US3105420A - Blank forming die - Google Patents

Description

1963 H. L. PHILLIPS ETAL 3,

BLANK FORMING DIE 3 Sheets-Sheet 1 Filed Feb. 7, 1961 INVENTORS HARRY L. PHlLLlPS y a i N E w YB B ATTORNEYS 9 H. L. PHILLIPS ETAL j 3,105,420

BLANK FORMING DIEM I Filed Feb. 7, 1961 S Sheets-Sheet 2 INVENTORS HARR LLIPS LYT FA'N BY ATTORNEYS Oct. 1, 1963 H. L. PHILLIPS ETAL 3,105,420

Y BLANK FORMING DIE Filed Feb. 7, 196.1 3 Sheets-Sheet 3 INVENTOR HARRY HILLI LYTT 5. FAIN ATTORNEYS San San This invention is a continuation in part of copending applications for United States Letters Patents Serial Nos. 754,632, now Patent No. 2,993,421, granted July 25, 1961 and 58,774, respectively filed August 12, 1958, and September 27, 1960, and has for one of its objects the provision of a die of the flat bed type adapted to simultaneously form a plurality of carton blanks that are identical to each other in every respect, and in which die all of the rules are frictionally held in place when in use and are adapted to be replaced after use or when readied for use without requiring the present costly and time consuming lock-up period.

Another object of the invention is the provision of a die of the fiat bed type in which the rules are adapted to be removed and replaced after the die is locked in a chase and has been readied for use, without disturbing the positions of the other rules relative to each other, and in which the replacement rules will be frictionally held rigid relative to other rules in the die irrespective of the inevitable variations that occur in the thicknesses of precision commercially produced rules of the same specifications.

A still further object of the invention is the provision v of a die for cutting md creasing carton blanks from a sheet of cardboard, and which die includes steel cutting and creasing rules that are frictionally held in cast engagement with a unitary body of hardened plastic material against movement relative to each other in positions extending completely through such body, transversely of the length of such rules, and which rules are replaceable for partial or complete re-ruling of the die many times without requiring shimming or other means than the body of the die itself for holding the replacement rules in said body irrespective of the inevitable variations that occur in the thicknesses of rules made under the same specifications.

An added object of the invention is the provision of a main die that is made up of a plurality of sub-dies, each including cutting rules or cutting and creasing rules that adapted to simultaneously form blanks from a sheet of material, and which rules may be withdrawn from any or several of the sub-dies, and replaced, without displacing or changing the positions of any of the other rules in any of the sub-dies or loosening any of the sub-dies relative to each other.

Another object of the invention is the provision of a die of the fiat bed type having a unitary body with steel blank forming rules extending therethrough so that said rules will be supported on their base edges against a rigid bed on the press during a blank forming operation, while the working edges of said rules, which are the blank forming edges, are exposed and project from the side of said body opposite to the side that is adjacent the base edges. These rules are releasably held in said body in cast engagement therewith and the rules are formed with generally Ushaped recesses opening outwardly of the base edges thereof for receiving therein rigid means connecting the portions of the cast body of the die at opposite sides of the rules thereby permitting the rules to be withdrawn from the side of the body opposite to the base edges of the rule, and other rules replaced, after said body is cast against the rules, without disturbing any of the other rules of the die.

Another object of the invention is the provision of a Edd-5,42%-

main die having steel rules adapted to simultaneously form a plurality of cuts and, or, creases in corresponding blanks and which rules are releasably, but rigidly, held together in a plurality of groups, each group relating to one of said blanks, and each group being releasably held as a unit relative to the other groups, and each of which groups is in a body of material rigid therewith and which bodies releasably support other blank cutting rules be tween them that are adapted to cut along lines common to adjacent blanks formed by said adjacent groups of rules.

Another object of the invention is the provision of means within a unitary die body that is in cast, frictionally holding relation to steel blank forming rules extending completelythrough such body, that enables an adjustment of such rules relative to each other in said body to prevent rocking of any of such rules in said body in the plane of each rule.

An added object is the provision of a method of making a single die that is adapted to simultaneously form a plurality of blanks that are identical to each other, and in which die predetermined multiples of the rules may be replaced as a unit, or individual rules in each multiple may be replaced, as desired, without changing the relative positions between the other rules or between dies employed for making blanks in which a very high degree of accuracy is required, are flat bed dies, or dies adapted to be used only on flat bed presses, and each die is adapted to cut and to crease a plurality of carton blanks of corresponding shape and size. The conventional Miehle and Mercury presses are examples of presses using fiat bed dies.

Thus it may be said that each die is a main die made up of a plurality of sub-dies, each of which sub-dies is adapted to form cuts or creases or both in each of the carton blanks. One of such main dies may be called a 10-011 die where ten carton blanks are to be formed, and these main dies may each include scores of sub-dies where small carton blanks are to be formed. Usually the smaller the size of the carton blank to be cut, the greater the number of sub-dies, and the larger the size of the carton blank, the larger the die. A 10-on die is shown in the drawings as Well as one of the units thereof, hence this size main die will be specifically referred to hereafter, but merely by way of an example.

The conventional method heretofore practiced in making a main die, such as a 10-011 die, has been to cut wooden pieces, one at a time, to shapes that will support, between adjacent pairs thereof, the rules of each die when the wooden pieces with the rules therebetween are locked in a chase. Since there are ten sub-dies in a 10-on die, each of which is intended to cut and crease a blank that is the same as the other nine blanks, it is obvious that the many of the wooden pieces that are cut for each sub-die should be of exactly the same size and contour as the pieces cut for the other sub-dies. This has, throughout the years since the invention of the wooden fixture or wooden furniture die, been found to be impossible. It is not possible for a workman to separately cut pieces that will be identical, and when the many Wooden furniture dies are placed in a chase in rule supporting positions, and the chase is tightened against the pieces to draw them into tight engagement with the rules, the slight variations in the Wooden pieces and in the shapes of the rules that have been separately and individually cut and 'bent, necessitates a long and costly lock-up period. In this conventional method the workmen use shims and other means in an effort to rectify the variations so that the rules will come within certain permissible tolerances. The lock-up period for a single main die may take as long as several days.

Once the main dies of the conventional type above mentioned are ready for use, variations in humidity and temperature will cause changes in the relative positions of the rules,resulting in the different blanks formed by the main die being different from each other, and when the dies are in use, the shocks and pressures incident to forming the blanks cause shifting of the wooden pieces and rules relative to each other, resulting in the blanks that are formed being different from each other.

As soon as these differences exceed any of thepermitted tolerances, the presses must be stopped and the positions of the rules rectified. Also in actual practice, some rules in a main diemust be replaced from time to time. In conventional wooden fixture or wooden furniture dies the chase must be loosened in order to effect the replacement. Once the chase is loosened, the adjust- .ment-originally made to insure accurate positioning of the rules relative to each other is destroyed, and the lengthy lock up time must be repeated after the rule replacement has been made. This. time may be a day and more.

Heretofore, where the conventional dies, above described, are used and an order of blanks has been furnished, if there is a likelihood of more blanks being ordered within the reasonably near future, the chase with the wooden furniture dies locked therein, will be stored for such future use in order to avoid or reduce the necessity for repeating the long and costly lock-up time.

with the result that all of the precautions taken to avoid the costly lock-up time is lost, and this is not discovered until the die is taken out of storage and put into use.

With the present invention, the original lock-up time is negligible, normally being less than an hour, and the rules may be changed in groups, or singly, without altering the positions of the other rules or their supports, and usually loosening of the chase is not necessary. When a run of blanks is completed, the sub-dies can be quickly removed and stored in a compact space, if desired, with the chase being individually released for other work, since the lock-up time in replacing the sub-dies and rules is negligible.

Efforts heretofore made to overcome the objections to the wooden furniture dies have been directed along the line of cuttingslots in solid blocks for the rules, and routing grooves in a plate or block on which the rules are intended to be supported. These have failed for various reasons one of which is the fact that irrespective of the precision with which saws or tools may cut the required accuracy together with the essential frictional resistance to movement of the rules relative to the rule holding body has not been possible. Irrespective of the precision with which the rules are made, they vary in thickness, and irrespective of how accurate a cutting saw or tool is made, theycannot accurately cut to the very high degree of precision required. Hence all such attempts on which fortunes have been expended, have been abandoned.

Other objects and advantages will appear in the description and in the drawings.

In the drawings:.

FIG. 1 is a top plan view of a l-on die including the chase.

FIG. 2 is an enlarged, fragmentary top plan view of a portion of the die of FIG. 1 in which one of the sub-dies is fully shown, with the dotted lines showing means within the body of the die making it a unitary body.

FIG. 3 is an enlarged, fragmentary sectional view taken along line 3--3 of FIG. 2.

FIG. 4 is a bottom plan view of the sub-die shown in FIG. 2.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 2.

In detail, a rectangular, conventional chase 1 is shown in FIG. 1, which chase has four side members 2 that are at right angles to each other and rigid relative to each other. Disposed within said chase on a flat, rigid bed, is a rectangular 10-on die generally designated 3. Each of the ten sub-dies forming the main die 3, is generally designated 4. FIG. 2 shows one of such subdies in top plan view and FIG. 4 is a bottom plan view of the sub-die shown in FIG. 2.

The main die 3 and sub-dies 4 are rectangular, the latter being identical to each other in every respect.

Between two of the adjacent rigid sides of the recangular chase I are movable rails 5, 6 that are parallel with the sides of the chase respectively adjacent thereto, and the lO-on die is disposed between these rails and the other two rigid sides of the chase. Conventional quoins 7 aredisposed between the rails 5, 6 and the rigid sides of the chase that are parallel with and adjacent thereto. These quoins are adapted to tighten the rails against die 3 and for locking the die in the chase against the rigid sides of the chase that are opposite to rails 5, 6. The chase, including rails 55', 6 and the quoins i, is conven-. tional.

The ed on which the chase and die 3 are supported in setting up the die, is not necessarily part of the chase, the latter normally being an open frame within which the die 3 and the euttin and creasing rules are held.

Except for the rules, each sub-die 4 may be substantially a unitary block of an epoxy compound that has been molded against the sides of the rules and that fills the spaces between rules substantially as described in copending application for United States Letters Patent,

Serial No. 9,545, filed February 18, 1960. In the example illustrated in FIG. 2 cutting rules are indicated at 8, and the creasing rules at 9. The cutting rules, in a die for forming carton blanks cut the outline of the blank, the flaps, locking tabs, slits, slots, etc., while the creasing rules form creases or scores along which portions of the blank are to be folded.

It should be mentioned that the rules in a blank forming die may all be cutting rules, and in some instances they may all be creasing rules, hence the use of the term cutting and creasing rules used herein is not intended to be restrictive. V

forming a blank therefrom.

The rules 8, 9 are formed with generally U-shaped recesses 16 that open outwardly of the base edges of the rules, such edges being those defining the edges of the rules that are opposite to the working edges thereof. Positioned within these recesses are metal tie rods 11, 12. As indicated in FIGS. 2, 5 the tie rods 11 are longones that may extend the major length and breadth of the die,- the one extending transversely of the length of the die being disposed crosswise to those extending the length. Tie rods 12 may be short ones such as extend across certain rules that usually are closer to the edges of the die than others and are positioned where it would otherwise be diflioult to extend one of the longer rods 11.

The function of these tie rods is to reinforce the material, such as where they extend across areas of substantial size between adjacent parallel rules, and to rigidly hold the plastic body of the die against opposite sides of the rules. Also said tie rods are good heat conductors, preferably being of aluminum, thereby reducing the coefficient of shrinkage that occurs during curing of the plastic material, preferably an epoxy compound, of which the body of the die is formed.

Disposed between the bottom edge of each recess 10 and against said edge and the tie rod nearest to said edge, is a small piece of compressible material 14. For cheapness, a piece of chipboard is adequate.

When the plastic material 15, which, as stated above, is preferably an epoxy compound, is poured into a frame enclosing the accurately positioned rules so as to extend from the base edges of the rules, in cast engagement therewith, to a level spaced from the working edges the desired distance the epoxy compound will bond rigid-1y with the tie rods, but not the rules or said frame or any other material it may contact, since the rules, frame and such other material is coated with a parting medium. However, as seen in FIG. 3, the piece of compressible material 14- Will be between the rule and the tie rods and should the epoxy compound in the pouring and curing steps slightly urge a rule in a direction outwardly of the body to the side thereof from which the working edges project, the result would be a slight rocking of the rule about ahigh point along the rule, which point would be at one or more of said recesses, as sometimes occurs. This may be approximately 00.001 of an inch, but it must be corrected. All that is necessary to overcome this difiiculty is a slight tap With a rawhide mallet on the working edge of any of the rules at any such high point and the rule will then compress the material 14- sufficiently for its base edge to seat against the bed of the press and to still be rigid with the die to be capable of being withdrawn for re-knifing.

The molding of the epoxy com-pound against and at opposite sides of the .rules is essential to the success of the die, and the compound must be of a character in which there is substantially no shrinkage during curing, in which case the rules are so rigidly held that they cannot become loose or shift relative to each other, irrespective of whether or not the die is in a chase, and a rule puller is required for pulling the rules in order to re-knife the die.

As seen in FIG. 3 some of the plastic material of the die body will pass through the 'U-shaped recesses in the rules to connect the plastic at opposite sides of the rules. However, the metal tie rods are mainly relied upon to hold the die body together as a unit.

Earlier in the description it was pointed out that any attempt to mechanically cut or form slots in a solid slab of material for the rules, is impossible, it being essential to the suc ess of the die and its operability in a press that the slots for the rules be molded against the rules and that the opposite sides of the rules be in cast engagement with the plastic body of the die. This is highly important, as is the fact compressive force on the rules in a blank forming operation should not be transmitted to the plastic, but directly to the bed of the press or the equivalent. Also, the rules within each sub-die are held rigid with the body of each sub-die independently of any pressure from the chase itself.

In making the main die 3, the sub-dies 4 (in the example shown) are positioned on two rows of five each with the rows extending longitudinally of the chase. This makes a -on die. This group of ten sub-dies is positioned against two of the rigid adjacent sides 2 of the chase, except for cutting rules 18, 19 that are respectively between two of said adjacent sides of the chase and the group of sub-dies. Opposed to rule 18 is a cutting rule 2%, and opposed to rule 19 is a cutting rule 21, which rules 29, 21 are respectively between the rails 6, 5 and the body of ten sub-dies. Thus the body of sub-dies is enclosed by cutting dies.

A cutting rule 22 extends between the rows of sub-dies from one end of the main die to the other, and rules 23 extend perpendicular to rule 22 between adjacent subdies in the rows. Whether rules 23 extend continuously betve [1 rules 18, 26 and rule 22 is in sections, or vice versa, is immaterial.

In the example the rules 18, 22, function to form cuts that define the end edges of the finished blanks, while It should be noted, of course, that the dimension of the die bodies must be such that the cutting edges of rules 18, 2t 22 will be held in positions for cutting along lines that accurately define the edges of the carton blank that is cut.

This factor must be observed wherever loose rules in the main die define outer edges of the blanks, and by the term loose rules is meant such rules as are held between the bodies of the sub-dies by pressure from quoins 7.

When the sub-dies 4 and rules 18-23 are positioned in a chase and the rails 5, 6 are tightened, no possible misalignment of rules or sub-dies can possibly occur, since the bodies of the sub-dies have all been produced from the same mold and they are of exactly the same overall dimensions. Thus the pressure transmitted to the dies and rules 18-23 by actuation of the quoins or whatever tightening means is used, will releasably hold the sub-dies and rules 1823 in fixed relation to each other, but this pressure will not be transmitted to the rules within the dies.

It will accordingly be apparent that the sub-dies themselves may be re-knifed without even unlocking the chase, and the replacement rules will be in exactly the same positions relative to any of the other rules in the main die and in the other sub-dies as before. While the so-called loose rules 13-43 may be also replaced without necessarily loosening the chase, it is immaterial insofar as lock. up time is concerned, whether the chase is loosened or not. The rules cannot be shifted to new or different positions.

In actual practice in forming cardboard carton blanks a normal re-knifing of the dies occurs after approximately 200,060 blanks have been formed, and when it is considered that some orders are for millions of blanks, the saving of time in eliminating the heretofore costly lock-up time may be many days.

With the present invention the dies may be re-knifed innumerable times without any noticeable difference in the tightness of the frictional fit of the rules in the die bodies.

There are instances where it may 'be found to be desin able to replace one or more of the sub-dies as a unit. This can readily be accomplished by merely loosening the chase and replacing one or more of the sub-dies with another or others without disturbing the accuracy of the main die. After sub-die or dies are replaced the chase may be again locked, and the rules will be in their exact desired positions.

In the present main die, no screws, clamps, or auxiliary means is required to firmly but releasably hold the rules in each of the sub-dies, whether the Working edges are directed upwardly or downwardly. The epoxy compound of each sub-die is unadected by humidity and changes in temperature within the range encountered in actual working conditions. Hence there is no popping of dies such as occurs in the case of Wooden furniture dies at relatively high atmospheric temperatures and relatively high humidity, and the weight of the epoxy compound is approximately that of the plywood heretofore used in ord-inary wooden furniture dies. This makes possible the use of large sub-dies of the present structure, in a commercial operation, free from objectionable weight.

Each sub-die may be described as being a rectangular block of plastic material cast against the opposite sides of the blank forming dies to form slots in said body conforming to the contour of said sides with the sides of said rules from their base edges to the marginal portions the chase. The rules 22, 25 maybe held between thesub-dies by variable pressure from actuation of the quoins 7, but constant and unvariable frictional resistance is maintained between the sides of the rules and the sides of the slots in the body of each sub-die, and which unvari-able frictional resistance can only be obtained by casting the plastic material against the sides of the mice. Were an attempt made to cut the slots for the rules, as previously stated, while variations would be slight they are sufficient to make the die inoperative for its intended manner of use.

From a structural standpoint, another feature that is shown in FIGS. 2 and 4 is that the tie rods 13 extending through each sub-die longitudinally of the latter are in exact longitudinal alignment with the adjacent sub-die in the main die 3 and the same is true of the tie rods 13 that extends transversely of each sub-die. Thus the pressure from the chase when the sub-dies are locked in the latter is transmitted, in unbroken lines, straight through the sub-dies both longitudinally and transversely of the latter.

It is to be understood that the claim appended hereto is intended :to cover such changes and modifications of 5% the example of the invention herein chosen for the purpose of disclosure, that do not depart from the spirit and scope of the invention.

We claim: A die for forming a blank from sheet material comprising: a plurality of blank forming rules having base edges on which said rules are adapted to be supported on a rigid, planar surface in positions perpendicular thereto,

and said rules having working edges opposite to said base edges adapted to engage such sheet material for forming said blank; said rules being formed with generally U- shaped recesses opening outwardly of said base edges whereby each recess has a bottom edge at the closed end thereof; a die body of hardened plastic material in tight, cast, frictional but releasable engagement with opposite sides of said rules extending substantially from said base edges to the marginal portions of said rules along said direction away from said working edges under predeterruined pressure against said working edges to position said base edges against such planar surface to eliminate rocking of said rules relative to said body during blank forming operations.

References Cited in the file of this patent UNETED STATES PATENTS 2,993,421 Phillips et al. July 25, 1961

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