US3307387A

US3307387A - Method and apparatus for perforating and corrugating metallic ribbon

Info

Publication number: US3307387A
Application number: US329744A
Authority: US
Inventors: Jr Elbert M Lacey; William F Rethwish; Dale S Harding
Original assignee: Rohr Inc
Current assignee: Rohr Inc
Priority date: 1963-12-11
Filing date: 1963-12-11
Publication date: 1967-03-07
Anticipated expiration: 1984-03-07
Also published as: GB1021566A; IL22149A

Description

E. M. LACEY, JR. ETAL 3,307,387 METHOD AND APPARATUS FOR PERFORATING March 7, 1967 AND. CORRUGATING METALLIC RIBBON 5 Sheets-Sheet 2 Filed Dec. 11, 1963 FIG.

FIG.

FIG. I2

FIG. l4

INVENTORS, E. M. LACEY, JR. W. F RETHWISH D. S HARDING A TTRNEY E. M. LACEY, JR., ETAL 3,307,387 METHOD AND APPARATUS FOR PERFORATING AND CORRUGATING METALLIC RIBBON March 7, 1967 5 Sheets-Sheet 5 Fil ed Dec. 11, 1963 Q9 wi INVENTORS. E. M. LACEY, JR. W. F. RETHWISH D'. S. HARDING I i A, 21- ATTORNEY United States Patentv C) 3,307,387 METHOD AND APPARATUS FOR PERFORATING AND CORRUGATING METALLIC RIBBON Elbert M. Lacey, Jr., Silver Spring, Nev., and William F. Rethwish, National City, and Dale S. Harding, Chula Vista, Calif., assignors to Rohr Corporation, Chula Vista, Calif., a corporation of California Filed Dec. 11, 1963, Ser. No. 329,744 15 Claims. (Cl. 72-324) This invention relates generally to machines for fab ricating honeycomb core and more particularly to a ribbon perforator for a corrugation punch press having provision for perforating unformed metallic ribbon preparatory to corrugating the same for use in the fabrication of honeycomb core. I

In a core fabricating machine such as disclosed in Patent No. 3,079,487, issued to F. H. Rohr for Method and Apparatus for Fabricating Honeycomb Core, a corrugated metallic ribbon is folded back and forth upon itself to form the successive layers of the core. In order to form quality high strength core in this manner, it is necessary that the corrugations in the ribbon be precisely formed and coined without introducing appreciable distortion or strain into the ribbon material during the corrugation process. This is imperative in order that the corrugated ribbon will have the same spacing from node to node such that the nodes of the confronting ribbon layers will be aligned and abutted preparatory to the resistance welding of the nodes together to form the cells of the core. As disclosed in the aforesaid patent, wherein provision is made for programming the corrugated ribbon of successive sections of different thickness to provide a core of predetermined structural pattern and density, it is equally important that the corrugation configuration and nodal spacing be precisely maintained since these parameters provide the reference datum in determining points in the fabricated core at which changes in density are to occur in accordance with the predetermined pattern.

wich panel by brazing metallic skins thereto, it usually is required, moreover, that the cell walls of the honeycomb be perforated so that the inert gas which provides a protective atmosphere during brazing can circulate freely through the honeycomb structure. a The perforations may be formed by the dies of the punch press itself, as by punching or blanking the openings in the manner disclosed in the aforesaid patent of Fred H. Rohr, but this arrangement is not entirely satisfactory in service for the In the fabrication of the honeycomb core into a sand- 5 reason that the blanks accumulate, are difficult to dispose of, and in many instances tend to find a way into and between the corrugating dies to thus obstruct the corrugation process.

Perforating the ribbon as by piercing or impaling the same as with a needle-like device is preferred to blanking, but this method heretofore has had the disadvantage of introducing incipient tearing, cracking, and fracturing of the ribbon material, which initial effect may be insidious and, in time, be the cause of a disastrous failure in flight. The pierced ribbon material has also been found to,be objectionable heretofore for the reason that the resulting protuberances in the ribbon corrugations have prevented free movement of the perforated ribbon through the corru-gating dies and have required inordinate undercutting of the indexing and electrode pins in order to clear the protuberances as the pins move into and out of the cells of the honeycomb in the process of fabricating the core from the corrugated ribbon.

Corrugation punch presses of the type disclosed in the aforesaid patent of Fred H. Rohr provide the required Patented Mar. 7, 1967 coining of the metallic ribbon as the corrugations are formed, but have not entirely solved the problem of minimizing the stresses and strains due to the drawing and in.- ordinate workingof the ribbon as the corrugations are formed. Even where, as in the aforesaid case, stages of spring loaded corrugation punches are used in the operation so that the corrugations are formed only one at a time by the spring loaded dies, the continuous and extensive drawing of the ribbon in the formation of each corrugation prohibits the use of pierced ribbon perforations since the protuberances cannot slide over the confrontliDng die teeth during this drawing movement of the rib- A corrugation punch press suitable for use in corrugating ribbon which has been pierced to form perforations therein in. accordance with the perforating process of the present invention, is disclosed and claimed in the copending application of William F. Rethwish and Dale S. Harding for Corrugation Punch Press, Serial No. 314,- 191, fiied October 7, 1963. In accordance with the arrangement of this. preferred form of corrugation press, upper and lower dies, respectively having differentially spring loaded die members, cooperate during the initial closing of the dies to yieldably clamp and holding a previously formed, substantially V-shaped ribbon corrugation between the spring loaded members and, thereafter, as the dies continue to close, to brake the unformed ribbon therebetlween in two steps, to thus form the two sidewalls of a new corrugation, as the holding die members bottom in successive order, after which the dies, together and as a unit with their holding die members, forcibly more together to coin the newly formed corrugation therebetween. In this operation, the braking action involves essentially a translatory swinging movement of the unformed ribbon portions about certain of the tooth edges of the'dies which act as pivotal points. The result of this action-is that the necessary drawing of the ribbon from the storage reel is due essentially to the braking action, and as such, does not interfere with the desired positioning of the protuberances in what become the sidewalls of the corrugation. 'Working of the ribbon material, such as may occur in the corrugation process, moreover, is held to a minimum, to thus substantially prevent the introduction of stresses and strains in to corrugated ribbon. Formed nodal portions of the ribbon experience no working of the' metal at all, save for ultimate coining which is desired; the nodal portions merely being translated, as required, in the corrugation process to place the nodes alternately at the peaks and valleys of the corrugated ribbon.

In using this corrugation press with the pre-pierced ribbon perforations, the same are spaced along the length of the ribbon such that the protuberances lie in what become the sidewalls of the corrugations, as aforementioned. As such, the protuberances lie in the portions of the ribbon which brake in the corrugation process, and

since the drawing of the ribbon is largely incidental to the braking of the same, the protuberances readily clear the die teeth and are positioned for' flattening thereby as the dies close. The flattened protuberances form an eyelet which prevent the extension of the incipient tearing due to piercing, and also minimize the undercutting of the electrode and indexing pins.

In accordance with the perforator process 'of the present invention, an array of piercing elements such, for example, as steel phonograph needles are supported on the anvil of the corrugation press and are arranged in rows whichlie transversely of the ribbon path. Each needle extends loosely upwardly from its support on the anvil, and its tip portion is disposed or impaled within a small mass of resilient material such, for example, as

a cylinder of soft -rubber which bears against or near the needle support. Each loosely mounted needle, together with its impaled rubber cylinder, is readily removed from the array for repair or replacement.

An elongated pad of resilient material, which may be of the same material as used in the cylinders, together with a backup support therefor, is also disposed transversely of the ribbon path, but these members are supported by the punch or ram of the corrugation press and depend therefrom initially in spaced relation to the ribbon such that the unformed and unperforated portion of the ribbon feeds freely between the confronting surfaces of the pad and the surface support afforded by the end faces of the array of the rubber cylinders. Following piercing of the ribbon by the needles, both the resilient backup pad and the resilient cylinders, which become compressed during the piercing operation, expand as the corrugation dies move toward open position and thus operate to strip the ribbon and its protuberances from the pad as well as from the needles whose tip portions again become fully impaled within their respective cylinders.

An object of the present invention is to provide a new and improved apparatus and process for perforating and corrugating metallic ribbon.

Another object is to provide a ribbon perforation and corrugation apparatus and process which pierces the ribbon and thereafter corrugates the same in such a manner that the protuberances which result from piercing of the ribbon fall into predetermined positions in the corrugations formed in the ribbon.

Another object resides in the provision of a ribbon perforating and corrugating process and apparatus in which protuberances resulting from piercing of the ribbon are pressed into eyelets between the confronting corrugation dies.

Still another object is to provide a ribbon piercing arrangement which is operable by the corrugation press and pierces the ribbon prior to corrugating of the same in the corrugation dies.

Yet another object in a ribbon piercing perforator resides in the provision of novel stripper arrangements for freeing the pierced ribbon and the resulting protuberances thereon from the perforator as the corrugation dies move to open position.

Still other objects, features, and advantages of the present invention other than those hereinbefore specifically set forth are inherent in, or are to be implied from the novel combination, construction, and arrangement of parts comprising the best mode thus far devised for car rying out the invention and for practicing the methods thereof. This mode and a specific embodiment thereof will become more fully apparent as the description proceeds with reference to the accompanying drawings wherein:

FIG. 1 is a view in elevation of the perforator and corrugation press of the present invention;

FIG. 2 is a view from the underside of the upper perforator and die of the corrugation press as viewed along the line 22 of FIG. 1 and rotated 90 counterclockwise from the position of FIG. 1;

1 FIG. 3 is an enlarged perspective view of the lower perforator assembly shown in FIG. 1;

FIG. 4 is a view in elevation of a needle and support assembly disclosed in FIG. 3;

FIG. 5 is a sectional view taken along the line 5--5 of FIG. 4;

FIGS. 6 to 9 are schematic views showing the successive steps of perforating a ribbon and forming a per forated ribbon corrugation therein between the dies of the corrugation press;

FIGS. 10a to c are diagrammatic views illustrating further details of the corrugation forming process performed on the perforated ribbon;

FIG. 11 is a detail view disclosing the operation involved in the piercing of the ribbon;

FIG. 12 is an enlarged view depicting the protuberance formed by piercing of the ribbon;

. FIG. 13 depicts the eyelet which is formed from the ribbon protuberance when the same is pressed and coined in the corrugation press; and

FIG. 14 is a sectional view taken along the line 1414 of FIG. 13.

Referring noW to the drawing for a more complete understanding of the invention, and first more particularly to FIGS. 1 and 2 thereof, 10 and 11 designate fixed and movable die supports which, in practice, may be re ferred to as shoes, but for purposes herein, conveniently may be considered as the anvil 10 and the ram or punch 11 of a conventional punch press. Support 11 is normally positioned above fixed support 10 and is slidably mounted on the upstanding and suitably spaced

cylindrical guides

13 and 14 for movement forcibly toward and away from the fixed support. For this purpose, guides 13 and 14 are suitably secured to fixed support 10, and movable support 11 is suitably driven from a power source acting through its coupling member 12.

Hubs

15 and 16 on support 11 extend the bearing surface afforded thereby on

guides

13 and 14.

Hubs

15 and 16 and guides 13 and 14 are disposed concentrically with respect to semi-cylindrical

lateral extensions

17 and 18 of support 11.

A die set comprising dies generally designated 19 and 20, respectively, are suitably secured by means (not shown) to the fixed and movable supports 10 and 11. Dies 19 and 20 are generally similar, and the same reference characters therefore, will be applied to the same or like elements of these dies throughout the several views.

Each of dies 19 and 20 comprises a forming die member 23 having one tooth 24, and a relatively movable holding die member 25 having two teeth 26. Die

members

23 and 25 for both dies 19 and 20 are identical and their opposing

teeth

24 and 26 complement each other such that the same intermesh and the line of engagement between the teeth depicts the corrugation configuration to be imparted to a metallic ribbon 27 interposed therebetween. As may be seen from this configuration, the resulting corrugations in the ribbon are generally V- shaped with flattened surfaces or

welding nodes

28 and 29 respectively provided at the crests and valleys of the corrugated ribbon.

Each forming die member 23 is suitably secured at the ends thereof to a pair of end plates 31, FIG. 2, which, in turn, are suitably secured to the die guide block and mounting member 33. Each member 33 has a mounting flange 34for mounting its

die

19 or 20, as the case may be, on its respective support 10 or 11, as aforementioned. End plates 31 also have fastening means (not shown) which serve further for this purpose.

Die

members

23, 31 and 33 when asembled and secured together, as aforedescribed, provide a guide channel 35 for the holding die member 25 which is provided with a flange or shoulder 36. Guide channel 35 is appropriately widened at 37 to accommodate the shoulder and also to provide a seat therefor to limit the movement of holding die member 25 forwardly or outwardly with respect to the forming or corrugating die member 23. It will be noted that the widened channel 37 has a greater length than that of the shoulder thereby to permit limited relative movement between the die members Band 25. Thus, when each die 19, 20 is mounted in position on its respective support 10, 11, die member 25 for each die is limited in its movement in the opposite direction as the shoulder engages the mounting surface of its associated support, as may be seen in FIG. 1 wherein the dies 19 and 20 are shown to be closed and the die members 25, insuch case, are properly shown to be bottomed on their respective supports. When die members 25 are thus bottomed, they effectively become a unit with their respective corrugator die members 23, and teeth 26 of each member 25 effectively act as a unitary structure with their as:

sociated tooth 24. This is important in the precision forming of corrugations in metallic materials such as stainless steels wherein it is desired to coin the formed corrugations in the final blow imparted thereto by the punch press in the instant of closing of the dies on the ribbon 27 interposed therebetween.

Holding die members 25, as may be seen in FIG. 1, are spring loaded as by coil springs 38, so as to be normally extended yieldably outwardly or forwardly of their respective forming die members 23, these members being sufiiciently elongated, as required, to corrugate ribbons of various widths. A plurality of springs are employed for each die member, and a socket 39 is provided therein for seating each spring 38. Similarly, supports and 11, are provided with sockets 40 which also serve to seat the springs, sockets 40 being aligned with and complementing the sockets 39 of the die members 25.

For reasons which will become more fully apparent as the description proceeds, die members 25 are differentially spring loaded, the spring loading of die member 25 of die 19 being made greater than that of member 25 of die as by using two, for example, more springs 38 for die member of die 19, than for member 25 of die 20. It will be understood that whereas differential spring loading has been particularly disclosed herein, the differential bias and'yieldable urging of the holding die members 25 may be accomplished by other means such, for example, as by using air pressure.

The corrugations formed in ribbon 27 are stretched and elongated in a controlled amount, by

stretcher members

47 and 48 of which member 47 serves as an anvil and is suitably secured to support 10. Member 48 is secured to and depends from support 11 as by the stud bolts 49 and is adjusted in position therefrom by the nuts 50. For reasons believed inherent in the coining of the corrugations in the punch press operation, the resultant spacing between nodes invariably is less than that of the die dimensions. The adjustably mounted member 48 is elevated or lowered at either or both ends relative to support 11, as required, to provide such spaced relation with respect to member 47 as will flatten and thereby stretch the corrugated ribbon sufficiently to compensate for the under-dimension forming of the spacing between nodes of the corrugations. In some instances, where the corrugation spacing tends to be greater at one side of the ribbon than on the other with resultant tapering of the corrugations over the width of the ribbon, this may be obviated by slightly raising or lowering one end of member 48 more or less than the other end relative to the set screws 50 individual thereto.

Means for perforating ribbon 27 preparatory to forming and coining the corrugations therein is generally disclosed in FIG. 1, and comprises a lower ribbon piercing assembly, generally designated 51, and an upper back up plate assembly, generally designated 52, which assemblies lie transversely of the ribbon path in confronting relation to each other and to ribbon 27 disposed therebetween. Assembly 51 is suitably supported on and secured to a block 53 which, in turn, is suitably supported on and secured to press support 10.

Back up plate assembly 52 comprises an elongated, relatively massive metal bar 54 which prefearbly is of square cross section and depended at the ends thereof from movable press support or ram 11 as by the stud bolts 55 which are suitably secured, as by the nuts 57, to the support 11 and bar 54, respectively. A resilient ribbon stripper or shedder strip 58 is suitably secured at the ends thereof to bar 54, as by-screws 59. Strip 58 may be formed of any material suitable'for the purpose such, for example, as sheet rubber (Duro 65).

Referring now more particularly to FIGS. 3 to 5, it will be seen that the ribbon piercing assembly 51 comprises a channel member 60 having a base 61 and side walls 62 which are reduced as at 63 in the end regions of channel member 60 to accommodate bifurcated adjusting 6 plates 64 which are releasably secured to base 61 as by the screws 65.

Channel sidewalls 62 and plates 64 form a shallow socket 66 for retaining the needle mounting and supporting members 67, the plates 64 being slidably adjusted in the channel, as required, to position and clamp the members'67 therebetwe-en. As may best be seen in FIGS. 4 and 5, each of members 67 is apertured transversely thereof to provide a plurality of openings 68 which taken together constitute a common bottoming plane for a plurality of needles 69. The needles are loosely received in openings 70 which are arranged to intersect respectively with the openings 68.

Needles 69 per se are essentially rod-like, being pointed at one end and flat at the other; and viewed as an array, are of uniform length. The needles may be of any configuration and formed of any material suitable for the purpose. For example, the needles may be commercially available Duotone filter point phonograph needles. Each needle 69 is impaled in the region of its tip portion 71 within a small resilient mass 72, preferably of cylindrical configuration, as shown, the cylinders being positioned at or near the upper surface 73 of each of members 67. Cylinders 72 may be formed of any material suitable for the purpose such, for example, as by being punched from soft sheet rubber (Dur-o 65 Referring again to FIG. 3, it will'be seen that the cylinders 72, and hence the needles 69, are spaced along the lengths of members 67 in accordance with the perforation pattern desired across the width of the ribbon, it being noted that the arrangement is such that the needles of one member 67 are staggered with respect to those of the other to avoid weakening of the ultimate honeycomb structure in its length dimension. In order to space the perforations in the ribbon so as to fall in the sidewalls of the successive corrugations, needle support members 67 are spaced between sidewalls 62 by a plurality of shims 74 and a marcel strip 75. Strip 75 is interposed between one of the sidewalls and one of members 67 and yieldably urges the same toward the other sidewall. The shims are interposedbetween this last named sidewall and the other of the needle support members 67 and also between the members themselves, as may be seen in the disclosed arrangement of FIG. 3.

Attention is now directed to FIGS. 6 to 14 for a description of the ribbon piercing and corrugating operation from which it will become more fully apparent how the essentially braking action of the corrugation press lends itself to the forming and coining of corrugations in a ribbon which has been pierced and protuberated.

With the parts positioned as disclosed in FIG. 6, the punch press is about to begin a new cycle of operations in which it will pierce a new double row of protuberances 56 and form a new corrugation in ribbon 27, the ribbon having been just previously advanced one corrugation by sliding over the rubber cylinders 72,.out of and over teeth 26 of the lower holding die member 25, and thence over anvil 47 of the stretch-out device. The ribbon preferably is advanced relative to the perforator, dies, and stretch-out as aforedescribed, by a hitch feed mechanism such as disclosed and claimed in the copending application of Elbert M. Lacey, Jr., for Method and Apparatus for Feeding Metal Strips, Serial No. 78,720, filed December 27, 1960, which application also discloses the stretchout operation on the corrugated ribbon.

With the previously formed corrugation of ribbon 27 thus seated on the lower die member 25, the opposing member 25 first engages the ribbon during the initial closing of die 20 toward die 19, the ribbon then being clamped yieldably between the upper and lower ribbon holding members 25, as depicted in FIG. 7, at which time the forming of the first portion of a new corrugation is about to begin. As die 20 continues to move toward die 19, the same moves relative to its holding die member 25 which cannot move at this time because of the greater spring force acting on the lower holder member 25 which does not move until after the upper die member 25 has bottomed on support 11.

During this relative movement of die member 23 with respect to its holding die member 25, a first unformed portion 41, FIG. 7, of ribbon 27, corresponding to one side of a new corrugation, is formed between tooth 24 of die 20 and confronting tooth 26 of die 19 as the dies take the position as shown in FIG. 8.

Members

23 and 25 of die 20 now move as a. unit to thus move holding member 25 of die 19 yieldably against its opposing spring force until the same bottoms on support 10, as diclosed in FIG. 9. During this movement, a second unformed portion 42, FIG. 8, of ribbon 27, corresponding to the remaining sidewall of the new corrugation, is formed between the confronting teeth 24 of the opposing corrugating die members 23. In the position of FIG. 9, both die members 25 being bottomed, the newly formed corrugation is coined in the instant of forcible closing of die 20 on die 19.

Shortly after the dies proceed to close further from the position of FIG. 8, as aforedescribed, shedder strip 58, FIG. 6, moves to engage ribbon 27, and on further closing of the dies, strip 58 compresses somewhat as the same moves the ribbon to compress the rubber cylders 72. As this action progresses, of course, the needles 69 further pierce the cylinders and then pierce the ribbon to form the protuberances 56 and, thence, proceed to penetrate somewhat into strip 58, as depicted in FIG. 11.

When the dies separate and move to open position, the compressed cylinders 72 expand and, in so doing, lift the perforated ribbon with respect to the needles 69 to thus retract the needles therefrom. The needles, of course, return to their partially impaled positions within the cylinders. The compressed shedder strip 58 likewise expands as the same moves with support 11 to pull away from the compressed cylinders 72 and, as this expansion of strip 58 occurs, the ribbon and its protuberances 56 are stripped from the shedder strip 58 and thus do not follow the continued upward movement of the strip to the open position of the dies, as depicted in FIG. 6.

Referring now more particularly to FIGS. 12 to 14, it will be seen that each of the protuberances 56 comprises a ring of more or less uniform peaks 76 distributed about the circumference of each perforation opening formed in the pierced ribbon 27. As otherwise expressed, the initially ruptured ribbon apparently proc-eeds to tear along uniformly spaced lines as the perforation is enlarged by the progressive penetration of the tapered needle into the pierced ribbon. These protuberance peaks double back upon themselves during the corrugation process to form an eyelet or more or less symmetrical ring 77 about the perforation opening, as disclosed in FIGS. 13 and 14, and this ring 77 prevents further tearing of the ribbon and thus avoids an extension of the incipient tearing of the ribbon which occurs as an icidence of the ribbon perforation.

Referring now more particularly to FIGS. a to c, for a more detailed discussion of the metal working aspects involved in the forming of a new corrugation from the perforated ribbon 27, it will be seen that the perforated ribbon portion 41, which has a length A corresponding to the sidewall of the corrugations to be formed, bears critically at P1 on tooth 26 of holding die member 25 of die 19, and also bears critically at P2 on tooth 24 of forming die member 23 of die 20. As the dies close and the forming occurs, ribbon portion 41 brakes about the point P1 in response to pressure applied at the point P2. It will be appreciated that the ribbon slides for a small distance over the point P2 of tooth 24 until the same reaches the position of FIG. 10b. In the braking action of the unformed ribbon portion 41, the end of the same follows the circular path about point P1 indicated by the dashed line 43. That diminishing portion of the unformed ribbon lying between this dashed line and point P2, of course, experiences a combined sliding and braking movement over point P2. While a purely braking action would be ideal, no adverse effects are manifested. The protuberance 56 in ribbon portion 41 is thus simply moved in a swinging motion to a position against the sidewall of tooth 26 of die member 25 of die 19 preparatory to being flattened thereagainst by the approaching surface of tooth 24 of die member 23 of die 20.

A second unformed ribbon portion 42, also having a length A and a protuberance 56, bnakes about the point P3 on tooth 24 of die member 23 of die 20, as die member 25 of die 19 moves to bottom on support 10, and a combined sliding and braking action of the ribbon occurs about the point P4. The braking action of unformed ribbon portion 42 about point P3 thus is such that the end of the ribbon portion effectively follows the circular path indicated by the dashed line 44 shown in FIG. 10b, and the protuberance 56 in ribbon portion 42 is simply translated in a swinging movement to a gposition against the sidewall of tooth 24 of die 20 preparatory to being moved and coined thereby against the confronting sidewall of tooth 24 of die 19.

That portion of the unformed ribbon, which lies between points P2 and P3, is designated 45 and has the nodal length B. Ribbon portion 45 is simply translated to the base of tooth 24 or die member 23 of die 19 as member 25 thereof moves to bottom on the die support 10. As a practical matter, unformed but coined ribbon portion 45 together with ribbon portion 41, may be considered to be a first unformed ribbon portion, in the same sense that the corresponding unformed but coined ribbon portion 46, FIG. 100, which lies between the points P4 and P5 at the closing of the dies, together with ribbon portion 42, may be considered to be a remaining ribbon portion, required to form a new complete corrugation, which will thus be made up of

ribbon portions

41, 45, 42 and 46, as may best be seen in FIG. 100. Although the corrugation width, i.e., as measured from node to node, may be seen to be B plus D, a length of ribbon corresponding to 2B plus 2A is required to form the new corrugation. Of this length, as has been described, there is no working of the B portions; only coining. D minus B, of course, does not equal 2A, since purely braking does not occur in the forming of the A portions; but this is substantially the case, and the ultimate coining of the formed ribbon in the region of points P2 and P4 removes any adverse effects which may have been introduced in the previous working of the material as it slides over the teeth at these points. In effect, the substantial length of each A portion and the protuberance thereon is simply translated in a swinging movement of the unformed ribbon portion about the edge of one of the die teeth.

The results of the combined perforation and corrugation process as aforedescribed are, first, precision forming of the perforated ribbon corrugations and, second, high quality blocks of honeycomb core free of incipient tear conditions when the blocksare fabricated from the perforated and precision corrugated ribbon. Such blocks are undistorted and unwarped and have optimum welds at abutting nodes which are aligned consistently from node to node. The fabrication of cores from such ribbon desirably may be programmed with assurance that the corrugation will be of uniform spacing and the nodes will properly align and abut preparatory to welding of the same together. The cores, moreover, having the perforated cell walls may readily be fabricated into sandwich structures in any brazing process requiring the circulation through the core of a protective gaseous atmosphere.

It will be apparent from the foregoing that a perforation and corrugation press and process has been provided 9 which is well adapted to fulfill the aforestated objects of the invention. It will be apparent, moreover, that this invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment of the invention is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Having thus described our invention, what we claim as new and useful and desire to secure by Letters Patent is:

1. Themethod of perforating and corrugating metallic ribbon to form substantially V-shaped perforated corrugations therein having nodal portions at the crests and valleys which comprises the steps of piercing the ribbon, and concurrently corrugating eyeleting and coining the pierced ribbon so that the protuberances resulting from the piercing of the same fall into predetermined po sitions in the sidewalls of the corrugations, and the protuberances become eyelets in the coining of said sidewalls.

2. The method as in claim 1 and further comprising the step of stretching the corrugated ribbon to set the nodal spacing of the-corrugations at a predetermined value.

3. The method of perforating and corrugating metallic ribbon to form substantially V-shaped corrugations having perforated sidewalls and nodal portions at the crests and valleys, comprising the steps of piercing the ribbon to form protuberan-ces therein spaced along the length thereof, braking successive portions of the pierced ribbon to corrugate the same such that said protuberances fall respectively in the sidewalls of the corrugations, coining the corrugations and transforming said protuberances therein to eyelets, and stretching the corrugated ribbon to set the nodal spacing of the corrugations at a predetermined value.

4. The method of perforating and corrugating metallic ribbon to form substantially V-shaped corrugations therein having perforated sidewalls and nodal portions at the crests and valleys, comprising the steps of advancing the ribbon intermittently longitudinally of the same, piercing the ribbon as the same advances to form protuberances therein spaced along thelength thereof, braking successive portions of the pierced ribbon to form said V-shaped corrugations therein such that said protuberances fall respectively in the sidewalls of the corrugations, coining the formed corrugations and eyeleting said protuberances therein, and flattening the corrugated ribbon to stretch the same and set the nodal spacing of the corrugations at a predetermined value.

5. The process as in claim 4 and wherein said piercing, corrugating, coining, eyeleting, and flattening of the ribbon occur concurrently during intervals between the intermittent advances of the ribbon.

6. A system of perforating and corrugating metallic ribbon to form V-shaped corrugations having perforated sidewalls comprising, in combination, means for piercing the ribbon transversely thereof and recurrently at predetermined spaced intervals along the length of the ribbon as the same is intermittently advanced longitudinally, and means operated concurrently with the piercing means for concurrently braking, eyeleting and coining the pierced ribbon to corrugate the same such that the resultant perfo rations in the ribbon fall in the sidewalls of the corrugations and become eyeletted as the corrugations are formed.

7. The system as in claim 6 and further comprising means operated concurrently with the piercing and corrugating means for stretching the formed corrugations.

8. Apparatus for perforating and corrugating metallic ribbon comprising, in combination, relatively movable and stationary members disposed for intermittent passage of a metallic ribbon therebetween longitudinally of the ribbon, die means respectively supported by said members for braking and corrugating the ribbon as the members close relatively toward each other, ribbon piercing means respectively supported by said members and disposed in advance of the corrugating means along the line of ribbon movement for forming perforations and resultant protuberances in the ribbon as the members close relatively toward each other, and corrugation stretcher means sup ported respectively by said members and disposed behind the corrugating means along the line of ribbon movement for flattening the formed corrugations thereby to stretch the same a predetermined amount as the members close relatively toward each other.

9. Apparatus as in claim 8, said ribbon piercing means comprising a plurality of sharpened ribbon piercing elements disposed in spaced relation in a row transversely of the ribbon and supported on the stationary member with their sharpened ends extended upwardly, a plurality of small masses of resilient ribbon stripping material impaled respectively on said ribbon piercing elements, an elongated back up plate supported by the movable member and aligned in opposed relation to said row of piercing elements, and a strip of resilient ribbon stripping material secured to said plate in confronting relation to said sharp ened elements, said resilient strip serving to strip the pierced ribbon and its resultant protuberances from the strip and said small resilient masses serving to strip the pierced ribbon from said piercing elements as the fixed and movable members relatively separate following piercing of the ribbon by said piercing elements during relative closing of the members toward each other.

10. Apparatus as in claim 9, said ribbon piercing means comprising two rows of said ribbon piercing elements, the elements of one row being staggered with respect to the elements of the other row.

11. Apparatus for perforating metallic ribbon comprising, in combination, relative movable and stationary members disposed for intermittent passage of a metallic ribbon therebetween longitudinally of the ribbon, a plurality of sharpened ribbon piercing elements disposed in spaced relation in a row extended transversely of the ribbon and supported loosely and removably on the stationary member with their sharpened ends extended upwardly, a plurality of small masses of resilient ribbon stripping material impaled respectively on said ribbon piercing elements such that each of said masses of stripping material and its associated ribbon piercing element forms a removable unit, an elongated back up plate supported by the movable member and aligned in opposed relationto said row of piercing elements, and a strip of resilient ribbon stripping material secured to said plate in confronting relation to said row of sharpened elements.

12. Apparatus as in claim 11, and further comprising two rows of said ribbon piercing elements and means for supporting the elements on said stationary member, said means comprising an elongated retainer plate for each row of elements, each said retainer plate having a plurality of openings respectively receiving said elements loosely therein, each of said plurality of openings having a transversely intersecting opening defining a bottom support surface for its respective element, a channeled support for said retainer plates, spacer means for varying the spaced relation of said retainer plates within said channeled support, spring means for yield ably retaining the retainer plates in adjusted spaced relation within the channeled support, means for adjustably spacing and securing the retaining plates longitudinally of the channel support, and means for securing the channeled support to the stationary member.

13. Apparatus as in claim 11, and further comprising two rows of saidribbon piercing elements, the elements of one row being staggered with respect to the elements of the other row.

14. Apparatus as in claim 11, said ribbon piercing elements comprising conventional phonograph needles.

References Cited by the Examiner UNITED STATES PATENTS 1,573,810 2/1926 Cunningham 72384 2,403,035 7/1946 WVhitson 83-l39 2,413,179 12/1946 Grandmont et a1. 72-404 1/1950 Urquhart 83139 1/1955 Lubeck 72-325 FOREIGN PATENTS 2/1934 France. 4/1942 Great Britain.

CHARLES W. LANHAM, Primary Examiner.

L. A. LARSON, Assistant Examiner.

Claims

1. THE METHOD OF PERFORATING AND CORRUGATING METALLIC RIBBON TO FORM SUBSTANTIALLY V-SHAPED PERFORATED CORRUGATIONS THEREIN HAVING NODAL PORTIONS AT THE CRESTS AND VALLEYS WHICH COMPRISES THE STEPS OF PIERCING THE RIBBON, AND CONCURRENTLY CORRUGATING EYELETING AND COINING THE PIERCED RIBBON SO THAT THE PROTUBERANCES RESULTING