 0.009 l0.l 2 180 0.011 12.3 3 160 0.0l4 13.4 4 I 0.0l9 14.9 5 120 v 0.025 15.6

, The conveyer portions of the above described device, such as feed trough 10, may be longitudinally vibrated in a manner known in the art if so desired to aid in or provide conveying motivation for material therein. The conveyer portions may also be of the conventional endless belt or fluidized bed types without exceeding the scope of the invention. I

The embodiment of FIG. 3 can be employed for the separation of objects into a greater number of categories. In this embodiment, components thereof cor-- responding to like components of the preceeding embodiment are indicated by like numerals, only of the next higher order. Components corresponding to like components within this embodiment are indicated by like numerals with the appropriate suffix.

A feed trough discharges fruit comprising relatively overripe, ripe and underripe'berries 1300, b, I

and 1300 respectively into a first vibrating trough 1 12a. The trough 1 12a is provided with a vibrator 1 16a in the manner of the embodiments of FIGS. 1 and 2. A receiving trough 126a is disposed adjacent and below the trough 112a for receiving berries ejected therefrom. A discharge conveyer trough 124a communicates with the discharge end of the trough 1120 to receive berries residual therein.

The receiving trough 126a serves as a feed trough for a second vibrating trough 112b which is activated by a second vibrator ll6b and discharges into a second discharge conveyer trough l24b. A second receiving trough 12612 is disposed adjacent and below the trough 1 12b.

In operation the vibrators 116a and 116k are set at the frequencies and amplitudes required to provide the desired separation of berries, the vibrator ll6b being set at a higher frequency than that of the vibrator 116a. The berries are then fed into the vibrating trough 1120, the ripe and underripe berries 130k and 1300 reacting to the vibrator 116a due to their higher natural frequency to be ejected from the trough 1120 into the receiving trough 126a. The overripe berries 130a are discharged from the end of the trough 1120 into the trough 124a for disposal. The berries 1301: and l30c are next fed into the vibrating trough 112b, the underripe berries reacting to the vibrator 1l6b due to their higher natural frequency and being ejected into the receiving trough l26b for disposal. The ripe berries 130b are discharged into the trough l24b for packaging or further processing.

Obviously, the berries could be separated into more categories by the addition of further vibrating trough stages and by proper selection of the frequencies and amplitude of the vibrations imposed thereon at the various stages.

Where particular objects are sensitive to very narrow frequency bands, it may be necessary to cycle the frequency of the vibrators so that allof the pertinent frequencies above a given level are covered during the time of passage of a given sample of objects through the trough. Timer controlled electronic or mechanical frequency varying means known in the art could be utilized for this purpose.

Where increased capacity is desired, parallel flow paths can be provided to multiply the capacity of the device. Such an embodiment is illustrated in FIG. 4 wherein components corresponding to like components of the preceeding embodiments are indicated by like numerals, only of the next higher order.

The device comprises a plurality of vibrating troughs 212a through 212d mounted on a common support 232 which is, in turn, resiliently supported by spring means shown schematically at 214. A vibrator 216 is mounted on the support 232 and simultaneously vibrates each trough 121a through 212d at the same frequency and amplitude.

A series of receiving troughs 226a through 226d are mounted on a common support 234 and are individually disposed adjacent and below the corresponding vibrating troughs 2120 through 212d. The support 234 can be fixed or vibratory to produce a conveying motion in troughs 226a through 226d as desired.

In operation, fruit comprising ripe and underripe berries 230a and 2305. are fed in parallel paths into each of the troughs 2120 through 212d. The underripe berries 230b react to the vibrations imposed by the vibrator 216 and are ejected into the corresponding receiving troughs 226a through 226d to flow therefrom in parallel paths. The residual berries 230a similarly flow from the troughs 2120 through 212d in parallel paths for common collection or further processing.

Obviously, the embodiment of FIG. 4 could be combined with that of FIG. 3 for plural separations without exceeding the scope of the invention.

What has been set forth above is intended as exemplary to enable those skilled in the art in the practice of the invention, and is should therefore be understood that the invention may be practiced other than as specifically described.

What is new and therefore desired to be protected by Letters Patent of the United States is:

l. A separator for objects of varied firmness comprismg:

means to channel a stream of objects to be separated through a separating zone, said separating zone comprising a pair of extended surface walls defining a V-shaped trough,

vibrator means secured to one of said pair of walls to vibrate the objects in said zone at a controlled amplitude and frequency by imparting vibrations to the separating zone transversely of the length of the trough and normal to the plane of said one wall and selectively bounce therefrom those objects having the higher natural frequencies,

first receiving means adjacent said zone for collecting objects bounced therefrom, and

second receiving means communicative with said zone for collecting the residual objects.

2. A separator in accordance with claim 1 wherein said first receiving means includes:

a second separating zone, said second separating zone comprising a pair of extended surface walls defining a second V-shaped trough,

second vibrator means secured to one of said pair of walls of the second separating zone to vibrate objects in said second zone at a controlled amplitude and frequency higher than that of said first zone by imparting vibrations to the separating zone transversely of the length of the second trough and normal to the plane of said one wall thereof to selectively bounce therefrom those objects having the higher natural frequencies, third receiving means adjacent said second zone for receiving objects bounced therefrom, and fourth recelvmg means communicative with said second zone for receiving objects remaining therein.

3. A separator in accordance with claim 1 wherein said means to channel a stream of objects includes conveyer means discharging to and transmitting from said separating zone.

4. A separator in accordance with claim 5 wherein said means to channel a stream of objects further comprises conveyer means transmitting from said receiving means.

Claims (4)

1. A separator for objects of varied firmness comprising: means to channel a stream of objects to be separated through a separating zone, said separating zone comprising a pair of extended surface walls defining a V-shaped trough, vibrator means secured to one of said pair of walls to vibrate the objects in said zone at a controlled amplitude and frequency by imparting vibrations to the separating zone transversely of the length of the trough and normal to the plane of said one wall and selectively bounce therefrom those objects having the higher natural frequencies, first receiving means adjacent said zone for collecting objects bounced therefrom, and second receiving means communicative with said zone for collecting the residual objects.

2. A separator in accordance with claim 1 wherein said first receiving means includes: a second separating zone, said second separating zone comprising a pair of extended surface walls defining a second V-shaped trough, second vibrator means secured to one of said pair of walls of the second separating zone to vibrate objects in said second zone at a controlled amplitude and frequency higher than that of said first zone by imparting vibrations to the separating zone transversely of the length of the second trough and normal to the plane of said one wall thereof to selectively bounce therefrom those objects having the higher natural frequencies, third receiving means adjacent said second zone for receiving objects bounced therefrom, and fourth receiving means communicative with said second zone for receiving objects remaining therein.

3. A separator in accordance with claim 1 wherein said means to channel a stream of objects includes conveyer means discharging to and transmitting from said separating zone.

4. A separator in accordance with claim 5 wherein said means to channel a stream of objects further comprises conveyer means transmitting from said receiving means.

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