Volume weighing system for onboard dynamic verification

Abstract

Wireless techniques that measure gross weight of sheet material on finished reels generate real-time weight readings. An apparatus for determining gross weight of sheet material on a roll, the apparatus comprising: a reel equipped with an RFID tag to identify its tare weight and / or its reel identification number, where the reel is configured to wind the sheet of material; means for lifting a roll of material wound on the reel and comprising a sensor configured to sense a force generated by the roll of material when lifted and to transmit a wireless signal comprising information representative of the force generated by the roll; and means for calculating the gross weight of the sheet of material wound on the roll. Rapid dynamic correlation between actual weight measurement and on-line weight measurement is achieved. Operating parameters of the actuator and the sensor can be adjusted after verification.

Description

Technical Field

[0001] The present invention generally relates to quality control techniques for manufacturing sheet materials, and more particularly to a system for measuring the actual gross weight of a roll immediately after it is produced in a sheet manufacturing facility. The weight data allows dynamic verification of the accuracy of the online basis weight measurement so that adjustments can be made to the operating conditions of the sheet manufacturing process. Background Art

[0002] In-line measurements are used to detect properties of sheet material during manufacture to enable prompt control of the sheet manufacturing process and thereby ensure sheet quality while reducing the amount of reject sheet material produced.

[0003] When making paper on a continuous paper machine, a paper web is formed on a traveling screen papermaking fabric by an aqueous suspension of fibers (slurry), and water is drained through the fabric by gravity and suction. The web is then transferred to the pressing section, where more water is removed by pressure and vacuum. The web then enters the dryer section, where steam-heated dryers and hot air complete the drying process. A papermaking machine is essentially a dewatering system. A typical forming section of a papermaking machine includes a continuously traveling papermaking fabric or wire that travels on a series of dewatering elements (such as table rolls, foils, vacuum foils, and suction boxes). The slurry is carried on the top surface of the papermaking fabric and is dehydrated to form a sheet of paper as it travels on a continuous dewatering element. Finally, the wet sheet is transferred to the pressing section of the papermaking machine, where enough water is removed to form a sheet of paper.

[0004] It is well known to continuously measure certain properties of paper materials in order to monitor the quality of the finished product. These online measurements typically include basis weight, moisture content, and sheet thickness (i.e., thickness). These measurements can be used to control process variables with the goal of maintaining output quality and minimizing the amount of product that must be discarded due to disturbances in the manufacturing process. Online sheet property measurements are typically accomplished by scanning sensors that periodically sweep the sheet material from edge to edge. After the sheet material leaves the main dryer section or at the take-up reel, the basis weight and / or thickness of the sheet material is typically measured with a scanning sensor. The basis weight of the produced sheet material is an important property, yet current production methods only provide online measurement estimates. Summary of the invention

[0005] The present invention is based in part on the development of wireless technology that measures the gross weight of sheet material wound on a finished product reel, which generates real-time weight readings to a control system. The actual weight measurement allows for rapid dynamic correlation and verification of the online estimated weight measurement. The operator can then adjust the operating parameters of various actuators and sensors in the papermaking process in response to the measurement discrepancies.

[0006] In one aspect, the present invention relates to a sheet material production system, the sheet material production system comprising:

[0007] a sheet of material moving in the machine direction (MD);

[0008] one or more actuators configured to form a sheet of material containing a liquid;

[0009] means for drying the sheet of material comprising the liquid to form a sheet of dried material;

[0010] means for calculating the basis weight of the sheet of dry material;

[0011] means for winding the produced travelling sheet of dry material to form a roll of material; and

[0012] Means for weighing the roll of material. Preferred means for weighing the roll comprises a load cell, which refers to any type of sensor that can be used to measure force, such as, for example, a force sensor, a force transducer, or the like.

[0013] In another aspect, the present invention relates to a method of operating a sheet manufacturing system that produces a continuous sheet traveling in the MD, the method comprising:

[0014] (a) forming a sheet of material comprising a liquid;

[0015] (b) determining the basis weight of the sheet of material;

[0016] (c) winding the advancing sheet of material into a roll;

[0017] (d) calculating the weight of the roll of sheets of the material using the basis weight determined in step (b) to produce an estimated weight; and

[0018] (e) weighing the roll to determine the actual weight of the sheets of material in the roll.

[0019] In another aspect, the invention relates to an apparatus for determining the gross weight of a sheet material on a roll, the apparatus comprising:

[0020] a reel equipped with a radio frequency identification (RFID) tag to identify its tare weight and / or its reel identification number, wherein the reel is configured to wind the sheet of material;

[0021] a device for lifting a roll of material wound on the reel, and the device includes a sensor configured to sense a force generated by the roll of material when being lifted and to transmit a wireless signal including information representative of the force generated by the roll of material;

[0022] and

[0023] A device for calculating the gross weight of the sheet of material wound on the roll.

[0024] In one embodiment, the apparatus includes a pair of lifting devices, each lifting device is equipped with a load sensor connected to a Wi-Fi signal transmitter or a Bluetooth signal transmitter.

[0025] While the invention will be shown as being implemented in papermaking, it will be appreciated that the invention is applicable to other continuous sheet manufacturing processes, such as, for example, in manufacturers of rubber sheets, plastic films, lithium ion battery electrodes, fabrics, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the papermaking system;

[0027] Figure 2 It is a scanning sensor;

[0028] Figure 3 is a side view of a lifting mechanism for weighing the roll; and

[0029] Figure 4 Schematic diagram of the lithium-ion battery electrode manufacturing system. DETAILED DESCRIPTION

[0030] Figure 1 A sheet material manufacturing system 10 is shown including a paper machine 2, a control system 4, and a network 6. The paper machine 2 produces continuous sheets of paper material 12 having a width that may exceed 10 meters, which are collected in a take-up reel 14. The paper material 12 of a particular width is produced from a pulp suspension stock consisting of an aqueous mixture of wood fibers and other materials, which undergoes various unit operations monitored and controlled by a quality control system 4. The network 6 facilitates communication between the components of the system 10.

[0031] The paper machine 2 includes a headbox 8 that evenly distributes an aqueous pulp suspension onto a continuous screen or wire 30 on the machine that moves in the machine direction (MD). The headbox 8 includes a slicing opening through which the pulp suspension is distributed onto the screen or wire 30, which includes a suitable structure, such as a mesh for receiving the pulp suspension and allowing water or other materials to drain or leave the pulp suspension. The formation of the paper sheet 12 is affected by a plurality of linear actuators 3 extending across the cross direction of the formed paper sheet 12. The actuators 3 control the weight of the sheet in the cross direction (CD). Sensors located downstream of the actuators measure the properties of the sheet. The stock is fed from the headbox onto the wire section 30 through a gap or elongated orifice 5. The orifice or gap is a relatively narrow opening extending across the width of the machine. Weight distribution control in this arrangement is achieved by locally adjusting the position of the slicing lip across the machine with a motorized linear actuator 3 to change the size of the gap or orifice immediately adjacent the actuator. As used herein, the "wet end" forming portion of the sheet manufacturing system 10 includes the headbox 8 and wire 30 and those sections before the wire 30, and the "dry end" includes the section downstream of the wire 30.

[0032] The sheet 12 then enters a press section 32 comprising a plurality of press rolls, wherein the sheet 12 travels through an opening (referred to as a "nip") between pairs of counter-rotating rolls in the press section 32. In this manner, the rolls in the press section 32 compress the pulp material to form the sheet 12. This can help remove more water from the pulp material and equalize the properties of the sheet 12 on both sides thereof. A tachometer 38 measures the MD line speed.

[0033] As the sheet 12 travels over a series of heated rollers in the dryer section 34, more water in the sheet 12 is evaporated. The calender 36 processes and conditions the sheet 12, for example by smoothing and imparting a finish, thickness, gloss, or other properties to the sheet 12. Other materials, such as starch or wax, may also be added to the sheet 12 to obtain a desired finish. An array of induction heating actuators 24 applies heat to one or more of the rollers along the CD to control the roller diameter and, thereby, the size of the roller gap. Once processed by the calender 36, the sheet 12 is collected on a reel 14. A Wi-Fi or Bluetooth receiver is positioned near the reel 14.

[0034] The sheet manufacturing system 10 also includes an array of steam actuators 20 that control the amount of hot steam projected along the CD. The hot steam increases the paper surface temperature and allows water to be removed more easily from the cross direction of the paper sheet. In addition, to reduce or prevent over-drying of the paper sheet, the paper material 14 is sprayed with water in the CD. Similarly, an array of rewet shower actuators 22 controls the amount of water applied along the CD.

[0035] To control the papermaking process, selected properties of the sheet 12 are continuously measured, and the papermaking machine 2 is adjusted to ensure sheet quality. Typical physical properties of paper that can be measured include, for example, thickness, basis weight, moisture content, chemical composition such as ash, surface roughness, gloss, thickness, color, and wrinkle pattern surface features. CD control can be achieved by measuring sheet properties using one or more scanners 26, 28 that can scan the sheet 12 and measure one or more properties of the sheet 12. For example, the scanner 28 can carry a sensor for measuring the dry weight, moisture content, ash content, or any other or additional properties of the sheet 12. The scanner 28 includes a suitable structure for measuring or detecting one or more properties of the sheet 12, such as a collection or array of sensors. The scanner 28 is particularly suitable for measuring the dry end dry weight and thickness of the paper product at the take-up reel 14. Suitable thickness scanning sensors are described in U.S. Pat. No. 6,967,726 to King et al. and U.S. Pat. No. 4,678,915 to Dahlquist et al., which are incorporated herein by reference.

[0036] The measurements from the scanners 26 and 28 are provided to the control system 4, which regulates various operations of various actuators or paper machine 2 that affect the machine direction and cross direction properties of the sheet 12. The machine direction properties of the sheet 12 generally refer to the average properties of the sheet 12 that vary in the machine direction and are controlled. In this example, the control system 4 is capable of controlling the dry weight of the paper sheet by regulating the supply of pulp to the headbox 8. For example, the control system 4 may provide information to a pulp flow controller that regulates the flow of pulp through a valve and to the headbox 8. The control system 4 includes any hardware, software, firmware, or combination thereof for controlling the operation of the sheet making machine 2 or other machine. The control system 4 may, for example, include a computer having a processor and a memory that stores instructions and data used, generated, and collected by the processor.

[0037] Figure 2 A specific embodiment of the scanning sensor is shown, which is located at the dry end, just at Figure 160 is moved back and forth in CD over the entire width of a moving sheet 60, which moves in MD, so that the characteristics of the entire sheet can be measured. The scanner 58 or measuring instrument is supported by two transverse beams 52 and 62, on which the upper scanning head 54 and the lower scanning head 56 are mounted respectively. The operating surfaces of the lower scanning head 56 and the upper scanning head 54 define a measurement gap or window for accommodating the sheet 60. The lower scanner head 56 may include a sheet stabilization system, such as an air bearing stabilizer (not shown), to keep the sheet in a consistent plane as it passes through the measurement window. The movement of the dual scanner heads 54, 56 is synchronized in speed and direction so that they are aligned with each other. The scanner is also equipped with an edge detector (not shown) for measuring the width of the sheet.

[0038] Depending on the property being monitored, the scanning sensor can be configured to operate in either a transmission mode or a reflection mode. Basis weight scanning sensors are described, for example, in U.S. Pat. No. 10,935,368 to Tixier and U.S. Pat. No. US2015 / 0022220 to Tixier and Hughes, which are incorporated herein by reference. For example, the scanner head 54 can house a radiation source that directs a radiation beam into the moving web or sheet 26, and the scanner head 56 can house a radiation receiver that detects radiation transmitted through the material. As the dual scanner heads advance back and forth along the CD, the sensor measures one or more properties of the web or sheet 60. In the reflection mode, the upper scanner head 54 can house both a radiation source and a detector to measure one or more characteristics of the web or sheet 26.

[0039] During the paper production process, the basis weight, thickness, sheet width and machine direction speed of the moving paper sheet are continuously monitored. The accumulated data allows the weight of the paper to be estimated when it is wound onto the reel of the finished roll.

[0040] Figure 3 A wound roll of sheet or web material 82 is shown having reached its desired diameter and in contact with a support drum 94. The reel 84 includes a shaft 86 that rests on a support rail 92 secured by posts 88, 90. It will be appreciated that each of the two ends of the reel is supported by a support rail. The reel 84 may also have a bearing housing (not shown) at each end that contacts the support rail. The RFID tag 80 secured to the reel 84 has an assigned identifying reel number and / or reel tare weight. The identification numbers of a plurality of reels used in a paper mill and their associated tare weights may be stored in the control system 4( Figure 1 ) in a database. In this way, once the identification number of the reel is known, its tare weight can be retrieved from the database.

[0041] RFID tags can be passive, active, or battery-assisted passive. Active tags have a battery and transmit a signal intermittently. When a battery-assisted passive tag is activated by an RFID reader, it is activated. Passive tags do not have a battery and use radio energy transmitted by the reader as its energy source. Passive tags include an integrated circuit coupled to a transponder antenna to receive an interrogation signal from the RFID reader antenna and transmit a transponder signal. In this example, the tag used is passive. Reading or scanning the reel label 80 displays the unique identification number of the reel, which in turn allows its tare weight to be retrieved from a database. Alternatively, the tare weight may be stored in the label 80 so that reading the label will display the tare weight.

[0042] The lifting device 96 includes a cable 98 having a distal end 100 that can be attached to an overhead crane or bridge crane (not shown) and a proximal end that is secured to the top end of a strain gauge load sensor 104 and to the lower end of which a crane hook 106 is connected. The load sensor is operatively connected to a wireless transmitter 108.

[0043] The load sensor 104 is capable of sensing the weight of the roll 82, and the transmitter sends a wireless signal including information representative of the weight. In operation, a pair of lifting devices are employed to lift the roll 82, each lifting device having a weight sensor and an associated wireless transmitter. The two load sensors in the pair of lifting devices are calibrated so that their combined readings indicate the weight of the roll. The transmitter device may be configured to operate according to any known wireless communication protocol such as, for example, Wi-Fi and Bluetooth. The wireless receiver 40 ( Figure 1 ) receives a weight signal from the pair of transmitter devices.

[0044] Figure 3 The RFID reader 110 in the embodiment has an antenna capable of sending an interrogation signal and receiving an RFID transponder signal from the reel tag 80 in response to the interrogation signal. The reel tag transponder signal includes its identification number and / or tare weight. The RFID reader 110 is operatively connected to the control system 4 ( Figure 1 ), the control system processes the transponder signal from the reel RFID tag. In addition, the control system 4 receives a weight signal from a pair of wireless transmitter devices. Based on this information, a computer in the control system calculates the actual gross weight of the sheet by subtracting the tare weight of the reel 84 from the weight of the roll 82. The computer also compares the actual gross weight with the estimated gross weight derived from the online measurement.

[0045] The invention may be applied to other sheet manufacturing processes producing liquid-containing materials wound into rolls, such as in the production of lithium-ion electrodes. Figure 4A process is shown for coating a metal web or sheet used to make electrodes for lithium ion electrochemical cells and batteries. To make the anode, the electrode coating contains an anode active material such as graphite, and to make the cathode, the electrode coating contains a cathode active material such as lithium metal oxide. The electrode includes a current collector metal foil coated on both sides of the foil with an electrode slurry, which may also contain carbon black, a binder, and a solvent. After the electrode slurry is applied to one side of the foil, the wet coated foil is heated in a dryer to extract the solvent, leaving a solid layer of electrode material adhered to the metal foil. Copper foil is the preferred anode current collector material, and aluminum foil is the preferred cathode current collector material. As Figure 4 As shown in FIG, a roll 200 is unwound from an unwinder and supplies a continuous metal web or sheet 230, which is coated with a layer of electrode slurry on the top surface by a coater 206. The basis weight, thickness and other characteristics of the metal web or sheet 230 from the roll 200 are generally known; the basis weight and / or thickness are measured using scanning beta meters 204 and 208, respectively, before and after the electrode slurry is applied by the coater 206.

[0046] The coater 206, such as a cast coater, includes an actuator that controls a slot die / blade to adjust the amount of slurry extruded onto the sheet 230. The dryer 210 removes excess solvent and solidifies the slurry on the moving coated sheet 232 to form an electrode layer on the sheet. The imaging devices 258 and 278 capture surface images of the coated sheet 232 before and after the dryer 210.

[0047] The scanning beta meter 212 measures the basis weight and / or thickness of the moving coated sheet 232 exiting the dryer 210 after the calender 254. The rolling supports 234, 236 then reverse the orientation of the moving sheet 238 so that the uncoated side is on top, whereupon the coater 214 applies a layer of electrode slurry on the top uncoated surface of the moving sheet 238. The basis weight and / or thickness of the double-sided coated sheet 240 is then measured with the scanning beta meter 16 before entering the dryer 218. The imaging devices 270, 272, 274, and 276 are strategically positioned to capture top and bottom surface images.

[0048] Further downstream, as the scanning device 224 moves back and forth on the double-sided coated sheet 242, a beta meter housed in the scanning device 224 together with an infrared temperature sensor measures the basis weight and / or thickness and temperature of the double-sided coated sheet 242. Specifically, the basis weight of each electrode layer is measured. The rewinder winds the double-sided coated sheet 242 into a roll 244, which includes a reel 246 supported on a guide rail (not shown). Surface defects on the top and bottom coatings are monitored by imaging devices 226, 228. The roll 244 is usually transferred to a calendering station, whereby the double-coated electrode layer from the roll is unwound and passed through a calender, which trims and smoothes the electrode layer.

[0049] The reel 246 includes an RFID tag that transmits an identification number and / or its tare weight. Figure 3 The pair of lifting devices shown in Figure 24 is used to obtain the weight of the roll 244. The gross weight of the roll 244 is determined by subtracting the tare weight of the reel 246 from the roll weight.

[0050] The foregoing describes the principles, preferred embodiments and modes of operation of the present invention. However, the present invention should not be construed as being limited to the specific embodiments discussed. Therefore, the above embodiments should be considered as exemplary rather than restrictive, and it should be understood that variations may be made in these embodiments by those skilled in the art without departing from the scope of the present invention as defined by the following claims.

Claims

1. A sheet production system, comprising: a sheet of material moving in a machine direction; one or more actuators configured to form a sheet of material containing a liquid; means for drying the sheet of material comprising liquid to form a sheet of dried material; means for calculating the basis weight of the sheet of dry material; means for winding the produced travelling sheet of dry material to form a roll of material; as well as Means for weighing the roll of material.

2. The system of claim 1 wherein the means for winding the advancing sheet of dry material comprises a reel onto which the advancing sheet of dry material is wound and wherein the reel has a radio frequency identification tag for identifying the reel and / or the weight of the reel.

3. The system of claim 2, comprising a computer including a database containing weight information for a plurality of reels associated with the sheet material production system.

4. The system of claim 1 , wherein the device for weighing the roll of material is configured to lift the roll of material and the device includes a sensor configured to sense a force generated by the roll of material when lifted and to transmit a wireless signal including information representative of the force generated by the roll of material.

5. The system of claim 4, wherein the sensor is operatively connected to a Wi-Fi transmitter or a Bluetooth transmitter.

6. A method of operating a sheet material manufacturing system for producing a continuous sheet material travelling in a machine direction, the method comprising: (a) forming a sheet of material comprising a liquid; (b) determining the basis weight of the sheet of material; (c) winding the advancing sheet of material into a roll; (d) calculating the weight of the roll of sheets of said material using the basis weight determined in step (b), to produce an estimated weight; as well as (e) weighing the roll to determine the actual weight of the sheets of material in the roll.

7. The method of claim 6 wherein in step (c) the traveling sheet material is wound on a reel and step (e) comprises lifting the roll of material and weighing the roll of material using a sensor that transmits a wireless signal including information representative of the weight of the roll and then subtracting the weight of the reel from the weight of the roll.

8. An apparatus for determining the gross weight of sheet material on a roll, comprising: a reel equipped with a radio frequency identification (RFID) tag to identify its tare weight and / or its reel identification number, wherein the reel is configured to wind the sheet of material; means for lifting a roll of material wound on the reel, and the means comprising a sensor configured to sense a force generated by the roll of material when lifted and to transmit a wireless signal including information representative of the force generated by the roll of material; as well as Means for calculating the gross weight of the sheet of material wound on said roll.

9. The device of claim 8, wherein the sensor is operatively connected to a Wi-Fi transmitter or a Bluetooth transmitter.

10. The apparatus of claim 8, wherein the sensor comprises a load sensor arranged to detect a force generated by the weight of the roll when lifted.

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