Patent Application
20080193272
The present invention relates generally to a method and systems for removing items that are stacked on a pallet and more particularly to a method and systems for removing items that are stacked on a pallet by using vacuum power to remove items from the pallet and a conveyor system to further process the items once the items are removed from the pallet.
Pallets are portable platforms on which goods are placed for storage or transport. Pallets are usually designed to allow forklifts or other industrial movers to efficiently transport the pallets, which in turn facilitates the movement of large quantities of goods. Goods of significant size can encompass an entire pallet while smaller goods can be arranged in various configurations so as to maximize the number of goods that can placed on each pallet. Such configurations may utilize layering techniques in which multiple goods can be arranged on the bottom layer while additional layers of goods are stacked on top of the bottom layer and so forth. Depending on the height of the goods to be stored or transported, a pallet may contain multiple layers of goods, the total capacity of a pallet being potentially limited by such factors as the size and weight of individual goods as well as considerations related to the storage, transport, loading, and unloading of goods. A load may consist of one or more layers of product and may be unitized (no pallet) or palletized (pallet).
In a typical situation, cartons containing goods are arranged on a pallet in a uniform pattern to facilitate the layering of goods. For example, a pallet may have the capacity to accommodate four rows of four cartons for a total of sixteen cartons that might comprise the bottom layer. Once the bottom layer is complete, sixteen additional cartons may be stacked on top of the original sixteen cartons to form another layer of cartons. Additional layers of cartons are then added until the pallet reaches predetermined height or weight limitations. While the foregoing example describes a scenario in which cartons of regular shape (e.g., cube-shaped) are stored on a pallet, irregularly-shaped goods can also be stored and transported using pallets. However, the arrangement of irregularly-shaped goods often provides additional challenges to maximizing pallet capacity as well as to the efficient removal of such goods from the pallet.
Once a pallet of goods had reached its destination, the goods on the pallet can be removed from the pallet either manually or through the use of equipment that can facilitate the unloading of the pallet. For example, pallets may be moved through the use of forklifts or hand-drawn jacks. When goods are heavy or unwieldy so as to prevent manual unloading, the blades of the forklift may be used to lift one or more products from the pallet by inserting the blades underneath the product or by raising the product from above using chains attached to the blades. In either scenario, a procedure to insert the blades or chain underneath the product without greatly increasing the likelihood of damaging the palletized goods becomes necessary. The use of slip sheets or other dividers to separate one layer of goods from the next has been implemented to effect some demarcation between layers and to reduce to some extent the danger of damaging the goods during the depalletization process. Slip sheets also act to stabilize a palletized or unitized load during transport because column stacking products on pallets (i.e., without slip sheets) often creates loads that are unstable. However, even when such procedures are implemented, safety issues may arise due the relative instability of the carton while it is being unloaded.
On the other hand, when the goods weigh relatively little, the goods are capable of being removed from the pallet manually. However, having a worker manually unload the goods from a pallet remains relatively inefficient and workers can be injured when attempting to unload heavy or unwieldy goods or merely by using the incorrect body mechanics when removing the goods from the pallet. Common health issues that are implicated include carpal tunnel syndrome, repetitive movement injuries, and various muscle (e.g., back) injuries. Further, although the manual unloading of goods from pallets onto store shelves may be appropriate in a retail scenario, when large volumes of palletized goods need to be unloaded quickly and efficiently for automated storage and/or processing applications, the manual unloading of such pallets is usually undesirable with respect to labor costs, reliability, and speed attributed to the pallet unloading process, or “depalletization” process. This will generally be true whether the goods are regularly-shaped or irregularly-shaped.
Proposed solutions that have been explored to facilitate the automation of the depalletization process have met with varying degrees of success based to some degree on the non-standard array of goods that can be stored and/or transported on pallets. For example, depalletization methods that may be utilized to remove large cartons (e.g., 8 cartons per pallet) may not be effective in removing smaller cartons (e.g., 1000 cartons per pallet). Irregular shaped goods provide additional challenges to the development of a universal yet efficient method for unloading pallets. Many products such as stacks of loose cartons, open top boxes, boxes with weak tops, and boxes with slip-on tops have provided challenges to the development of a standard method and system for depalletizing products. Prior methods aimed at improving the depalletization process include the use of custom slip sheets that have a matrix of bumps or an array of corrugations to permit small forks to get under the product. However, this method has its disadvantages in the expense associated with the custom slip sheets and the automation necessary to detect the bumps or corrugations so that the forks can be properly inserted to prevent damage to the palletized goods. Although the emergence of pallets revolutionized the material handling industry by allowing more goods to be loaded and unloaded faster with less labor, a parallel efficiency in the depalletization of goods has yet to be realized.
The present invention claims a system that uses a vacuum hood to remove goods from a pallet a layer at a time along with a slip sheet that separates each layer of goods. The system is comprised of a vacuum hood that is lowered down onto the topmost layer of palletized goods. The vacuum hood forms a seal with the slip sheet so that the goods can be removed from the pallet along with the slip sheet once the vacuum is turned on. Effectively, the vacuum hood and the slip sheet form a container in which the layer of goods is contained, which is then moved off of the pallet. The system is further comprised of a conveyor system where the vacuum hood places layers of goods. The conveyor system is made up of at least two independent conveyor sections so that the slip sheet may be removed between a space between the conveyor sections while the goods continue along conveyor system. There are a number of techniques and associated equipment that can be used to guide the slip sheet through the space so that it can be removed from the system. After the slip sheet is removed, the goods may then continue along the conveyor system for further processing without the slip sheet.
The present invention also claims a method in which each layer of palletized goods are removed from the pallet along with a slip sheet that separates each layer of goods. The goods are removed using vacuum power from a vacuum hood. Once the vacuum hood is lowered down onto the top layer of palletized goods, the vacuum hood will form a seal with the slip sheet. Once the vacuum power is turned on, the vacuum hood removes the captured layer of goods from the pallet. The vacuum hood can then place the goods and the slip sheet onto a conveyor system. Once the goods and slip sheet are placed on the conveyor system, the slip sheet can then be removed through a space between conveyor sections so that the goods can continue along the conveyor system for further processing without the slip sheet.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.
For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:
Each of side walls 102 may be expanded or retracted individually so that vacuum hood 100 can accommodate a range of palletized products without retooling. For example, side walls 102 may fold inward to facilitate the capture of a layer of goods that encompasses an area less than that of vacuum hood 100. Side walls 102 on opposite sides of vacuum hood 100 may be closed and opened with synchronized motion. In a preferred embodiment, if a target layer of goods is not initially centered underneath vacuum hood 100, compliance float 106 allows vacuum hood 100 to be repositioned so that the goods may be removed. Guide plates 108 are located on the sides of vacuum hood 100, forming slots for corner members 104.
Compliance float 106 allows vacuum hood 100 to move and accommodate pallets that have layers misaligned in relation to the position of vacuum hood 100. Individual layers of goods can be located off center due to rough handling by a supplier or shipper. Therefore, compliance float 106 allows vacuum hood 100 to “float” and center itself properly over the layer of goods to be depalletized. Once vacuum hood 100 is properly aligned and placed over the layer of goods to be depalletized, ceiling 110 is lowered down onto the goods. Ceiling 110 may be flat or may comprise one or more attachments that can be used to fill in large voids in a patterned layer to be depalletized.
In one embodiment of the invention, the system uses a suction generator to pump air out of vacuum hood 100, which creates sufficient negative pressure to facilitate the capture of layers of palletized goods lift the product layer. During the depalletizing process, air should be suctioned continuously from vacuum hood 100, which acts to provide constant negative pressure that is sufficient to lift the weight of the goods being removed from the pallet. The line of atmospheric change is located at the bottom of the layer of goods to be depalletized and the product is effectively pushed into vacuum hood 100 by the higher atmospheric pressure. In a preferred embodiment, side walls 102 are stiff or have limited flexibility. A stiff wall typically provides added friction to the interaction between the goods and vacuum hood 100. In certain embodiments, side walls 102 provide additional clamping force because the vacuum power acts to draw in side walls 102 toward the center of vacuum hood 100.
In one embodiment of the invention, vacuum hood 100 may be configured to automatically detect slip sheets placed between layers of goods. One or more pressure transducers may also be mounted on vacuum hood 100 in order to monitor vacuum pressure within vacuum hood 100 and maintain a predetermined vacuum pressure level. Some pressure leakage may occur within the system and each layer of goods may have a leakage factor varying from the norm. Because a good seal may not be possible, a high flow, low pressure blower that allows for significant air leaks may be used so that leaks do not cause dramatic drops in pressure. To provide a constant lifting force under conditions of unpredictable leakage, a pressure transducer can be used to measure the negative pressure in vacuum hood 100. The pressure transducer may be utilized as a feedback mechanism in a closed-loop control system to ensure that the pressure is maintained at or near optimum levels. For example, if the pressure transducer detects that the negative pressure level is insufficient, the vacuum generating source will receive a signal to increase the vacuum pressure within vacuum hood 100. Conversely, if the pressure transducer detects that the negative pressure level is unacceptably high, then the vacuum generating source will receive a signal to decrease the vacuum pressure within vacuum hood 100.
In a preferred embodiment, collision sensors are incorporated into vacuum hood 100 so that collisions between vacuum hood 100 and other objects can be immediately detected to prevent further damage. In this embodiment, the activation of the collision sensor may act to trip an emergency stop circuit that automatically stops movement of vacuum hood 100 and may also issue a warning signal to the operator of vacuum hood 100.
As shown in
Each slip sheet 306 has a surface area that ideally extends beyond the area occupied by product 302 in order to facilitate the seal formed between vacuum hood 100 and slip sheet 306. The composition of slip sheets may be dependent on the nature of the goods being depalletized or the method or methods of slip sheet removal implemented in the embodiment of the invention. Slip sheets may be composed of materials selected for such characteristics as stiffness or flexibility. For example, one embodiment of the invention may use slip sheets made out of corrugated material so that the slip sheet is flexible in one plane and stiff in the perpendicular plane. This placement of slip sheet 306 allows vacuum hood 100 to be lowered onto the topmost layer of the pallet and form a seal with slip sheet 306, which effectively creates an enclosure in which the goods can be removed from pallet 300. Each slip sheet 306 forms a barrier between each layer of stacked goods and can vary in its composition to allow for flexibility or rigidity depending on the nature of the palletized goods and the embodiment of the invention being practiced. The slip sheets are inserted between the each layer when the goods are initially loaded onto the pallet. Further, a slip sheet should be inserted between the top of the pallet and the bottom layer of goods so that the bottom layer can be unloaded in the same manner as the upper layers.
As shown in
When vacuum hood 100 is properly positioned so that the all of the walls of vacuum hood 100 form a seal with slip sheet 306, the vacuum is turned on. An airtight seal is not necessary and may not be practical or possible depending on the embodiment of the claimed invention. Top layer 400 is secured by the seal created by the vacuum between vacuum hood 100 and slip sheet 306. In one embodiment of the invention, the amount of vacuum pressure exerted on the goods is regulated such that the vacuum pressure used is exactly the vacuum pressure needed to effectively practice the claimed invention and no more. As shown in
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As indicated in
The conveyor separation techniques that may be used to sort, separate, or otherwise align the goods for efficient downstream processing are highly dependent on the nature of the goods (e.g., size, shape, weight) and the nature of the downstream processing, if any. Embodiments of the present invention comprise methods and systems that are designed to handle high volumes of the same or similar goods that have the same or similar characteristics as well as goods that do not share the same physical or packaging characteristics. Such considerations may affect the selection of the conveyor separation technique employed in this embodiment of the invention.
For example, if the goods are moving along the conveyor system in a side by side configuration such as that shown in
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods, and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
