FLAPPER GATE FORMING TUBE ASSEMBLY FOR PACKAGED PRODUCE CONTAINERS
A system for reducing metal and product-in-seal contamination in a package of produce product is provided. The system includes a tube and a flapper gate assembly. The flapper gate assembly is connected to the top of the tube, and includes a pivot and a flapper gate. The pivot is positioned outside the tube. The flapper gate is positioned inside the tube and is connected to the pivot. The flapper gate is configured to regulate product flow in the tube by rotating around the pivot when the pivot is rotated.
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1. Field
This application relates generally to a system for reducing metal contamination and product-in-seal failures in packaged produce containers and, more specifically, to interrupting or regulating flow of fresh produce into a bag using a forming tube assembly flapper gate device.
2. Description of the Related Art
A protective container, such as a polypropylene bag, can be used to preserve the quality of packaged produce product while it is being transported and stored before consumption. The container isolates fresh produce contents from environmental elements that can cause damage or premature spoilage. The container also protects the produce from contaminates and physical contact by forming a physical barrier. The container may also help to preserve the produce by maintaining environmental conditions that are favorable to the produce. For example, a protective container may reduce oxygen consumption and moisture evaporation by trapping a pocket of air around the packaged produce. Properly sealing the container is essential to maintaining the desired internal atmosphere and extending shelf life of the product.
One common protective container is the polypropylene bag, which is flexible, durable, and allows for the visual inspection of the product by the manufacturer, retail grocer, and end user. Polypropylene bags can be produced at a relatively low cost, and are compatible with numerous high-volume automated packaging techniques. For example, a vertical form, fill, and seal (VFFS) packaging process can be used to place fresh produce into polypropylene bags as they are formed. In a VFFS packaging process, a partially enclosed cavity is created by folding or sealing the polypropylene film to form a pocket. The fresh produce is placed in the pocket and then sealed as the pocket is formed into a fully enclosed polypropylene bag. In an alternative process, a polypropylene sleeve can be used to form an open-ended pocket. Fresh produce is placed in the pocket and the open end (or ends) are sealed using sealing jaws. While these two examples have been discussed, various other techniques exist for packaging fresh produce.
As a typical result of these packaging processes, ambient air is trapped in the sealed polypropylene bag. For some types of produce, the oxygen content of ambient air may be harmful to the longevity of a retail produce product. For example, if the produce includes fresh lettuce leaves, the oxygen content of ambient air (having oxygen content of approximately 20 percent) can cause a polyphenoloxidase reaction that degrades the quality of the lettuce leaves. The shelf-life of packaged lettuce leaf may be significantly extended if it is packaged in a protective container that maintains oxygen levels between 1 percent and 9 percent. The container must be properly sealed to maintain the desired oxygen levels.
Alternatively, air can be removed from a partially enclosed polypropylene bag to reduce the amount of oxygen by applying a vacuum or by heat shrinking the bag to conform to the dimensions of the produce. However, some fresh produce products, including lettuce leaf and other leafy vegetables, are too delicate to withstand either a vacuum sealing or heat shrinking process. As a result, most packaging processes for leafy vegetables trap at least some volume of air in the polypropylene bag. In fact, in some cases, a slight positive pressure of air inside the bag may even be desirable as it provides some mechanical cushioning for the produce product by slightly expanding the walls of the polypropylene bag away from the leafy vegetable contents.
A leak in the seal of the bag can prevent the desired oxygen level from being maintained and cause the bag to lose internal pressure. Therefore, it is desirable to properly seal the protective container to maintain the desired internal atmosphere.
In addition to the integrity of the seal, metal contamination is another concern when using a mechanical device such as a VFFS machine to package produce. As a typical result of using a mechanical device in the packaging process, components such as loose or misaligned nuts and bolts can fall into the protective container and contaminate the packaged product. Metal shavings from dynamic portions of the machine can also contribute to contamination. Thus, it is also desirable to reduce the risk of metal contamination due to the failure of mechanical components in a packaging system.
SUMMARYOne exemplary embodiment includes a system for reducing metal and product-in-seal contamination in a package of produce product. The system includes a tube, a partially enclosed cavity, a flapper gate assembly, and a sealing assembly. The tube is positioned substantially vertically, and has a top, bottom, inside, and outside. The partially enclosed cavity contains the produce product, and has a cavity opening positioned below the bottom of the tube. The flapper gate assembly is connected to the top of the tube and includes a linkage assembly, a pivot assembly, and a flapper gate. The linkage assembly has a bracket attached to the outside of the tube and a linkage arm connected to the bracket in a fixed position relative to the tube. The pivot assembly is positioned outside the tube and is attached to the linkage arm. The pivot assembly includes an actuator, a piston rod, a pivot arm, and a hinge. The actuator is configured to drive the piston rod, and the piston rod is connected to the pivot arm, which rotates around the hinge when the piston rod is driven. The flapper gate is positioned inside the tube and is connected to the pivot arm via the hinge. The flapper gate is configured to rotate around the hinge when the pivot arm is rotated to regulate product flow in the tube. The sealing assembly is configured to seal the partially enclosed cavity to form a fully enclosed package.
In some embodiments, the flapper gate assembly is connected to a vertical form, fill and seal (VFFS) machine. In some embodiments, the package is a polypropylene bag. In some embodiments, the flapper gate is a single-piece stainless steel gate.
One exemplary embodiment includes a method of reducing metal and product-in-seal contamination in a package of produce product. The method includes the steps of loading the produce product into a tube, opening a flapper gate located at the top of the tube to allow the produce product to flow through the tube into an opening of a partially-enclosed cavity positioned below the tube, closing the flapper gate to stop the flow of produce product through the tube, and sealing the partially enclosed cavity to produce a fully enclosed package containing the produce product.
In some embodiments, the method includes the step of collecting the produce product inside the tube using the flapper gate. In some embodiments, the partially enclosed cavity is sealed when the partially enclosed cavity is determined to be full. In some embodiments, the method is implemented as part of a VFFS packaging operation.
The figures depict one embodiment of the present invention for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein can be employed without departing from the principles of the invention described herein.
DETAILED DESCRIPTIONThe following description sets forth numerous specific configurations, parameters, and the like. It should be recognized, however, that such description is not intended as a limitation on the scope of the present invention, but is instead provided as a description of exemplary embodiments.
As mentioned above, a protective container can be used to protect fresh produce product while it is being transported from the packaging facility to a retail grocer and from the grocer to an end-user's kitchen. A protective container may also prolong the shelf-life of fresh produce product by isolating the contents from environmental factors that could cause damage or premature spoilage. In particular, the shelf-life of packaged produce including fresh lettuce can be extended if oxygen content is maintained between 1 percent and 9 percent. In particular, the integrity of the seal is critical to maintaining the desired oxygen level, and thus the shelf-life of packaged produce including fresh lettuce.
In packaging machines such as the VFFS discussed above that use sealing jaws to seal the protective container, seal integrity can be compromised by small foreign particles falling into the sealing area during sealing. The particles get caught in the sealing jaws potentially causing leaks in the seal. Leaks result in product-in-seal failures that cause the container to lose the desired internal conditions. The amount of foreign objects in the sealing area may be reduced by interrupting the constant flow of particles in the VFFS machine.
A flapper gate device can be used to modulate delivery of product to interrupt the flow of product into the polypropylene bag before it is sealed. Introducing a gate, however, adds mechanical components required to operate the gate into the flow path of the product, which increases the potential for metal objects to fall into the bag and contaminate the product. The flapper gate device described below reduces the potential for metal objects falling off the flapper gate and into the packaging. Techniques described herein provide similar performance to existing systems, while reducing or eliminating some of the problems.
In an exemplary embodiment described below, a flapper gate device coupled to the top or throat of a forming tube assembly is constructed using a single-piece stainless steel gate, which is relatively inexpensive to produce. Locating the flapper gate device at the top of the tube allows all removable metal parts required to operate the gate to be removed from inside the tube, which reduces metal contamination. The flapper gate device can also be removed and disassembled more easily outside the tube, which facilitates regular sanitation and maintenance operations.
A flapper gate provides more precise control over the flow of product than other gate configurations. The flapper gate can be controlled to provide real-time process feedback so that the VFFS system can be adjusted either manually or automatically. For example, the flapper gate may be pneumatically connected to an air piston or other device that actuates a pivot arm to open and close the assembly. A pneumatic control provides feedback to the VFFS system operator. The flapper gate is controlled by the packaging machine operator for optimum VFFS efficiency. Alternatively or additionally, the flapper gate control system can be adjusted to account for changes in packaging operation parameters including, for example, packaging speed.
1. Process for Packaging Produce Using a Flapper Gate AssemblyAs mentioned above, a protective container, such as a polypropylene bag, can be used to preserve the quality of packaged produce product while it is being transported and stored before consumption. Polypropylene bags can be produced at a relatively low cost, and are generally compatible with high-volume automated packaging techniques. For example, VFFS machinery can be used to form a polypropylene film into a pocket or partially enclosed cavity in an automated fashion. A polypropylene film is fed into the machinery via a roll or sheet of material. The film is typically folded to form a partially enclosed cavity into which fresh produce can be loaded. In some cases, the partially enclosed cavity is sealed length-wise using a roll sealer to form a tube-shaped partially enclosed cavity. Once loaded with fresh produce, the formed cavity can be sealed on one or both ends using heat-sealing jaws to form a fully enclosed polypropylene bag.
Alternatively, other bag-filling machinery can be used to fill partially formed polypropylene bags with fresh produce in an automated or semi-automated fashion. For example, a polypropylene sleeve material can be used to create a partially enclosed cavity by sealing the sleeve at one end. Produce product can be placed in the partially enclosed cavity either manually or using automated machinery. The open end of the cavity can be sealed to form a fully enclosed polypropylene bag.
In operation 110 of process 100, a produce product is loaded. As shown in
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Because of the elongated stream of large particles and the dispersed, slower falling small particles, there is rarely a break in the flow of product through the cavity opening. As a result, produce particles interfere with the sealing operation and prevent a clean seal from being made. If enough product gets caught in the sealing jaws, a product-in-seal failure occurs, which causes the container to leak and lose the desired internal conditions. Additionally, the package must be reworked to discard the failed bag and salvage the lettuce leaves. A one percent savings in product-in-seal packages may be worth approximately $900,000 per year.
The mechanics of operation 300 may vary depending on the packaging machinery being used to package the produce. As shown in
In some cases, the partially enclosed cavity 402 is placed or formed over a forming tube 406. For example, if a VFFS packaging operation is used, the partially enclosed cavity 402 may be formed around falling lettuce product and sealed at one end (the bottom end) using heat-sealing jaws 414. In a typical VFFS packaging operation, the flapper gate assembly 416 opens and closes to regulate the flow of product through tube 406 while the partially enclosed cavity 402 is formed from a continuous sheet of packaging film. As shown in
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Variations of process 300 shown in
Additionally, when process 300 (
The flow rate may also depend on the type of produce being packaged. Packaging operations for produce that is whole leaf or has a smaller cut size require lower packaging rates. Lower rates are required to account for the greater variation in the speed at which produce particles of these types fall into the partially sealed container. Conversely, packaging rates may be increased for produce that is wet or denser, as there is less variance in the rate at which product particles fall.
Feedback in the packaging operation can be implemented manually by a package machine operator. In some cases, the feedback will be used to maintain product-in-seal failure rates within a specified range. The specific range and target values vary depending on the produce product being packaged. Lettuce and salad mix products may have a target product-in-seal failure rate as low as 2 percent and as high as 10 percent.
2. Flapper Gate AssemblyThe flapper gate assembly 500 depicted in
Linkage assembly 510 includes bracket 514 and linkage arm 512. Bracket 514 is attached to the outside of the junction between hopper 508 and forming tube 506. The flapper gate assembly 500 is attached to the outside of the top of tube 506 via bracket 514. Linkage arm 512 is connected to the bracket 514 in a fixed position relative to the tube 506.
The pivot assembly 520 is adapted to pivot without removable metal coupling attachments inside the tube 506. It includes actuator 522, piston rod 524, pivot arm 526, and hinge 528. Hinge 528 is attached to linkage arm 512 and is located at the intersection of the bracket 514 and tube 506. Actuator 522 drives piston rod 524, which is attached to pivot arm 526. Actuator 522 is attached to linkage arm 512 such that when actuator 522 is activated, force is transferred from linkage arm 512 to pivot arm 526 via actuator 522 and piston rod 524. Actuating piston rod 526 rotates pivot arm 526 around hinge 528.
In the present embodiment, the flapper gate 530 is pneumatically connected to the actuator 522 via piston rod 524 and the pivot arm 526 to open and close the assembly. Flapper gate 530 is connected to pivot arm 526 via hinge 528. Because the pivot assembly 520 contains all the removable parts, flapper gate 530 can be positioned in the tube 506 to regulate product flow to a sealing area without introducing removable parts inside the forming tube 506. For example, the flapper gate 530 may consist of a single piece of metal shaped such that forming tube 506 is nearly completely closed when the flapper gate 530 is positioned at an approximately 45 degree angle with respect to the vertical wall of the tube 506. When closed the flapper gate preferably forms an angle between approximately 35 degrees and 55 degrees with the vertical wall of the tube. When the flapper gate is fully open, it may form an angle of approximately zero degrees with the vertical wall of the tube.
The flapper gate 530 depicted in
Locating the flapper gate assembly at the top or throat of the forming tube assembly has several advantages. First, it allows all removable parts to be located outside the forming tube. A gate located in the mid-to-lower portion of the tube would require an internal mechanism to operate the gate. An internal mechanism introduces connecting rods or bolt attachments that can come loose and fall into packaged product causing metal contamination. Compared to systems without gates, gate systems having removable parts inside the forming tube have been shown to produce 30 percent of the total metal contamination due to metal parts falling off the system. Because the described flapper gate assembly has no removable parts inside the forming tube assembly, it eliminates the possibility of metal contamination, thus reducing total metal contamination by 30 percent.
Locating all removable parts of the flapper gate assembly outside the forming tube also makes the assembly amenable to sanitation and cleaning. Any debris or produce product that accumulates on the assembly does not enter the packaged product because it is outside the tube. Also, the assembly is less likely to collect product debris and become dirty because it is not in the product flow path.
Locating the flapper gate assembly at the top of the forming tube assembly also allows the produce product to accumulate at a higher distance above the opening of the packaging. This allows the released charge of produce product to achieve greater velocity when entering the partially enclosed cavity. Higher velocities can compress the produce towards the bottom of the partially enclosed cavity as it enters the packaging. Compression of the product allows the desired amount of produce to fit into the cavity without the product on top interfering with the sealing jaws.
3. System Testing and ResultsThe performance of a device having a flapper gate assembly was compared to a control device that did not include a flapper gate assembly. In both devices, produce was fed into the top of a forming tube assembly and packaged using a VFFS machine. The control device was operated according to process 100 described in
The tests were conducted at the Soledad, California production facility. Tests were conducted for three different lettuce products: baby spinach, classic iceberg, and shred iceberg. The baby spinach was packaged at a rate of 50 bags per minute. The classic iceberg and shred iceberg were packaged at a rate of 60 bags per minute. The average rate for all products was 55 bags per minute.
The tests were designed to determine whether the performance of the flapper gate assembly met or exceeded the performance of existing designs. As shown in
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For classic iceberg lettuce, 5.41 percent of tested containers packaged without using a flapper gate assembly had product-in-seal failures that resulted in leaking packages. This is compared to 2.88 percent of tested containers packaged using a flapper gate assembly. Accordingly, the flapper gate assembly resulted in a 46.77 percent reduction in product-in-seal failures for classic iceberg. The z-test value of −8.3437 is less than −1.96, which indicates that the product-in-seal failure rates are statistically different at the 0.05 confidence level.
For shred iceberg lettuce, 5.34 percent of tested containers packaged without using a flapper gate assembly had product-in-seal failures that resulted in leaking packages. This is compared to 3.37 percent of tested containers packaged using a flapper gate assembly. Accordingly, the flapper gate assembly resulted in a 36.95 percent reduction in product-in-seal failures for shred iceberg. The z-test value of −5.9612 is less than −1.96, which indicates that the product-in-seal failure rates are statistically different at the 0.05 confidence level.
When averaging the three types of products, 6.77 percent of tested containers packaged without using a flapper gate assembly had product-in-seal failures that resulted in leaking packages. This is compared to 3.38 percent of tested containers packaged using a flapper gate assembly. Therefore, although the data in
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A review of metal contamination results shows that flapper gate assemblies located in the mid-to-lower portion of the forming tube were used in 15 percent of VFFS machines but contributed 30 percent of the metal contamination due to nuts, bolts and other metal parts falling off the linkage assembly that drives the flapper gate. Because the flapper gate assembly had no removable parts inside the forming tube, it reduced total metal contamination by 30 percent.
The foregoing descriptions of specific embodiments have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and it should be understood that many modifications and variations are possible in light of the above teaching.
Claims
1. A system for reducing metal and product-in-seal contamination in a package of produce product, the system comprising:
- a tube positioned substantially vertically, the tube having a top, bottom, inside, and outside;
- a partially-enclosed cavity for containing the produce product, the partially-enclosed cavity having a cavity opening positioned below the bottom of the tube;
- a flapper gate assembly, connected to the top of the tube, comprising a linkage assembly, a pivot assembly, and a flapper gate, the linkage assembly having a bracket attached to the outside of the tube and a linkage arm connected to the bracket in a fixed position relative to the tube; the pivot assembly positioned outside the tube and attached to the linkage arm, the pivot assembly comprising an actuator, a piston rod, a pivot arm, and a hinge, wherein the actuator is configured to drive the piston rod, and the piston rod is connected to the pivot arm, which rotates around the hinge when the piston rod is driven; and the flapper gate positioned inside the tube and connected to the pivot arm via the hinge, wherein the flapper gate is configured to rotate around the hinge when the pivot arm is rotated to regulate product flow in the tube; and
- a sealing assembly configured to seal the partially-enclosed cavity to form a fully-enclosed package.
2. The system of claim 1, wherein the flapper gate assembly is connected to a vertical form, fill, and seal (VFFS) machine.
3. The system of claim 1, wherein the package is a polypropylene bag.
4. The system of claim 1, wherein the flapper gate is a single-piece stainless steel gate.
5. A system for reducing metal and product-in-seal contamination in a package of produce product, the system comprising:
- a tube having a top and bottom; and
- a flapper gate assembly, connected to the top of the tube, comprising a pivot and a flapper gate, the pivot positioned outside the tube; and the flapper gate positioned inside the tube and connected to the pivot, wherein the flapper gate is configured to regulate product flow in the tube by rotating around the pivot when the pivot is rotated.
6. The system of claim 5, wherein the flapper gate assembly is connected to a vertical form, fill, and seal (VFFS) machine.
7. The system of claim 5, wherein the package is a polypropylene bag.
8. The system of claim 5, wherein the flapper gate is a single-piece stainless steel gate.
9. A flapper gate device for reducing metal contamination in a package of produce product, the flapper gate device comprising:
- a linkage assembly having a bracket and a linkage arm connected to the bracket in a fixed position relative to the bracket;
- a pivot assembly attached to the linkage arm, the pivot assembly comprising an actuator, a piston rod, a pivot arm, and a hinge, wherein the actuator is configured to drive the piston rod, and the piston rod is connected to the pivot arm which rotates around the hinge when the piston rod is driven; and
- a gate connected to the pivot arm via the hinge, wherein the gate is configured to rotate around the hinge when the pivot arm is rotated,
- wherein the flapper gate device is configured to connect to the top of a tube such that the pivot assembly is outside the tube and the gate is positioned inside the tube to regulate the flow of the produce product through the tube.
10. The flapper gate device of claim 9, wherein the flapper gate device is connected to a vertical fill-form-seal (VFFS) machine.
11. The flapper gate device of claim 9, wherein the package is a polypropylene bag.
12. The flapper gate device of claim 9, wherein the gate is a single-piece stainless steel gate.
13. A method of reducing metal and product-in-seal contamination in a package of produce product, the method comprising:
- loading the produce product into a tube;
- opening a flapper gate located at the top of the tube to allow the produce product to flow through the tube into an opening of a partially-enclosed cavity positioned below the tube;
- closing the flapper gate to stop the flow of produce product through the tube; and
- sealing the partially-enclosed cavity to produce a fully-enclosed package containing the produce product.
14. The method of claim 13, further comprising collecting the produce product inside the tube using the flapper gate.
15. The method of claim 13, wherein the partially-enclosed cavity is sealed when the partially-enclosed cavity is determined to be full.
16. The method of claim 13, wherein the method is implemented as part of a vertical fill-form-seal (VFFS) packaging operation.
17. The method of claim 13, wherein the package is a polypropylene bag.
18. The method of claim 13, wherein the flapper gate is a single-piece stainless steel gate.
19. The method of claim 13, wherein opening the flapper gate occurs before loading the produce product into the tube.
20. The method of claim 13, wherein loading the produce product into the tube occurs before opening the flapper gate.
Type: Application
Filed: Jan 24, 2013
Publication Date: Jul 24, 2014
Applicant: DOLE FRESH VEGETABLES, INC. (Salinas, CA)
Inventors: Jerry L. CRAWFORD (Salinas, CA), Bob J. DULL (Akron, OH), Robert TARANGO (Soledad, CA), Stephen C. Jens (Winchester, MA), Serafin Albarran (Salinas, CA)
Application Number: 13/749,608
International Classification: B65B 7/00 (20060101);