US2666995A - Drying apparatus - Google Patents

Description

Jan- '26, 1954 A. H. KIRKPATRICK DRYING APPARATUS 2 Sheets-Sheet l Filed Aug. 17, 1950 JL "l I Jan. 26, 1954 A. H. KIRKPATRlcK 2,666,995

DRYING APRARATUS Filed Aug. 17, 1950 2 Sheets-Sheet 2 Patented Jan. 26, 1,954

DRYIN G APPARATUS Arthur H. Kirkpatrick, Detroit, Mich., assignor to Frederic B.

Stevens Incorporated, Detroit,

Mich., a corporation of Michigan Application August 17, 1950, Serial No. 180,065 f 9 Claims. (Cl. 34-164) A further object of the invention resides in' the provision of a dryer having adjustment features which enable varying the operating characteristics of the dryer in accordance with the type and size of work piece being dried.

More specifically, the invention contemplates a dryer in the form of a casing through which a stream of heated air is circulated. Within the dryer there are mounted a plurality of perforated trays, the trays being slightly inclined and in an echelon arrangement. Means are provided for vibrating the trays so that when a charge of parts to be dried are placed upon the uppermost tray, the work pieces cascade from one tray to the next through the dryer.

In the drawings:

Fig. 1 is a side elevation, partly in section, of the dryer of this invention.

Fig. 2 is a fragmentary perspective view of the tray arrangement.

Fig. 3 is a fragmentary sectional view of the trays and the supports therefor.

Fig. 4 is a bottom perspective view of one of the trays.

Fig. 5 is a sectional view taken substantially along the lines 5 5 in Fig. 3. y

Fig. 6 is a perspective view of a work piece which may be advantageously dried in the drying apparatus of this invention.

Referring to the drawings and particularly to Fig. l, the dryer generally comprises two pair of spaced apart upright supportsIO and I2 which are connected together at their lower and upper ends by transverse members I4 and I6, respectively. A sheet metal casing I1 having side wall panels I8 is supported on uprights I0 and I2. Casing I1 is provided with a bottom wall 20 and a top wall 22, the top Wall 22 being centrally apertured as at 24. A nned heating coil 26 is supported within a casing 28 over opening 24 on top wall 22, casing 28 having an outlet opening therein registering with opening 24. Casing 28 is also provided with an inlet opening 30 which is connected as by a duct 32 with the outlet 34 of a centrifugal blower 3S. The inlet 38 of blower 36 opens into the interior of casing I1, the arrangement being such that when the blower is 2 f turned on, air is withdrawn from the casing into the blower through inlet 38, the air passing through the duct 32 into casing 3D and downwardly through the heating coil 26 and into casing I1 through opening 24. Heating coil 26 may be of any conventional type and, for the purposes of illustration, is shown connected with pipes 40 through which hot water from a suitable source may be circulated.

Casing I1 is partially closed at each end by end walls 42 and 44. End wall 42 extends downwardly from the top of the casing and provides an outlet opening 46. End wall 44 extends upwardly from the bottom of the casing and provides an inlet opening 48. Within casing I1 and at each side thereof there is mounted an inclined supporting rail 50. Rails 50 are secured to upright members I0 and I2 by means of right-angle brackets 52 and project at each end out of casing I1 through openings 46 and 48. Uprights I6 and I2 are provided with a plurality of longitudinally spaced apertures 54 in which brackets 52 may be selectively secured, as by screws 56. Between brackets 52 and the underside of rails 5U, which may be advantageously formed as angle irons, there are interposed compression springs 68. Springs resiliently support rails 50 within the casing. It will be observed that brackets 52 may be secured to their respective supports I0 and I2 in a plurality of vertically spaced positions by selecting the desired set of apertures 54 and, in

this way, the 4inclination of rails 50 may be varied.

Rails 50 support a plurality of perforated trays. There is shown, by Way of illustration and not by limitation, four such trays, a loading tray 62, rst and second drying trays 64 and 66, respectively, and a discharging tray 68. Each of these trays are supported at their front ends by means of pintles 10 projecting from each side of the tray which are loosely journalled in U-shaped bearings 12 formed in rails 50. Adjacent its rear end, each tray is provided on the bottom side thereof with a transverse plate 14 which rests upon the upper end of a screw 16 which is threadedly engaged with transverse supports 18 which are fixed at each end on the side rails 56. The threaded connection between screws 16 and supports 18 is preferably in the form of a nut 88 which is Welded or otherwise alixed on the underside of supports 18. Each of said supports i8 is preferably provided with a plurality of spaced nuts 8l) so that screws engage Vthe underside of the tray at any of a plurality of transversely spaced points.

The work pieces are caused to travel from one tray to the next by means of vibration and, ac-

16 may be arranged to v cordingly, each tray is provided on the underside thereof with a vibrator Sii. Vibrators 86 may be operated either pneumatically, mechanically or electrically. They may be of any suitable type adapted to produce high speed small amplitude vibration. The vibrators 86 illustrated are arranged to be driven -by compressed air and are accordingly connected as by conduits BS with an air pressure line Sil.

As is sh-own more clearly in Figs. 2 and 3, the trays are arranged on side rails 50 such that the lower or front end of one tray overhangsl the upper or rear end of the next succeeding tray. Each tray is provided with a peripherallange 82 which is notched along the rear side of trays d,

66 and 63 as at 8:1 to accommodate the lower ends of the preceding tray. The opposite ends of flange 82 are spaced apart at the lower end of each tray such as to provide an outlet opening through which the parts may cascade from one tray or to the next.

The trays are preferably coated with a plastic material so that the work pieces will not be scratched or marred by contact with the tray. Each tray has a bottom wall 92- preferably formed of a perforated sheet material. The bottom wall 92 of each tray is substantially nat at the entrance or upper end thereof. At the discharge or lower end thereof, the bottom wall SQ is sloped downwardly from each side toward the center of the tray as is generally indicated at 9i. I have found that by forming the trays with a substantially flat bottom wall at the entrance end thereof and with a bottom wall that is inclined downwardly towards the center of the tray at the discharge end, the material passing through the dryer travels in a well dened and desirable pattern. This bottom wall construction has a tendency to spread the workas it enters the trays and then to concentrate the work as it leaves the tray thus providing a tortuous path of travel for the work pieces generally illustrated by the arrows 535 and preventing an accumulation of work at the corners of the tray adjacent the discharge opening.

The rate of travel of the work over each particular tray is determined by the inclination or that tray, and the pitch of the side rails 5.9, determines the speed at which through the dryer. The inclination of each tray may be adjusted by turning screw I6 in either one direction or the other to raise or lower the entrance or the upper end of the tray. II'oe inclination of side rails 50 may be varied by raising and lowering brackets l and I2.

Many types of work pieces, such as that generally referenced 93 and illustrated in Fig. 6, have blind holes or cupped surfaces such as is indicated at 94 and 96. When work pieces of this general typ-e are conveyed through a dryer, care must be exercised to make certain that theliquid on the part, which, in the case of plating, may be either Water or some chemical solution, is completely removed from the surface of the work piece as well as from within the cupped surfaces. In the arrangement illustrated in the drawings, removal of the liquid from the cupped surfaces is insured by conveying the work pieces through lthe dryer such that they travel across one tray right side up and across the next tray bottom side up. 'Ihe work pieces can be caused to automatically invert themselves as 'they travel from one tray to the next by adjusting the vertical distance between the discharge end of one tray and the en- 52 on either of supports the material passes` the vibration pattern desired.

trance end of the next succeeding tray. This adjustment is obtained by manipulating screws 16. As is illustrated more clearly in Fig. 3, screws 16 are adjusted such that at the overlapping ends of the trays the distance between the bottom walls of adjacent trays is slightly greater than half of the length of the work pieces being dried. With the trays adjusted in this manner the work piece slides to the discharge end of the tray and, in falling from that tray to the next, it tumbles into an inverted position and, in the next succeeding tray, it travels in an upright position. In this way removal of the liquid from the cupped surfaces in the work piece is insured, since the Work-piece travels through a portion of the dryer right side up and through another portion of the dryer bottom side up.

The loading tray E2 and the rst drying tray 54- are preferably adjusted with slightly less pitch than the next succeeding trays. In this way the work travels more slowly over the rst two trays and a greater portion of the liquid is shaken from the parts by vibration so that when the work pieces enter the zone of the dryer in which the drying air is conducted downwardly through the work pieces and the perforated trays, a greater portion of the liquid has already been removed. This results in a saving in heat required in the lower evaporating trays and consequently reduces thc amount of heat which must be supplied to the circulating air. It will also be noted that the downward direction of the heated air stream also tends to drive the liquid downwardly through the perforated trays as a liquid. |This reduces the amount of evaporation required to dry the work pieces.

I have found that the vibration pattern of the pan itself may be Varied considerably by mov ing the support for the free end of the tray in a direction transversely of the tray. In the prescrit instance the pattern may be varied by engaging screw 16 with any of the three nuts Sil on supporting bars 18. In operation these screws "it are engaged with one of the nuts 8l) which produces Thereafter, the screw is adjusted up or down to set the tray at the desired inclination and to secure the proper spacing between the overlapping ends of adjacent trays.

The work to be ldried is loaded at the upper end of loading tray 62. The loading may be either the batch type or continuous loading from a conveyor. When the vibrators 8E are set in operation, the vibration moves the work pieces gently across each tray and produces a wiping action where the work and tray come in contact. This prevents the solution from collecting in drops on the lowest point of the work piece.

Since the work piece has a different radius of gyration than the solution, the surface tension between the metal and the liquid is Kbroken by the vibration thus rallowing the liquid to be shaken off of the work piece in the upper trays. When the work pieces travel into the path of the downwardly moving heated air, the liquid remaining on the work pieces is partly evaporated and partly -driven oil? as a liquid. The vibration assists materially in the removal of this remaining liquid by increasing the effective surface area of the -Work piece in contact with the heated air and by decreasing the skin effect thus allowing more of the drying air to come into more intimate contact with the moisture on the surface of the work piece.

The temperature of the air circulated through 5 casing I 1 depends upon the heat supplied thereto by heating coil 26 and the rate at which the air is conducted through the casing. A greater portion of the drying air is recirculated, but means (not shown) are preferably provided for exhausting a portion of the heated air from the system and admitting an equal amount of fresh air so that'the humidity or" the recirculated air will vbe maintained Iwithin the desirable limits.

Thus it will be seen that I- have provided a dryer which is admirably adapted for drying relatively small work pieces efficiently and in a rapid manner. The adjustment features of the dryer, such as the screws 16, enable setting of the dryer trays to accommodate the particular type and size of work piece being handled and insures` the removal of liquid from the cupped surf-aces of the ywork pieces. The adjustability of the inclination of each tray also enables the rate of travel o-f the work through the dryer to be controlled such that a large portion of the liquid on the work pieces is shaken off before they come into contact with the downwardly moving heated air stream.

I claim:

1. A dryer for work pieces comprising a casing, means for conducting a stream of heated air through said casing, inclined supports at each side of said casing extending longitudinally of the casing, and a plurality of trays mounted in echelon -arrangement on said supports, said trays having a charging end and a discharging end, said trays being arranged on said supports with the discharging end of one tray overlying the charging end of the next adjacent tray, means for vibrating said trays such that work pieces deposited on the uppermost tray gradually travel to the lowermost tray, said trays being inclined downwardly in the direction of their discharge ends, the trays -adja-cent the upper end of said supports being inclined to a lesser extent than the trays adjacent the lower ends of said supports, said last mentioned trays being positioned in said stream of heated air and said trays adjacent the yupper end of said supports being disposed out of the direct path of travel of said heated stream of air.

2. A dryer for work pieces comprising a casing, means for conducting a stream of heated air through said casing, a pair of inclined supports in said casing extending longitudinally of the casing, a plurality or trays mounted in echelon arrangement on said supports, said trays having a charging end and a discharging end, said trays being arranged on said supports with the discharging end of one tray overlying the charging end of the next adjacent tray, means for vibrating said trays such that work pieces deposited on the uppermost tray gradually travel to the lowermost tray, said trays being inclined downwardly in the direction of their discharge ends, the trays adjacent the upper end of said supports being inclined to a lesser extent than the trays adjacent the lower ends of said supports, said last mentioned trays being positioned in said stream of heated air and said trays adjacent the upper end of said supports being disposed out of the direct path of travel of said heated stream of air, and means for varying the inclination of said trays relative to each other.

3. A dryer for work pieces comprising a casing, means for conducting a stream of heated air through said casing, inclined supports in said casing extending longitudinally of the casing, a plurality of trays mounted in echelon arrangementl on said supports, said trays having a charging end and a discharging end, said trays Abeingarranged on said supports with the discharging end of one tray overlying the charging end of the next adjacent tray, means for vibrating said trays such that work pieces deposited on the uppermost tray gradually travel to the lowermost tray, said trays being inclined downvvardly inthe direction of their discharge ends, the trays adjacent th-e upper end of said supports being inclined to av lesser extent than the trays .adjacent therlower ends of said supports, said last mentioned trays being positioned in said stream of heated air and said trays adjacent the upper end of said supports being disposed out of they direct'path of travel of said heated stream of air, and means for varying the inclination of said supports.

4, A dryer for work pieces comprising a casing, means for conducting a stream of heated air through said casing, inclined supports in said casing extending longitudinally of the casing, a plurality of trays mounted in echelon arrangement on said supports, said trays having a charging end and a discharging end, said trays being arranged on said support with the discharging end of one tray overlying the charging end of the next adjacent tray, means for vibrating said trays such that work pieces deposited on the uppermost tray gradually travel to the lowermost tray, said trays being inclined downwardly in the direction of their discharge ends, the trays adjacent the upper end of said supports being inclined to a lesser extent than the trays adjacent the lower ends of said supports, said last mentioned trays being positioned in said stream of heated air and said trays adjacent the upper end of said supports being disposed out of the direct path of travel of said heated stream of air, means for varying the inclination of said trays relative to each other, and means for varying the inclination of said supports.

5. A dryer for work pieces comprising a casing, means for conducting a stream of heated air through said casing, a plurality of trays pivotally supported in said casing in echelon arrangement with one end of one tray overlapping the opposite end of the next adjacent tray, means for vibrating said trays, and means for pivotally adjusting each of said trays to vary the inclination thereof, the overlapped end of each tray comprising the charging end of the tray and the overlapping end of each tray comprising the discharging end of the tray, each tray having a bottom wall which is substantially iiat at the charging end thereof and slightly concave at the discharging end thereof whereby the work pieces traveling along said trays tend to spread out as they are deposited at the charging end of each tray and then converge toward the discharging end of each tray.

6. A dryer for work pieces comprising a casing, means for conducting a stream of heated air through said casing, a plurality of vertically spaced trays supported in said casing in echelon arrangement with one end of one tray overlapping the opposite end of the next lower adjacent tray, said trays being pivotally supported at one end, means forming a localized support at the opposit@ end 0f each tray, said supports being shiftable in a direction transversely of the trays and being positioned beneath the trays, said trays being freely supported at one end by said supports and being pivotable relative to said supports, and neans associated with each tray for vibrating the rays.

ARTHUR H. KIRKPATRICK.

Referencesy Cited in the file of this patent UNITED STATES PATENTS Number 5 Re. 1,434 1,107,028 1,603,108 2,031,086 2,0943 85 2,214,981 2,223,455 2,346,176 2,497,703

Number Name Date Schuyler Mar. 17, 1863 Busch Aug. 11, 1914 Heinz Oct. 12, 1926 Woodruff et al Feb. 18, 1936 Flint Oct. 5, 1937 Vissac Sept. 17, 1940 McLauchlan Dec. 3, 1940 MoAleer Apr, 11, 1944 Todd Feb. 14, 1950 FOREIGN PATENTS Country Date France Sept. 17, 1934

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