Method for measuring width and edge profile of a single substrate in a stack of substrates - Patent Application 20070122997

Abstract

The present disclosure provides systems and methods for continuous wallboard manufacturing, and in particular provides methods that include using a laser scanner, preferably a two-dimensional (2D) laser scanner positioned a distance from a post-kiln conveyor, to measure widths and edge profiles of wallboards in a post-kiln stack of at least two or more wallboards, and performing a laser scan of the stack as it passes on the post-kiln conveyor.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 410,343, filed September 27, 2022, and U.S. Provisional Patent Application No. 18 / 136,505, filed April 19, 2023, the entire disclosures of which are incorporated herein by reference in their entireties.

[0002] FIELD OF THE INVENTION FIELD OF THE DISCLOSURE The present disclosure relates to systems and methods for continuous wallboard manufacturing, and more particularly to systems and methods for measuring wallboard width and edge profile within a stack of multiple wallboards. [Background technology]

[0003] Wallboard is commonly used in construction, including for interior walls and ceilings of buildings. Wallboard can be manufactured by mixing a gypsum slurry and dispensing it between two paper cover sheets, as described, for example, in U.S. Patent No. 9,745,222, the entire disclosure of which is incorporated herein by reference.

[0004] During production on a wallboard production line, a first paper sheet, called a facer, is fed from a roll onto a conveyor belt. Gypsum slurry is dispensed onto the facer from a mixer. A second paper sheet, called a backer, is fed from the roll and is used to overlay and cover the gypsum slurry to form a continuous ribbon. This sandwiched continuous ribbon of wallboard precursor may travel on the conveyor belt until the gypsum has hardened sufficiently for the ribbon to be cut into individual wallboards, which are then transported to a drying oven (kiln). When the gypsum slurry is dispensed onto the facer, it should be distributed as evenly as possible between the center of the facer and its edges. The width of the wallboard should also be constant or have only a slight deviation from a preset value. Many factors can affect the quality of the gypsum slurry distribution, including the temperature at which the production line operates, the composition of the gypsum slurry, the source of water and other components in the gypsum slurry, the paper used as the facer, the paper used as the backer, and / or humidity.

[0005] Various methods for monitoring and measuring the width and edge profile of gypsum wallboard while the ribbon precursor is moving on a conveyor are known in the art.For example, U.S. Patent No. 9,745,222 describes a method in which at least one laser scanner and a processor are installed in a wallboard production line to monitor the width and edge profile of gypsum wallboard in real time during production.WO 2000 / 012963 describes a method and system for detecting the edge angle of gypsum board.This system includes a light source and a camera, and requires taking pictures to obtain information about the slurry distribution in the gypsum board.

[0006] After the wallboard panels are dried in the kiln, they are stacked face-to-face into stacks that may contain two, four, five, or more wallboards. Currently, there is a need in the art for a system and method that can accurately measure the width and edge profile of a single dried wallboard within a stack of multiple post-kiln wallboards. Summary of the Invention

[0007] The present disclosure addresses at least some of these needs and provides a method and system for measuring the width and edge profile of a single wallboard in a post-kiln stack of multiple wallboards.

[0008] In one aspect, the present disclosure provides a method for manufacturing a semiconductor device comprising: i) scanning with a laser beam of a first 2D laser scanner at least a first portion of a cross-machine surface of a stack of at least two wall panels, the first wall panel having a first front long surface and the second wall panel having a second front long surface, the second front long surface of the second wall panel being positioned above the first front long surface of the first wall panel in the stack; a first portion of the stack including a first machine direction edge of the stack, and using a sensor of a first 2D laser scanner, generating a first array of distance measurements from the first 2D laser scanner to the scanned first portion, each measurement in the first array of distance measurements having a horizontal coordinate x and a vertical coordinate y; ii) scanning at least a second portion of the cross-machine surface of the stack, including an edge of the stack opposite the first machine direction, with a laser beam of a second 2D laser scanner and generating a second array of distance measurements from the second 2D laser scanner to the scanned second portion using a sensor of the second 2D laser scanner, each measurement in the second array having a horizontal coordinate x and a vertical coordinate y; iii) transmitting the first array of distance measurements and the second array of distance measurements to a processor; iv) executing the computer program with the processor to select a subset of distance measurements from the first array and the second array for a second wallplate, the second wallplate being the target wallplate; v) generating an edge profile of the target wallboard from the subset of distance measurements; vi) calculating a width value of a target wallboard, and classifying the stack as width value conforming if the width value of the target wallboard is within the width tolerance range, and classifying the stack as width value non-conforming if the width value of the target wallboard is not within the width tolerance range; vii) moving the stack to a taping station if the stack is classified as width value compliant, and moving the stack for recycling if the stack is width value non-compliant.

[0009] Preferred embodiments of the method include those in which the width tolerance is defined as the specified nominal plus or minus 3 / 32 inch (-2.4 mm). In the method, the stack may include two, three, four, five, or six wallboards. In some preferred embodiments, the wallboards in the stack may have straight or tapered machine direction edges. Some preferred embodiments of the method include those in which step iv) comprises: a) executing a computer program with a processor to analyze the first array and identify, within the first array, horizontal and vertical coordinates of vertices between the rear long surface of the first wallsheet and a machine direction edge of the first wallsheet, preferably by using decreasing distance measurements within the array; b) determining horizontal and vertical coordinates of a vertex between the machine direction edge of the first wallboard and the front long surface of the first wallboard, preferably by using incremental distance measurements in the array; c) identifying horizontal and vertical coordinates of a vertex between the front long surface of the second wallboard and the machine direction edge of the second wallboard, preferably by using decreasing distance measurements in the array, and marking these coordinates as a first lower vertex of the target wallboard; d) identifying horizontal and vertical coordinates of a vertex between the rear long surface of the second wallsheet and the machine direction edge of the second wallsheet, preferably by using incremental distance measurements in the array, and marking these coordinates as a first upper vertex of the target wallsheet; e) repeating steps a) through d) for a second array to mark the coordinates of a second lower vertex and a second upper vertex of the target wallboard; f) using a subset of the distance measurements between the two lower vertices and the two upper vertices in steps v) and vi) to generate an edge profile and calculate a width value.

[0010] In some embodiments, the first 2D laser and the second 2D laser may be the same, but with the ability to generate two laser beams simultaneously.

[0011] In any of these embodiments, the method may further include displaying the edge profile generated in step v) on a display device.

[0012] In some embodiments, the method may further include sending a signal from the processor to the controller when the stack is classified as width value non-compliant.

[0013] Some embodiments of the method may be carried out with the stack positioned on a post-kiln conveyor with the rear long surface of the first wall panel disposed on the surface of the post-kiln conveyor.

[0014] In another aspect, the present disclosure provides a system for manufacturing wallboard, comprising: Wallboard production line, one or more kilns configured to receive wallboard from a wallboard production line; a post-kiln conveyor configured to receive two or more stacks of wallboard from one or more kilns, the post-kiln conveyor further configured to move the stacks along a length of the post-kiln conveyor; and one or more 2D laser scanners positioned at a distance from the post-kiln conveyor, the one or more 2D laser scanners having a field of view from a position on the cross-machine surface of the stack located at a location along the length of the post-kiln conveyor.

[0015] Embodiments of the system include those in which the system may further include a taping station configured to receive the stack from the post-kiln conveyor. In some embodiments of the system, one or more 2D laser scanners are operatively disposed with a processor, the processor is operatively disposed with a non-transitory computer-readable medium, and the non-transitory computer-readable medium stores a computer program that, when executed by the processor, selects a single target wallboard from the stack for calculation and calculates a width and edge profile of the single target wallboard in the stack.

[0016] The system further includes a controller operatively arranged with the one or more 2D laser scanners. Preferably, each of the one or more kilns may have a number of shelves, and each shelf may be further configured to accommodate two or more wall panels.

[0017] In yet another aspect, the present disclosure provides a method for manufacturing wallboard, comprising: mixing a gypsum slurry from calcined gypsum, water, and one or more additives; depositing a gypsum slurry onto a cover sheet moving continuously on a production line; covering the gypsum slurry with a backing paper cover sheet; forming a ribbon precursor of a wallboard; cutting the ribbon into wallboards; transferring the wallboard to a kiln; drying the wallboard in a kiln; placing the wallboards in a stack of two or more wallboards on a post-kiln conveyor while removing the wallboards from the kiln; and moving the stacks on the post-kiln conveyor past a location where each stack is scanned on its cross-machine surface with a 2D laser to generate a first array of distance measurements for a first machine direction edge of the stack and a second array of distance measurements for a second machine direction edge of the stack.

[0018] Some embodiments of the method may further include analyzing the first array and the second array for conformance to end product specification requirements, where the analysis includes sending the arrays to a processor, where the processor executes a computer program to select a target wallboard in the stack and calculate a width and edge profile of the target wallboard. Preferably, selecting the target wallboard may include finding horizontal and vertical coordinates for each of two lower vertices in the array and finding horizontal and vertical coordinates for each of two upper vertices of the target wallboard, where more preferably, finding the lower vertices is performed by using decreasing distance measurements and finding the upper vertices is performed by using increasing distance measurements. [Brief explanation of the drawings]

[0019] [Figure 1A] 1 is a perspective view of a wallboard having square machine direction edges. This view is not drawn to scale. [Figure 1B] 1 is a perspective view of a wallboard section, focusing on one tapered machine direction edge and its profile. This view is not drawn to scale. [Figure 2] 1 illustrates a cross-machine surface of a section of one embodiment of a kiln back wall sheet stack according to the present disclosure. [Figure 3A] 1 is a flow chart illustrating one embodiment of a method for measuring the width and edge profile of a single wallboard in a post-kiln stack of multiple wallboards. [Figure 3B] 1 is a flow chart illustrating one embodiment of a method for identifying a target wallboard in a post-kiln stack of at least two wallboards. [Figure 4] 1 is a partial schematic side view of a system for manufacturing wallboard, showing one embodiment for positioning a laser scanner relative to a post-kiln conveyor. This view is not drawn to scale. DETAILED DESCRIPTION OF THE INVENTION

[0020] In this disclosure, the term "calcined gypsum" may be used interchangeably with any of the following terms: calcium sulfate hemihydrate, stucco, calcium sulfate semi-hydrate, calcium sulfate half-hydrate, or calcined gypsum.

[0021] In this disclosure, the term "gypsum" can refer to either naturally mined gypsum (ore), gypsum dust, and / or synthetic gypsum. The term "gypsum" can be used interchangeably with the term "calcium sulfate dihydrate." "Synthetic gypsum" can also be referred to as "chemical gypsum."

[0022] In this disclosure, the term "wallboard" refers to a gypsum panel having a gypsum matrix core sandwiched between two paper cover sheets. The term "wallboard" may be used interchangeably with any of the following terms: gypsum panel, gypsum wallboard, drywall, gypsum board, or board.

[0023] In this disclosure, the term "about" refers to a range of ±5% of the stated value. For example, "about 100" means 100±5, and "about 200" means 200±10.

[0024] In this disclosure, the term "wt. %" means percent by weight.

[0025] When stucco (CaSO₄·½H₂O) is mixed with water to form a slurry, the stucco hydrates and hardens into a gypsum matrix. This hardening reaction can be represented by the following equation: CaSO4·1 / 2H2O+3 / 2H2O→CaSO4·2H2O

[0026] In this disclosure, "calcination" refers to the process of dehydrating gypsum (CaSO 2H O) to calcined gypsum (CaSO ½H O). This process involves heating the gypsum to evaporate the water of crystallization. Calcined gypsum can be produced in different crystalline forms, such as alpha calcium sulfate hemihydrate and beta calcium sulfate hemihydrate. All crystalline forms and any mixtures thereof are suitable for compositions according to the present disclosure.

[0027] Various tests may be described in this disclosure. If temperature, atmospheric pressure, and / or humidity are not mentioned in connection with a particular test, it means that the test was conducted at room temperature, defined as 68-77°F (20-25°C), standard atmospheric pressure of about 101 kPa, and humidity in the range of about 68 to about 75 percent.

[0028] In this disclosure, ASTM tests refer to tests published by ASTM International, formally known as the American Society for Testing and Materials. Detailed test protocols for ASTM tests are available on the ASTM International website.

[0029] In this disclosure, "gypsum slurry" refers to an aqueous gypsum slurry in which calcined gypsum is mixed with at least water and preferably one or more additives.

[0030] The present disclosure provides a method and system for measuring the width and edge profile of a single wallboard within a stack of several post-kiln wallboards. Referring to FIGS. 1A and 1B, two embodiments of wallboards according to the present disclosure are shown. The embodiment of FIG. 1A, generally 10, has square edges, while the embodiment of FIG. 1B, generally 50, has tapered edges. Wallboards 10 and 50 are composed of a set gypsum core 12 sandwiched and bonded between two paper cover sheets: a facing cover sheet, which may also be called a facer 14, and a backing paper cover sheet, which may also be called a backer 16. In some embodiments, gypsum core 12 is bonded directly to paper cover sheets 14 and 16. In some embodiments, at least one of cover sheets 14 and 16 may include an adhesive coating over at least a portion of the surface that contacts gypsum core 12. In some embodiments, gypsum core 12 may include several layers, each formulated from a gypsum slurry that may differ in formulation from the gypsum slurries used in the other layers. In some preferred embodiments, the gypsum core 12 may have a density of approximately 30 pcf to 40 pcf. When the gypsum core 12 includes several layers, the layer in contact with the facer cover sheet 14 and / or the backer cover sheet 16 may have a density greater than that of the central core layer. The paper cover sheets may include manila paper, kraft paper, and / or newsprint paper. Multi-layered paper, such as manila cardboard and MH manila HT (high tensile) paper, may also be used. The front cover sheet 14 and the backing cover sheet 16 may be made from different grades of paper, and each cover sheet may have a different weight. Suitable paper weight ranges include, but are not limited to, a range of approximately 33 lbs / MSF to approximately 65 lbs / MSF. For example, the face cover sheet 14 may include high-density manila paper, preferably approximately 55 to approximately 65 lbs / msf, although paper cover sheets of different weights may be used as well. A low density newsline paper of about 35 to about 45 lbs / mfs can be used as the back cover sheet 16 .In some embodiments, one or both cover sheets 14 and 16 may have a coating, such as, for example, a mildew-resistant and / or water-resistant coating, on the surface of the cover sheet that is not attached to gypsum core 12.

[0031] The gypsum core 12 preferably comprises set gypsum mixed with various additives. The additives may include, but are not limited to, one or more of starch, fiber, dispersants, foaming agents, phosphate compounds, and / or agents that accelerate or retard the setting reaction in the gypsum slurry. Suitable phosphate compounds include monobasic salts or monovalent ions of cyclic polyphosphates, condensed phosphates, and orthophosphates. Particularly preferred phosphate compounds include, but are not limited to, trimetaphosphates and tetrametaphosphates. Particularly preferred phosphate compounds include sodium trimetaphosphate ("STMP"), potassium trimetaphosphate, ammonium trimetaphosphate, sodium hexametaphosphate, tetrapotassium tripolyphosphate, ammonium polyphosphate, aluminum trimetaphosphate, or any combination thereof. The gypsum slurries and gypsum cores of the present disclosure may comprise from about 0% to about 1% by weight of the calcined gypsum of one or more phosphate compounds, preferably from about 0.1% to about 1% by weight of the calcined gypsum of one or more phosphate compounds.

[0032] The gypsum core and gypsum slurry according to the present disclosure may contain one or more dispersants. Suitable dispersants include naphthalene sulfonates and derivatives (including sodium and / or calcium naphthalene sulfonates), polycarboxylate dispersants, particularly polycarboxylic acid ethers (including those described in U.S. Patent Nos. 5,798,425, 6,777,517, and 7,767,019). Some gypsum cores and gypsum slurries may also contain one or more lignosulfonates. The gypsum slurries and gypsum cores of the present disclosure may contain from about 0.05% to about 2% by weight of the calcined gypsum of one or more dispersants, preferably from about 0.1% to about 1% by weight of the calcined gypsum of one or more phosphate compounds.

[0033] The gypsum core and gypsum slurry according to the present disclosure may contain one or more set retarders and / or set accelerators. These are compounds that modify the rate at which the gypsum slurry sets. Preferred set accelerators include "CSA," which may contain approximately 95% calcium sulfate dihydrate co-ground with 5% sugar and then heat-treated, as described in U.S. Pat. No. 3,573,947. Other suitable accelerators include "HRA," which contains potassium sulfate and freshly ground calcium sulfate dihydrate with sugar at a ratio of about 5 to about 25 pounds of sugar per 100 pounds of calcium sulfate dihydrate, as described in U.S. Pat. No. 2,078,199. Other accelerators for controlling the setting reaction in the gypsum slurry include wet gypsum accelerators (WGA), as described in U.S. Pat. No. 6,409,825. Typically, set accelerators can be used in any amount suitable for controlling the hydration rate of the calcined gypsum. Preferably, the gypsum slurry according to the present disclosure may include from about 0.1% to about 4% by weight of the calcined gypsum of one or more accelerators (accelerators), such as HRA or CSA, more preferably from about 0.5% to about 2% by weight of the calcined gypsum of one or more accelerators.

[0034] Suitable set retarders slow the hydration reaction of the calcined gypsum. Such set retarders may include, but are not limited to, the commercially available protein inhibitor SUMA, diethylenetriaminepentaacetic acid (DTPA), tartaric acid, citric acid, maleic acid or their salts, particularly sodium citrate and / or potassium hydrogen tartrate (cream of tartar), or any combination thereof. Set retarders can be used in small amounts, for example, in an amount ranging from about 0.01% to about 1.5% by weight of the calcined gypsum, preferably in an amount ranging from about 0.05% to about 0.5% by weight of the calcined gypsum.

[0035] In some embodiments, wallboard may include those in which the gypsum core contains air bubbles and is formed from a gypsum slurry mixed with a foaming agent (surfactant or soap) delivered as a foam from a foam generator, as described, for example, in U.S. Pat. Nos. 5,643,510 and 5,683,635, the disclosures of which are incorporated by reference.

[0036] Various commercially available foaming agents can be used, including, but not limited to, foaming agents containing sodium dodecyl sulfate, magnesium dodecyl sulfate, ammonium dodecyl sulfate, potassium dodecyl sulfate, sodium decyl sulfate, alkoxylated alkyl sulfate surfactants, sodium laureth sulfate, potassium laureth sulfate, magnesium laureth sulfate, ammonium laureth sulfate, or any mixture thereof. In some embodiments, any foaming agent or blend of foaming agents can be used in any suitable amount to produce a gypsum core having the desired density and strength. In some embodiments, about 0.01% to about 0.5% foaming agent by weight of the calcined gypsum can be used.

[0037] In some embodiments, the gypsum core 12 according to the present disclosure may include one or more water repellents, preferably siloxanes. In these embodiments, a polymerizable siloxane may be added to the gypsum slurry, preferably as an emulsion, which may include an emulsifier. A catalyst may also be added to the gypsum slurry to improve siloxane polymerization. Suitable siloxane formulations and catalysts, such as magnesium oxide, Class C fly ash, and dead-burned magnesium oxide, are disclosed in U.S. Pat. Nos. 7,892,472 and 7,803,226, the disclosures of which are incorporated herein by reference in their entireties. In some embodiments, the gypsum core 12 may include the siloxane in an amount of about 0.3% to about 2% by weight of the calcined gypsum.

[0038] The gypsum core 12 can be formed from a gypsum slurry in which calcined gypsum (stucco) solidifies (hardens) by reacting with water. Suitable calcined gypsum (stucco) can be obtained by calcining naturally occurring and / or synthetic gypsum. Suitable gypsum slurries include those having a weight ratio of water to calcined gypsum (known as the water-to-stucco ratio, WSR) in the range of 0.5 to 1.5, preferably 0.5 to 1.3, more preferably 0.7 to 1, and most preferably 0.7 to 1.3, e.g., 0.7, 0.8, 0.9, 1, 1.1, 1.2, or 1.3. The gypsum slurry may contain about 40% to about 70% calcined gypsum by weight. The gypsum slurry may also contain various additives.

[0039] When a wall or ceiling is assembled from wallboards 10 and / or 50, each wallboard is typically attached to a stud, such as a wood stud, with back cover sheet 16 facing the stud and front cover sheet 14 on the opposite side. When wallboards 10 and / or 50 are in use, front cover sheet 14 faces the room.

[0040] As described in U.S. Patent No. 8,931,230, which is incorporated herein by reference, wallboard edges are generally identified as being in the machine direction or the cross-machine direction based on the wallboard orientation during its formation on a continuously moving manufacturing conveyor. The edge along the direction of conveyor (machine) movement is typically the longer edge than the cross-machine edge. The machine direction edge is typically wrapped with a paper cover sheet during wallboard manufacturing, and gypsum slurry is deposited onto the moving paper cover sheet (e.g., on a conveyor) to initially form a long, continuous ribbon of wallboard precursor that is ultimately cut in the cross-machine direction into wallboard. The wallboard is then transferred to a kiln for drying.

[0041] Wallboard 10, as shown in FIG. 1A, has machine direction edges 18 and 18. Wallboard 10 also has two cross-machine edges 20 and 20. FIG. 1B shows a segment of machine direction edge 52 and a segment of cross-machine edge 56 of wallboard 50. In this disclosure, the machine direction edges may be referred to as "long edges." The machine direction edges are laterally spaced apart from one another along the cross-machine direction. In this disclosure, the "cross-machine edges" may be referred to as "short edges."

[0042] The wallboard 10 or 50 has a width X, a length Y, and a thickness Z. Preferably, the length Y is greater than the width X, so that the wallboard 10 or 50 has two long surfaces with an area (X × Y): a first (front) long surface 10F or 50F, which is covered with a front cover sheet 14 and faces the room when the wallboard 10 or 50 is in use, and a second (rear) long surface 10B or 50B, which is opposite the first front long surface. The rear long surface 10B or 50B is covered with a back paper cover sheet 16 and faces the studs when the wallboard 10 or 50 is in use. The wallboard 10 or 50 also has two cross-machine surfaces, of which the first surface 10z or 50z is shown in FIG. 1A or FIG. 1B, and the opposite second cross-machine surface is not visible in the drawings. In this disclosure, the "front long surface" may also be referred to as the "front surface." In this disclosure, the "posterior long surface" may be referred to as the "posterior surface."

[0043] In the embodiments of FIGS. 1A and 1B, the machine transverse edges 20, 20 or 56 are substantially square. In the embodiment of FIG. 1A, the machine direction edges 18 and 18 are also square, which means that the thickness Z is substantially the same at the center and the long edges of the wall panel 10. In the embodiment of FIG. 1B, both machine direction edges are tapered, which means that the wall panel 50 tapers on its front long surface 50F from the wall panel thickness Z to a reduced thickness Z1 towards each of the two machine direction edges 52, where Z1 < Z. Thus, the front long surface 50F has recesses (tapers) 54 at each of the two machine direction edges 52. The depth D of the recess 54 may vary. In some embodiments, the depth D of the recess 54 may be in the range of about 0.001 inch to about 0.08 inch when measured at the lowest point of the taper slope. The length L of the recess (taper) 54 may vary, including some embodiments where the length L may be in the range of about 1 / 4 inch to about 2 / 3 inch.

[0044] Referring to FIG. 1B, the embodiment of the wall panel 50 has a tapered edge profile (contour, shape or outer shape) with respect to its two machine transverse surfaces 50z, and the wall panel 10 has a straight edge profile with respect to its machine transverse surface 10z as shown in FIG. 1A. In the present disclosure, a "machine transverse surface" may also be referred to as a "transverse surface" because this surface is perpendicular to the direction in which the wall panel ribbon precursor being formed moves on the production line. In a further embodiment of the wall panel (not shown), the wall panel may have rounded or chamfered machine direction edges.

[0045] Wallboards may have thicknesses (Z) ranging from about 1 / 4 inch to about 1 inch, depending on their expected use and application. Wallboards may also include those with lengths (Y) ranging from 8 to 16 feet, e.g., 8 feet, 10 feet, or 16 feet (2438 to 4877 mm), and widths (X) of 4 feet (1219 mm) or 54 inches (1372 mm). Any of these panels may have thicknesses from about 1 / 4 inch to about 1 inch, with some preferred embodiments having a thickness (Z) of 5 / 8 inch (15.9 mm). In embodiments where the wallboard has tapered edges, its thickness (Z1) at the tapered portion may be reduced by a value ranging from about 0.001 inch to about 0.08 inch.

[0046] Each wallboard must meet product specifications for width and edge profile, among other specifications. The width and edge profile of the ribbon precursor is preferably monitored with a laser scanner while the ribbon precursor is still moving on the production line. After the ribbon is cut into wallboards, it is dried in a kiln. It has been discovered that high temperatures in the kiln and / or several other factors can affect the width and edge profile of the kiln back wallboards, but measuring the width and edge profile of each single kiln back wallboard with a laser scanner can be tedious and time-consuming, especially because the kiln back wallboards are typically arranged in a stack of at least two or more wallboards.

[0047] In one aspect, the present disclosure provides a method in which a wallboard in a stack of several post-kiln wallboards is analyzed for its width and edge profile using a laser scanner before the stack can be packaged for shipment. One technical advantage of the method of the present invention is that the entire stack of wallboards can be analyzed for width and edge profile compatibility, rather than having to analyze each wallboard in each stack individually. The method disclosed herein can provide significant energy and time savings.

[0048] In some preferred embodiments, the present disclosure relates to a method for manufacturing wallboard 10 or 50 that includes measuring the width X and edge profile of a single wallboard in a stack of post-kiln wallboards before the stack is packaged for shipment.

[0049] In this method, the stack may be at least two wallboards high. For example, the stack may include two, three, four, five, or six wallboards arranged such that the long surface of one wallboard rests on top of the long surface of another wallboard in the stack. The wallboards in the stack may have straight, tapered, rounded, or chamfered machine direction edges.

[0050] In some embodiments, the stack may be comprised of wall plates having straight machine direction edges, as described in connection with the embodiment of FIG. 1A. In some embodiments of the stack, the wall plates may have tapered machine direction edges, as described in connection with the embodiment of FIG. 1B. Referring to FIG. 2, a portion of a cross-machine surface for one embodiment of a post-kiln stack wall plate is shown generally as 100, and four tapered wall plates 50, 60, 70, and 80 may be arranged in stack 100. In stack 100, first wall plate 60 has a front long surface 60F and a rear long surface 60B. Second wall plate 50 has a front long surface 50F and a rear long surface 50B. The first wall panel 60 and the second wall panel 50 are aligned in the stack 100 with the front long surface 50F of the second wall panel 50 positioned on top of the front long surface 60F of the first wall panel 60 so that the front long surface 50F of the second wall panel 50 covers the front long surface 60F of the first wall panel 60. If the stack 100 includes a third wall panel 70, the rear long surface 50B of the second wall panel 50 in the stack 100 may be covered by the rear long surface 70B of the third wall panel 70, so that the second wall panel 50 and the third wall panel 70 are aligned with the rear long surface 70B of the wall panel 70 over the entire rear long surface 50B of the second wall panel 50. Because the first tapered wall panel 60 in the stack 100 and the second taped board 50 in the stack 100 are aligned with their front surfaces, the stack 100 has a gap 154 ​​between the tapered edge portions 52 and 62 of the wall panels 50 and 60. However, because the second wall panel 50 and the third wall panel 70 are aligned with their non-tapered rear long surfaces 50B and 70B, there is no appreciable gap in the stack 100 between the second wall panel 50 and the third wall panel 70 in the stack 100. With respect to the third wall panel 70 and the fourth wall panel 80, they may be aligned with their front surfaces to form a gap 184 between the tapered edge portions 72 and 82 of the wall panels 70 and 80.

[0051] The cross-machine surfaces in stack 100 are made up of cross-machine surfaces 60z, 50z, 70z, and 80z of wall plates 60, 50, 70, and 80 assembled in stack 100. The machine direction edge of stack 100 is made up of machine direction edges 62, 52, 72, and 82 of wall plates 60, 50, 70, and 80. In some preferred embodiments of post-kiln stacks according to the present disclosure, it is important that first wall plate 60 and second wall plate 50 are positioned in stack 100 with second front surface 50F positioned above first front surface 60F so that recesses from tapered edges 62 and 52 of the first and second wall plates form gap 154. Even in embodiments having straight machine direction edges, stack 100 may still have gap 154 ​​at its long edge between the first and second wall plates, which gap 154 ​​is detectable with a laser scanner.

[0052] When three or more wall panels are arranged in stack 100, the third wall panel or other subsequent wall panels may be oriented rear surface to rear surface, front surface to front surface, or rear surface to front surface.

[0053] 3A, certain embodiments of a method according to the present disclosure may include one or more of the steps listed in the flowchart of FIG. 3, generally at 300. The method may be practiced with a stack of at least two or more wallboards, with one preferred embodiment of the stack comprising stack 100.

[0054] In step 310, at least a portion of a cross-machine surface of a stack of at least two wallboards according to the present disclosure, including a first machine direction edge of the stack, is scanned with a laser beam from a light source of a first two-dimensional (2D) laser scanner positioned a distance from the cross-machine surface of the stack. Preferably, two 2D laser scanners are used in step 310. The first 2D laser scanner scans a portion of the stack including at least a first machine direction edge of the stack, and the second 2D laser scanner scans a portion of the stack including the opposite machine direction edge of the stack. Preferably, the wallboards have tapered machine direction edges (e.g., wallboards 60 and 50). In the stack, a first wallboard 60 having a first front long surface 60F and a second wallboard 50 having a second front long surface 50F are arranged in the stack with the second front long surface 50F positioned above the first front long surface 60F.

[0055] In step 312, a sensor of a first 2D laser scanner captures light reflected from the illuminated cross-machine surface as an array of distance measurements, each measurement in the array having a horizontal coordinate and a vertical coordinate. The first 2D laser scanner generates a first array of distance coordinates relative to a first machine direction edge of the stack, and the sensor of a second 2D laser scanner generates a second array of distance coordinates relative to an opposite long edge of the stack. Steps 310 and 312 can be performed simultaneously, with the first and second arrays being generated in real time while the first and second laser beams scan the cross-machine surface of the stack.

[0056] In step 314, the sensor of the first 2D laser scanner transmits a first array of distance measurements for the first machine direction edge and the sensor of the second 2D laser scanner transmits a second array of distance measurements for the second machine direction edge to the processor, the processor being operatively disposed with a non-transitory computer-readable medium storing a computer program that, when executed, calculates a width and edge profile of a single target wallboard in a stack of multiple wallboards, e.g., at least two, three, four, five, six, or more.

[0057] In step 316, the processor executes a computer program that analyzes the first array of distance measurements and the second array of distance measurements and selects from the first array and the second array only a subset of distance measurements for a second wallboard in the stack, the second wallboard being the target wallboard.

[0058] In step 318, a subset of the distance measurements of the second wallboard is used to generate an edge profile of the target wallboard. The edge profile may be displayed on a computer monitor operatively disposed with the processor. The edge profile of the target wallboard may be compared to the edge profile of the control.

[0059] In step 320, the width of the target wallboard is calculated from the subset of distance measurements based on the known distance between the first 2D laser and the second 2D laser. The width of the target wallboard is compared to a width value (nominal width) provided by the final product specifications. If the width of the target wallboard is within the width tolerance of the final product, the stack including the target wallboard is moved to a taping station in step 322, where the stack corners may be end-taped and the stack may be packaged with other stacks for shipment to the user. Preferably, the width tolerance may be defined as the nominal width value plus or minus 3 / 32 inches (-2.4 mm).

[0060] However, if the width of the target wallboard is not within tolerance, for example, if the nominal value is more than 3 / 32 inch larger than the width, then instead of step 322, the stack containing the target wallboard is moved for recycling in step 324.

[0061] Various methods can be used to identify the target wall sheet 50 in the post-kiln stack 100. Some preferred embodiments include a method in which a laser scanner is used to detect a gap 154 ​​in the cross-machine surface of the stack and identify the second wall sheet in the stack 100 based on the position of the second wall sheet relative to the gap 154, e.g., a machine direction edge of the second wall sheet is positioned next to the gap 154.

[0062] Referring generally to FIG. 3B, which is a flowchart of one embodiment of a method that may be used to identify a target wallsheet 50 in a stack 100, at 400. In step 410, a processor executes a computer program that analyzes a first array of distance measurements generated from a first laser scan of a first machine direction edge of the stack and finds the coordinates of the vertex between the rear long surface of the first wallsheet and the machine direction edge of the first wallsheet by using decreasing distance measurements in the array.

[0063] In step 420, the computer program identifies the coordinates of the vertex between the machine direction edge of the first wallboard and the front long surface of the first wallboard by using the incremental distance measurements in the array.

[0064] In step 430, the computer program uses the decreasing distance measurements in the array to identify the horizontal x and vertical y coordinates of the vertex between the front long surface of the second wallboard and the machine direction edge of the second wallboard, which will be marked as the first lower vertex of the target wallboard.

[0065] In step 440, the computer program uses the incremental distance measurements in the array to identify the x and y coordinates of the vertex between the machine direction edge of the second wallboard and the rear long surface of the second wallboard, which will be marked as the first upper vertex of the target wallboard.

[0066] The same steps 410 through 440 are performed using a second array obtained from a laser scan of the opposite machine direction edge to mark the coordinates of a second bottom vertex of the target wallsheet and a second top vertex of the target wallsheet.

[0067] The subset of distance measurements between the lower apex of the target wallboard and the upper apex of the target wallboard can now be used in steps 318 and 320, with the distance between the two lasers known, to generate an edge profile and calculate a best fit line for the edge and the overall width of a single wallboard in a multiple wallboard stack, as described in connection with the flowchart of FIG. 3A.

[0068] It has been found that the method of the present disclosure, in which a post-kiln stack of at least two or more wallboards is analyzed for conformance with width and edge profile specifications based on a target wallboard as described above, provides accurate and rapid measurements for the entire stack, and that the real-time display of the edge profile as it is generated during scanning simplifies the operator's monitoring task.

[0069] In yet another aspect, the present disclosure relates to a system for manufacturing wallboard, including wallboard 10 or 50. Referring to Figure 4, one embodiment of the system generally 200 includes a production line 202 in which wallboard is formed from gypsum slurry deposited on a facer cover sheet and covered with a backer cover sheet, one or more kilns 206 each having one or more shelves for drying wallboards 50 and 60, and a post-kiln conveyor 208 that receives wallboards 50, 60, 70, and 80 from the one or more kilns 206 and / or one or more shelves, where the post-kiln wallboards are arranged in stacks of at least two or more wallboards, e.g., three, four, five, or six or more wallboards, and are scanned by two 2D laser scanners 210. The system includes a post-kiln conveyor 208, a controller 212, a processor 216, and a taping station 220, where a first 2D laser 210 is positioned a distance from the post-kiln conveyor 208 so that it can scan at least a portion of the cross-machine surface of the stack 100, including a first machine direction edge of the stack, and a second 2D laser 210 is positioned a distance from the post-kiln conveyor 208 so that a second 2D laser (not shown) can scan at least a portion of the cross-machine surface of the stack 100, including a second machine direction (opposite the first machine direction) edge of the stack 100.

[0070] Production line 202 includes a mixer for mixing the gypsum slurry, which is disposed above a moving conveyor on which a facer cover sheet is deposited from a roll. The gypsum slurry is then deposited onto the moving facer cover sheet and covered with a backer cover sheet, which is deposited onto the gypsum slurry from a second roll. The formation continues on the conveyor to a forming station, which presses the formation into a continuous ribbon precursor of wallboard, then moves to a knife station, where the ribbon is cut into wallboard, which is then transferred off the production line to a kiln 206 where the wallboard is dried at an elevated temperature. Embodiments of wallboard manufacturing methods and production lines are known, for example, from U.S. Pat. Nos. 6,494,609, 6,874,930, and 6,986,812, the entire disclosures of which are incorporated herein by reference.

[0071] After this drying process is complete, the wallboards are transferred from the kiln 206 to a post-kiln conveyor 208. During this transfer, the post-kiln wallboards are arranged in stacks of two or more wallboards.

[0072] The 2D laser scanner 210 includes a laser source 212 that generates a laser beam and a sensor 214 that is operatively disposed with a processor 216 when the system 200 is in use. In use, the laser source 212 scans a surface with the laser beam, and the sensor 220 detects light reflected from the surface and generates an array of distance measurements, each measurement having a horizontal coordinate x and a vertical coordinate y. In system 200, for the source 212 to scan the cross-machine surface of the stack 100 with the laser beam, the first 2D laser 210 and the second 2D laser 210 are positioned at a distance from the post-kiln conveyor 208 such that the cross-machine surface of the stack, including the cross-machine surface 50F of the target wallboard 50, is within the field of view of the laser source 212 as the stack of wallboards 100 is transported on the conveyor 208 in a direction from A to B.

[0073] When the system 200 is in use, the 2D laser scanner 210 is operatively arranged with the processor 216 such that the sensor 214 can transmit an array of distance measurements to the processor 216, which is operatively arranged with a non-transitory computer-readable medium carrying a program for analyzing the data array of distance measurements transmitted from the sensor 214 to the processor 216.

[0074] The 2D laser scanner 210 is operatively disposed with a controller 218. The 2D laser scanner 210 may be configured to operate and perform laser scanning in response to receiving command signals from the controller 218, which may be configured to determine the time intervals at which the laser scanning is performed. The controller 218 may include one or more user interfaces and / or input devices, such as, for example, a keyboard and / or a display screen, that may be adapted to receive input signals from a user. In some embodiments, the controller 218 may be in the form of a desktop computer, a laptop computer, a computer tablet, or a smartphone.

[0075] The processor 216 may be configured to send input signals to the controller 218 as well as receive input signals from the controller 218. The processor 216 is operatively arranged with the 2D laser scanner 210 to receive the data array of distance measurements from the sensor 214. The processor 216 may include any suitable computing device, e.g., a microprocessor, a portable computing device. It may also include one or more input / output devices, e.g., a keyboard and / or a display. The processor may have one or more memory devices, e.g., a RAM (random access memory).

[0076] Preferably, processor 216 is configured to execute a program stored on a non-transitory computer-readable medium, such as a hard drive, that is configured to analyze the array of distance measurements, identify a subset of distance measurement coordinates for a target wallboard in a stack according to an embodiment of the present disclosure, and then use the subset to generate an edge profile for the target wallboard and calculate a width for the target wallboard. The program may include a graphical user interface that may be displayed on a display device, including input by a user and output generated by the program, including an edge profile image. In each embodiment, the program may be configured to analyze the array of distance measurements, find the coordinates of the bottom and top vertices of the target wallboard, and perform an embodiment of methods 300 and 400.

[0077] In system 200, taping station 220 is positioned to receive wallboard stack 100 from post-kiln conveyor 208. At taping station 220, the cross-machine edges may be taped and stack 100 is packaged for shipment to a user.

[0078] System 200 may further include various additional components and stations commonly used in the manufacture or packaging of wallboard. For example, the system may include one or more laser scanners positioned in production line 210 to monitor the formation of the gypsum ribbon, as described, for example, in U.S. Patent No. 9,745,222.

[0079] In yet another embodiment, the present disclosure relates to methods for manufacturing wallboard, embodiments of which may be performed using system 200. Various methods for manufacturing wallboard on a production line are known in the art, including those described in U.S. Patent Nos. 9,745,222 and 10,620,052, the disclosures of which are incorporated herein by reference in their entireties.

[0080] A method according to the present disclosure may include mixing a gypsum slurry from calcined gypsum, water, and one or more additives; depositing the gypsum slurry on a facer paper cover sheet that moves continuously on a production line; covering the gypsum slurry with a backing paper cover sheet; forming a ribbon precursor to wallboard; cutting the ribbon into wallboard; transporting the wallboard to a kiln; and drying the wallboard in the kiln, the method further characterized by arranging the wallboards in stacks of two or more wallboards on a post-kiln conveyor during removal of the wallboards from the kiln; and moving the stacks on the post-kiln conveyor past a location where each stack is scanned on its cross-machine surface with a 2D laser to generate a first array of distance measurements to a first machine direction edge of the stack and a second array of distance measurements to a second machine direction edge of the stack.

[0081] A technical advantage of the manufacturing method according to the present disclosure is that the method further includes analyzing the first array and the second array for conformance to specification requirements of the final product, the analysis including transmitting the arrays to a processor that executes a computer program to select a target wallboard in the stack and calculate a width and edge profile of the target wallboard.

[0082] Embodiments include those in which selecting a target wallboard includes finding horizontal and vertical coordinates for each of two lower vertices and each of two upper vertices of the target wallboard in the array. Preferably, finding the lower vertices may be performed by using decreasing distance measurements, and finding the upper vertices is performed by using increasing distance measurements. In further embodiments, the method may include calculating a width value of the target wallboard, classifying the stack as width value conforming if the width value of the target wallboard is within a width tolerance range, and as width value non-conforming if the width value of the target wallboard is not within the width tolerance range, and moving the stack to a taping station if the stack is classified as width value conforming, and moving the stack for recycling if the stack is width value non-conforming.

Claims

1. 1. A method for preparing kiln backwall board for shipment, comprising: i) scanning with a laser beam of a first 2D laser scanner at least a first portion of a cross-machine surface of a stack of at least two wall plates, the first wall plate having a first front long surface and the second wall plate having a second front long surface, the second front long surface of the second wall plate being positioned above the first front long surface of the first wall plate in the stack; a first portion of the stack including a first machine direction edge of the stack, and a first array of distance measurements from the first 2D laser scanner to the scanned first portion are generated using a sensor of the first 2D laser scanner, each measurement in the first array of distance measurements having a horizontal coordinate x and a vertical coordinate y; ii) scanning at least a second portion of the cross-machine surface of the stack, including an edge of the stack opposite the first machine direction, with a laser beam of a second 2D laser scanner and generating a second array of distance measurements from the second 2D laser scanner to the scanned second portion using a sensor of the second 2D laser scanner, each measurement in the second array having a horizontal coordinate x and a vertical coordinate y; iii) transmitting the first array of distance measurements and the second array of distance measurements to a processor; iv) executing a computer program with a processor to select a subset of distance measurements from the first array and the second array for a second wallplate, the second wallplate being a target wallplate; v) generating an edge profile of the target wallboard from the subset of distance measurements; vi) calculating a width value of a target wallboard, and classifying the stack as width value conforming if the width value of the target wallboard is within a width tolerance range, and classifying the stack as width value non-conforming if the width value of the target wallboard is not within the width tolerance range; vii) moving the stack to a taping station if the stack is classified as width value compliant, and moving the stack for recycling if the stack is width value non-compliant.

2. The following features: - the width tolerance is defined as the specified nominal value plus or minus 3 / 32 inches (-2.4 mm); - the stack comprises 2, 3, 4, 5 or 6 wall plates, and / or The method of claim 1 further characterized by one or more of: - the wallboards in the stack have straight machine direction edges or tapered machine direction edges.

3. Step iv) is a) executing a computer program with said processor to analyze said first array and identify, within said first array, horizontal and vertical coordinates of vertices between said rear long surface of said first wallboard and said machine direction edge of said first wallboard, preferably by using decreasing distance measurements within said array; b) determining horizontal and vertical coordinates of a vertex between the machine direction edge of the first wallboard and the front long surface of the first wallboard, preferably by using incremental distance measurements in the array; c) identifying horizontal and vertical coordinates of a vertex between the front long surface of the second wallboard and the machine direction edge of the second wallboard, preferably by using decreasing distance measurements in the array, and marking these coordinates as a first lower vertex of the target wallboard; d) identifying horizontal and vertical coordinates of a vertex between the rear long surface of the second wallboard and the machine direction edge of the second wallboard, preferably by using incremental distance measurements in the array, and marking these coordinates as a first upper vertex of the target wallboard; e) repeating steps a) through d) for a second array to mark the coordinates of a second lower vertex and a second upper vertex of the target wallboard; f) using a subset of the distance measurements between the two lower vertices and the two upper vertices in steps v) and vi) to generate an edge profile and calculate a width value.

4. The following features: - the first 2D laser and the second 2D laser are the same; the method further comprises the step of displaying the edge profile generated in step v) on a display device, the method further comprising the step of sending a signal from the processor to a controller when the stack is classified as width value non-compliant; and / or - the stack is positioned on a post-kiln conveyor with a rear long surface of the first wall panel disposed on a surface of the post-kiln conveyor.

5. 1. A system for manufacturing wallboard, comprising: Wallboard production line, one or more kilns configured to receive wallboard from a wallboard production line; a post-kiln conveyor configured to receive two or more stacks of wallboard from one or more kilns, the post-kiln conveyor further configured to move the stacks along a length of the post-kiln conveyor; one or more 2D laser scanners positioned at a distance from the post-kiln conveyor, the one or more 2D laser scanners having a field of view from a location on the cross-machine surface of the stack located at a location along the length of the post-kiln conveyor.

6. The system has the following features: the system further comprises a taping station configured to receive the stack from the post-kiln conveyor; the one or more 2D laser scanners are operatively arranged with a processor, the processor being operatively arranged with a non-transitory computer readable medium, the non-transitory computer readable medium storing a computer program that, when executed by the processor, selects a single target wallboard from the stack for calculation and calculates a width and an edge profile of the target wallboard in the stack; the system further comprises a controller operatively arranged with the one or more 2D laser scanners; and / or The system of claim 5, further characterized by one or more of the following: - the one or more kilns have several shelves, each shelf configured to accommodate one or more wallboards.

7. 1. A method for manufacturing wallboard, comprising: mixing a gypsum slurry from calcined gypsum, water, and one or more additives; depositing the gypsum slurry onto a facer paper cover sheet that moves continuously on a production line; covering the gypsum slurry with a backing paper cover sheet; forming a ribbon precursor of a wallboard; cutting the ribbon into wallboards; transferring the wallboard to a kiln; drying the wallboard in a kiln; placing the wallboards in a stack of two or more wallboards on a post-kiln conveyor while removing the wallboards from the kiln; moving the stacks on the post-kiln conveyor past a location where each stack is scanned on its cross-machine surface with a 2D laser to generate a first array of distance measurements for a first machine direction edge of the stack and a second array of distance measurements for a second machine direction edge of the stack.

8. 8. The method of claim 7, further comprising analyzing the first array and the second array for conformance to end product specification requirements, the analysis comprising transmitting the arrays to a processor, the processor executing a computer program to select a target wallboard in the stack and calculate a width and edge profile of the target wallboard.

9. 9. The method of claim 8, wherein selecting the target wallboard comprises finding horizontal and vertical coordinates for each of the two lower vertices in the array and finding horizontal and vertical coordinates for each of the two upper vertices of the target wallboard.

10. The method of claim 9 , wherein locating the lower vertex is performed by using the decreasing distance measure and locating the upper vertex is performed by using the increasing distance measure.

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