Abstract:
An apparatus and method for distributing a charge falling onto an article. The apparatus includes a baffle to present a continuous deflection surface to the falling charge, the deflection surface deflecting at least a portion of the charge radially outwardly, and a guide arranged downstream of the baffle to deflect at least a portion of the charge radially inwardly to cause the charge to fall onto the article with a required distribution. The baffle and the guide may be adjustably mounted such that the relative positions of the guide and the baffle can be adjusted to achieve a desired distribution of the charge.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims priority of British Patent Application No. 9807247.3 filed Apr. 3, 1998, the contents being incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and apparatus for distributing a charge as it falls towards an article. 
     2. Description of the Related Art 
     A conventional system for distributing a particulate charge as it falls towards an article is disclosed in U.S. Pat. No. 5,109,760. In the conventional system, a conical screen is supported above a pizza upon which cheese is to be deposited. Cheese particles are dropped in a mass upon the screen and distributed by gravitational force in an even pattern over the pizza. The conical screen has a baffle portion at an upper region of the screen, a circular opening at the apex of the baffle, and a screen with screen openings at a lower region of the screen. The conical screen is mounted in a cylinder with a gap between the outer periphery of the screen and the cylinder. Cheese particles deposited upon the pizza will either have fallen through the opening in the apex of the screen, the screen openings, or the gap between the screen and the cylinder. 
     An alternative system for distributing a particulate charge is described in U.S. Pat. No. 5,678,476. In this alternative system, a food feed hopper is mounted above a food spreader housing having movable paddles therein and a porous bottom member spaced above the surface upon which the food is to be spread. 
     A problem with the systems disclosed in U.S. Pat. Nos. 5,109,760 and 5,678,476 is that the particulate charge can be unevenly distributed. In particular, it is difficult to direct product to the center of the article. U.S. Pat. No. 5,109,760 attempts to address this problem by providing a circular opening at the apex of the baffle so that the product in the center falls straight through. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a system for distributing a particulate charge as it falls towards an article. 
     It is another object of the present invention to provide a baffle, a director and a guide for distributing a particulate charge as it falls towards an article, the director directing at least a portion of the charge radially inwardly onto the baffle, the baffle deflecting the charge outwardly and the guide deflecting the charge inwardly. 
     Objects and advantages of the present invention are achieved in accordance with a first embodiment of the present invention with an apparatus for distributing a charge falling onto an article, comprising a baffle to deflect at least a portion of the charge radially outwardly; a director arranged upstream of the baffle to direct at least a portion of the charge radially inwardly onto the baffle; and a guide arranged downstream of the baffle to deflect at least a portion of the charge radially inwardly, wherein the charge falls onto and is distributed across the article. The baffle may present a continuous deflection surface to the charge. 
     Objects and advantages of the present invention are achieved in accordance with a second embodiment of the present invention with a method of distributing a charge falling onto an article, comprising the steps of directing at least a portion of the charge radially inwardly onto a baffle with a director arranged upstream of the baffle; deflecting at least a portion of the charge radially outwardly with a baffle; and deflecting at least a portion of the charge radially inwardly with a guide arranged downstream of the baffle, wherein the charge falls onto the article and is distributed across the article. 
     The present invention provides an apparatus for and a method of directing a charge toward the center of an article which has advantages over the prior art. For example, U.S. Pat. No. 5,109,760 directs particles towards the center of the article by the provision of an opening in the baffle. In contrast, the present invention deflects a portion of the charge towards the center of the article using a guide arranged downstream of the baffle. The effect of the baffle is enhanced by directing at least a portion of the charge so that it is moving with a radially inward component as it strikes the baffle. This increases the angle of deflection of the baffle. 
     By deflecting a portion of the charge towards the center of the article using the guide arranged downstream of the baffle a number of advantages are achieved with the present invention. Firstly, the present invention enables the baffle to present a continuous deflection surface to the charge, in contrast to U.S. Pat. No. 5,109,760 where the baffle requires a central opening. As a result, the baffle is more easily constructed, easier to support and easier to clean. Secondly, it has been discovered that surprisingly the distribution can be conveniently controlled by adjusting the relative positions of the baffle and the guide. In contrast, in U.S. Pat. No. 5,109,760 the particle distribution is fixed by the form of the conical screen. 
     In accordance with the present invention, the baffle may deflect the charge by rotating about a vertical axis. However, the baffle preferably has an outwardly angled deflection surface which deflects the charge radially outwardly. The baffle can then deflect the charge radially without moving. 
     In accordance with the present invention, the deflection surface can be suitably shaped to provide a desired distribution. For example, if a circumferentially uniform distribution is required (e.g., on a pizza), then preferably the deflection surface is substantially frustoconical. 
     In accordance with the present invention, the guide and/or baffle are adjustably mounted, wherein the relative positions of the guide and the baffle can be adjusted to achieve a desired distribution. In accordance with an embodiment of the present invention, the baffle is slidably mounted on a baffle support and locking means is provided to lock the baffle at a required position. In accordance with another embodiment of the invention, the baffle has a threaded bore which receives a threaded baffle support and the baffle is moved by screwing it up or down the threaded baffle support. 
     In U.S. Pat. No. 5,109,760, the conical screen is supported by ledge pins which extend radially towards the screen, and it is not possible to suspend the screen from above since this would obscure the central opening at the apex of the screen. In contrast, in accordance with the present invention, the baffle can be supported by a baffle support which extends towards the baffle from a position upstream of the baffle. Therefore, in accordance with the present invention, the baffle and the baffle support together present the continuous deflection surface to the falling charge. This support arrangement is simple and more sturdy than that disclosed in U.S. Pat. No. 5,109,760. 
     In accordance with the present invention, the director may comprise a set of air jets which direct the charge radially inwardly onto the chute. Alternatively, the director may comprise a chute having inwardly tapered walls which define a convergence position, wherein the baffle is arranged at least partially upstream of the convergence position. 
     As a result, at least a portion of the charge is converging as it strikes the baffle. The chute is typically frustoconical, although alternative tapered shapes could be used. 
     In accordance with the present invention, the chute preferably has an outlet and inwardly tapered walls which define a convergence position, and the baffle is arranged between the outlet and the convergence position and the chute focuses at least a portion of the charge onto the baffle. This focusing of the charge increases the angle of deflection by the baffle, and thus ensures that at least part of the charge is subsequently deflected radially inwardly by the guide and deposited at the center of the article. 
     In accordance with embodiments of the present invention, the apparatus further comprises a second baffle arranged upstream of the outlet of the chute for deflecting the charge radially outwardly. The second baffle also acts to break up the main mass of the charge. 
     The guide may be fixed, or the apparatus may further comprise means for moving the guide to and from a masking position adjacent to or abutting with the article whereby the charge falls onto the article with a border defined by the guide. In a preferred embodiment, the guide comprises a fixed outer cylinder and a movable inner cylinder which can be moved to and from the article. The guide and chute may be formed integrally, but preferably they are separated by a gap. This provides access to the interior of the system and enables the relative positions of the guide and chute to be adjusted. 
     The charge may comprise any suitable charge which can be deflected by the guide and the baffle. The charge is typically particulate and the particles may have a variety of sizes ranging from powdery or granular particles to even larger particles. In a preferred embodiment, the charge comprises particles of food. For example, the charge may comprise breadcrumbs, or a pizza topping such as cheese, pepperoni, mushrooms etc. 
     The article may be inedible (for example a plate or baking tray) but in a preferred embodiment the article comprises an article of food such as a pizza base. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which: 
     FIG. 1 is a front view of an apparatus for depositing a charge onto an article in accordance with a first preferred embodiment of the present invention; 
     FIG. 2 is a side view of the apparatus shown in FIG. 1 in accordance with the first embodiment of the present invention; 
     FIG. 3 is a plan view of a shutter mechanism shown in FIG. 1 in accordance with the first embodiment of the present invention; 
     FIG. 4 is a side view, partially in section, of the apparatus for depositing a charge onto an article in accordance with the first embodiment of the present invention; 
     FIG. 5 is a cross-section of a cylinder assembly and drive mechanism of the apparatus shown in FIG. 1 in accordance with the first embodiment of the present invention; 
     FIG. 6 illustrates in detail a clamp assembly shown in FIG. 1 in accordance with the first embodiment of the present invention; 
     FIG. 7 is a schematic side view, partially in section, of the apparatus of FIGS. 1 and 2 showing a charge falling onto a pizza base in accordance with the first embodiment of the present invention; 
     FIG. 8 is a front view of an apparatus for depositing a charge onto an article in accordance with a second preferred embodiment of the present invention; and 
     FIG. 9 is a plan view of a spreader system used in the apparatus shown in FIG. 8 in accordance with the second embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
     Referring to FIGS. 1 and 2, a series of articles  1 , for example, pizza bases, are transported on a conveyor  2  to a deposition position  3 . A dosing system comprising a combinational weigher  5  and a distributor  6  is mounted above the deposition position  3  on a frame  4 . 
     The combinational weigher  5  comprises a funnel  7  into which a charge, for example, grated cheese, is fed. The cheese falls down a cone shaped dispersion device  8  onto a number of weighing units  9 - 12  which are distributed around the periphery of the dispersion device  8 . Each weighing unit  9 - 12  includes a trough-shaped dispersion feeder  9   a - 12   a  coupled with an electromagnetic vibrator  9   b - 12   b.  Each weighing unit  9 - 12  also includes a pool hopper  9   c - 12   c  into which the grated cheese is supplied via the trough shaped dispersion feeders  9   a - 12   a  as they are vibrated, each pool hopper opening via a respective gate into a weigh hopper  9   d - 12   d.  Each weigh hopper  9   d - 12   d  is coupled with a respective scale cell (not shown) so that the weight of their contents can be determined. The combinational weigher  5  described above is conventional and examples are described in more detail in, for example, EP-A-0818669. 
     When a controlling microprocessor (not shown) of the combinational weigher  5  determines that a desired weight of grated cheese is located in a particular combination of the weigh hoppers  9   d - 12   d,  weigher gates (not shown) of selected weighers are opened so that their contents empty into chutes  13 - 16  which guide the cheese into a timing hopper  17  (shown in detail in FIG.  4 ). 
     As shown in FIG. 4, the timing hopper  17  includes a pair of pivoting doors  18 ,  19 . At a suitable point in the cycle, such as when a pizza base  1  is at the deposition position  3 , the pivoting doors  18 ,  19  are opened to release the charge onto an iris-type shutter mechanism  70 . FIG. 3 is a plan view of the shutter mechanism  70 . As shown in FIG. 3, three identical horizontal shutter blades  71 - 73  are shown in full lines in their closed position, and in chain-dotted lines in their fully open position. The shutter blades  71 - 73  are pivotally mounted on a base  74  by pivot pins  75 ,  76 ,  77 , respectively. Shutter mechanisms of the type illustrated in FIG. 3 are described in more detail in EP-A-0787431, GB-A-2288595 and U.S. Pat. No. 5,806,725. 
     When a pizza  1  is at the position  3 , the shutter blades  71 - 73  are rapidly opened so that the cheese is relatively undisturbed and falls directly downward into the distributor  6  over an area substantially equal to the area of the upper surface of the shutter blades  71 - 73 . 
     As shown in FIGS. 2 and 4, the distributor  6  comprises a chute  20  in the form of an inverted frustocone, and a cylinder assembly  80 . The cylinder assembly  80  and chute  20  are mounted on a pair of vertical support arms  22 ,  23  which are suspended from the frame  4  (FIG.  2 ). 
     FIG. 5 is a cross-section through an upper part of the cylinder assembly  80  showing a drive mechanism of the cylinder assembly in accordance with the present invention. The cylinder assembly  80  comprises an outer cylinder  21  which is rigidly mounted to the support arms  22 ,  23  by support pins  81 - 84  shown in FIG.  2 . The outer cylinder  21  preferably has an inner diameter of 300 mm, although this will vary depending on the size of the pizzas. A pneumatic drive mechanism  85  is bolted to the outer cylinder  21  via a bracket  86 . The drive mechanism has a drive arm  87  which is bolted to an inner cylinder  28  via a bracket  88 . The inner cylinder  28  preferably has an internal diameter of 270 mm (suitable for 12″pizzas). The inner cylinder  28  is driven between a raised position (shown in dashed lines) and a lowered position (shown in solid lines) by the drive mechanism  85 . An identical drive mechanism (not shown) is also provided on the opposite side of the cylinder assembly  80 . 
     Three clamp assemblies are provided for clamping the pizza base  1  in the deposition position  3  below the cylinder assembly  80 . The three clamp assemblies are distributed at equal angular distributions around the periphery of the cylinder assembly  80 . Only one of the three clamp assemblies is shown in FIGS. 1 and 4, as indicated by reference numeral  24 . Another one of the clamp assemblies  89  is shown in detail in FIG.  6 . 
     As shown in FIGS. 4 and 6, a pneumatic cylinder  90  is pivoted on a bracket  91  which is bolted to the outer cylinder  21 . A drive rod  92  of the cylinder is pivotally attached by an attachment  93  to a pivoting arm  94 . The pivoting arm  94  is pivotally attached to a bracket  95 , which is shown in its upper and lower positions in dashed and full lines respectively. An actuating arm  96  is pivoted to the pivoting arm  94  at pivot point  97 , and to a second pivoting arm  98  at pivot point  99 . The end of the actuating arm  96  includes a curved clamping segment  100 , shown in full lines in its lowered clamping position and in dashed lines in its raised position. 
     As the drive rod  92  extends, the clamping segment  100  is lowered to its clamping position in which it engages the outer edge of a pizza base  1 . When a pizza base  1  is in position, the three clamping segments are pivoted into position using the pneumatic cylinders  90  and the inner cylinder  28  is moved down using the drive mechanism until it abuts the pizza base  1 . 
     Referring to FIG. 4, a suspension arm  31  having an angled portion  32  and a vertical portion  33  is mounted to the chute  20  at  34 . A pair of conical baffles  35 ,  36  are threaded onto the vertical portion  33  of the suspension arm  31 , and locked into place with a respective collar  37 ,  38  and locking pin (not shown). The baffles  35 ,  36  can be moved up and down by releasing their respective locking pin and sliding the baffle  35 ,  36  up or down the suspension arm  31  to a required position. An angle of the deflection surface of the upper baffle  35  is greater than an angle of the deflection surface of the lower baffle  36 . The baffles  35 ,  36  have solid deflecting surfaces and, together with the suspension arm  31 , present a continuous deflection surface to the falling charge. That is, there is no central hole as disclosed in U.S. Pat. No. 5,109,760. 
     FIG. 7 illustrates the principal of operation of the distributor  6 . When a pizza base  1  is in position and clamped in place, the inner cylinder  28  is moved down to its masking position, and the shutter blades  71 - 73  (FIG. 3) are opened to release a charge into the distributor  6 . As the charge is released, a portion of the charge hits the upper baffle  35  (as indicated by arrows  42 - 44 ), a portion (indicated by arrows  45 - 47 ) hits the tapered inner wall  41  of the chute  20  directly without hitting the upper baffle  35 , and a portion (indicated by arrow  48 ) falls unimpeded through the outlet  49  of the chute  20 . The upper baffle  35  acts to break up the main mass of the charge and push it out to the sides of the chute  20 . 
     The lower baffle  36  is positioned downstream of the chute  20  between the outlet  49  of the chute  20  and a focal position (indicated generally at  50 ) which is defined by the convergence point of the tapered inner wall  41  of the chute  20 . As a result, at least part of the charge converges radially inwardly onto the lower baffle  36 , as indicated by arrow  52 . The lower baffle  36  then reflects a portion of the charge out to the sides of the cylinder  28  as indicated by arrow  51 . The charge is contained by the cylindrical inner wall of the inner cylinder  28 , and some is deflected back towards the center line  53  as indicated by arrow  54 . The result of the various deflections from the chute  20 , baffles  35 ,  36  and cylinder  28  is a uniform distribution across the surface of the pizza base  1 . 
     The proportions and angles of the chute  20 , baffles  35 ,  36  and cylinder  28  are selected to give consistent results. The relative sizes may be varied to allow for different charge sizes and different amounts of bounciness of the articles passing through. The positioning of the lower baffle  36  can be adjusted to allow more or less product to be gathered at the periphery or in the center of the pizza base  1 . In experiments it has been determined that as the lower baffle  36  is moved down, more cheese is deposited at the outer periphery of the pizza base  1 . 
     Alternatively, the chute  41  and baffles  35 ,  36  may be moved away from the center line  53  to deposit the charge more towards one area of the pizza base  1 . 
     When the cheese has been deposited, the clamping segments  24 ,  89  are rotated away from the pizza base  1  as indicated at  61 ,  62 , the inner cylinder  28  is retracted by distance A to prevent the cylinder from dislodging the deposited cheese, and the coated pizza base  1  is transported away from the deposition position  3  by the conveyor  2 . 
     In an alternative embodiment, the vertical portion  33  of the suspension arm  31  may be threaded, and the baffles  35 ,  36  may be provided with internally threaded bores. The baffles  35 ,  36  can then be adjusted by rotating the baffles so that they move up and down the support arm on the thread. 
     Furthermore, the combinational weigher  5  may be replaced by an alternative dosing device, such as a volumetric depositor, bucket system or any other apparatus which can deliver equal charges into the timing hopper  17 . With an accurate dosing device the timing hopper  17  and/or the shutter assembly  70  may not be required. The timing hopper  17  may also have horizontally retracting doors, for instance as shown in U.S. Pat. No. 5,806,725. 
     If cheese collects on the angled portion  32  of the suspension arm  31 , then the angle of the angled portion  32  can be increased from the angle shown in FIG.  3 . In a further alternative embodiment, the suspension arm  31  may extend vertically into the timing hopper  17 , with a suitable central aperture being formed by the pivoting doors  18 ,  19  and the shutter blades  71 - 73  to receive the suspension arm  31 . 
     In the first embodiment of the present invention described above with reference to FIGS. 1 and 7, a single delivery system is used. In order to increase production speed, the delivery system of the first embodiment can be arranged to traverse above the pizza as cheese is delivered. This could be carried out with a single delivery system, but in a second preferred embodiment of the invention shown in FIGS. 8 and 9, a double delivery system is used. As shown in FIG. 8, the double delivery system comprises a pair of distributors  6 A,  6 B having constructions very similar to the distributor  6  of FIG.  1 . The distributors  6 A,  6 B are mounted to a carriage  100  which is supported by rollers  101  on a pair of laterally spaced tracks  102  (FIG.  9 ). The carriage  100  is driven via a drive belt  103  which is secured to the carriage at a securing point  104 . The drive belt  103  is rotated by a motor  105  to which it is coupled via a drive belt  106  and a pulley  107 . 
     The combinational weigher  5  shown in FIG. 8 has the same form as shown in FIGS. 1 and 2 and terminates in a pair of delivery funnels  110 A,  110 B located above entry funnels  111 A,  111 B of the distributors  6 A,  6 B respectively. The exits to the delivery funnels  110 A,  110 B are positioned so that they remain in alignment with the funnels  111 A,  111 B, respectively, throughout the lateral movement of the distributors  6 A,  6 B. As shown in FIG. 8, the funnels  110 A,  110 B are located at the left side of the funnels  111 A,  111 B while following maximum movement of the carriage  100  to the left, the funnels  110 A,  110 B will be aligned with the right hand side of the funnels  111 A,  111 B. One group of the weighing units  9 - 12  is associated with the funnel  110 A and another group of the weighing units is associated with the funnel  110 B. 
     In order to convey pneumatic control to the respective sets of shutter blades, a flexible delivery conduit system  112  is provided. 
     In operation of the delivery system in accordance with the second embodiment of the invention, the distributors  6 A,  6 B are located at a home position, as shown in FIG.  8 . As a pizza is conveyed beneath the distributors  6 A,  6 B on a conveyer, the arrival of the first pizza is detected and the control system (not shown) which determines the speed of movement of the pizzas, waits until the pizza is aligned with a cylinder  80 B of the distributor  6 B and then activates the distributor  6 B to lower the cylinder  80 B, as previously described. The pizzas are supplied to the conveyor in such a manner that when a pizza is aligned with the distributor  6 B, another pizza is aligned with the distributor  6 A. (The cylinder of the distributor  6 A is omitted in FIG. 8 for clarity). The distributors  6 A,  6 B are then operated as previously described, but at the same time the distributors  6 A,  6 B are caused to move with the pizzas by a suitable activation of the belt  103 . During this movement, cheese is supplied to the pizzas. When the distributors  6 A,  6 B reach their leftmost position, the cylinders  80  are retracted allowing the pizzas to continue beyond the machine while the motor  105  is activated in its opposite direction to cause the carriage  100  to return to its start position shown in FIG.  8  and the process is then repeated. 
     The advantage of this process is that it allows pizzas to be fed at high speeds of up to 35 per minute while still allowing enough time for the cheese to be distributed. In the first embodiment, the pizzas would need to either be stopped during the distribution stage or to move more slowly to allow enough time for the cheese to be distributed. 
     In a further alternative embodiment, which is applicable to both the first and second embodiments described above, the cylinder arrangement is replaced by the use of two fingers which align the pizzas. 
     Although a few preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.