US 3757574 A
A pick and bond tester employs a pivotable sample block upon which a sample of paper to be tested is supported. A transparent, pressure sensitive tape is adhered to the sample and partially doubled back for adhesion to a belt-like strip or web positioned along and in abutting relation to the pressure sensitive tape and sample. This web is transported at a selected velocity or acceleration for withdrawing the tape from the sample in a direction such that the tape is turned at an angle of 180 DEG as removed. The picking resistance of the paper is determined according to the web speed at which picking first occurs, while the sample's Z-direction strength is determined by the speed at which complete delamination takes place.
Claims available in
Description (OCR text may contain errors)
llnited States Patent [191 l lankinton 1 Sept. 11, 1973  'lnventor: RobertPlankinton,668 McVey,
Apt. 109, Lake Oswego, Oreg. 97034  Filed: Sept. 28, 1971  Appl. No.: 184,417
Primary Examiner-Richard C. Queisser Assistant Examiner-Denis E. Corr AttorneyStephen W. Blore et a].
l 5 7 ABSTRACT A pick and bond tester employs a pivotable sample block upon which a sample of paper to be tested is supported. A transparent, pressure sensitive tape is adhered to the sample and partially doubled back for adhesion to a belt-like strip or web positioned along and in abutting relation to the pressure sensitive tape and sample. This web is transported at a selected velocity or acceleration for withdrawing the tape from the sample in a direction such that the tape is turned at an angle of 180 as removed. The picking resistance of the paper is determined according to the web speed at which picking first occurs, while the samples Z- direction strength is determined by the speed at which complete delamination takes place.
13 Claims, 8 Drawing Figures Patented Sept. 11, 1973 3 Sheets-Sheet 2 ROBERT P LANKINTON INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS Patented Sept. 11, 1973 3,757,574
5 SheetsSheet 5 FIG. 6 24; 3o
200 ON CONSTANT A46 8 L2 F ACCEL. 515E SEME C T OR L k SWITCH SPEED ADJUST LIMIT SWITCH 0-20 0-40 0-60 o-ao K I Q L A v V l P l48 Q4, H f V ST RT 7 RA GE P SELECTOR Pl 22 21-1-1 SCR CONTROL v ROBERT PLAN KINTON INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS APPARATUS FOR DETECTING THE ABILITY OF PAPER TO WITHSTAND PRINTING PROCESSES AND THE LIKE BACKGROUND OF THE INVENTION The present invention relates to apparatus for detecting the ability of paper to withstand forces tending to remove surface portions thereof, and particularly to such apparatus for providing reproducible results in gauging the quality of paper suitable for various printing processes.
Printing processes vary as to the quality of paper re quired because of printing speed, tackiness of the inks employed, and the like. A paper acceptable in one case may be characterized by undue picking in another, that is, bits of paper and loose fibers may adhere to the ink and result in subsequent printing defects. lf undue picking occurs, the printing speed may have to be lowered.
The adaptability of a given type of paper to a given printing process may, of course, be ascertained by acutually employing the given paper in a printing press. However, the picking resistance of the paper is desirably measurable in advance of the printing process by some convenient means, for instance whereby papers can be tested substantially concurrently with production and their picking characteristics accurately predicted. A high degree of correlation should exist between the test selected and the actual results in a printing process.
One method heretofore employed for pick testing is known as the Dennison Wax Pick Test. A number of different waxes in the form of sticks and manufactured to controlled tackiness are heated so that their ends are molten and while still molten are pressed against the paper surface to be tested. After a prescribed cooling period, the waxes are pulled from the paper and picking is observed. The waxes are numbered according to their tackiness. The highest numbered wax that removes nothing from the paper is reported as the pick number of the paper. Unfortunately, tests of this type are not exceptionally reproducible because the wax covers only a very small area, 0.4 to 0.5 in, so that material which is likely to pick in printing is often missed. Wax pick tests are also strongly affected by the type of adhesive used in paper coating. This fact seriously limits the usefulness of wax pick tests in comparing papers of unknown manufacture. Furthermore, wax pick tests frequently do not predict the actual results in the case of a printing process. Correlation between wax pick test results and picking in actual printing is often nonexistent.
SUMMARY OF THE INVENTION According to the present invention, apparatus for detecting the ability of paper to withstand forces tending to remove portions thereof comprises a sample support means havlng a surface elongated in at least one direction and adapted to receive a sample of paper secured thereto. An elongated strip of pressure sensitive tape is adhered to the sample, and the sample support means with the sample and tape thereon is positioned relative to an elongated web of strip material movable in relation to the said sample. The elongated web extends in abutting relation to the strip of tape and is attached to the tape for pulling the tape from the sample in a direction for doubling the tape back at an angle of 180. Means are provided for transporting the elongated material web at the predetermined or selectable velocity, and the pick resistance may be taken as the web speed at which picking first occurs. Z-direction strength is judged by the speed at which delamination starts.
It is found that the picking resistance determined in this way has a high correlation with actual results achieved in printing and can predict the success which a given paper will meet under given printing conditions. Thus, the pick resistance measured in this manner can be employed as a production standard whereby the quality of paper can be maintained relative to allowable picking characteristics in a given printing process.
It is an object of the present invention to provide an improved apparatus for detecting the ability of paper to withstand forces tending to remove portions thereof, which apparatus will provide reproducible results having a high degree of correlation with picking occurring during printing processes.
It is a further object of the present invention to provide improved apparatus for detecting picking of paper by means of which tests may be performed in a minimum period of time.
It is a further object of the present invention to provide an improved pick and bond tester which is economical in construction, efficient in operation, easy to operate, and adaptable for production use as well as laboratory use in ascertaining the quality of paper for printing processes.
The subject matter which I regard as my invention is particularlypointed out and distinctly claimed in the concluding portion of this specification. The invention, however, both as to organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings wherein like reference characters refer to like elements.
DRAWINGS FIG. 1 is a front elevational view of a new and improved paper pick and bond tester according to the present invention; a
FIG. 2 is a plan view of the FIG. 1 tester;
FIG. 3 is a rear elevational view of the tester in FIG.
FIG. 4 is an enlarged vertical sectional view taken along line 4-4 in FIG. 1;
FIG. 5 is an enlarged vertical sectional view, partially broken away for convenience of illustration, taken on line 5-5 of FIG. 3;
FEG. 6 is an enlarged fragmentary sectional view through a sample block according to the present inven tion to show the method of attaching the sample to the block;
FIG. 7 is a face view of the control panel for the pick and bond tester; and
FIG. 8 is a schematic diagram of circuitry for operating the tester according to the present invention.
DETAILED DESCRIPTION Referring now in detail to the drawings, the pick and bond tester 10 has a frame 12 comprising a pair of vertical front and back plates 14 and 16 supported by and attached to a base plate 18 which also supports motor drive unit 20. A sample block 24 is pivotally mounted on the front plate 14 by means of a pin 26 which passes through and is welded to vertical plates 14 and 16, with the block being positioned on pin 26 by locking collar 28. Lower surface 30 of the block 24 is convexly curved or contoured downwardly, maintaining pressure against strip material 32 as will be subsequently described in greater detail, while the outer end of the block 24 is provided with an angle 34 fastened thereto with capscrews 36. Angle 34 contacts a stop 37 bolted to the front plate 14 when the block is in closed position.
Prior to loading the block 24 with a test sample 38, the block is pivoted about pin 26 to the phantom line position illustrated at the left in FIG. 1. Briefly, the test sample 38 is fastened in parallel relation along the block 24 by a piece of pressure sensitive tape 39 at the end nearest the outer end of the sample block, and a piece of transparent, non-stretching, pressure sensitive tape 40 is also applied on top of the sample in adhering relation. Tape 40 is suitably three-fourths inch wide by 8% inches long and the end 42 of the tape 40 is folded back to expose the sticky side leaving approximately 8% inches of the tape in completely adhered contact with the paper sample 38 (see FIG. 6). As the block 24 is pivoted to the full line position shown in FIG. 1, the unstuck end 42 will come into contact with a strip material 32 and will adhere to the top surface of such strip material. This strip material 32 is suitably black lead in strip often employed in connection with 35 mm. photographic film, this strip having been loaded onto a reel 44 and threaded over upper film idler spool 46, over drive sprocket 48, and then around lower idler spool 50 to powered takeup reel 52. The strip 32 is appropriately provided with sprocket drive holes and is driven by sprocket 48. The control 22 is designed to pull approximately 17.9 inches of strip material 32 from reel 44 past the sample bar 24 onto reel 52 during a given test, at which time part of the sample may remain adhered to the tape.
The reel 44 is attached to an idler shaft 54 turning in bearing block 56 which forms a part of frame 12, the shaft 54 also extending beyond the rear plate 16 to a brake assembly 58. This brake assembly includes a rotatable brake plate 60 having a leather face 62 which is adjustably positioned along shaft 54 for bearing against pressure plate 66, the latter being backed by compression spring 68. Nut 64 locks the brake plate in place on shaft 54, but the pressure plate 66 has four holes that are positioned over pins 70 preventing the pressure plate from rotating. This brake structure prevents overrun of strip material from reel 44.
Idler spools 46 and 50 have rearward extending shaft portions 72 which rotate in bearing blocks 74 being held in position by set collars 76, and the takeup reel 52 (see FIG. 4) is mounted on shaft 78 which rotates in and is supported by bearings 80 mounted in a bearing block 82. At the rearward end of the said shaft 78 there is located a clutch assembly 84 consisting of a clutch plate 86 with a leather face 88 which bears against a pressure plate 90 attached to shaft 78 and positioned between thrust washers 92 by nut 94. Also forming part of the clutch plate 86 is a pulley 96 for receiving drive belt 98, suitably fonned of timing belt material. The clutch plate 86 rotates on a bushing 100 on the shaft 78 as belt 98 is driven by pulley 102 on output shaft 104 of the motor drive unit 20. The same belt also drives pulley 106 attached to shaft 108 on which toothed sprocket 48 is mounted for positively driving strip 32, the shaft 108 being joumaled in the bearing block 110. The belt 98 also passes around an adjustable idler roller 112 which increases the circumferential contact of belt 98 on the aforementioned pulley 96.
Variable speed control 114 is also driven by the motor unit 20 via pulley 116 mounted on shaft 108, belt 118 (suitably formed of timing belt material) and pulley 120 pivotably mounted on stub shaft 122 by bushing 124. (See FIGS. 3 and 5). The stub shaft 122 forms part of a bracket 126 bolted to the back side of the rear plate 16. The pulley 120 carries a cam 128 which operates a variable speed control 130 through a rack 132 and pinion 134, wherein the said rack is secured to crosshead 144.
FIG. 3 illustrates the cam 128 and speed control 130 in the at rest or ready to start position with the cam follower 154 positioned at the smallest radius of the cam. The bracket 126 has ears or projections in which bushings 142 have been provided and within which the cam shaft 136 may slide. When the motor 20 is started, the cam 128 will rotate in the clockwise direction (as viewed in FIG. 3) causing the shaft 136 to move downwardly carrying with it the crosshead 144 upon which the rack 132 is secured. This in turn will rotate the variable speed control 130, the latter suitably comprising a potentiometenlf the mode selector switch 146 is in the accelerating position, the motor 20 will accelerate under the direction of control 130 until the cam 128 has made one complete revolution. While the cam shaft 136 and crosshead 144 move downwardly they carry therewith the plunger rod 150 of a dash pot 152. Thus, as the cam follower 154 drops off the high point 156 of the cam, the spring 138 urges shaft 136 upward, but the dash pot 152 slows the ascent of the rod 136 preventing it from seating the cam follower too rapidly. The motor 20 is stopped after one revolution by means of limit switch 158 actuated by a pin 160 mounted on the face of the pulley 120.
Referring now in particular to FIG. 8, comprising a schematic diagram of control 22 for operating the present invention, the apparatus is powered across a 115- volt, 50 or 60 cycle AC line comprising conductors L1 and L2. A double pole, single throw switch 200 comprises the OFF-ON switch for the apparatus and is disposed with one set of contacts in series with each of the lines L1 and L2. Further disposed across the line, on the load side of switch 200, is a series circuit comprising contacts 202 of limit switch 158 and operating coil LS. A further circuit connected across the line comprises start pushbutton 21 in series with normally closed contacts LS1 and operating coil P, energized in response to depression of pushbutton 21. Among the contacts operated by coil P are normally open contacts Pl disposed in holding relation across the terminals of pushbutton 21.
A first pair of diodes, 206, have their respective anodes connected to the lines, and their cathodes connected together for providing current for motor field coil, F, associated with motor drive unit 20. The remaining terminal of field coil, F, is connected to the anodes of diodes 208 having their respective cathodes connected to the respective lines. Also, the common anode connection of diodes 208 is coupled via resistor 218, in series with the parallel combination of normally open contacts P2 and LS2, to one terminal of motor armature 212. The remaining terminal of armature 212 is returned to a common cathode connection between a pair of silicon controlled rectifiers 210 having their anodes connected to the respective lines. The silicon controlled rectifiers 210 are employed for controlling the speed of the motor and are triggered on successive cycles of the alternating current wave at their gate electrodes via leads 214 from SCR control unit 216. The SCR control unit 216, together with most of the control circuitry as herein described is substantially similar to a DC motor speed controlof the Boston gear RATIO- TROL type, Type Tl2A, manufactured by the Boston Gear Division, North American Rockwell, Quincy, Mass, with modifications as hereinafter discussed. Also a lamp across the armature draws minimum current.
The input transistor for such control unit is illustrated separately at 236, and comprises a PNP transistor having its emitter returned to control unit positive bus 233 via resistor 232, and having its collector returned to control unit negative bus 239 via the series combination of resistor 234 and capacitor 236 as shown. The transistor 236 is employed for successively charging capacitor 236 which, in turn, fires a unijunction transistor (not shown) within SCR control unit 216 via lead 238. The unijunction transistor provides an impulse for initiating conduction of silicon controlled rectifiers 210 in a conventional manner.
Control unit positive bus 233 is further commoned with the junction between resistor 2118 and contacts P2, while also being returned to point B by capacitor 248. A series circuit, comprising capacitor 235, resistor 226, and resistor 228, is interposed between bus 233 and point B, with the base of transistor 236 being coupled to the junction between resistors 226 and 228. A resistor 224 joins the interconnection between capacitor 235 and resistor 226 to the movable tap of a potentiometer 226 disposed across resistor 218, having the purpose of circuit adjustment in accordance with the current drawn by the motor armature. Also, a resistor 246 connects the positive armature terminal to the aforementioned point B. The above described circuitry, substantially corresponding to circuitry of the above mentioned type T12A for motor speed control, operates for bringing about the proper firing of silicon controlled rectifiers 2M) in proper phase relation with the input waveform to achieve the desired speed. As hereinafter discussed, the conventional speed potentiometer, usually associated with such a control unit, is replaced by a plurality of potentiometers 130, 256, 260, 262 and 264 for achieving desired speed characteristics for the strip material 32.
A DC offset or zero speed setting potentiometer 242 couples bus 233 to point A, which is connected to one of the movable terminals of double pole, double throw, mode selector switch 146. Also, a maximum speed potentiometer 246 in series with resistor 252 couples bus 239 to point C, which is connected to the remaining movable terminal of switch 146. In the lower position, as illustrated in FIG. 8, switch 146 places potentiometer 256 in circuit between points A and C, whereby potentiometer 256 operates as the speed potentiometer of the circuit. This position corresponds to the "constant" speed position of switch E46 as illustrated in FIG. 7, such speed being selectable with potentiometer 256. it will be seen that adjustment of this potentiometer places a variable bias at point B and upon the base of input transistor 230 of thecontrol unit whereby the charging rate of capacitor 236 is altered to the extent desired. if the charging rate is decreased, silicon controlled rectifiers 210 will fire later during each cycle, and the motor will slow down, while if the charging rate of capacitor 236 is increased, the motor will speed up. In the constant speed mode of operation for the present apparatus, strip material 32 is pulled at a constant selected speed.
With the switch 146 thrown to the upper position in FIG. 8, corresponding to an accelerating mode, switch terminals 266and 268 are disposed in series between points A and C. in this instance, potentiometer (which is a 360 potentiometer) is placed in series with one of the potentiometers selected by range selector 1148, and the combination is electrically interposed between points A and C. As will be recalled, potentiometer ll30-comprises the control means operated by cam 128 and consequently its resistance changes during the course of a given operation as tape is pulled from a particular paper sample. The speed range is selected by means of the range selector switch 148 by means of placing differing resistances in series with the control potentiometer 130. In one of the switching positions of switch 148, no resistance is placed in series with potentiometer 130, while in other positions thereof, potentiometers 260, 262 or 264 are respectively placed in series with the control potentiometer 130, and these potentiometers are adjusted to provide the speed range as desired. It will be seen that since the setting of potentiometer 130 is changed during the tape-pulling operation, the velocity will change accordingly. The potentiometer is connected in a sense such that a positive acceleration will be given to the aforementioned strip material 32, i.e., with the strip material speed increasing progressively and constantly from the start of each operation to the finish. Linear acceleration is established by constructing the cam 128 substantially as shown in FIG. 3, and employinga linear 360 potentiometer 130, but alternatively, the same characteristic can be achieved with a differently shaped cam, and a potentiometer 130 having a nonlinear taper properly compensating the cam to result in linear acceleration of the strip material 32.
Further considering operation of the apparatus, it will be seen that depression of pushbutton 21 operates coil 1? which, in turn, closes a holding circuit around pushbutton 21 and also closes a path, via contacts P2, to armature 212. The motor then causes sprocket 48 to rotate either with constant velocity or with acceleration as hereinbefore described, until pin operates limit switch 58, i.e., when the strip material has withdrawn a complete length of tape from the paper sample. Proximate the end of a cycle, limit switch contacts 202 energize operating coil LS, and contacts LS1 are opened, breaking the circuit to coil P for opening contacts P2 to armature 212. However, contacts LS2, which are normally open contacts operated by coil LS, maintain the armature circuit until the exact end of the cycle, i.e., until pin 160 operates the limit switch, which is a momentary contact type, further so that its contacts open again. The limit switch contacts close, momentarily, only when the limit switch lever is pushedin one direction. One tape-pulling operation is now complete and the system will await redepression of the pushbutton 211 for completing another cycle of operation.
The apparatus is generally operated in the accelerating mode (setting of switch 146) in the instance of unknown paper sample. After the paper sample is secured upon sample bar 24, and the machine operated as hereinbefore described, the pressure sensitive tape 40 will remain adhered to the strip material 32 and will appear along location 33 of strip material 32 as illustrated in FIG. 1. The pick resistance is taken as the speed at which picking first occurs, which in turn can be determined according to the length of the tape from its start, i.e., the location at which it was initially folded back, to the point where picking appears. For this purpose, a scale (not shown) may be provided along the lefthand side of the apparatus in FIG. 1, or a hand-held ruler can, of course, be employed for this purpose. It is found that successive tests with the same type of paper are quite consistent, i.e., the tests show very adequate reproducibility whereby the pick resistance determined in this manner may be utilized as a standard in selecting paper. Moreover, the pick resistance determined in this way correlates well with actual experience employing the same papers in printing processes, e.g., in the case of letterpress and both sheet fed and web fed offset printing. Thus, the tests made employing the present tester will consistently select papers which are capable of application in a given printing process with a given ink and at a given speed. Papers having a pick resistance as measured by the present apparatus may -be employed in printing processes where other papers having the same pick resistance have been found acceptable. It will be realized, of course, that the particular number associated with the length of the tape from its start to the point where picking first appears will be a function of the acceleration range selected. However, length is generally converted to speed at which picking first occurred by means of a scale employed for that purpose. Since acceleration is linear, the scale is linear between the minimum and maximum speeds along material 32. In the case of a particular apparatus according to the present invention, the speed ranges were 2 to 20 inches per minute, 4 to 40 inches per minute, 6 to 60 inches per minute, and 8 to 80 inches per minute.
Thus, the faster the tape is pulled, the more severe is the demand on the surface strength of the paper, and the speed at which picking occurs may be taken as a measure of the pick resistance of the paper, while the speed at which complete delamination occurs is a measure of the Z-direction strength of the paper, commonly known as intemal bond. Not only may the picking and bond resistance be determined in this way, but also the tape pulled from the paper may be readily examined under a microscope to identify the material which is actually removed from the paper. It is also noted that results are stored on takeup reel 52.
The variable speed or accelerating mode tests according to the present invention are advantageously carried out in the case of an unknown sample of paper. These tests are quite reproducible, as hereinbefore mentioned, and are also rapidly performed. However, for routine testing of production paper runs, the constant speed mode (setting of switch 146) is usually employed. For this purpose a manufacturing aim" picking resistance is predetermined, and the speed corresponding thereto is set upon control 256. Then, if picking occurs in the case of samples taken from a particular production run, measures can be taken for improving the quality of the paper. Paper samples which pick when subjected to the manufacturing aim" test can then be tested at a lower predetermined speed which can be called a "shipping limit." If the paper does not pick at that speed, it is safe to ship. However, if it picks at the shipping limit" speed, it should be withheld from shipment or diverted to a less demanding customer or printing process.
It is important to note that the tape as pulled from the paper is bent back upon itself or doubled at since this is found most closely to duplicate the results actually occurring in a printing process. If the tape were merely pulled sideways from the sample, undue damage to the paper sample would result without producing an adequate measure of the pick resistance of the paper. The apparatus is constructed to insure the proper 180 pulling angle, with the sample bar 24 being advantageously arcuately curved or contoured along its lower surface tending to compress the strip material 32 downwardly providing close contact between the strip material 32 and the other layers involved. Consequently, the material 32 pulls against sample block 24, along the contour thereof, always pulling the tape back at 180. The material 32 pulls the tape up to and around sprocket 48 where the sample block is curved or cut out to match the outer periphery of the sprocket 48. The latter construction continues to maintain the 180 turn of the tape, as the strip material 32 passes around the sprocket 48. The block 24 is ordinarily formed of rather heavy material, i.e., it is conventionally a solid metal member, and therefore the weight thereof will maintain such member in either of the positions illustrated in FIG. 1. However, if desired, a lighter block 24 may be employed and means may be provided for locking the block 24 in the right-hand position, as illustrated in FIG. 1, when a tape is being pulled.
As hereinbefore mentioned, the tape employed is desirably transparent, essentially non-stretching, pressure sensitive tape. For this purpose, Scotch No. 600 cellophane tape, three-quarters inch wide, is suitably employed since this particular tape has been found to have advantageous non-stretching qualities, that is, stretching is minimized. However, it is understood the present invention is not limited to a particular type of pressure sensitive tape. A given type of tape should be designated in specifying pick resistance inasmuch as different tapes have difi'erent tacks and may be more or less severe in their demands on the paper sample.
While I have shown and described a preferred embodiment of my invention, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from my invention in its broader aspects. I therefore intend the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.
What is claimed is:
1. Apparatus for detecting the ability of paper to withstand forces tending to remove portions thereof, said apparatus comprising:
sample support means having a surface elongated in at least one direction and adapted to receive a sample of said paper in secured relation thereto and an elongated strip of pressure sensitive tape in adherent relation to the exposed side of said paper sample along said sample support means surface,
an elongated web also extending substantially in said one direction for at least a portion of its path with a surface thereof in facing, abutting relation to the said strip of tape along the sample on the sample support means, said web being adapted for attachment to said strip of tape proximate one end of the adherently related length of said tape and sample,
said elongated web being adapted for lengthwise relative movement with respect to said sample sup port means toward the opposite end of the adherently related length of said tape and sample from the first end, for progressively removing said tape from said sample and receiving said tape upon said web, said tape doubling back directly along said sample at its point of removal,
and means for providing said relative movement between said web and said sample and for controlling said movement to provide a predetermined velocity characteristic therefor whereby the speed of paper removal from the sample may be determined.
2. The apparatus according to claim 1 wherein said sample support means comprises an elongated block and pivot support means for said block, said block being pivotable for revealing the said sample support means surface and for swinging into said abutting relation with the elongated web.
3. The apparatus according to claim 2 wherein said support means surface is convexly contoured for impressing said sample as overlaid by said tape firmly against said elongated web for insuring the said doubling back of said tape as it is removed from said sample by said web.
4. The apparatus according to claim 3 wherein said elongated web is supported by rotatable means proximate ends of said block, one of said rotatable means comprising a drive means for transporting said elongated web.
5. The apparatus according to claim 1 wherein said means for providing said relative movement between said web and said sample and controlling said movement comprises drive means for said.web including means for providing a predetermined acceleration to said web during movement thereof.
6. The apparatus according to claim 5 wherein said last mentioned means includes a cam driven by the drive means for said web, cam follower means controllable therefrom, and speed control means for said drive means wherein said speed control means is operated by said cam follower means to generate a predetermined acceleration characteristic, said drive means including a motor.
7. The apparatus according to claim ll wherein said means for providing said relative movement between said web and said sample and for controlling said movement comprises drive means for said web including a motor, and means for selecting a plurality of operating speeds for said motor.
8. The apparatus according to claim 1 wherein said means for providing said relative movement and controlling said movement comprises a payout reel upon which a length of said web is stored, a takeup reel onto which said web is fed, roller means between said payout reel and said takeup reel along the path of said web over which said web passes, said roller means positioning a portion of said web with a surface thereof disposed in abutting relation to the said strip of tape along the sample support means and adapted to adhere to a turned back portion of said tape, motive means for empowering one of said rollers as a drive roller at a position at least past the major portion of said sample support means along said path for causing movement of said elongated web at a desired speed, and means for operating said takeup reel for receiving said web, said motive means having speed control means associated therewith for selecting the speed of the drive roller for adjusting the speed of said web.
9. The apparatus according to claim 8 wherein a said roller means is located to position a length of said web adjacent an accessible side of said apparatus for viewing thereof subsequent to movement thereof adjacent said sample support means, said last mentioned length corresponding to a length of said tape adhered to said sample.
10. The apparatus according to claim 8 wherein said web is provided with sprocket holes and wherein said drive roller comprises a sprocket for engaging said sprocket holes and providing positive drive to said web.
11. The apparatus according to claim 8 wherein said sample support means is movable adjacent said drive roller and is peripherally contoured around a portion of said roller means for maintaining a angle in said tape as the tape is removed from said sample.
12. Apparatus for detecting the ability of paper to withstand forces tending to remove portions thereof, said apparatus comprising:
sample support means adapted to receive a sample of said paper and a strip of pressure sensitive tape in adherent relation to the exposed side of said paper sample, second means comprising a movable web-disposed substantially immediately adjacent said support means and said sample and maintained in substantially abutting relation thereto for removing said tape from said sample in a direction bending said tape back at an angle of 180 as the tape is removed from said sample, and means for causing relative movement between said second means and the said sample to provide a predetermined velocity characteristic for such relative movement, including rotating means for translating said web along said sample,
said apparatus being provided with limit switch means for determining when a predetermined length of tape has been removed from said sample for stopping said rotating means.
13. The apparatus according to claim 12 further including a cam movable in conjunction with said rotating means and a speed control responsive to movement of said cam for varying the speed of said rotating means fora predetermined period as said tape is removed from said sample to provide a predetermined acceleration characteristic for the speed of said web as it is removed from said sample.
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