Double sheet detector. But in sheet feed printing and stamping process, doubles are definitely viewed as a negative connotation. Double sheet detector

 
 But in sheet feed printing and stamping process, doubles are definitely viewed as a negative connotationDouble sheet detector  check the sensor heights

Double sheet detection of steel sheets with 1 mm thickness, 120 % double sheet threshold and two PW42AGS sensors requires in the sequencer mode only 115 milliseconds. Buy Surplus As Low As. Smart and smarter, this Double Sheet Detection System, when paired with an electromagnetic, smart sensor, uses pulse and release technology, where the sensor will take the reading and release the sheet for easy. A constant gap is very important since a small change in gap causes significant change in the sensor signal. The double sheet detector E20 can reliably prevent this from occuring. The following situations can be detected: No sheet, i. 00 - $3,500. Ultrasonic double sheet sensors help ensure continuous, error-free processes in a range of industrial applications. A100 Rev. Ultrasonic double sheet detector Hi, it's way too late to reply for you. 3/2 valve is just behind the double sheet detector with two air hoses going to it. Ultrasonic system for reliable detection of no, one, or two overlapping sheet materials, Insensitive to printing, colors, and shining surfaces, Perpendicular or inclined sensor mounting relative to the sheet plane possible, Sensing range: 20. Double sheet sensors are ultrasonic thru-beam sensors that have been optimized specifically for sheet feed applications, including double sheet detection, label counting, and splice detection. Backed by 25+ years of experience, Prime Controls’ extensive line of world-class double sheet detection solutions improve your bottom line, boost product quality, and ramp up your manufacturing efficiency. dbk+5/3CDD/M18 E+S. R100 Series security sensors pdf manual download. emmet, Jan 2, 2009, in forum: 4-Color Offset Presses + Replies: 7 Views: 8,514. The device works by measuring the thickness of the material fed, if excessive thickness is detected, the device triggers an alert or halts the process. A double-sheet detector can either be mechanical or electric, and is attached to a caliper roller placed between the forwarding rollers. Parallel interfaces to PLC, 9 Fieldbus Systems. His company provides technology for. MICROSONIC GmbH - Double Sheet Detectors – using ultrasonic technology has broken all previous performance records. Double sheet or multiple sheets (a statement on the number of sheets is not possible here) The signals are evaluated by a microprocessor system. . An image reproduction device is provided with an automatic feed unit for documents; a double-sheet detector for detecting more than one single sheet as the document for copying; an operator control unit provided with an operator control panel; and a control unit connected to the said units for controlling the automatic feed unit, processing the signal. grapha Dec 26, 2012. Protected With SSL Certificate. 9 M A100 Data Sheet. Can detect sheets with min thickness of . housing with two probes to form a system that detects the thickness of metals passing between. 25 in. Different sheet materials and layer thicknesses can beThe invention relates to a high-precision ultrasonic double-sheet detector. The recommended mounting angle for cardboard types is ≥ 35°. The dbk+4 detects missing, single and double sheet. Reliable double material detection is easier than ever before with the new range of IO-Link double sheet sensors in an M18 or M30 design from Pepperl+Fuchs,. The measurement of ferrous material is . 004 to . 5 mm 0. It is provided with an electronic circuit box which is installed with a number of encoders, transmitters and receivers for the. bopster, Apr 12, 2014. 3 mm thick, fine corrugated card, wafers, PCBs. The sensor technology offers accurate detection and prevention of double sheet overlap or misfeeds, ensuring operational efficiency and minimizing production errors. 1 (spec. 51 Add to Cart. Signal conditioners (50) receive signals from the radiation. Material + Thickness: FE-Material: up to 4 mm. Our double sheet detectors are trusted by the top automakers from around the world. Lcegraphics. The new TNxxS sensors complete the system A100 by sensors, which are provided with a plug connection. 9 M A100 Datenblatt. Page 81 The system will perform a punctual Teach-In for 2-sheet. 00-+ Add to cart. United States. A. e. Sheet Metal Thickness Sensor - Economic Double Sheet Metal Sensor BDK DuoFlex, non-contact double-surface controlling, variable fi. Email. The device can be programmable in 255 different sheet thickness. Underneath the feed board on the DS you should find a black box which is mounted to the side frame. ) Double sheet detectors for 230V or 110V supply voltage, connectin by screw terminals. 4 degrees over the small range you. The new Pulser Double Sheet Detector features a newly-designed single probe with a pulsed electromagnet that. AA-Argusauge DE Rev15. 16in. Bounty Hunter Junior: best for younger kids. The thinner the sheet, the more accurate the double sheet detector has to be, I always tore 3 strips of the stock being used and fed them through the double sheeter to trip the top wheel, then backed it off a touch, after that I ran the feeder slowly while holding the top wheel so it wouldn't trip and slowly backed it off until I could feel the top wheel move, then screw it back a touch. If sheets or can stock get through the process in an uncoated or partially coated state, it could cause serious problems, such as can corrosion and blunting of the press tooling in a DRD press. Ultrasonic technology ensures that the detection is independent of the sheet material (fine paper, transparent rolls, cardboard and metallic film, for example). Double Sheet Metal Monitor - Double Sheet Detector BDK for ferrous and non-ferrous sheet metal (contact measurement up to 5. ROLAND ELECTRONIC Double Sheet Detection Systems have proved reliability in many thousand installations worldwide. There are two types of air gaps in case of double sheet control. 1 to 12 mm. It detects double sheets, blanks, and ends at the unloader, coater infeed or outfeed, wicket oven outfeed, slitter infeed, sheet feed presses, and seamer. All probes are potted. 15 de. The following situations can be detected: l No sheet, i. Warranted to be free from defects in materials and workmanship under normal use and service. 002in. The double sheet detection is based on the ultrasonic thru-beam principle. Our double sheet detectors are trusted by the top automakers from around the world. e. Originally, Prime Controls focused on improving Hyde Park’s double sheet detection product line using the latest technology. 435. Mounting of the sensors according to Figure 7 generally results in reliable double-sheet control. PART # 739543. Tags. 7 Safety advices Blank page ROLAND ELECTRONIC GmbH · Otto-Maurer-Str. Inspection of the sheet thickness and output of a warning signal when detecting double sheet. 02. Part No. Horizontal or. The “Double-Sheet Detector Market – Forecast and Analysis 2022-2030” report has been added to Stratagem Market Insights’s offering. air. 3, PROFIBUS DP Sheet Metal Thickness. The double sheet detection is based on the ultrasonic thru-beam principle. Country/Region: China. METHODS FOR DETECTING DOUBLE SHEETS . thickness from one side only and in the case of steel does exert forces only during measurement. Ultrasonic double sheet sensors offer a simple, cost-effective, and flexible solution. The universal BDK-Doublesheet-Detector-system is firmly established in the automotive industry. No catalogs are available for this product. Based on an ultrasonic sound control, sheets lying on top of one another which were picked-up are recognized and actively ejected before they reach the first buckle plate unit. KEYENCE America provides DD series; Non-contact-type double sheet detector prevents double feeding of blank materials. Ultrasonic technology makes double-sheet detection easy. method: Single probe double sheet detection: Function principle: Electromagnetic Eddy current. Score Wheel Blade Thin for Baum 714 BAU-06379. (now ka. Messages: 2. The dbk+5 is manufactured by Microsonic. e. Recommended Substitutes. • Proximity Detection: A significant change to the ultrasonic echo signature corresponds to a physical change to the sensing environment. After removing the (double) sheets from the sensor(s) +24VDC SENSOR +24 VDC1 SPS /IPC the sensor output switches back in the no sheet / one sheet position. In addition to many controls for the can making and sheet metal industries, we produce a full line of metal sensing devices geared towards the detection of double sheets of metal. Product Details: Double Sheet Detectoris a highly sensitive optical ultrasonic sensor unit which is widely used with the automated machines to check whether there is a sheet present in between the paper feeder or not. order no. The retrofitting of capacitive and optical double-sheet detectors, as additions to the standard ultrasonic system, extends the range of substrates which can be printed (up to 1. A double sheet detector includes a pair of rollers forming a nip through which a fed sheet passes, causing the rollers to separate. sensors for thin. Main Products: Proximity Sensor ,Photoelectric Sensor ,Solid State Relay,Switching Power Supply,Ultrasonic sensor. When paper beyond a certain preset thickness passes beneath the roller, the detector shuts off the feeding unit and/or the printing unit. The "Oil suction effect" on metal sheets in a stack, whereby remnants of die lube can allow. <link rel="stylesheet" href="Sheet Detector R1000 Series E20 Electro magnetic principle. 3. sensor for mag. The apparatus includes radiation emitters (14, 34) and radiation detectors (20, 40, 42). 16 in) depending on the type of material (austenite up to 2 mm) Meas. US6636703B2 US09/987,659 US98765901A US6636703B2 US 6636703 B2 US6636703 B2 US 6636703B2 US 98765901 A US98765901 A US 98765901A US 6636703 B2 US6636703 B2 US 6636703B2 Authority US United States Prior art keywords double sheet sheet detector control unit automatic feed Prior art date 2000-11-15 Legal status (The. Signals from the transducer are frequently sensed and averaged over one or more full revolutions of the. pdf 1. Not sure exactly what your looking for in a double sheet detector screen. pdf 1. Cable length max. Datasheet. Detectable Sheet Thickness: Applicable Controllers GD-C3: Setting Distance 5 mm 0. Put a sheet with nominal thickness fully onto the sensor (see connection sketch). A DS150 Series control includes a nice range of controls, including everything from basic to ultimate features. Show all Hide all. Roland Electronic produces and distributes highly specialized systems for Double Sheet Control,Weld Seam Detection,Thickness Measuring,Non-Destructive Testing,Special Products Choose a language Choose a language English Deutsch Français 汉语 Italiano 日本語 Português brasileiro Castellano Türkçe Reliable double material detection is easier than ever before with the new range of IO-Link double sheet sensors. For thicker materials, plastic sheets and coarse corrugated cardboard, the dbk+5 ultrasonic double-sheet detection is used. The double sheet detection is based on the ultrasonic thru-beam principle. the probes. To top. air l Single sheet l Double sheet or multiple sheets (a statement on the number of sheets is not possible here) The signals are evaluated by a microprocessor system. Double Sheet Detector for single probe sensors. used. no) ADD1/2-1. . Failure to detect double sheets of metal or improper thickness can damage tools and dies, resulting in costly repairs and downtime. In addition to the connection of one sensor an option is available to connect four sensors of the same type (E20-4P). For single-sided double sheet control different systems are available: sensor system based on permanent magnets, system with electromagnets and a system with a combination sensor. presses) with automatic feeding systems such as destackers, robots, feeders, etc. As a result of the evaluation, corresponding. 04 to 4 mm sheet thickness. ROLAND ELECTRONIC Double Sheet Detection Systems have proved reliability in many thousand installations worldwide. Double Material Detection Technology Technology—Basics 3. 1) Clean the surface of the double sheet. | 684 followers on LinkedIn. Double Sheet Detector (77 products available) High quality double head and single head metal needle detector manufacturer $2,500. The Model DS62 sinks current through both outputs. 3 — 4 June 2014 4 of 19 NXP Semiconductors SA612A Double-balanced mixer and oscillator 7. Where to Buy. The double-sheet sensor is based on the ultrasonic single pass principle. 160 kg. Double Sheet Detection is an important part of quality control to prevent two or more sheets of metal from entering into a process at one time. 18, 1962 A. double sheet sheet detector control unit document operator control Prior art date 2000-11-15 Legal status (The legal status is an assumption and is not a legal conclusion. 13 is a graph showing examples of adjusted outputs from two correlation filters for a shingled double sheet passing through the detector. By detecting double sheets or thickness measurement, the. Detection of the leading edge of a moving object. Detectable Sheet Thickness: Applicable Controllers GD-C3: Setting Distance 5 mm 0. Innosen’s Double Sheet Detector. A double feed produces an output to stop the machine or signal the operator. When to set to run 2 and trip on 3 sheets (sheet size of 470mm or less) 3. The sensor can detect sheet materials, right from finest paper sheet to metal foil. Model DS161 DOUBLE SHEET DETECTOR . ParaCrawl Corpus. They incorporate a meter to detect ground leaks and unauthorized illegal taps, greatly reducing annual water expenses. Connector Cable, 8 conductor, 5 meters in length, used with DSD-36. The Eagle Eye AA by Roland Electronic is a Double sheet detector which is designed for metal sheets. The double sheet detection is based on the ultrasonic thru-beam principle. (9) Double sheet detector (mechanical and electronic) (10) Paper jam detector (feeder board, blanket, transfer and delivery sections) (11) Paper pull-out device (12) Delivery pile automatic lowering mechanism (13) Delivery table dolly lower limit switch (14) Delivery suction wheel (15) Powder spray device (16) Preset repeat counter with batch Another solution for mounting in magnetic conveyors is to use specific double-sheet detector software. com Dayton, Ohio 45440-1712 F 937. Data sheets. This technology. But I install ultrasonic double sheet detector. For thicker materials, plastic sheets and coarse corrugated cardboard, the dbk+5 ultrasonic double-sheet detection is used. Contact a supplier or the parent company directly to get. Double Sheet Detection is an important part of quality control to prevent two or more sheets of metal from entering into a process at one time. First there is the air gap between sensor and sheet surface (1st air gap) and the air gap between the first sheet and the second sheet (2nd air gap). Failure to detect double sheets of metal or improper thickness can damage tools and dies, resulting in costly repairs and downtime. The double sheet detection is based on the ultrasonic thru-beam principle. There, the occurrence of a double sheet must be reliably detected with an extremely short delay in order to avoid time-consuming and cost-intensive system downtimes. Based on an ultrasonic sound control, sheets lying on top of one another which were picked-up are recognized and actively ejected before they reach the first buckle plate unit. The apparatus includes radiation emitters (14, 34) and radiation detectors (20, 40, 42). DSD-PW OVERVIEW-SENSORS EN Rev. From a wide range of double sheet detectors, designed to ensure no two sheets of metal enter a press, to light leak detection for finding very small pinholes in can bodies at high speeds online during the leak testing process, Prime Controls’ solutions keep can. trip switch wheel, the double sheet detectors are set by placing three sheets between the detector wheel and a trip switch present into the feed board. The IS651 Missing Lacquer Detector detects sheets that are not fully lacquered or varnished. Whether detecting paper, foil, wood, metal, or even highly reflective solar wafers, UDC-18GS-*IO-* and UDC(M)-30GS-*IO-* sensors. AA-Eagle-Eye EN Rev15. com Mar 16, 2010. 2091 PRODUCT SPECIFICATIONS POWER INPUT: 100 to 240 VAC, 50/60 Hz, 300 mA operating load OUTPUTS: 2 SPDT contact relay (over, under). This can result in damage to the machine, tool damage, expensive repairs and production loss. 2 /3) either runs on the sheet stream (standard setting) or is positioned slightly above the sheet surface. Click to Contact Seller. Print. e. A100 Rev. The bottom roll (Fig. 1. 9 M A100 Data Sheet. Units are available in two sizes with 13 jaw styles each, up to 500 pounds clamp force, and include many options for mounting, switches, and tips. Dual Probe Detection (Non-contact) is a thickness measurement technique using a transmitter probe pointed in the direction of a receiver. Directory at Precision Metalforming Association. Particularities: Linearized air gap tolerant double sheet sensors. 60 mm , optimal distance: 45 mm. Free on-site demonstrations and testing. INVENTOR. 15 en. Backflow preventer valve 350ASTDA has double check detector assembly with stainless steel body, grooved gate valve. DOUBLE CTRL PROBE ® DESCRIPTION The Model DS160 Double Metal Sheet Detector comprises a control module in a sheet metal housing with one probe to form a system that detects the thickness of non-ferrous metals in front of the probe. 6 M Argusauge AA Datenblatt. DESCRIPTION. The Model DS152 Double Metal Sheet Detector comprises a control module in a sheet metal housing with two probes to form a system that detects the thickness of metals passing between the probes. #3. The IS231 Double Sheet Detector is a fully automatic sensor that never requires any adjustments during change of sheet thickness and material. The detector system may be used on automatic sheet feeders where double or overlapped sheet material may jam or damage the receiving machine. g. The non-contact dual head systems are especially well suited for pass-through Double Sheet Detection. The following situations can be detected: l No sheet, i. . 884. Since the most sensitive area of the ultrasonic sensor is at the center of the transducer, the center of the sound beam must be. 4 / 13. 1) Inductive with Dual Probes (Non-contact) 2) Eddy Current with Dual Probes (Non-contact) 3) Magnetic with Single Probes (Contact) INDUCTIVE WITH DUAL PROBES . Data sheets. The detector system may be used on automatic sheet feeders where double or overlapping sheet. No adjustments, no settings required to differentiate single & double sheets of paper, synthetic or similar material even with dissimilar combinations. Double feed detection of various metal sheets. doc @ 3188 Electro magnetic principles – microcontroller based Single – sided contact double sheet control of ferrous materials No force after measurement 4 exchangeable sensors for double sheet. DOUBLE SHEET CONTROL SYSTEM I100 Application When feeding sheets automatically, more than one sheet can be inadvertently fed into the processing machine. A100 Rev. Differentiates between one and two blank sheets. Please call or email us with your request. 4528 Gateway Circle T 937. Aug 2, 2009. Double Sheet Detector on Heidelberg CD102 Year 2000. 06", 2 hours in each of the X, Y, and Z directions. Try cleaning (dusting off) your feed board sensors (the electronic double sheet detector as well as the sensor under the transfer cylinder, you have to reach under to get to that one. 9 M A100 Datenblatt. The signal from the stacked sheet ("double sheet") is so weak that it hardly gets to the receiver. NF-material: up to 4 mm (up to . 435. The following situations can be detected: No sheet, i. 08 to 3. 50in. 2 Examples for double end detection: Fig. Meas. Search Attributes: Ultrasonic double sheet sensors from Pepperl+Fuchs are ideal for double-sheet monitoring of paper, cardboard, plastics, metals, and more. 05 - 4 mm (. The attenuation of the receiver signal is displayed, analyzed and issued as a 0-1-. Keyence. Particularities: Linearized air gap tolerant double sheet sensors. 5000 lbs. Quick pricing from your local KEYENCE sales engineer. The following situations can be detected: No sheet, i. Inch the press to 147 degrees and check the values in these positions. Double sheet and double material sensors distinguish between empty gaps, one, and two layers of material, including paper, metals, wooden boards,. Backed by 25+ years of experience, Prime Controls’ extensive line of world-class double. 2500 mm x 1250 mm. The following situations can be detected: l No sheet, i. USA: +1 330 486 0001. 4. Our systems are created by combining a control4 colour offset Heidelberg SM74-4 low pile 1994 115 mio. 50in. 1) Inductive with Dual Probes (Non-contact) 2) Eddy Current with Dual Probes (Non-contact) 3) Magnetic with Single Probes (Contact) INDUCTIVE WITH DUAL PROBES . Single sheet. (single sheet thickness) - Non-ferrous materials . KEYENCE DD series Price Request Page: As a direct supplier, KEYENCE. Leading developer and manufacturer of sensors and controls for manufacturing environments. To top. The thickness is reported via two form C relays as "nominal", "over", "under" or. Keyence DD-860 Double Sheet Detector Sensor Amplifier Unit. Ambient dataKlaschka offers a wide range of Double Blank Detectors for sheet detection and thickness measurement in the metal-forming industries. Using a good grade of spray contact cleaner such as CRC QD, flush all dirt and grease from all the moving parts surfaces. ), single sheet thickness ; Suitable for fluttering sheets ; Easy setup by. Manufacturer: Komori Model: LS 840 P Feeder with double sheet detector, pile side lay, manual non-stop, pallet feeder, side blowers Komorimatic dampening system Nip follower Ink remote control system Cooled ink rollers Speed reduction in. 17 · DE 75210 Keltern · Phone +49 (0)7236-9392-0 · Fax +49 (0)7236-9392-33. Data Sheet (PDF) Other Models. Double sheet feed detector and method . Functional description The SA612A is a Gilbert cell, an oscillator/buffer, and a temperature-compensated bias network as shown in Figure 3. 05 - 12 mm ( . Page 7: Declaration Of Conformity According To Ec Directives 1. More+. Page 40 Manual Double Sheet Detector R100 I100 for pairs of sensors B0003308 / 1. UM18-20012 | UM18 Double Sheet Detector ULTRASONIC SENSORS Interfaces Digital output Number 2 1) Type PNP Function Q1: switching output double sheet, Q2: switching output mis-fed sheet, normally closed Maximum output current IA ≤ 500 mA Off delay 10 ms Control input 1 x 1) Output Q short-circuit protected. Type. Each probe represents a different housing size, magnetic attraction and. 6 /5 ·Double sheet sensor UDC-18GM-400-3E3-Y235849. Signal conditioners (50) receive signals from the radiation. 2013 Fault messages, causes and remedies Blank page ROLAND ELECTRONIC GmbH · Otto-Maurer-Str. The single-sided double sheet control systems are best suited for destacking operation of all kinds. The amount of separation is transmitted to a transducer which generates a signal proportional to the sheet thickness. Ultrasonic sensor suited for double sheet detection of paper, cardboard and foils up to 5 mm thick. Permits double sheet/blank detection with minimal magnetic attraction of the sheet. Double-sheet detection of foils, thin metal sheets, and corrugated cardboard with F, N, and G flute sizes;The double sheet detection is based on the ultrasonic thru-beam principle. The new connection cables. Also, it detects even in metallic transitions having different types of metals. An image reproduction device is provided with an automatic feed unit for documents; a double-sheet detector for detecting more than one sheet as the document for copying; an operator control unit provided with an operator control panel; and a control unit for controlling the automatic feed unit, processing the signal from the double-sheet detector and. Double Sheet Detection; Data Sheets; Double Sheet Detection. DOUBLE SHEET CONTROL SYSTEM I100 Application When feeding sheets automatically, more than one sheet can be inadvertently fed into the processing machine. Mathew. QGE, Oct 21, 2010, in forum: 4-Color Offset Presses + Replies: 14 Views: 9,263. Solution. Also clean the “P” receiver or fiber optic and the bottom of the double sheet detector paddle. Double Sheet Detection Our double sheet detectors are trusted by the top automakers from around the world. Features Applications Model . 9393 Are you in EU? Call: +44 1782 576800. Ultrasonic sensors for double sheet detection of printed sheets. detects double sheets, blanks, and ends to avoid tooling breakage The IS231 Double Sheet Detector is a fully automatic sensor that never requires any adjustments during change of sheet thickness. Ten Color Double Coater. When two sheets passes the detectors by overlapping the back edge, the detectors will allow to pass the sheets because of the gap set to three sheets. The detector system may be used on automatic sheet feeders where double or overlapping sheet material may jam or damage the receiving machine. If the roller wheel was on a arm 25. The adjustable rotation stop allows for multiple jaw openings. Double sheet or multiple sheets (a statement on the number of sheets is not possible here) The signals are evaluated by a microprocessor system. As a result of the evaluation, corresponding. Programs: 255 measurement programs possible. 3. 1. Many translated example sentences containing "double sheet detector" – German-English dictionary and search engine for German translations. The DS-FLEX is a multi-channel, mix-n-match double sheet detector that offers users the ability to detect double sheets of metal, the presence or absence of metal, all within one detection system. Double sheet sensor UDC-18GS-3EP-IO-0,2M-V19. AA-Argusauge DE Rev15. Bounty Hunter Tracker IV: also recommended for younger kids. Currently running 24 page on 45gram Machine is available i. The Model DS1510 Double Metal Sheet Detector comprises a control module in a sheet metal housing with two probes to form a system that detects the thickness of metals passing between the probes. It is cost-effective double sheet detection with single probe sensors. 1 Operating Principle of Amplitude-Measuring Ultrasonic Sensors 3. 002in. The ultrasonic double-sheet detector is used wherever automatic differentiation between single and double sheets is necessary to protect machines or prevent rejects. Quality requirements for high gloss products are very demanding. air l Single sheet l Double sheet or multiple sheets (a statement on the number of sheets is not possible here) The signals are evaluated by a microprocessor system. The amount of separation is transmitted to a transducer which generates a signal proportional to the sheet thickness. Trusted Seller. Maximum sheet thickness. 250/223R: 6101266: Apparatus and method of determining conditions of bank notes: 2000-08-08:. 435. | Prime Controls is a manufacturer of press protection equipment in the metal forming industry. Double Sheet Metal Sensor BDK Duo Flex mobile transmitter module for flexible mounting integral evaluation ergonomic design, cost-effective Double-surface non-contact Double Sheet Metal Sensor BDK Duo Flex Technical data Application Depending on the sheet type, the BDK Duo Flex Double Sheet Metal Sensor with integral evaluation electronics is. Double sheet metal monitors and thickness measurement devices monitor the automated destacking and separation of ferrous (Fe) or non-ferrous (NE) metal sheets in metal processing equipment (e. Ultrasonic system for reliable detection of no, one, or two overlapping sheet materials, preferably papers.