US3126778A

US3126778A - Early

Info

Publication number: US3126778A
Authority: US
Publication date: 1964-03-31
Anticipated expiration: 1981-03-31

Description

- March 31, 1964 H. c. EARLY 3,126,778

. APPARATUS FOR PUNCHING OR EMBOSSING TRAVELING.

WEBS BY USE OF AN ELECTRIC SPARK Filed May 29, 1961 2 Sheets-Sheet 1 all 1 "ll" 45 v4 l Hi-HI II lull" I/VVEIVTOR: 0 6w ATTORNEYS,

' March 31, 1964 3,126,778 AJRAVELING H. C. EARLY APPARATUS FOR PUNCHING OR EMBOSSI OF AN ELECTRIC WEBS BY USE Filed May 29, 1961 2 Sheets-Sheet 2 w v m ATTORNEYS.

United States Patent Oflice 3,126,778 Patented Mar. 31, 1964 3,126,778 APPARATUS FOR PUNCHING OR EMBOSSING TRAVELING WEBS BY USE OF AN ELECTRIC SPARK Harold C. Early, Ann Arbor, Mich, assignor to Meredith Publishing Company, Des Moines, Iowa, a corporation of Iowa Filed May 29, 1961, Ser. No. 113,536 8 Claims. (Cl. 83-177) This invention relates to apparatus for punching or embossing traveling Webs and more particularly to elec tric spark operated apparatus for perforating or embossing Webs of paper, or the like traveling at relatively high speeds.

The present invention constitutes an improvement over the apparatus disclosed and claimed in the patent to Early et al., No. 2,737,882, and in co-pending application Serial No. 691,512, filed October 21, 1957, now Patent No. 3,027,791 and is particularly concerned with producing holes on the order of A inch to inch in rapidly moving webs of paper in high speed printing operations, although it is applicable to other perforating and embossing operations. As used in the specification and appended claims the term punching holes is intended to include operations such as embossing in which a portion of the material of the web or sheet is merely displaced without being severed. In electric spark punching, a spark on the order of 20,000 volts at 1200 amperes is delivered at a power of 2 to 4 watt seconds between the anvil and the web which is supported on a die opposite to the anvil. The high temperature created by the spark causes instantaneous expansion of the air or other gas between the anvil and the web with an explosive eifect which drives the web into the die to produce clean perforations or embossments despite the high velocity of the Web.

One difficulty encountered with this type of apparatus is the insurance of sufiicient space between the anvil and the web to provide adequate gas for expansion without the space becoming so large that the gas is not properly confined to perform the perforating operation. Another difficulty, particularly in connection with the punching of relatively large holes, is the provision of a sufficiently long path of travel for the spark discharge between the anvil and the web evenly to heat the air or the gas.

It is a principal object of the present invention to overcome these diiiiculties and to insure the trapping of sulficient air or gas between the anvil and the web to effect the desired punching and to provide a highly eflicient spark discharge to insure adequate and instantaneous heating of the air or gas.

A specific object of the invention is to provide apparatus for punching holes in traveling Webs in which the surface of the anvil is formed with a series of projections to engage the web with the spaces between the projections containing the desired quantity of air or gas and with the projections creating a tortuous path for the spark discharge.

According to a feature of the invention, the anvil is formed by a disc or wheel having its periphery engaged and traveling with the web and having a knurled rim thereon moving in engagement with the web.

Still another object is to provide apparatus for punching holes in traveling webs in which the spark discharge occurs in a plurality of spaced parallel paths, one of which registers with the die opening and others of which are adjacent to opposite sides of the die opening.

According to a feature of the invention, the spark discharge is produced between the electrodes of a plurality of pairs of electrodes which are spaced circumferentially of the anvil disc and which electrodes lie closely adjacent to the periphery of the disc.

A further object is to provide apparatus for punching holes in traveling webs in which the die is mounted for universal angular movement to maintain itself floatingly in flat surface contact with the Web at all times.

The above and other objects and features of the invention will be more readily apparent from the following description when read in connection with the accompanying drawings, in which:

FIGURE 1 is a side elevation of punching apparatus embodying the invention with parts in section;

FIGURE 2 is a section on the broken line 2-2 of FIG- URE 1;

FIGURE 3 is an enlarged partial elevation of the rim of the anvil disc showing the position of the electrodes and the path of travel of the spark discharge therebetween;

FIGURE 4 is an elevation of the anvil disc showing the mounting of the electrodes adjacent thereto;

FIGURE 5 is an enlarged section through the die and die mounting means, including a portion of the anvil disc; and

FIGURE 6 is a face view of the die on the line 66 of FIGURE 2.

The apparatus, as shown, comprises a plate ll) made of aluminum or other rigid material and which serves as a support and guide for the moving web or strip 11 of paper, or the like, to be perforated. The plate may be disposed either vertically or horizontally, but is preferably disposed vertically, as shown in FIGURE 1. The plate is formed with an opening 12 therein to receive the perforating die indicated generally at 13 and is provided with arcuate grooves 314 registering with the opening 12 to receive the edge portion of an anvil disc, as described iereinaftcr.

The die 13 may be a perforating die, as shown, with an opening completely therethrough or may be an embossing die provided only with recesses in its surface adjacent to the Web 11, as desired. As best seen in FIGURES 5 and 6, the die proper comprises a disc 15 formed of dielectric material and having a central perforating opening therethrough. The disc is supported around its periphery in a recessed ring 16 which is preferably formed of plastic material and which is in turn supported in an outer ring 17 also formed of a plastic material. The rings are so proportioned as to provide a slight clearance therebetween which may be on the order of inch and are pivoted together for relative pivotal movement about a diametrical axis. As shown, each ring carries a metal insert 18 extending through only a short portion of its periphery and the rings are assembled with the inserts aligned and with pivot pins joining them. The metal inserts are employed to reinforce the plastic rings for pivotal interconnection since it is preferred to pivot the plastic rings together adjacent the edge thereof closest to the web and metallic reinforcement is preferable for this purpose.

The outer ring 17 is pivotally connected in a yoke 19, as best seen in FIGURE 1, on an axis perpendicular to the pivotal axis between the rings. This defines a gimbaltype mounting giving the die complete universal freedom of angular movement so that it can float to maintain flat surface contact with the web under all operating conditions. A vacuum hose 21 may be connected to the yoke 19 and to a suitable source of vacuum to carry away cut out portions of the web and to flush ionized and conducting air from the die opening.

The side of the web opposite to the die is engaged by an anvil which is provided, as shown, by a rotatable disc 22. The disc itself, or at least the rim portion thereof, is made of a nonconducting material and may be formed of ceramic material. However, it is preferably formed of a plastic material such as nylon (polyamide) but may be formed of polytetrafiuoroethylene or polytrifiuoroethylene (Teflon). Nylon is preferred because of its excellent dielectric strength, the fact that it will evaporate to a minor degree under the heat of the arc to provide additional quantities of gas and its high dimensional stability. The disc 22 is somewhat thicker at its edge than the opening in the die, as shown at 23, the relationship preferably being approximately as indicated in FIGURE 3, and the face of the die is curved to conform to the curvature of the disc. At its hub portion the disc is clamped between supporting plates 24 and is mounted for rotation on a bearing 25. As illustrated in FIGURE 2, the bearing may be mounted for axial adjustment so as to align the edge of the disc properly with the opening in the plate and with the die. The bearing is supported in a framework 25 which is adjustable on a base 27, as shown in FIGURE 1, by mounting the support slidably on the base and providing a worm 28 on the support rotatable by a handwheel Z9 and meshing with a rack 31 fixed on the base. By this means the anvil disc can be shifted toward or away from the die to maintain its periphery properly in engagement with the traveling web at all times and with the desired degree of pressure.

The anvil disc is preferably power driven at a speed such that its rate of peripheral movement is equal to the rate of travel of the Web. For this purpose a motor, indicated generally at 32, is provided on the support 26 and is connected through gearing partially shown at 33 in FIG- URE 2 to the disc to drive it. The motor is preferably a variable speed motor whose speed can be accurately adjusted by a rheostat, or the like, to make the peripheral speed of the disc correspond closely to the rate of travel of the web.

A spark is adapted to be produced between the anvil disc and the web by means of electrodes positioned at the sides of the disc to perforate the web. According to the present invention, three pairs of electrodes indicated at 34, 35 and 36 are provided with the electrodes of each pair lying closely adjacent to the sides of the disc at its periphery. The pairs of electrodes are spaced circumferentially of the disc with the center pair of electrodes 35 registering substantially centrally with the die opening 23 and with the pairs 34 and 36 lying on opposite sides of the die opening and spaced slightly therefrom while being relatively close thereto. The electrodes may be in the form of relatively short lengths of wire which are supported in insulating block 37 mounted on insulating supports 38. The supports 38, as shown in FIGURE 1, are adjustably carried by an extension 39 on the frame 26. The supports 38 are pivoted on mounting screws 41 and are urged toward the sides of the anvil disc 22 by resilient arms 42. In this way, the supporting blocks 37 for the electrodes are maintained in light frictional engagement with the sides of the anvil disc so that the electrodes themselves will always be spaced close to the disc sides. The support 39 may itself be adjusted radially of the anvil disc through an adjusting arm 43 pivoted on the support 26 and retained in adjusted position by a locking screw 44-. The arm 43 is connected to the support 39 to shift it radially so that the electrodes can be properly adjusted to bring their tips substantially into registration with the peripheral edge of the anvil disc. The electrodes may be connected to a suitable high voltage source, indicated at 45, to supply them With a high voltage sparking current at controlled intervals determined by the desired spacing of the perforations and rate of travel of the web. It will be understood that connection of the source to the electrodes may be controlled by a suitable timer switch so that they will be energized to produce a spark at the proper intervals.

According to an important feature of the present invention, the surface of the anvil disc 22 which engages the web is formed with a series of spaced protrusions which engage the web and which define between them an open space to insure that the desired quantity of air for expansion will be confined between the anvil and the web. These protrusions also lie in the path of a spark between the electrodes of the different pairs and cause the spark to follow a tortuous path. The electrodes are preferably energized through a circuit, as more particularly disclosed and claimed in the co-pending application of Harold C. Early, Serial No. 93,739, filed March 6, 1961, so that a separate spark discharge will occur between the electrodes of each pair.

In the preferred construction, the peripheral edge of the anvil disc 22 is knurled, as indicated at 46 in diagonal lines, to define spaced projections aligned diagonally and separated by valleys. With this construction, as best seen n FIGURE 3, the spark discharge between the electrodes of each pair follows a zig-zag path through the valleys so that its effective discharge path in the space between the anvil disc and the web is relatively long. In operation of the unit, each time the electrodes are energized, the air or gas in the grooves will be ionized and a spark discharge will occur through the ionized gas. In the present invention, a high current density discharge is employed having a peak value on the order of 200,000 amperes per square centimeter. Due to this high current density and to the diagonal knurling of the anvil each spark discharge will spread into all possible alternative paths of equal length to produce a pattern approximately as indicated in dotted lines in FIGURE 3. This will produce a very rapid expansion of substantially all of the air or gas trapped between the anvil and the web opposite to the die to create an instantaneous explosive pressure to perforate the web cleanly regardless of the high speed at which it is traveling. In this way relatively large perforations can be produced in webs traveling at high speed such as in high speed rotary printing presses.

While one embodiment of the invention has been shown and described herein, it will be understood that it is illustrative only and not to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

1. In apparatus for punching holes in moving webs comprising a die over which the web moves, an anvil having a surface overlying the web on the side thereof opposite to the die and in registration with the die and electrodes at opposite sides of the anvil in registration with the die to produce a spark discharge between the anvil and the web, the improvement which comprises a series of projections on the surface of the anvil between the electrodes to cause the spark discharge to follow a tortuous path between the electrodes.

2. In apparatus for punching holes in moving webs comprising a die over which the web moves, an anvil having a surface overlying the web on the side thereof opposite to the die and in registration with the die and electrodes at opposite sides of the anvil in registration with the die to produce a spark discharge between the anvil and the web, the improvement which comprises a series of crossing corrugations on the surface of the anvil at acute angles to the line of travel of the web.

3. In apparatus for punching holes in moving webs comprising a die over which the web moves, an anvil overlying the web on the side thereof opposite to the die and electrodes at opposite sides of the anvil to produce a spark discharge between the anvil and the web, the improvement which comprises a plurality of pairs of electrodes spaced in the direction of travel of the web with one pair registering with the die opening and other pairs adjacent to opposite sides of the die opening.

4. In apparatus for punching holes in moving webs comprising a die over which the web moves, an anvil having a surface overlying the web on the side thereof opposite to the die and in registration with the die and electrodes at opposite sides of the anvil in registration with the die to produce a spark discharge between the reams ,a 3 anvil and the web, the improvement which comprises a knurled surface on the anvil defining tortuous paths for spark discharges between the electrodes and a plurality of pairs of electrodes spaced in the direction of travel of the web with one pair registering with the die opening and other pairs adjacent to opposite sides of the die openings.

5. Apparatus for punching holes in moving webs com prising a die over which the Web moves and having an opening therein, a circular disc mounted for rotation on an axis transverse to the axis of the die opening and having a flat periphery movable adjacent to the die and on the side of the Web opposite to the die, and electrodes at the sides of the disc at its periphery registering with the die, the periphery of the disc being knurled with the lines of knurling at acute angles to the disc axis and to the line of discharge between the electrodes.

6, Apparatus for punching holes in moving Webs comprising a die over which the web moves and having an opening therein, a circular disc mounted for rotation on an axis transverse to the axis of the die opening and having a fiat periphery movable adjacent to the die and on the side of the web opposite to the die, and a plurality of pairs of electrodes, the electrodes of each pair being on opposite sides of the disc and the pairs of electrodes being spaced circumferentially of the disc with one pair 6 registering with the die opening and other pairs adjacent to opposite sides of the opening.

7. Apparatus for punching holes in moving webs comprising a die over which the Web moves and having an opening therein, a circular disc mounted for rotation on an axis transverse to the axis of the die opening and having a flat periphery movable adjacent to the die and on the side of the Web opposite to the die, and a plurality of pairs of electrodes, the electrodes of each pair being on opposite sides of the disc at its periphery and the pairs of electrodes being spaced circumferentially of the disc with one pair registering with the die opening and other pairs adjacent to opposite sides of the opening, the periphery of the disc being knurled with the lines of knurling hein g at acute angles to the lines of discharge between the electrodes of the pairs.

8. The apparatus of claim 1 in which the anvil is formed of nylon.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. IN APPARATS FOR PUNCHING HOLES IN MVING WEBS COMPRISING A DIE OVER WHICH THE WEB MOVES, AN ANVIL HAVING A SURFACE OVERLAY THE WEB ON THE SIDE THEREOF OPPOSITE TO THE DIE AND IN REGISTRATION WITH THE DIE AND ELECTRODES AT OPPOSITE SIDES OF THE ANVIL IN REGISTRATION WITH THE DIE TO PRODUCE A SPARK DISCHARGE BETWEEN THE ANVIL AND THE WEB, THE IMPROVEMENT WHICH COMPRISES A SERIES OF PROJECTIONS ON THE SURFACE OF THE ANVIL BETWEEN THE ELECTRODES TO CAUSE THE SPARK DISCHARGE TO FOLLOW A TORTUOUS PATH BETWEEN THE ELECTRODES.