Patent Application
20120176490
This disclosure generally relates to the use of interleaving materials upon stacked sheets, and more particularly relates to the application and/or analysis of interleaving materials upon glass sheets prior to stacking for transportation and/or storage.
Glass sheets or panels (sometimes referred to as lites in the industry) are commonly stacked together for transportation and/or storage following production. For example, lites may be stacked in a variety of pack, box, pallet or rack configurations. While stacking multiple lites provides a convenient packaging configuration for transportation and/or storage, the close proximity and fragile nature of the lites can lead to scratching, marring, cracking, and/or breaking of the lites due to relative movement and/or collisions between adjacent lites. In addition, it is well known that water can slowly react with glass over time, leading to staining and corrosion of the glass when subject to prolonged exposure to even small amounts of water. For example, over time water reacts with soda-lime-silica glass and becomes highly alkaline and corrosive. Thus staining is a concern after lites are packaged and shipped because transportation and storage conditions cannot always be controlled.
To address these concerns, glass manufacturers commonly use a variety of interleaving materials between the surfaces of stacked glass sheets. The interleaving materials often include acid compounds to neutralize highly alkaline water and reduce stain damage to the sheets. The interleaving materials also provide physical separation of the glass sheet surfaces to minimize physical damage. A common interleaving material comprises polymethylmethacrylate (PMMA) beads for physical separation and adipic acid for neutralizing alkaline water.
Lite production facilities can use a variety of types of applicators to apply the interleaving materials to the surfaces of the glass sheets as the sheets advance along a conveyor. For example, interleaving materials may be mechanically dispersed in particulate form using a hopper. In another application, a powdered interleaving material is dispersed in an aqueous composition, such as in atomized water or in a conventional liquid application technique. In some cases the interleaving material may inherently provide a stain-inhibiting acid, while in some cases the interleaving material may also include individual stain-inhibiting acid materials and physical separation beads, which may be applied separately or as a heterogeneous mixture.
In addition to regularly inspecting lites for chips, scratches, and other deformities before stacking and packing, glass manufacturers may also from time to time inspect the interleaving material upon the glass sheets to determine whether the material has been adequately applied according to a desired standard. One common method of inspecting the interleaving material involves a worker removing a lite sample from the production line and inspecting the layer of interleaving material with a microscope.
Embodiments of the invention generally relate to the use of interleaving materials upon stacked sheets, and more particularly provide systems and methods for analyzing the interleaving material after it is applied to the sheets. In some embodiments, feedback is provided for adjusting subsequent application of the interleaving material based on the analysis.
According to a first aspect of the invention, a system for analyzing interleaving material on sheets of material to be stacked is provided. The system includes a cross-conveyor support frame, a camera system coupled to the support frame, and a control module coupled to the camera system. The cross-conveyor support frame is adapted to span across a conveyor that advances sheets of material to be stacked. The sheets of material have an interleaving material applied to at least one surface. The camera system is adapted to capture images of the interleaving material at multiple positions along a width of the conveyor. The control module includes a processor programmed with instructions for analyzing the interleaving material. In some cases the analyzing includes receiving the images of the interleaving material from the camera system and assessing coverage of the interleaving material upon the sheets of material from the images. The analyzing optionally includes one or more of determining adjustments for application of the interleaving material based on the assessed coverage and communicating the adjustments to an interleaving material applicator.
According to another aspect of the invention, a system is provided for applying an interleaving material to sheets of material that are to be stacked. The system includes a conveyor that advances sheets of material, e.g., through a portion of a production line. The system also includes an interleaving material applicator positioned proximate to the conveyor. The interleaving material applicator applies an interleaving material to the sheets of material as they advance along the conveyor. A cross-conveyor support frame is provided spanning across the conveyor, and a camera system is coupled to the support frame. The camera system is adapted to capture images of the interleaving material at multiple positions along a width of the conveyor as the sheets of material advance along the conveyor. The system also includes a control module coupled to the camera system and the interleaving material applicator. The control module includes a processor programmed with instructions for analyzing the interleaving material. In some cases the analyzing includes receiving the images of the interleaving material from the camera system and assessing coverage of the interleaving material upon the sheets of material from the images. The analyzing optionally includes one or more of determining adjustments for application of the interleaving material based on the assessed coverage and communicating the adjustments to an interleaving material applicator.
According to another aspect of the invention, a system is provided for analyzing interleaving material on sheets of material to be stacked. The system includes a cross-conveyor support frame adapted to span across a conveyor advancing sheets of material to be stacked. The sheets of material typically have an interleaving material applied to at least one surface of the sheets of material. The system also includes a camera system coupled to the support frame and a control module coupled to the camera system. The camera system includes a moving camera head that moves along the support frame to multiple positions along a width of the conveyor in order to capture images of the interleaving material at the multiple positions. The camera system also includes at least one light for illuminating the sheets of material and the interleaving material during image capture. The control module coupled to the camera system includes a processor programmed with instructions for analyzing the interleaving material from the images captured by the camera. The analysis includes flashing the at least one light, actuating the camera system to capture illuminated images of the interleaving material during the flashing, receiving the illuminated images of the interleaving material from the camera system, and assessing from the illuminated images coverage of each of at least two types of particles in the interleaving material upon the sheets of material.
According to another aspect of the invention, a method is provided for analyzing interleaving material on sheets of material to be stacked. The method includes moving a camera head along a support frame across a conveyor advancing sheets of material to be stacked. The sheets of material have an interleaving material applied to at least one surface of the sheets of material. The method also includes capturing with the camera head images of the interleaving material at multiple positions along a width of the conveyor and assessing coverage of the interleaving material upon the sheets of material from the images. Adjustments for application of the interleaving material are optionally determined based on the assessed coverage and communicated to an interleaving material applicator.
Some embodiments of the invention can provide one or more of the following features and/or advantages. In some cases, systems and/or methods provide real-time analysis of interleaving material on sheets advancing along a conveyor within a production line without the need to remove a sheet sample for manual inspection. The analysis can occur during a temporary stop of the production line, although in some cases the analysis can be performed in an on-line configuration without the need to stop production.
Among other features, the analysis can provide measurements of one or more of the number of particles, area coverage, total mass, and/or density of the interleaving material. In some cases the analysis can distinguish between different types of particles within the interleaving material and provide measurements corresponding to each different type of particle. This breakdown can be helpful for troubleshooting problems in the application of interleaving materials containing, for example, both separation beads and acid particles.
In some cases, analysis and/or measurements are displayed or made otherwise available to manufacturing personnel. Actions for addressing any perceived application problems can then be determined and applied. In some embodiments the control module of the system determines adjustments for applying the interleaving material based on the analysis. Optionally, the analysis system is communicatively coupled with one or more parts of a production line, such as an interleaving material applicator. The system provides a feedback control or communication to the plant, thus providing a closed loop control of interleaving material application.
Some embodiments provide one or more analyses of the application of interleaving material. For example, an analysis may provide the average density of the interleaving material across an entire sheet of material, thus providing feedback on the overall level of interleaving material being applied to the sheet. In another example, an analysis determines a profile of the density of interleaving material across the width of a sheet of material, thus enabling specific problem areas to be targeted quickly and efficiently.
Thus, some embodiments can monitor, report, and/or correct for too little or too much interleaving material on the entire sheet as a whole, or at specific points along the width of a sheet of material. Monitoring and correcting for too little interleaving material being applied can help ensure that a sufficient level of interleaving material is applied to the sheets, thus leading to a reduction of glass quality rejections based on stained glass. In addition, ensuring adequate material coverage can reduce motion scratches during shipping and reduce the likelihood that adjacent sheets may adhere together. Monitoring and correcting for too much interleaving material is also helpful in some cases. For example, ensuring optimum coverage of the interleaving material may allow for a reduction in the amount of interleaving material being applied, thus generating a cost saving. In addition, excess interleaving material can make washing the glass more difficult for downstream processors who must wash the glass before performing value added work, such as coating applications. Inadequate washing may leave an interleaving residue that detrimentally affects the subsequent value added work. In addition, reducing the overall amount of interleaving material used can decrease the excess interleaving material that tends to accumulate in and around the area of application, e.g., the plant conveyor and/or other equipment, which may also decrease the need for equipment cleaning and/or the risk of slipping on the interleaving material.
These and various other features and advantages will be apparent from a reading of the following detailed description.
The following drawings are illustrative of particular embodiments of the present invention and therefore do not limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description. Embodiments of the present invention will hereinafter be described in conjunction with the appended drawings, wherein like numerals denote like elements.
The following detailed description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the following description provides some practical illustrations for implementing exemplary embodiments of the present invention. Examples of constructions, materials, dimensions, and manufacturing processes are provided for selected elements, and all other elements employ that which is known to those of ordinary skill in the field of the invention. Those skilled in the art will recognize that many of the noted examples have a variety of suitable alternatives.
Although embodiments of the invention are described herein as analyzing interleaving material upon glass sheets, it is contemplated that embodiments of the invention may be useful for analyzing and/or applying interleaving materials to other types of sheet material, and the invention is not limited in this regard.
The roller conveyor 30 conveys the caps in a direction 31 toward the snap roll assembly 32, where the caps are received and subsequently snapped therein via known glass snapping mechanisms along the machine direction scores to produce lites (shown in
Following the production, the lites are introduced into a chip blower assembly 36, which functions to clean/remove glass chips/fragments from the surface of the lites after the snapping process. The chip blower assembly 36 possesses two blowers 38 and 39 that are opposingly mounted on the sides of a V-shaped tube 40. In some cases the V-shaped tube 40 is frontally formed as an air knife to channel air generated by blowers 38 and 39 onto the lites.
The chip blower assembly 36 is further positioned over an acceleration conveyor 42. Thus, while the lites are subjected to the chip blower assembly 36, they are also simultaneously conveyed over acceleration conveyor 42, which accelerates the lites and thus create gaps between each lite for facilitation of the stacking process of lites. The acceleration conveyor 42 may possess any suitable dimension and speed in accord with industry standards and desires. In some cases the acceleration conveyor 42 is rotatable via conventional drive shafts, timing belts and motors as known within the art.
Once past acceleration conveyor 42, the lites pass by an interleaving material applicator 44, which applies, disperses, and/or distributes an interleaving material upon the lites. The interleaving material applicator 44 can incorporate any known techniques for applying interleaving materials. In some cases the applicator 44 mechanically disperses a particulate form of interleaving material (e.g., synthetic polymeric beads or natural porous cellulose materials such as wood flour) using, for example, a hopper. In some cases, the applicator 44 disperses an aqueous solution of a powdered interleaving material, such as in atomized water or in a conventional liquid application technique such as drip, flow, roll coating, conventional spray, reciprocating spray, rotary spray, or curtain spray. In some cases the interleaving material includes a mixture of physical separation beads and stain-inhibiting acid particles containing, e.g., boric acid, citric acid or tartaric acid.
After application of the interleaving material, the lites are introduced onto an inspection conveyor 50. According to some embodiments of the invention, the inspection conveyor 50 provides inspection of one or more characteristics of the lites. For example, in some embodiments a camera system 52 is coupled to a support frame 54 spanning the conveyor 30. The camera system 52 allows for capturing multiple images of the lites, thus enabling ready inspection of the lites via the images. As will be further discussed herein, in some cases the camera system 52 is part of an analysis system which allows for the analysis of interleaving material on the lites. Of course the camera system 52 can allow for inspection of other aspects of the lites, and/or one or more additional camera systems may be provided for dedicated inspection of other aspects of the lites. For example, in some cases the lites are inspected with a camera system in order to remove damaged and/or defective lites from the conveyor 30 prior to packaging. The inspection conveyor 50 may possess any suitable dimension and speed in accord with industry standards and desires. The inspection conveyor 50 is rotatable via conventional drive shafts, timing belts and motors as known within the art.
Following application of the interleaving material and inspection on the inspection conveyor 50, the lites may be advanced to a stacker (e.g., a single or double tipple assembly) 60, which permits the rejection of damaged/defective lites. In some cases the rejected lites are then removed and crushed via an infeed conveyor as known in the art. The stacker 60 may possess any suitable dimension and speed in accord with industry standards and desires. In some embodiments, the stacker 60 is rotatable via conventional drive shafts, timing belts and motors as known within the art.
Upon leaving the stacker 60, the lites are introduced onto an alignment conveyor 70 that aligns the outer edge of each lite. In some cases the first half of the alignment conveyor 70 is designed as a chevron conveyor, thus allowing the lites to be pushed to outer tank tracks 72 and 74 in this double stream arrangement. A bar 76 assists in the separation of the lites into two streams of lites for eventual introduction into separate rotating elements of stacking apparatuses 80 for subsequent stacking of the lites, as is known in the art. The alignment conveyor 70 may possess any suitable dimension and speed in accord with industry standards and desires. The alignment conveyor 70 is preferably rotatable via conventional drive shafts, timing belts and motors as known within the art.
It should be appreciated that
The interleaving material is applied to the lites 202 by an interleaving material applicator 206. The interleaving material can be any suitable material known in the art. In some cases the applicator 206 may apply a mixture of synthetic polymeric beads (e.g., poly(methyl methacrylate) (PMMA)) or natural porous cellulose materials such as wood flour, along with particles of a stain-inhibiting acid such as boric acid, citric acid, tartaric acid, or adipic acid. For example, one mixture of interleaving material useful for separating sheets of material contains about 65% synthetic polymeric beads and about 35% acid particles by mass.
The applicator 206 may apply the interleaving material using any known technique, such as mechanical dispersion, atomization, and/or conventional liquid application techniques. In some cases the applicator 206 includes a metering device that distributes interleaving material using vibration metering. The metering device is fed by a hopper or reservoir of powdered interleaving material and in turn feeds one or more powder hoses and nozzles. The amount of interleaving material distributed by the metering device can be controlled by adjusting the device's “metering gap” and/or by changing the intensity of the device's vibrations. In some cases a metering device can distribute interleaving material to multiple nozzles through a common powder hose and a nozzle pipe or spray bar positioned over the conveyor. Examples of some possible metering devices are those available from GRAFIX USA LP, Bolingbrook, Ill.
According to some embodiments of the invention, the system 200 includes a cross-conveyor support frame 210, a camera system 212 coupled to the support frame 210, and a control module 214 coupled to the camera system 212. The system 200 also includes the interleaving material applicator 206, which is communicatively coupled with the control module 214, thus optionally allowing the control module 214 to adjust application of the interleaving material based on the analysis. However, in some embodiments the applicator 206 may not be considered a part of the analysis system 200. For example, in some cases the applicator 206 may not communicate with the control module 214 to adjust material dispersion and the control module may only provide functions such as analysis of the interleaving material and subsequent reporting.
The cross-conveyor support frame 210 can be provided in any suitable form capable of positioning the camera system 212 within the desired proximity to the lites 202 and the conveyor 204. For example, the support frame 210 may be provided as a gantry suspended above the conveyor 204 with vertical support members attaching the gantry to a support surface below, to the side, and/or above the conveyor 204. In the some embodiments the support frame 210 may alternatively extend below the conveyor 204, thus allowing the attached camera system 212 to image the lites 202 from below the conveyor 204. According to some embodiments, the support frame 210 at least spans the width 216 of the conveyor 204 and the width 217 of the lites 202.
The camera system 212 includes one or more cameras capable of capturing images of the lites 202 and the interleaving material applied to the lites 202. For example, the camera system may include one or more digital still cameras, although video cameras are also contemplated. In the embodiment shown in
Any suitable movement mechanism 222 can be used to move the camera head 220 along the support frame 210. For example, the camera head 220 may roll or slide along the support frame 210 with the assistance of motor driven wheels, trolleys, sliders, etc. The linear speed of the head can vary, depending for example, on whether multiple images are to be captured across the width of a single lite. In one embodiment the camera head 220 has a cross-conveyor speed of about 200 mm/s. The movement mechanism 222 may move the camera head 220 through a continuous range of multiple positions or a series of multiple discrete positions along the support frame. In some cases control of the movement mechanism 222 is provided by the control module 214, which may be communicatively coupled to the movement mechanism 222 via a wired or wireless connection. Other known cables, mounts, adjusters, motors and/or drives may also be incorporated in the design of the movement mechanism as desired.
Turning to
The camera 402 may be chosen to meet desired performance characteristics based on factors such as the speed of the conveyor, the speed of cross-conveyor movement if any, the size of the particles within the interleaving material, the desired imaging resolution, the physical configuration of the camera system and support frame, and other such factors. In one embodiment a camera having a frame rate of about 12 frames per second is used in conjunction with a conveyor belt traveling about 120 meters per minute.
Two potential camera configurations useful for interleaving materials of different size are shown in Table 1 below:
In some cases different fields of view (and thus different pixel sizes) can be obtained by changing the height of the camera with respect to the lites. In one embodiment the camera is mounted above the conveyor with one or more extension tubes of different lengths. In one example, a first extension tube provides the camera system with 33 millimeters of extension to provide a first field of view. A second extension tube provides the camera system with an additional 6 millimeters of extension to reduce the field of view for smaller powder particles. In addition, in some cases more or less resolution may be required, which may affect the choice of camera configuration. For example, in some cases it may not be necessary to distinguish between different types of interleaving particles, and thus a larger pixel size and larger field of view can be used.
Returning to
According to some embodiments, the processor is programmed with instructions (e.g., coded in hardware, firmware, and/or software) for controlling the camera system 212 and the movement mechanism 222, as well as analyzing images received from the camera system 212 to assess the interleaving material upon the sheets 202. The processor may be further programmed to receive the images from the camera system 212 and analyze the images in order to characterize the interleaving material upon the lites 202.
For example, in some embodiments the processor is programmed to move the camera head 220 to multiple positions along the support frame 210 (and thus along the width of the conveyor) and actuate the camera to capture images of different portions of the lites 202 and interleaving material passing by the camera. The image capture rate is preferably determined based on the desired tracking plan (e.g., the number of images requested per sheet), the frame rate of the camera, and the speed of the conveyor. In the event that the tracking plan calls for more images per sheet than is possible given the frame rate and conveyor speed, the processor may actuate the camera to capture the desired number of images across multiple sheets. As an example, a tracking plan may call for an image every 4 inches along a sheet. If this rate is incompatible with the camera frame rate and conveyor speed, the processor may be programmed to break up the tracking plan to instead capture the desired images across two sheets. Thus, the camera system may capture an image every 8 inches on a first sheet (e.g., at 4 inches, 12 inches, 20 inches, etc.), and then capture an alternating image every 8 inches on the next sheet (e.g., at 8 inches, 16 inches, 24 inches, etc.).
Of course, a number of variations in the timing for image capture are possible. In some cases the processor is programmed to actuate the camera head 220 to capture multiple successive images at each position before moving the camera head to another position. This allows the system to capture a series of images at each of the positions, allowing for analysis of long term trends in the application of the interleaving material across the width of the conveyor 204. In some embodiments the processor is programmed to time the image capture with the speed of the conveyor 204 in order to capture a single image per lite 202 passing by the camera system. More than one image per lite may also be captured in some cases. For example, the camera system 212 may be timed with the conveyor 204 to capture two or more images of a lite for a single position along the width of the conveyor 204. Of course, the camera system may capture any other combination of images per lite depending upon the speed and timing of the camera system and conveyor.
As discussed with reference to
In some cases the processor may employ image analysis and recognition routines to assess the coverage of the interleaving material upon the lites. For example, in some cases a blob analysis of a captured image can be used to identify and characterize particles of the interleaving material. A blob analysis and/or other image processing techniques can be used to determine (directly or by inference) the number of particles of the interleaving material (e.g., within varying unit areas), the area coverage, the total mass of the material, and/or the density of the material across a portion of a lite, among other characteristics.
The processor is optionally programmed to analyze the interleaving material while also distinguishing between different types of particles within the material (e.g., polymeric separation beads, acid particles, indeterminate particles, etc.). In one embodiment the processor employs an image processing routine that distinguishes particles based on how light from the camera system (e.g., lights 404 in
According to some embodiments, the processor may be programmed to perform an imaging process that determines the size of interleaving material particles (e.g., including beads and/or acid particles) based on light reflected by the particles. Such an analysis can assist in determining the relative amount of each type of particle upon the lites. Referring to
Fewer or greater than four lights may be used depending upon the accuracy and reliability of the particular imaging routine being used. For simpler processing routines it is generally helpful to include more lights rather than less because the distance between any two reflected lights is smaller. This decreases the likelihood that the imaging routine will interpret two farther apart light reflections as belonging to two different beads when in reality they belong to the same bead. Of course any combination is possible and the invention is not limited in this regard. In one case using four strobe lights, and a simple blob analysis, Applicants have discovered that the system is about 98.5% accurate in distinguishing PMMA beads from adipic or boric acid particles.
After capturing one or more images of the interleaving material and assessing/analyzing coverage of the material upon the lites 202, the control module 214 may further provide one or more reporting features to inform plant personnel of the current state of interleaving material application. For example, the control module processor may be programmed with instructions for displaying detailed visual data in real-time with corresponding measurement displays, as well as data and statistics across one or more time periods. Reporting features can range from simple measurement breakdowns to long-term trending and statistics. In some cases data is displayed in a format compatible with popular spreadsheet or other analysis packages, allowing comprehensive management reports to be produced easily and quickly. Summary reports may also be automatically printed to any printer on the network at user-configurable times such as at the end of a shift.
In addition to controlling the camera system 212 and providing for the analysis of the interleaving material and reporting of findings, the control module 214 may also provide a number of other features and capabilities. For example, in some cases the control module 214 is provided by a personal computer with all the standard capabilities and features normally provided in a computer. For example, in some cases the control module runs a commonly available operating system, such as Microsoft Windows, which provides a secure platform for mission critical applications. The control module 214 may also interface with plant control equipment via opto-isolated I/O, Ethernet, serial communications links, and/or other known communication standards. In some cases the control module is provided with networking capabilities, allowing the control module to be connected to an internal plant networking infrastructure. This can provide for remote interactive sessions to be run on monitors throughout the plant.
In addition, in some cases the control module 214 provides for manually driving the position of the camera head 220 to any desired location across the conveyor/lite in order to acquire an image of a particular location on the lite. The user interface shown in
A number of actions and outcomes are possible based on the captured images of the lites and the subsequent analysis. For example, the assessment can be a source of information for troubleshooting quality control problems with the interleaving material, which may be apparent from sticking, marking, sliding, staining, etc., of the stacked sheets of material. In addition, the interleaving material can be manually reviewed to determine potential problems with and/or adjustments for the interleaving material applicator. For example, if the material level is low at one point along the width of the lite, an operator may check for clogs and obstructions along the dispersion line of the applicator. A modification to the arrangement of the applicator spray bar (e.g., moving or disabling a nozzle) may also be necessary. In some cases, the control module processor is programmed to compare aspects of the current interleaving material coverage to a desired coverage profile. Thus, the interleaving material coverage can be automatically analyzed and potential adjustments determined without the need to stop the production line, extract a sample, and manually inspect the sample under a microscope to determine the coverage quality.
Some embodiments of the invention provide for using the assessment of interleaving material coverage to automatically adjust subsequent application of the interleaving material upon the lites. After comparing and determining desired adjustments to the current coverage, the processor may in some cases communicate the adjustments to the interleaving material applicator 206, e.g., over control line 215 shown in
According to some embodiments, the applicator 206 can receive a control signal from the control module 214 that allows the control module to adjust one or more aspects of the applicator based on the interleaving material analysis. For example, the applicator 206 may respond to a signal for adjusting a metering gap within the applicator and/or a vibration intensity. According to one example, the vibration setting of the applicator is adjusted using a 0-10 V analog signal supplied by the control module to the applicator. The magnitude of the signal sets the percentage of the current vibration setting being used for dispersing. For example, if the feedback signal from the controller to the applicator is 5V (50% of the range maximum of 10V), the vibration setting is reduced by half.
Once the system determines that a current density value is outside the acceptable range, the control module can quickly calculate a new control signal to modify the output of the applicator. In some cases the processor is programmed to potentially adjust the applicator's interleavant dispersion every 50 ms. Thus, the applicator can be updated very quickly after an analysis indicates there is a problem.
Turning to
Thus, embodiments of the invention are disclosed. Although the present invention has been described in considerable detail with reference to certain disclosed embodiments, the disclosed embodiments are presented for purposes of illustration and not limitation and other embodiments of the invention are possible. One skilled in the art will appreciate that various changes, adaptations, and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.
