Patent Publication Number: US-2002000361-A1

Title: Line pressure control device for packaging line

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates generally to conveyor systems and more particularly to an assembly for use in conveyor systems to control the line pressure so as to permit effective further downstream processing on a packaging line.  
       BACKGROUND OF THE INVENTION  
       [0002] The packaging process has evolved into a highly automated processing system where products are manufactured and then delivered to a packaging station. It is known in the packaging field to provide a continuous feed of articles, such as food items including bottles, spaced at precise intervals in order to most effectively accommodate interaction with a downstream processing station of the packaging line, such as a slitter/sealer which serves to complete the packaging processing by cutting package flaps, packaging, orienting, or folding the flaps and adhering the flaps to the package carton itself. However, an associated disadvantage of many prior art devices is that the devices often have a non-uniform supply of product from upstream equipment. For example, the upstream equipment provides surges of product from time to time with a greater number of products being sent downstream.  
       [0003] One of the associated disadvantages of these conventional devices is that the line pressure of the system is not maintained at optimum operating conditions but rather is too excessive or is too low resulting in less than optimum operating conditions. Therefore, either too many package cartons will stack up against one another resulting in increasing line pressure or too few package cartons will be transferred downstream resulting in low line pressure and inefficient operating conditions or carton crushing. In typical conventional devices, one or more belt mechanisms are periodically stopped so as to curtail the advancement of the package cartons and thus reduce line pressure in the system. Once the line pressure is reduced, the belt mechanisms are started again and the package cartons are advanced downstream. This process may be repeated a number of times during normal operation in an effort to maintain the desired line pressure in the system. While this process may serve to reduce line pressure, it is not an especially efficient manner of reducing the line pressure because various working components are required to be placed off line and requires supervision. Also, large gaps or spaces are created in the packaging line when the belt mechanisms are stopped.  
       [0004] It is therefore desirable to provide an automated process in which the line pressure of the system is continuously monitored and maintained at a predetermined level which permits the system to operate at an efficient line pressure.  
       SUMMARY OF THE INVENTION  
       [0005] The above discussed and other drawbacks and deficiencies are overcome or alleviated by a line pressure control device for use in a packaging line. According to the present invention, the line pressure of the system is maintained by monitoring the product package cartons as they are transferred from a first belt to a second belt as the cartons continue to be advanced in a downstream direction. More specifically, the present invention utilizes a sensing mechanism which serves to detect the speed of the package carton as it passes by a sensor which forms a part of the sensing mechanism. The sensing mechanism also monitors the distance between next adjacent package cartons as they travel by the sensor in a downstream direction.  
       [0006] The present system is designed such that the first belt (high friction) is powered by a first motor and the second belt (low friction) is powered by a second motor. The first belt and the first motor are interfaced with a controller which communicates with the sensing mechanism so that information sensed by the sensor is provided to the programmable controller. The controller permits a user to input specific operating conditions, including but not limited to, the length of the package carton, the processing speeds of downstream devices, and the desired gap between next adjacent package cartons. Once the user selects the desired gap based on a number of considerations enumerated herein later, the present system is designed so that the gap between next adjacent package cartons is maintained and this corresponds into maintaining the line pressure of the system.  
       [0007] The sensing mechanism preferably comprises a photoeye device and an opposing reflector and is designed to detect the time period for which the sensor beam is obstructed by the passing package carton and the time period for which the sensor beam is reflected back to the sensor, indicating that there are is no package carton passing through the sensor beam (this corresponds to a gap between package cartons). Because the programmable controller and the sensing mechanism communicate with each other, the controller includes a comparator type device which compares the sensed information from the sensing mechanism with stored optimum operating conditions. The line pressure is maintained at the desired level by adjusting the speed of the first belt so that the package cartons are transferred to the second belt with the gap therebetween being kept in tact. For example, if the speed of one of the downstream devices is reduced and less package cartons are being processed, the package cartons will begin to stack against one another along the downstream belts and this leads to increased line pressure. The present invention maintains the optimum line pressure under varying operating conditions by adjusting the speed at which the package cartons are delivered to the downstream devices along the downstream belts. For example, when the speed of the downstream device is reduced, the gap between the package cartons is maintained by reducing the speed of the first belt so as maintain the desired gap distance between package cartons. Once the downstream device increases its speed again, the sensing mechanism will detect that the line pressure is dropping and will simultaneously increase the speed of the first belt so that the programmed gap is maintained and the line pressure is likewise maintained at an optimum level. These advantageous features are possible because of the interfacing between the programmable controller, the sensing mechanism, and the first belt/first motor.  
       [0008] The above-discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009] Referring to the Figures wherein like elements are numbered alike in the several Figures:  
     [0010]FIG. 1 is a simple schematic diagram of a conveyor system embodying the present invention;  
     [0011]FIG. 2 is a top plan view of a portion of a conveyor system according to one embodiment of the present invention; and  
     [0012]FIG. 3 is a side elevational view of the conveyor system of FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0013] Referring first to FIG. 1 in which a simple schematic diagram illustrating the present invention is provided. According to the present invention, a conveyor system  10  is provided and can be used in a variety of applications and is particularly useful in the food or beverage packaging industries. The conveyor system  10  generally includes an upstream device  12  which may comprise any number of conventional upstream devices which are used to process the product before it is delivered to other upstream or downstream devices for further processing. It will be understood that the upstream device  12  may comprise more than one upstream device and/or transfer belts which link the upstream devices to one another. According to one embodiment of the present invention, the upstream device  12  is designed to feed products into package cartons which are then delivered downstream for further processing such that the products are delivered downstream in the package carton. The upstream device  12  is linked to an upstream belt assembly  14  which is designed to transport the package cartons holding the products to a line pressure control device and belt assembly according to the present invention and generally indicated at  16 . As will be described in greater detail hereinafter, the line pressure control device and belt assembly  16  receives the package cartons from the upstream belt assembly  14  and maintains optimum spacing of the package cartons along the assembly  16  so as to maintain optimum line pressure. The assembly  16  communicates at another end with a main feed belt assembly  18  which transports the package cartons  100  from the assembly  16  to one or more downstream devices, generally indicated at  20  and described in greater detail hereinafter. It will be appreciated that the one or more downstream devices  20  may also include any number of belt assemblies (not shown) which are designed to transport the package cartons to additional processing stations. It is further understood that the configuration shown in FIG. 1 is merely exemplary in nature and that any number of configurations may be used so long as the line pressure control device and belt assembly  16  of the present invention is provided in the conveyor system  10 .  
     [0014] Now referring to FIGS.  1 - 3  which illustrate a section of the conveyor system  10  shown in FIG. 1. FIGS. 2 and 3 illustrate the relationship between the line pressure control device and belt assembly  16  and the main feed belt assembly  18 . According to the present invention, the line pressure control device and belt assembly  16  includes a pair of first and second rotatable members  30 ,  32  which are driven by a motor  34 . The motor  34  may comprise any number of suitable motors and for example, may comprise a servo motor, a stepper, a DC motor, a variable speed AC motor, hydraulic motor, pneumatic motor, or the like. A first belt  40  is disposed about the first and second rotatable members  30 ,  32  and provides a first conveying surface. Preferably, the first belt  40  is snugly fit about the first and second rotatable members  30 ,  32  so that a firm conveying surface is provided. The first belt  40  preferably comprises a high friction belt which prevents the package cartons  100  from excessive movement or slippage on the first belt  40  as the package cartons  100  are received from the upstream belt assembly and transported along the belt  40  to the main feed belt assembly  18 . For example, one suitable first belt  40  is formed of a polymeric material having high friction characteristics and also includes a plurality of ribs (not shown) which provide a better engagement and retention surface for the package carton  100  during transportation thereover.  
     [0015] At a first end  42  of the assembly  16 , the first belt  40  receives the package cartons  100  from the upstream belt assembly and a second end  44  of the assembly  16  comprises a transfer section where the package cartons  100  are transferred from the assembly  16  to the main feed belt assembly  18 . The main feed belt assembly  18  also includes first and second rotatable members  50 ,  52  which serve to support a second belt  60  which provides a second conveyor surface. The main feed belt assembly  18  and more specifically, the second belt  60  thereof, is preferably driven by a separate second motor, generally indicated at  62 . Alternatively, the second belt can be powered, partially or wholly, by a power take-off from a subsequent machine. According to the present invention, the second belt  60  preferably comprises a low friction support surface which permits the package cartons  100  to continue forward feeding along a surface of the second belt  60  and slip along the surface until the appropriate desired relationship is obtained between next adjacent package cartons  100 . Any number of suitable low friction belts may be used as second belt  60 .  
     [0016] The present invention includes a sensing mechanism  70  which is designed to sense a number of parameter including the distance between next adjacent package carton  100  as they travel along the first belt  40  and are transferred to the second belt  60  of the main feed belt assembly  18 . The sensing mechanism  70  includes a sensor bracket  72  which supports a sensor  74  with the sensor  74  being moveable along a length of the sensor bracket  72  so that the sensor  74  may be positioned at a desired location. As best shown in FIG. 2, the sensor bracket  72  is located at a first side  76  of the main feed belt assembly  18  and extends generally parallel to the second belt  60 . The sensor  74  is thus positioned adjacent to one edge of the moving second belt  60 . In the illustrated embodiment, the sensor  74  and the sensor bracket  72  are disposed proximate to the motor  34  which serves to control the speed of the first belt  40 . The sensor  74  may comprise any number of sensors so long as sensor  74  is capable of sensing the distance, if any, between next adjacent package cartons  100  as they are fed from the assembly  16  to the main feed belt assembly  18 . Possible sensors include photoelectric sensors, ultrasonic sensors proximity sensors, cameras (video, line scanning, and the like), electronic switches, and the like, as well as combinations comprising at least one of the foregoing. In the embodiment with the photoelectric sensor, the sensing mechanism  70  further includes a reflector  80  adjustably disposed within a reflector bracket  82 . The reflector bracket  82  is thus located on a second side  84  of the main feed assembly  18  and more specifically is located across from the sensor bracket  72  adjacent to the second belt  60 . The reflector bracket  82  extends parallel to both the second belt  60  and the sensor bracket  72 . Preferably, the lengths of the reflector bracket  82  and the sensor bracket  72  are similar so that the reflector  80  may be positioned directly across from the sensor  74  and the reflector  80  may be adjusted within the reflector bracket  82  so as to be directly across from the sensor  74  whenever the sensor  74  is adjusted within the sensor bracket  72 . As is known in the art, the sensor  74  emits a light beam and if no object is disposed between the sensor  74  and the reflector  80 , the beam will strike the reflector  80  and will return to the sensor  74 . When the sensor  74  detects a reflected beam, the sensor  74  generates a first signal which is indicative of no object being sensed between the sensor  74  and the reflector  80 . When an object, e.g., one of the package cartons  100  passes between the sensor  74  and the reflector  80 , the beam is broken and the sensor  74  does not receive the reflected beam from the reflector  80 . When this occurs, the sensor  74  calculates the amount of time that the beam is broken until the package carton  100  continues traveling along the second belt  60  and clears the beam resulting in the beam traveling across and contacting the reflector  80  which reflects the beam back to the sensor  74 .  
     [0017] The sensing mechanism  70  communicates with a programmable controller  90  which is connected to and communicates with at least the motor  34 . The programmable controller  90  controls the speed that the motor  34  is run at and more specifically, speed at which the first belt  40  is run. The programmable controller  90  is preferably designed so that the user may input selected parameters which govern how the line pressure control device and belt assembly  16  should be operated. For example, the user will preferably input the type of product being used, e.g., 24-12 ounce bottles; the length of the package carton  100 ; and the preselected optimum speed of the main feed belt assembly  18  in terms of the number of package cartons 100 per minute which pass along the main feed belt assembly  18  to the downstream device  20 . Possible controllers include an electronic controller, computer, photoeye, microprocessor, programmable logic controller, and the like, as well as combinations thereof.  
     [0018] Typically, the main feed belt assembly  16  communicates with a timing device  95  which forms a part of the downstream device  20 . The timing device  95  includes a number of lugs (not shown) which are designed to hold one individual package carton  100  being fed from the main feed belt assembly  18  to the one or more downstream devices  20 , such as a slitter machine which serves to further process the package cartons  100  as for example by cutting flaps then packaging the flaps and/or adhering the flaps to the other structural parts of the package cartons  100  so that the package cartons  100  is fully enclosed and ready for further processing. The timing device  95  has an associated speed which is expressed in terms of number of cases per unit of time, e.g., cases per minute. The timing device  95  is preferably operated by a motor  97 .  
     [0019] As previously mentioned, the programmable controller  90  communicates with the sensing mechanism  70  so that the operating conditions sensed by the sensor  74  are relayed to programmable controller  90 . The programmable controller  90  includes a comparator type device which is designed to compare the sensed operating conditions with stored optimum operating conditions. As the package cartons  100  are transferred from the line pressure control device and belt assembly  16  to the main feed belt assembly  18 , the package cartons  100  begin to abut one another because individual package cartons  100  are fed into the timing device  95  and the lugs thereof prevent the package cartons  100  from continued travel to downstream locations until the timing device  95  retracts the lugs and releases the package cartons  100  to downstream locations. As previously mentioned, the package carton  100  typically travels from the timing device  95  to the downstream device  20  by means of another conveyor system or the like. The timing device  95  thus has an associated speed which is often expressed in terms of cases per minute. In other words, the timing device  95  will only process a certain number of cases in a given time, such as one minute, and therefore, if the package cartons  100  are delivered to the timing device  95  at a greater rate than the processing speed of the timing device  95 , the package cartons  100  begin to stack up against one another along one or more upstream conveyor belt assemblies which in this exemplary embodiment is the main feed belt assembly  18 .  
     [0020] By inputting the length of the package carton  100  and the speed of the timing device  95 , the programmable controller  90  calculates the time period which it should take for one package carton  100  to pass through the sensing mechanism  70 . For example, if the length of the package carton  100  is 12 inches and the speed of the timing device is 60 cases per minute, one particular package carton  100  travels 60 feet per minute and therefore, it will take one (1) second for one package carton  100  to travel through the sensing mechanism  70 . In other words, under desired optimum operating conditions, one package carton  100  being transferred onto the second belt  60  will obstruct the beam of the sensor  74  for one (1) second as it passes through the sensor beam. Thus, the sensor  74  should not see a reflected beam for 1 second and if the sensor  74  does not see a reflected beam for greater than or less than about 1 second, then the speed at which the package carton  100  is traveling is not the optimum speed and should either be increased or decreased. The sensing mechanism  70  and the sensor  74  also determines the reflection time of sensor  74 . In other words, the sensor  74  will calculate the time period in which the beam is reflected back to the sensor  74 . Because the user inputs into the programmable controller  90  the desired gap in terms of length between next adjacent package carton  100 , the reflection time period can be determined in view of the length of the package carton  100  and the speed of the timing device  95  and second belt  60 . For example, if the operating conditions are the above-mentioned conditions (package length is 12 inches and speed is 60 cases per minute), then under normal, optimum operating conditions, a programmed 4 inch gap will correspond to a reflection time period of 0.333 seconds. If the sensing mechanism  70  measures that the reflection time period is less than or greater than 0.33 seconds than the gap between next adjacent package cartons  100  is either too great or too small. The optimum gap to maintain between next adjacent package cartons  100  is selected and programmed into controller  90  according to a number of parameters including but not limited to product type, the specific layout of the line, and the overall speed of the line. The optimum desired gap for any given application does not vary according to the speed of the timing device  95  and therefore, the programmed gap should be maintained irrespective of the current speed of the timing device  95 .  
     [0021] The speed of the timing device  95  will vary depending upon any number of operating conditions and other external conditions and events. For example, if there is a delay in the operation of the downstream device  20  or if one of the package carton  100  becomes misted as it travels from the main feed belt assembly  18  to one or more of the downstream devices  20 , the timing device  95  retains each package carton  100  for a greater period of time so as not to release an excessive amount of package carton  100  to the one or more downstream devices  20 . It will be appreciated that if the package cartons  100  are continuously fed to the timing device  95  at the same rate as before, the package cartons  100  will begin to stack against each other along the main feed belt assembly  18 . This creates what is known as line pressure which is caused by the package cartons  100  stacking up against each other with little or no forward movement being made by the package cartons  100 . As the package cartons  100  stack up against each other along the length of the second belt  60 , the second belt  60  continues to be driven by the second motor  62 . The force necessary to continue to drive the second belt  60  increases as the package cartons  100  stack against each other along the moving second belt  60  and this results in increasing friction between the package cartons  100  and the second belt  60 . This is represented as line pressure within the conveyor system  10 .  
     [0022] For example, if the speed of the second belt  60  (the low friction belt) slows down from 60 cases per minute to 30 cases per minute, then the 12 inch package carton  100  should pass the sensor  74  in 2 seconds under normal operating conditions. If the package carton  100  passes the sensor  74  in a time period either greater than or less than 2 seconds, then the optimum line pressure is not being achieved and either not enough package cartons  100  are being transferred to the timing device  95  or too many package cartons  100  are being transferred to the timing device  95  resulting in a line pressure build-up. For example, if one package carton  100  passes the sensor  74  in 1.75 seconds and not 2 seconds, the desired 4 inch gap is not being maintained and there is a reduction in line pressure. In contrast, if the package carton  100  took too long to pass the sensor  74 , the gap is too small and should be increased. As will be described in greater detail hereinafter, the present invention is designed to compensate for this reduction in line pressure by adjusting the operating conditions of the system  10 .  
     [0023] According to the present invention, the assembly  16  permits the conveyor system  10  to operate at optimum line pressures and maintain these optimum line pressures by monitoring and making any necessary adjustments relative to the speed of the first belt  40  so as to maintain the programmed gap between next adjacent package carton  100  and therefore maintain the desired optimum line pressure. Because the first belt  40  is driven by the first motor  34  which is independent of the motors  62 ,  97  which drive the second belt  60  and the timing device  95 , the speed of the first belt  40  may be controlled by varying the speed of the motor  34 . The programmable controller  90  receives information from the sensing mechanism  70  and because the programmable controller  90  communicates with the motor  34 , the programmable controller  90  will direct the motor  34  to either increase or decrease its speed depending upon the observed operating conditions. This causes the speed of the first belt  40  to be accordingly adjusted. By carefully monitoring the time it takes for each package carton  100  to pass the sensor  74  and the reflection time period between next adjacent package cartons  100  (which corresponds to the gap), the present assembly  10  maintains optimum line pressure by adjusting the speed at which the package cartons  100  are transferred from the first belt  40  to the second belt  60 . By maintaining the desired gap between next adjacent package cartons  100 , the line pressure is controlled and maintained at the optimum rate.  
     [0024] It should be understood that although a specific example of the present invention has been provided, it should be understood that other embodiments are possible, including, but not limited to, the use of multiple equipment, e.g., additional sensors, belts, controllers, etc.  
     [0025] In contrast with the fully automated assembly  10  of the present invention, conventional assemblies typically maintain line pressure by having to start and stop one or more line belts in an effort to regulate and control the line pressure. For example, if the line pressure increases because package cartons  100  are stacking against one another a long the length of one or more line belts, an operator will shut down for a period of time one or more other line belts so as to permit one or more of the package cartons  100  to be processed by the timing device.  
     [0026] While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.