US2763234A - Coating or enrobing machines - Google Patents

Description

Sept 18, 1956 w. D. MEAGHER E-rAL 2,763,234v

COATING OR ENROBING MACHINES Filed Jan. 26. 1955 2 Sheets-Sheet 1 #Wm/Tow sept 18, l956 w. D. MEAGHER ETAL 2,763,234

COATING OR ENROBING MACHINES 2 Sheets-Sheet 2 Filed Jan. 26, 1953 United States Patent 'COATING 0R ENROBING NIYAKHI. NESl Walter Denis Meagher and George Meagher, ESt. Annes-on-Sea, England Application January 26,y 1953,V Serial No..3,3,3,056

7 Claims. (Cl. 11S- 16) reference to that type of machine in which the articles under treatment are carriedo'n a moving conveyor through a falling curtainiof the coating substance, it being usual to construct the conveyor so as .to leave the undersides of the articles thereon exposed to an upsurge of the coating substance produced by suitable means.

In connection with these so-called enrobing machines, it is known practice to deliver the coating substance continuously to a suitable receiver from which the aforesaid curtain falls, and it is also known to produce the upsurge beneath the conveyor by means of a roller partially immersed in a tank of vthe coating substance.

The chief object of the present invention is to provide for a more precise control of the thickness and uniformity of the curtain than is possible when the latter is produced by, say, a fishtail nozzle, and thereby to obtain greater accuracy and consistence in the coatings applied to the individual articles. The improved controlling means hereinafter described allows ready variation in the thickness of the curtain" (and hence of the applied coating) whilst preserving the aforesaid precision and uniformity with all thicknesses within the available range `of variation.

A further object of the invention is to facilitate adjustment of the height of the curtain to suit the thickness of the articles to be coated. f

Yet another object of the invention is a simple but etl'ective means for controlling the upsurge of coating substance against the undersides of the articles under treatment, and thus permitting the coatings produced by such upsurge to conform to those applied to other surfaces of the articles.

`According to this invention, a coating machine of the type referred to is characterised in that the curtains issue from slots provided at the base of a hopper and in the bottom of a grooved member which contains a rotary valve, the outlet available being parallel-sided when the valve is open, but variable in width vaccording to the angular position of such valve.

The valve (or each valve if there are two, as is preferred) and the groove inwhich it works may both be of half-round section, the axis of the valve being substantially flush with the upper surface of the grooved member.

Means may be provided for simultaneously raising or lowering opposite ends of the hopper so as to maintain its outlet or outlets parallel to the plane of the conveyor during adjustment of its or their height above the latter.

For example, there may be a pair of lead Screws in threaded engagement with the hopper ends, the latter being suitably guided for vertical movement, and the two screws being interconnected by chain or other gearing so as to be simultaneously rotated when one of them is operated by a hand-crank or other means.

When .the machine has means for coating the undei'- A 2,763,234 Patented Sept. 1,

sides of the articles on the conveyor, such means. preferably comprises a tray disposed beneath the conveyor so as to collect the coating substance escaping from the hopper, a roller continuously rotatedabout an axis transverse to said conveyor, and between the latter and 'the substance collected in said tray, a doctor co-operating with said roller and adapted, when such roller is partly immersed in the collected substance, to deliver an upsurge of the latter to said-conveyor, and means for adjusting said doctor to vary the height of such upsurge relatively to said conveyor. f Y

In a convenient arrangement, the doctor is carried by, or forms part of a horizontalsurge plate disposed between the roller andthe conveyor, 'and capable of adjustment towards or away from the latter.

The roller (or each roller, if there are two rotating in the same or opposite directions as may be required) may be mounted upon a stationary airis, the depth of immersion of such roller in the collected substance being variable by bodily adjusting the tray up or down and/or by adjusting an overflow weir associated with such tray. A

In the accompanying drawings:

Fig.` l is a part-sectional side elevation of curtainforming means according to the present invention,

FigjZ is an end elevation of thesame,

vFig. 3 is a section, to an enlarged scale, on the line 3,-3 of Fig-. l, and

Fig. 4 s `a fragmentary plan view, to the same enlarged scale, of one end of the 'curtainforming means.

Fig. 5 is a sectional side elevation of part. ofv accating machine showing the curtain-forming means aforesaid and preferred means for producing upsurge of the coating` material against the undersides of the articles under treatment.

Fig. 6 is a view corresponding -to Fig. 5, but showing the `upsurge-producing means adjusted to produce, a lighter coating onV the articles.

In the example illustrated, the articles to be coated or enrobed are Vcarried upon a moving conveyor band 10, preferably formed of stainless-steel wire mesh, which passes beneath a trough-like hopper 11 fed with molten chocolate or other coating substance 12; from a fishtail nozzle 13 above it.

This feed nozzle 13, to which the coating substance may be delivered by a pump. and suitable piping from a kettle or other container, preferably has a width about one-third that of the conveyor 10 and is disposed with its orifice horizontal and at right angles to the length o f such conveyor.

The hopper 11, situated directly/*below the nozzle 13, is likewise arranged transversely of the conveyor and constructed of stainless steel sheet.

The length of the hopper 11 is such that it projects beyond both lateral edges ofthe conveyor 10, its end walls 11a being vertical and parallel to such edges'. Adjacent each such end wall a transverse partition 14 is fixed to form an overflow weir,4 the. lower parts of the end walls 11a and partitions 14 depending below the body of the hopper as at 15 and being suitably arranged to direct any overflowing substance clear of, but close to, the edges 0f the conveyor 10 (see Fis- 1) Between the partitions or weirs 14 the hopper is of generally traperzoidal section, its side walls 11b converging downwardly and having their lower edges connected by a stout metal plate 16 in whose upper face are formed two n iutually parallel, longitudinal grooves 17 of semicircular (or at least part-circular) cross-section. Atthe bottom-@Mach Such groove., and extending the full distance between the partitions or weil-S14, is a vertical slot 18;

'. 'Ifhe ends of the groovedvplate 16 project vsomewhat beyond the partitions or weirs aforesaid and are provided with bearing caps `19 having complementary partcircular recesses which co-operate with the groove ends to tit cylindrical portions 20a of two valves 20.

The intervening parts of these valves are made of the same cross-sectional shape and size as the grooves 17 in which they lie, so that, in one angular partition of each valve, its flat face 20b is coplanar with the upper face of the plate 16 (as in the case of the right-hand valve in Fig. 3).

It will be appreciated that, ifsuch valve is rotated, it eventually begins to uncover the slot 18 at the bottom of its groove 17, and in its nal position leaves such slot fully open (see the left-hand valve in Fig. 3), the trailing edge of the valve face 20b being at all times parallel to the slot edge which it rst exposed, so that there is produced at the base of the hopper 11 an elongated parallel-sided outlet of any desired width within the range available.

To ensure the valves 20 maintaining close contact with their seatings throughout the whole length of the latter, they are preferably spanned at intermediate positions by recessed members 21 corresponding to the bearing caps 19, the inner surfaces of the recesses 22 being engaged by radial spacer pins 23 on the valves.

Corresponding ends of the two valves 20 are extended beyond the grooved plate 16 and the outside of the adjacent hopper end wall 11a, where they are provided with short handles 24, and such handles (or the valves 20) may have projecting parts adapted to engage suitable abutments on the hopper 11 to dene the fully-open positions of the respective valves.

When either of the valves 20 is opened by means of its handle 24, a curtain 25 of chocolate or other coating substance falls from the resultant outlet as shown in Figs. and 6. This curtain being of uniform thickness throughout its length, and such thickness remaining constant at each setting of the valve, a wide variation in the curtain thickness is'readily obtainable.

Preferably the top of the hopper 11 is covered by an upwardly concave lter 26 which may be formed of wire mesh.

Fixed to the top of each hopper end wall 11a is a block 27 which slidably engages a vertical slot 28 in a guide plate 29 carried by the adjacent side 30 of the machine.

Each such block 29 has a tapped hole 31 in which works a vertical lead screw 32, the lower end of such screw having a footstep bearing in a bracket 33 carried by the plate 29 and being axially located by nuts 34.

The upper ends of the lead screws 32 are journalled in a -hocd 35 enclosing theV curtain-forming mechanism in course of description, and one of them is provided with a hand-crank 36 or the equivalent.

At a lower level, the lead screws 32 are connected by an endless chain 37 which engages sprockets 38 thereon, or by some other form of gearing whereby rotation of the hand-crank 36 will effect a simultaneous rotation of both screws 32 and thereby raise or lower the hopper 11 in its` guides whilst maintaining it horizontal at all times. Obviously, if desired, the hand-crank 36 or its equivalent may drive the adjacent lead screw 32 through gearing instead of directly. v

The mechanism above described enables the height of the hopper 11 to be quickly adjusted to suit the thickness of the articles to be enrobed, and if desired the shtail nozzle 13 may also be made vertically adjustable.

Below the conveyor and extending rearwardly from a position directly beneath the hopper 11 is a rectangular surge tray 39, which is pivoted at its front end about a stationary axis 40 transverse to the length of the conveyor.

The rear or free end of this tray 39 has its corners supported by screwed members 41 which pass through inwardly directed anges 30a on the sides of the machine and 'are lprovided Awith -adjusting nuts 42 above such flanges. The sides of the tray 39, which is made wide enough to project beyond both lateral edges of the conveyor 10, are recessed to clear the spindles 43 of the horizontal rollers 44', 442. These latter extend transversely beneath the conveyor 10, in spaced parallel relationship, and are journalled in xed bearings in the machine sides 30.

The roller 44 is continuously rotated in co-operation with a vertical doctor plate 4S, which is carried by a flat horizontal surge plate 46 disposed between the conveyor 10 and the tops of the rollers 44', 442. The plates 45, 46 are bodily adjustable in a vertical direction by means of manually-operable screws 47 which engage tapped bushes 48 at opposite ends of the plate 46 and are mounted in the flanges 30a, coil springs 49 threaded on these screws being compressed between the flanges aforesaid and the top of the plate 46.

It will be appreciated that when one or both of the hopper outlets is dischargingv a curtain 25 of the coating substance, such of the latter as does not remain upon the articles under treatment will pass through the conveyor band 10 and will fill 4the tray 39 up to the level of an overow weir 50 at its free end.

Obviously, if neither the curtains 25 is in operation (as when it is not desired to enrobe the tops and sides of the articles on the conveyor 10) the coating substance delivered by the nozzle 13 to the hopper 11 will escape from the latter over thc partitions or weirs 14 and thence through the ducts 15 into the tray 39 without touching the conveyor.

When the tray 39 is held substantially horizontal by the screwed members 41, the rollers 44', 442, are fairly deeply immersed in the collected coating substance S1, and if the surge plate 46 is adjusted into close proximity to the conveyor 10, the associated doctor 45 allows the bulk of the substance adhering to the periphery of the roller 44' to be directed across the top of the plate 46, so that there is a heavy upsurge of such susbtance through the conveyor 10 as at 52 (see Fig. 5).

The roller 442 is illustrated as being rotated in the same direction as the roller 44', but provision may be made for rotating it in opposition to the latter, to increase the height of the upsurge 52, and hence the thickness of the coating applied to the bottoms of articles on the conveyor 1t). Such contra-rotation of the rollers 44', 442 will usually be employed only when the articles under treatment are suicientlyheavy to avoid any risk of their translational movement being checked by the upsurge 52.

To decrease the thickness of the applied coating, the screws 47 are operated so as to separate the surge plate 46 from the conveyor 10 and at the same time to bring the doctor plate 45 closer to the periphery of the roller 44', thus reducing the height of the upsurge relatively to the conveyor 10.

Alternatively, or in addition, the level of the collected coating substance (and hence the quantity thereof picked up by the roller 44') may be lowered by slackening olf the nuts 42 on the screwed members 41 which support the free end of the tray 39, and/ or by reducing the effective height of the overflow weir 50, which latter has a hinge 53 at its lower edge and is angularly adjusted by means of a lever 54.

When it is not desired to coat the bottoms of the articles on the conveyor 10 at all, the hinged weir 50 is fully lowered so that the substance 51 runs through the tray 39 completely clear of the rollers 44', 442 (see Fig. 6) and hence none of such substance is picked up by the rollers whatever the setting of the plates 45, 46. It will be appreciated that this arrangement permits the tray 39 being completely drained of the collected substance 51 during stand-by periods.

We claim:

l. A machine for coating articles with molten or plastic substances comprising a movable conveyor for carrying the articles to be coated through a falling curtain of the coating substance, a hopper for holding a quantity of said coating substance having a base member positioned above and extending transversely across said conveyor, said base member having a groove of partially circular cross section formed in the upper surface thereof, the axis of which is parallel to the plane of the conveyor therebeneath, and a slot extending downwardly from the bottom of said groove to the bottom surface of said base member through which said coating substance is adapted to issue from said hopper, a valve of cross-sectional shape similar to that of said groove rotatably seated in said groove for controlling the flow of coating substance through said slot, said valve cooperating with said slot to form a parallelsided "curtainforming outlet from said hopper, means for rotating said valve to vary the width of said outlet according to the angular position of said valve in said groove, and means for applying an upsurge of the coating substance to the undersides of the articles on the conveyor, said last named means comprising a tray disposed beneath said conveyor so as to collect the coating substance escaping from saidhopper, a roller continuously rotatable about an axis-transverse to said conveyor and positioned between the latter and the substance collected in said tray, a doctor co-operating with said roller and adapted, when said roller is partly immersed in the collected substance, to deliver an upsurge of the latter to said conveyor, and means for adjusting said doctor to vary the height of such upsurge relatively to said conveyor.

2. A coating machine according to claim 1, including a horizontal surge plate connected to the doctor and disposed between the roller and the conveyor and means for adjusting said surge plate vertically with respect to the conveyor.

3. A coating maohine according to claim l, wherein the roller is mounted upon a stationary axis and which includes means for adjusting the tray up and down to vary the depth of immersion of said roller in the collected substance.

4. A coating machine according to claim l, wherein both the roller and the tray are mounted upon stationary axes transverse to the conveyor and which includes means for tilting the tray about its axis to vary the height of the collected substance with reference to the roller.

5. A coating machine according to claim l, including an overflow weir associated with said tray, and means for adjusting the position of said Weir to vary the depth of immersion of said roller in the collected substance, said Weir being adjustable to one extreme position permitting complete drainage of the tray.

6. A coating machine according to claim 2, including a pair of the rollers aforesaid, the two rollers being arranged in spaced side-by-side relation and co-operating with opposite edges of the surge plate.

7. A coating machine according to claim 1, further characterised in that the hopper is provided with overflow means for establishing the height of the coating substance contained in said hopper, said overtlow means being-so arranged as to deliver overowing coating substanceto the tray without contact with the conveyor.

References Cited in the le of this patent UNITED STATES PATENTS 1,550,183 Sontshagen Aug. 18, 1928 1,775,475 Savy Sept. 9, 1930 2,081,888 Birdsall May 25, 1937

Images