Apparatus and method for cleaning peeling machines

[0001] This application is a continuation-in-part of co-pending U.S. Ser. No. 12/207,575, filed Sep. 10, 2008, the disclosure of which is entirely incorporated by reference.

[0002] The invention relates generally to roller-type peeling machines and, more particularly, to robotic tools for cleaning the peeling channels of roller-type peeling machines.

[0003] Roller-type peeling machines are used most often to peel shrimp. These machines typically have side-by-side peeling channels, each of which is formed by a bottom roller and a pair of flanking side rollers slightly elevated above the bottom roller. The bottom and side rollers reciprocate back and forth. Smaller-diameter, metal insert rollers occupy the spaces between the bottom and side rollers. The rollers are typically inclined downward from a higher entrance end where unpeeled shrimp are loaded into the peeling channel to a lower exit end from which peeled shrimp meats drop. The bottom and side rollers are rubber-coated to frictionally rotate the insert rollers. The back-and-forth rotation of the rollers shifts the shrimp alternately from one side of the peeling channel to the other. Consequently, the shrimp are presented in constantly changing orientations to nips formed between the bottom roller and the inserts for fresh grips by the peeling rollers. Most of the shells, swimmerettes, and shrimp juices squeeze between the bottom roller and the inserts, where they are collected below. But some of the juices and solid debris cling to the inserts and degrade the grip of the insert and bottom rollers on the shrimp. Therefore, it is necessary to clean the inserts often to peel effectively.

[0004] Some peeling machines are equipped with an array of spray nozzles directed at the insert rollers at discreet points along their lengths. The nozzles extend from a network of parallel pipes crossing the peeling channels at spaced intervals. The nozzles are positioned along each pipe just above each insert roller to clean it. Other nozzles are often positioned on the underside of the rollers and the inserts to assist in washing away shell and other shrimp matter clinging to the rollers or wrapping around the inserts.

[0005] One shortcoming of these fixed spray-nozzle arrays is that they require many nozzles, each of which may clog at some time or another, to clean the inserts. Another shortcoming is that the fixed array does not allow the entire length of each insert to be subjected to the same spray pressure. Still another shortcoming is the large amount of water used by multiple-nozzle arrays.

[0006] These shortcomings and others are overcome by an apparatus for cleaning the peeling sections of roller-type cleaning machines that embodies features of the invention. The apparatus, which is designed for cleaning the peeling section of a roller-type peeling machine having peeling channels formed by a plurality of parallel, overlapping rollers, comprises a robot and a controller coupled to the robot to control its operation. The robot, which is disposed above the cleaning section, has a cleaning tool that can be moved within a working envelope encompassing the array. The controller is coupled to the robot to move the cleaning tool along a predetermined cleaning path within the working envelope to clean the peeling section. An underside cleaner is controlled by the controller to act on the underside of the peeling section directly beneath the position of the cleaning tool moving along the predetermined cleaning path.

[0007] In another aspect of the invention, a method for robotically cleaning an array of parallel inserts in a roller-type peeling machine comprises: (a) advancing a robotically positionable cleaning tool along the lengths of a first insert to clean it; (b) translating the cleaning tool to a second insert; (c) advancing the cleaning tool along the length of the second insert to clean it; (d) repeating steps (b) and (c) on other inserts until all have been cleaned; and (e) coordinating the operation of the cleaning tool with the operation of an underside cleaner to cause the underside cleaner to act on the inserts at a position directly beneath the advancing cleaning tool.

[0008] In yet another aspect, a peeling machine embodying features of the invention comprises a frame supporting a peeling section of the peeling machine. The peeling section is defined by side-by-side peeling channels formed by a reciprocating bottom roller and the pair of flanking side rollers rotated by contact with the bottom roller. Cylindrical insert rollers occupy spaces between the bottom and side rollers along the length of the peeling channels. An x-y robot mounted to the frame above the peeling section has a cleaning tool that can be translated along x and y axes. The axes define a working envelope that encompasses the peeling section of the machine. A controller is coupled to the robot to move the cleaning tool along a predetermined cleaning path within the working envelope to clean the peeling section. An underside cleaner is controlled by the controller to act on the underside of the peeling section directly beneath the position of the cleaning tool moving along the predetermined cleaning path.

[0009] Another aspect of the invention provides apparatus for cleaning the underside of the peeling section of a roller-type peeling machine having peeling channels formed by a plurality of parallel, overlapping rollers. The apparatus comprises a plurality of cleaning tools laterally spaced across the width of the peeling section to act on the bottom sides of the rollers. A translator translates the cleaning tools together laterally across the peeling section between a first position and a second position. In the first position, the cleaning tools act on a first portion of the underside of the peeling channels; and, in the second position, the cleaning tools act on a second portion of the underside of the peeling channels.

[0026] A peeling machine with an insert-roller cleaning system embodying features of the invention is shown in FIGS. 1-3. The peeling machine 10 includes a peeler 12 and a robotic insert cleaning system 14. The exemplary peeler shown in FIG. 1 is a cold-water shrimp peeler such as one of those manufactured and sold by Laitram Machinery, Inc. of Harahan, La., U.S.A. The peeler is a roller-type peeler with an upper peeling section 16 comprising a number of side-by-side peeling channels 18.

[0027] Each channel is formed by a bottom roller 20 and a pair of flanking side rollers 22 elevated slightly above the bottom roller. The bottom roller is rotated back and forth by a drive mechanism 24 at an elevated end 26 of the upper peeling section. The side rollers, which rest on the bottom rollers, are rotated by tangential contact with the rotating bottom rollers in the opposite direction. Shrimp or whatever products are to be peeled are loaded into the upper peeling section at the elevated entrance end 26. The bottom and side rollers are coated with rubber for frictional contact with each other and the shrimp. Smaller-diameter metal insert rollers 28 (“inserts,” for short) occupy spaces between the bottom roller and the side rollers. (Inserts are not shown in the drawings in every space to better show the spaces.) The inserts are biased downward against the bottom and side rollers by spring-loaded hold down members 30 attached to the peeler's supporting frame 32. The back-and-forth rotation of the bottom and side rollers causes the inserts to rotate. Unpeeled shrimp loaded into the upper peeling section are urged down the peeling channels to a lower exit end 27 of the upper peeling section by water sprayed onto the peeler from outlets in a pipe 34 at the entrance end and the action of gravity in the declining upper peeling section.

[0028] The heads and shells of the shrimp are unwrapped from the meats in peeling nips formed between the inserts and the rubber rollers. The reciprocating action of the rollers alternately grabbing and releasing the shrimps shifts them from one side of the channel to the other and presents them in different orientations to the peeling nips for thorough peeling.

[0029] After exiting the upper peeling section, the largely peeled shrimp meats enter a lower peeling section 36 comprising lower channels 38 formed by the powered bottom rollers, which extend past the exit end of the upper peeling section into the lower peeling section, and idle base rollers 40, on which the powered bottom rollers are supported. Residual shrimp shell and gristle are removed in the gentler lower peeling channels without damage to the largely exposed meats. The peeled shrimp meats exit the peeler at an output end 42 of the lower peeling section for further processing.

[0030] To dislodge and wash away shrimp fluids, shells, and other debris from the inserts 28, the peeler is equipped with the robotic cleaning system 14. The cleaning system is realized by an x-y, or gantry, robot comprising x- and y-axis assemblies 44, 45 that together position an end effector, in this case, a cleaning tool 46, within a working envelope encompassing the upper peeling section 16 and the inserts. The y-axis assembly 45 is affixed to the peeler frame 32 and includes a motor 48 driving a lead screw 50 to translate a nut 52 along a y axis 54 parallel to the axes of the inserts 28 and the channel-forming rollers 20, 22. Attached to the nut 52 is a trolley 56 to which the x-axis assembly 44 is attached. The trolley rides along a rail 58 parallel to the y axis.

[0031] Like the y-axis assembly, the x-axis assembly includes a motor 49 driving another lead screw 51 to translate a nut 53. The motor rides on the trolley from which the lead screw and x-axis support rails 60, 61 extend and define an orthogonal x axis 55 perpendicular to the insert's axes. A trolley 62 attached to the x-axis nut 53 rides along the lower rail 60 and supports the cleaning tool 46 just above the peeling channels in the upper peeling section, as also shown in FIG. 4. The cleaning tool 46 shown is a spray nozzle mounted to the trolley 62 and fed liquid by a hose 64. In a preferred cleaning arrangement, the liquid spray is aimed directly at the inserts 28 to clean them.

[0032] Wheels 66 on the ends of the x-axis rails 60, 61 opposite the motors ride along a y-axis side rail 59 as the cleaning tool is translated along the y axis. Flexible cable and hose trays 68, 69 confine electrical wires and fluid hoses from the peeler to the x- and y-axis assemblies of the x-y robot.

[0033] As shown in FIG. 2, the x-y robot defines an x-y Cartesian coordinate system whose origin O may be considered to arbitrarily lie at the lower end of the leftmost insert 28′ for a system designed specifically to clean the roller inserts. As also shown in FIG. 2, the working envelope of the robot for this cleaning arrangement is confined generally to the upper peeling section 16 between the leftmost and rightmost inserts 28′, 28″. The robot positions the cleaning tool at any coordinates within the working envelope between (x, y)=(0, 0) and (X_max, Y_max), where Y_max represents the length of the inserts and X_max represents the distance between the rightmost and leftmost inserts.

[0034] FIGS. 5A-5C show some alternative cleaning tools to the fluid spray nozzle 46 of FIG. 4. FIG. 5A shows an air-jet nozzle 70 that would screw into the trolley 62 and be connected by hoses to a source of compressed air. Unlike fluid and air nozzles, some cleaning tools, such as a brush 72 with bristles 73 as in FIG. 5B and a scraper 74 with a contoured blade 75 as in FIG. 5C, must physically contact the inserts. As a consequence, these contacting cleaning tools require a third degree of freedom in their movement to avoid hitting the elevated side rollers 22 as the tools move along the x axis to another insert. The robot or the contacting tools has a further z-axis control to raise and lower the cleaning tool as indicated by arrow 76. Any small, conventional linear actuator may be used to raise and lower the cleaning tool.

[0035] Details of the lead screw as used in both the x- and y-axis robot assemblies are shown in FIG. 6. In this case, the x-axis screw 51 is shown. Preferably, the lead screw is a stainless-steel, high-helix lead screw, such as one of those manufactured by Eichenberger Gewinde AG of Burg, Switzerland. The high helix angle allows the nut 53 to move rapidly along the screw as it is rotated by its motor. Preferably, the nut is a thermoplastic flange nut made out of POM-C. A support arm 78 of the cleaning tool trolley 62 is bolted to the flange 80 of the nut.

[0036] One alternative for providing linear motion in the x-y robot is shown in FIG. 7A. In this example, the x axis is defined by a rack gear 82. The cleaning tool 46 is mounted to a carrier 84 that houses a motor 86 driving a pinion gear 88 along the rack to position the tool along the x axis 55.

[0037] Another alternative to the lead screw is shown in FIG. 7B, in which an endless toothed belt 90 is trained around drive and idle gears 92, 93. The cleaning tool 46 is mounted to a trolley 94 and is firmly affixed to the belt. A drive motor (not shown) is coupled to the drive gear 92 to position the belt and the attached cleaning tool on the x axis 55.

[0038] Cleaning may be improved in some cases by an underside cleaner as shown in FIGS. 12-15. The underside cleaner shown by way of example includes an array of pipes 134 extending across the upper peeling section just beneath the bottom rollers 20 and the side rollers 22. Each pipe has a number of nozzles 136 along its length. Instead of using nozzles as cleaning tools in the spray system of this example, the underside cleaner, like the topside robot cleaner, could use other cleaning tools, such as scrapers or brushes acting on the bottom sides of the rollers or inserts. The nozzles are preferably shaped to produce a fan spray pattern 138 slightly angled relative to the axis of the rollers as shown in FIG. 15. The spray patterns overlap to provide complete coverage of the underside, as indicated by the dashed lines 140 in FIG. 14. As shown in FIG. 12, the underside nozzles 136 are spaced apart a distance equal to the lateral pitch of the upper peeler section with the nozzles shown directing spray at the inserts on the right-hand side of each channel as viewed from the lower end of the peeler. A translation device, such as a mechanical, motorized, or pneumatic linear actuator 142, translates the pipe 134 laterally, as indicated by arrow 144, between the position shown and a second position, in which the nozzles 136′ are aligned with the inserts on the other side of the peeling channel. Thus, only half as many nozzles are needed than for a fixed array. The array is mounted to a support frame 146 coupled to the linear actuator 142. The water to each pipe 134 is controlled by a valve 148. All the valves are supplied water from a water supply 150 through a conduit 152.

[0039] Control of the topside robotic cleaning system and the underside system is provided by a controller 96, such as a programmable logic controller or a general-purpose computer via output control lines 97, 98, 99, 130, 132. The control function is schematically illustrated in simplified form in FIG. 8. Signals on the output control lines 97, 98, 99 control the position of the cleaning tool in the x-y coordinate system and the cleaning action of the cleaning tool. The signal on the control line 97 controls the x-axis motor 49 in the x-axis assembly 44 to position the cleaning tool along the x axis. The signal on the control line 98 controls the y-axis motor 48 in the y-axis assembly 45 to position the cleaning tool along the y axis. The signal on line 99 activates and deactivates the cleaning action of the cleaning tool. In the example shown for a liquid spray nozzle, the signal turns on and off a pump 100 that draws liquid from a reservoir 102 and delivers it to the spray nozzle via the hose 64. For an air jet, the signal would control a compressor or a pneumatic valve. For one of the contact cleaning tools, the signal on the line 99 would control the z-axis position of the tool to raise and lower it. Feedback is provided to the controller by x- and y-position sensors 104, 105 such as rotary encoders, that allow the controller to determine the instantaneous x and y coordinates of the cleaning tool. Signals on the output lines 130 and 132 control the underside cleaner. Each of the control lines 130 connects to one of the valves 148. The signals on those lines selectively open and close the valves to turn the spray on in the corresponding pipe. If proportional valves are used, the signals can be used to control the flow rate and the water pressure as well as the sequencing. The signal on the control line 132 controls the linear actuator 142 to translate the underside nozzle array to one or the other of its two positions on opposite sides of each peeling channel. The controller has a user interface 106 that allows an operator to set various control parameters, such as the cleaning repetition rate, the cleaning speed, and the delay between consecutive cleaning cycles, and to calibrate the robot.

[0040] The flowchart of an example insert cleaning routine that can be downloaded or programmed into the controller is shown in FIG. 9. The routine illustrates just one exemplary method of robotically cleaning the inserts. In a first step 110, by signals on lines 97 and 98 of FIG. 8, the controller moves the cleaning tool to an initial position, such as the lower exit end of the leftmost insert 28′, which, for convenience, may define the origin O, (x, y)=(0, 0), of the robot's x-y Cartesian coordinate system shown overlying the upper peeling section of FIG. 2 and reproduced diagrammatically in FIG. 10. In a second step 112, the controller delays a fixed or selectable predetermined time before activating the cleaning action of the cleaning tool, such as turning on the spray by means of a signal on line 99 to the pump 100 for a spray nozzle tool, in step 114. In a next step 116, the controller advances the cleaning tool upward along the y axis to clean the insert (y=y+Δy). If a controllable underside cleaner is used, its operation is coordinated with the operation of the robot by an optional nozzle control routine in step 117, which is described later in more detail. As the cleaning tool advances, the controller, in step 118, monitors the y coordinate of the tool by the feedback signal from the y-axis sensor 105. When the tool reaches or passes the upper end of the insert, for which y≧Y_max, the controller deactivates the cleaning action (e.g., turns off the spray) in step 120. Next, in step 122, the controller compares the x coordinate of the cleaning tool to X_max to determine if the cleaning tool has reached or passed the upper end of the rightmost insert—the last to be cleaned in the cleaning cycle. If x≧X_max, indicating the end of the cleaning cycle, execution of the routine returns to the initial step 110 to reposition the cleaning tool at the lower end of the leftmost insert (the origin, O) for the start of the next cleaning cycle. If x<X_max, the controller, in step 124, advances the cleaning tool to the lower end of the next consecutive insert with the signals on lines 97 and 98. While the tool is advancing (x=x+Δx; y=y−Δy), the controller, in step 126, compares the x and y coordinates of the tool to the coordinates of the lower end of the next insert. When the cleaning tool reaches the start of the next insert (x≧X_next and y=0, where X_next is the distance from the origin to the next insert to be cleaned), the routine continues at step 114 to activate the cleaning action and advance the cleaning tool upward along the length of the insert. Thus, in this example, the controller is programmed to command the x-y robot to move the cleaning tool along a predetermined cleaning path running sequentially along the lengths of the inserts and then back to the origin, as indicated by arrows 128. But, instead of returning the cleaning tool directly back to the origin, the robot could reverse the cleaning tool's path to clean the inserts in reverse order on the way back to the origin as shown for the single cleaning tool 46 in FIG. 11A.

[0041] The controller can alternatively be programmed to clean the inserts 28 with two tools spaced apart a distance D₁ that corresponds to the distance between inserts on opposite sides of each elevated side roller 22, as shown in FIG. 11B. (The illustrations in FIGS. 11A-11D show the cleaning tool advancing from right to left, but apply as well to left-to-right advancement.) With two cleaning tools, the robot would have to make half as many passes as for the single-tool system to clean each insert once per cleaning cycle. And each translation along the x axis for the two-tool system from one insert pass to the next would be the same distance, unlike for the one-tool system, because the inserts on opposite sides of each side roller are farther apart than the inserts within each peeling channel 18. Another two-tool system is shown in FIG. 11C. It differs from the system in FIG. 11B in that the tools are spaced apart a shorter distance D₂ that corresponds to the distance between the inserts on opposite sides of each peeling channel. In both cases (FIG. 11B and FIG. 11C), the tools may be incremented along the x axis a distance P that corresponds to the transverse (x-axis) pitch of the peeling channels to clean each insert once per cycle. As shown in FIG. 11D, three cleaning tools may be robotically controlled to clean the peeler. In this example, the three tools are spaced apart a distance P corresponding to the transverse pitch of the peeling channels. The controller can be programmed to move the robot similar to the one-tool example given by the flowchart of FIG. 9, in which case each insert would receive three cleaning passes, one per tool, in each cycle. Clearly, there could be other arrangements and numbers of cleaning tools that could be robotically controlled by this system. The controller can also be programmed to control the speed of the cleaning tool along the inserts.

[0042] The coordination of the topside robot cleaner with the underside cleaning system is described with reference to FIG. 14 and the flowchart of FIG. 9. According to step 116 of the flowchart, the robot's cleaning tool 46, a spray nozzle in this example, advances along the y axis of the upper peeling channel as indicated by the arrow 152 in FIG. 14. As the nozzle advances along the channel, the underside nozzle control routine coordinates the opening and closing of the underside control valves 148 with the position of the topside nozzle. First, the routine checks whether the topside spray is on in step 154. If not, the controller closes all the valves according to step 156, and the execution returns to the topside robot control routine. If the topside spray is on, the controller, in step 158, turns on the valve that controls the nozzle whose spray pattern acts on the bottoms of the rollers and the insert beneath the position of the topside nozzle, as indicated by the unshaded open pipe 134 in FIG. 14. The valves for all the other pipes 134′, shown as shaded, are closed according to step 160. Thus, each valve has associated with it a range of y values for which it is opened in conjunction with the position of the robot insert cleaner's cleaning tool. As the cleaning tool advances up the upper peeler section, the subsequent valves are sequentially opened as the previously opened valves are closed. Coordinating the robot and the underside cleaners provides effective cleaning of the inserts from both top and bottom with less water consumption.

[0043] Although the invention has been described in detail with respect to a few preferred versions, other versions are possible. For example, the x- and y-axis assemblies could each have a different kind of actuator from the other. And linear actuators other than those described could be used, for example, hydraulic or pneumatic linear actuators. As another example, x- and y-position sensors other than rotary encoders could be used. Linear encoders that ride with the nuts or proximity switches at known positions along the x and y axes could be used. Furthermore, the controller could even dead reckon the position of the cleaning tool without feedback sensors. And the cleaning routine could be modified to provide different predetermined cleaning paths within the robot's working envelope over the peeling section, such as cleaning up one insert and down the next, alternately cleaning a given insert in opposite directions each consecutive cycle, making up and down cleaning passes on each insert before advancing to the next, cleaning on the return, and cleaning areas of the peeling section away from the inserts. And just as the topside robot cleaning system may be used without the underside cleaning system, the underside cleaning system may be used without the topside robot. So, as these few examples suggest, the scope of the claims is not meant to be limited to the specific details of the preferred versions.