The present invention is generally related to the field of automated bag closure systems.
For many years, manufacturers have used plastic bags to package a wide variety of products. In some industries, it is desirable to provide a plastic bag that can be repetitively opened and sealed by the consumer. For example, bread is often enclosed in a plastic bag that is bound with a twist-tie. The twist-tie closure allows the consumer to open and close the bag multiple times, thereby extending the use of the bag for the life of the product.
Although twist-ties are favored for their inexpensive cost, competing closure mechanisms have also been employed. For example, plastic lock-tabs are frequently used to close plastic bags containing perishable bakery items. Lock-tabs are easy to apply and offer the packager a surface upon which information can be printed. While generally acceptable, lock-tabs are relatively expensive. As an alternative, manufacturers have employed tape closure systems in which the neck of the bag is captured by a piece of one-sided tape. Tape closure systems offer the cost benefits of twist-ties and the ability to print information on the closure provided by lock-tabs.
Prior art tape closure systems function by applying a preset amount of tape to the neck of the bag. In these systems, changes in the diameter of the bag neck tend to create variations in the “legs” of the tape that extend from the neck. Variations in the lengths of the tape legs increase the difficulty of printing information on the tape and may present problems during use by the consumer. Accordingly, there is a need for an improved tape closure system that overcomes these deficiencies of the prior art.
In preferred embodiments, the present invention includes a tape closure device for securing the neck of a bag with an adhesive film and a non-adhesive backing. In the preferred embodiment, the device includes a closure application assembly that has a guide rail, a contact member and a cutting member. The guide rail preferably includes a contact section, a gathering section and a staging section. The contact member preferably includes a contact surface adjacent the contact section of the guide rail. The tape closure device also preferably includes a tape feed assembly, a paper feed assembly and a bag feed assembly. Each of these components cooperates in the preferred embodiment to produce a continuous, linear-motion tape closure operation.
In accordance with a preferred embodiment, the present invention includes a tape closure system for use in conjunction with an automated packaging system. Although the preferred embodiment is disclosed for use in a bakery environment, it will be understood that the tape closure device could find utility in a wide variety of other applications.
Referring to
The operation of the tape closure device 100 is generally depicted in
Starting on the upstream side of the conveyor system 118, unclosed bags 120 are fed through the tape closure device 100 with the open end 122 of the bag 120 passing through the closure application assembly 108. As the bags 120 pass through the tape closure device 100, the tape closure device 100 gathers the open ends 122 of each bag 120 into a neck 124 and applies a closure 126 around the neck 124 to keep the bag 120 closed. The closure 126 is preferably formed with one-sided releasable adhesive tape that is partially secured to a non-adhesive backing paper to facilitate release of the closure 126. The closure 126 is configured to be repetitively removed and re-attached to the neck 124 of the bag 120.
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Similarly, the paper feed assembly 106 preferably includes a spool 136, a drag pulley 138 a pay-out linkage 140 and a pneumatic or hydraulic cylinder (not shown). Between closure cycles, the cylinder retracts and the pay-out linkage 140 pulls a selected amount of backing paper from the spool 136 and drag pulley 138. The cylinder then extends to provide a desired amount of slack in the backing paper.
The closure application assembly 108 preferably includes a tape guide pulley 142, a guide rail 144, a contact member 148, a cutting member 150, a paper feed pulley 152, and a blade guard 154. The guide rail 144 preferably includes a staging section 156, a gathering section 158 and a contact section 160. Paper is fed from the left side of the closure application assembly 108 around the paper feed pulley 152 and through a slot 38 in the contact section 160. Tape is fed from the right side of the closure application assembly 108 around the tape guide pulley 142 towards the contact section 160. The tape is preferably fed such that the adhesive side of the tape is oriented towards the guide rail 144.
In the preferred embodiment, the gathering section 158 of the guide rail 144 is slightly lower than the contact section 160. In a particularly preferred embodiment, the gathering section 158 is approximately 0.5 mm lower than the contact section 160. There is an additional, more substantial step down to the staging section 156. The profile of the guide rail 144 is well illustrated in
Referring now also to
The contact member 148 is connected to a pivot arm 166 that is journaled about pivot 168. The distance and relative position of the contact member 148 and the pivot 168 cause contact member 148 to translate in a substantially vertical direction. A first end of a spring 167 is attached to post 171 and when placed in tension applies a moment through pivot arm 166 about pivot 168 to create a downward force on the contact member 148. The second end of spring 167 is attached to a pin (not shown in
The contact member 148 preferably includes a bag stop 172. The bag stop 172 is preferably configured as a “finger” that extends downward toward the gathering section 158 of the guide rail 144. The width of the bag stop 172 is preferably configured to be approximately the same as the width of the tape. The bag stop 172 is configured to rotate about axle 174 to a retracted position inside recess 176 in contact member 148. The bag stop 172 is preferably spring-biased against retraction into the contact member 148.
The cutting member 150 preferably includes a blade 178 and a lever arm 180. The cutting member 150 is configured to independently rotate about pivot 168. A spring 182 biases the cutting member 150 in a retracted position. When the neck 124 of the bag 120 contacts the lever arm 180, the cutting member 150 rotates in a clockwise direction. The clockwise rotation of the cutting member 150 causes the blade 178 to sever the trailing tape and paper from the closed bag neck 124. When the closed-neck 124 clears the lever arm 180, the cutting member 150 returns to its default position and the plunger 184 returns to its home position in preparation for a subsequent cycle of operation.
When tape and paper are loaded into the closure application assembly 108, the cutting member 150 must be manually retracted by rotating the cutting member in a counterclockwise direction. When lifted in this way, the blade 178 is exposed and presents a risk of harm to the operator. The blade guard 154 conceals the blade 178 while the cutting member 150 is in the retracted position. After the paper and tape have been loaded into the closure application assembly 108, the cutting member 150 is deployed to its operative position by rotating the cutting member 150 in a clockwise direction.
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Auxiliary brushes 194 are configured to encourage the movement of the open end 122 through the tape closure device 100 as the body of the bag 120 moves along the conveyor system 118. In a particularly preferred embodiment, only the lower auxiliary brush 194 is powered and the upper auxiliary brush 194 turns in response to contact with the upper auxiliary brush 194. In a preferred embodiment, the speed at which the auxiliary brushes 194 turn is proportional to the speed of the drive rollers 196. The internal location of the auxiliary brushes 194 is best seen in
The drive rollers 196 are configured to rotate in opposite directions at a speed proportional to the speed of the conveyor system 118. In the preferred embodiment, the upper drive roller 196 is configured to translate vertically during operation, while the lower drive roller 196 is fixed. The articulation of the upper drive roller 196 allows the closure application assembly 108 to accommodate bags 120 of different sizes without incurring damage to the tape closure device 100.
The sensor 198 preferably includes a trigger 200 and a counterweight 202. As the open end 122 of the bag 120 enters the tape closure device 100, the bag lifts the trigger 200 which causes the sensor 198 to send a signal to the programmable logic control (PLC) to start a bag closure cycle. In a particularly preferred embodiment, the sensor 198 is configured to identify the trailing edge of the flattened bag 120 as it enters the tape closure device 100. The action on the trigger 200 is preferably light such that the sensor 198 is capable of detecting the presence of thin bags 120. To keep the trigger 200 from overextending, counterweight 202 is positioned to deflect the movement of the trigger 200 beyond a preset point.
In operation, the brushes 192 flatten the open end 122 as the bag 120 moves downstream with the conveyor system 118. The flattened open end 122 of the bag 120 trips the sensor 198 to initiate a closure cycle. As the closure cycle begins, the bag 120 continues its downstream movement through the tape closure device 100 and the open end 122 is passed through the auxiliary brushes 194 to the drive rollers 196. The drive rollers 196 push the open end 122 into the gathering section 158 of the guide rail 144 where the bag neck 124 is formed.
Turning now to
The upper and lower gathering belts 206, 208 rotate in opposite directions and transport the bag from right to left through the tape closure device 100. Upper gathering belt 206 travels clockwise around the three upper belt pulleys 210, 212 and 214. Lower gathering belt travels counter-clockwise around lower belt pulleys 216, 218, 220 and 222. The path of upper gathering belt 206 is not affected by the presence of the lower gathering belt 208 or any of the lower belt pulleys 216, 218, 220 or 222. Changing the tension of upper gathering belt 206 has no significant effect on the ability of the belt drive system 204 to pull the bag 120 forward.
The lower belt pulleys 216, 218, 220 and 222 are placed such that the lower gathering belt 208 actually wraps around the upper gathering belt 206, which is itself wrapped around lower belt pulleys 216, 218, 220 and 222. Lower belt pulleys 216 and 220 are used to tension the lower gathering belt 208. The angle of belt wrap around lower belt pulleys 210 and 212 is small (approximately 10 degrees). However, it is this wrap angle that gives the belt drive system 204 its entire authority to pull the bag 120 forward into the closure application assembly 108. As tension is increased in the lower gathering belt 208, the lower gathering belt 208 presses harder against the upper gathering belt 206, but only in the two contact regions where the lower gathering belt 208 is wrapped around the upper gathering belt 206 on upper belt pulleys 210 and 214. Between the contact regions, the upper and lower gathering belts 206, 208 are relatively parallel and there is no contact pressure between them, so this section of the belts is not effective in pulling the bag 120 forward.
As a belt passes around a pulley, the belt becomes curved to match the shape of the pulley. When the belt is curved, that portion of the belt nearer the center of the pulley becomes compressed and moves relatively slowly, while the surface of the belt farthest from the pulley center gets stretched and moves at a slightly higher speed. Between the inner and outer surfaces of the belt, there is an internal surface that is being neither compressed nor stretched. This “neutral” surface travels at a speed that is intermediate between the speed of the inner and outer surfaces.
If the lower gathering belt 208 has a small amount of wrap around the upper gathering belt 206 on upper belt pulley 214, it is desirable to have the speed of the lower surface of upper gathering belt 206 be precisely the same as the speed of the upper surface of lower gathering belt 208, so that the tendency of the two belts to scuff against each other is eliminated. To satisfy this requirement, it is necessary for the lower surface of the lower gathering belt 208 be traveling at an even higher speed, as befits its larger radius from the center of upper belt pulley 214. Therefore, the neutral surface of the lower gathering belt 208 must be traveling at a greater speed than the neutral surface of the upper gathering belt 206.
Between upper belt pulleys 210 and 214, the lower gathering belt 208 is substantially straight, so the upper and lower surfaces of the two belts travel at the same speed. The same applies to the upper gathering belt 206. In this area, the linear speed of the lower gathering belt 208 will be significantly greater than that of the upper gathering belt 206. This does not contribute to a belt wear problem because the belts have essentially no contact pressure between them.
In the preferred embodiment, upper belt pulleys 212 and 214 are substantially the same size. That is, upper belt pulleys 212 and 214 preferably have the same pitch diameter. This is necessary so that the belts assume the same curvature around upper belt pulley 212 as they do around upper belt pulley 214. If lower belt pulley 216 and upper belt pulley 210 are driven at the same rotational speed, which is typical, then pulley lower belt pulley 216 must have a pitch diameter that is a few percent greater than upper belt pulleys 210 or 214. The percentage difference depends, among other things, upon the thickness of the belts being used. Although this system might work well for a particular set of belts, the variation in profile between different production belts from the same and different suppliers can cause undesirable belt wear to occur.
A particularly preferred embodiment of the belt drive system 204 allows the upper gathering belt 206 to be driven by its contact with the lower gathering belt 208. This ensures that the contact surfaces of the two belts are traveling at the same speed (assuming sufficient wrap angle and belt tension to drive the upper belt without slipping), regardless of the belt profile.
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In
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As shown in
The paper 226 connected along the inside of the first and second legs 232, 234 faciliates the opening of the closure 126 by prevening the first and second legs 232, 234 from sealing against one another. In a preferred embodiment, the tape 224 is a PVC film coated on one side with a rubber-based adhesive. Suitable tape is available from Decker Tape Products, Inc., of Fairfield, N.J. The paper 226 can be any paper that is capable of adhering to the adhesive side of the tape 224 and which can be easily torn to open the closure 126.
The closure application assembly 108 provides a non-stop, linear mechanism that provides a tight tape closure .126 as bags 120 pass through the tape closure device 100. The linear, constant movement of the bag 120 through the closure application assembly 108 enables the tape closure device 100 to be used for high-speed, high-volume operation. Furthermore, because the amount of tape and backing paper applied for each closure is variable and dependent upon the size of the neck 124 of the bag 20, the length of the first and second legs 232, 242 formed by the closure 126 can be easily controlled. Controlling the dimensions of the tape closure 126 facilitates the application of printed information on the closure 126.
In another aspect, preferred embodiments provide a method for applying a tape closure 126 around a bag neck 124. The method includes the steps of using the bag feed assembly 110 to deliver the open end 122 of the bag 120 into the closure application assembly 108, using the bag feed assembly 110 to gather the neck 124 of the bag 120 under the tape 224, using the plunger assembly 102 to push the neck 124 of the bag 120 into the bag stop 172 and contact member 142 to begin the formation of a loop 234, using the plunger assembly 102 to push the neck 124 under the contact member 142 to further define the loop 234 around the bag neck 124, using the plunger assembly 102 to push the bag neck 124 beyond the contact member 142 to allow the contact member 142 to fall against the contact section 160 of the guide rail 144 to close the loop 234 and using the plunger assembly 102 to push the bag neck 124 into the cutting member 150 to cause the cutting member 150 to rotate and sever the trailing portion of the tape 224 to complete the formation of the bag closure 226.
It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and functions of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms expressed herein and within the appended claims. It will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other systems without departing from the scope and spirit of the present invention.
This application claims the benefit of United States Provisional Patent Application Ser. No. 60/597,139 filed Nov. 11, 2005, entitled “Apparatus and Method for Automated Tape Closure,” the disclosure of which is hereby incorporated.
Number | Date | Country | |
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60597139 | Nov 2005 | US |