US 3570355 A
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Description (OCR text may contain errors)
United States Patent Inventor Ernst Maximilian Spengler Bergen-Enkheim, Germany App]. No 731,535
Filed May 23, 1968 Patented Mar. 16, 1971 Assignee Roeder & Spengler OHB Bergen-Enkheim Hessen, Germany Priority May 24, 1967 Germany ROTATIONAL DIE STAMPING TOOL 5 Claims, 28 Drawing Figs. I
US. Cl 83/663, 76/107, 83/665, 83/698 Int. Cl B26d l/l2 Field 01' Search 83/663,
Primary Examiner- Frank T. Yost Attorney-Wolfgang G. Fasse ABSTRACT: The present die stamping tool has a baseplate shaped to conform to the surface of a rotational body, such as a cylinder. Working blades are held in grooves or slots of the baseplate by means of serrated back edges which may be provided with gripping teeth. The rotational die stamping toolis made by shaping or bending the baseplate, cutting said grooves or slots, serrating the back edges of said working blades and anchoring said serrated back edges in the grooves or slots.
Patented I March 16, 1911 3,570,355
4 Sheets-Sheet 1 Patented March 16, 1971 4Sheets-Sheet J S QW WWWMWWW ROTATKGNAL THE STAMPING TOOL The present invention related to rotational die stamping tools and to methods of making such tools which are used for die stamping, grooving, slitting, cutting or similarly outlining of shapes, especially of contours or shapes or configurations made of paper, cardboard or the like. Such shapes may be used to make, for instance, packaging cartons.
Prior art die stamping tools for the above purpose comprise cutting blades inserted, in the desired shape configuration, into plain base plates of synthetic, plastic or similar material. The desired shape configuration or outline is cut into the known plates by means of a jigsaw. The outlines cut by the jigsaw are interrupted at suitable spacings by bridge members so as to hold the plate portion the outlines of which constitute the shape configuration, in place in the plate.
The working blades of such tools are made of band steel, a working edge of which is sharpened while the opposite or back edge is inserted into the jigsaw cut shape configuration. Due to said bridge members the blades are provided with indentations having a depth corresponding to the width of the base plate and they are broad enough to accommodate the bridge members thus preventing that the bridge members interfere with the insertion of the blades. The back edge of the blades usually extends fully through the base plate but does not protrude therefrom. The plates are attached to the stamping member of a stamping press and the sharpened edges of the blades protrude from the base plate to an extend'corresponding to any desired cutting depth.
Due to the plain base plate prior art die stamping tools are not suitable for a rotational cutting motion and are thus limited to a reciprocating cutting motion.
It is an object of the invention to increase the operating speed of such die stamping tools.
Another object is to provide a rotational die stamping tool which may be operated by means of a rotating member rather than by a reciprocating stamping member.
Yet another object is to provide a method for making such rotational die stamping tools suitable to be attached to a rotating drum.
According to the invention the above objects have been attained by providing a base plate which is bend to conform to the periphery or circumference of a rotational body, such as a drum or cylinder, and into which working blades are inserted having a serrated back edge.
A particularly advantageous embodiment of the invention comprises teeth along the back edge, which have anchoring hooks or recesses which may be bend out to protrude from or be inserted within the plane of the teeth.
The serrations of the back edges may have quite closely spaced teeth and the spacings between adjacent teeth may have bottoms of predetermined shape, for example, the bottoms may have corners, especially straight corners, or they may have a circular or heart shape.
The cutting blades are preferably provided with apertures between the working edge and said serrations which apertures improve the bendability of the blades as well as the bendability of the entire shape or contour outlined by the blades thus facilitating the bending of the blades in conforming them to the rotational base plate which may be made of metal such as aluminum, brass, bronze or the like, or of thermoplastic material, such as hard polyvinyl chloride or a heat curable synthetic material. The width of the base plate and its strength and/or other characteristics will be selected in such a manner that the inserted working blades are securely held in the base plate and any bending down is avoided.
According to the invention there is further provided a method for making the above-mentioned die stamping tools wherein a base plate is bent to conform to the diameter, or rotational shape of a rotational body, such as a cutting roller, the base plate is then provided with radially extending incisions outlining the desired contour to be cut and working blades which have been prepared as a band having a serrated back edge are then inserted with such back edge into said incisions whereupon the back edge is securely anchored in the material of the base plate whereby the working blade or band is shaped to conform in space to the desired rotational surface.
The incisions in the base plate may be made in any known manner, for example, by means of a jigsaw or by a heat treatment. However, the invention teaches that the incisions should extend radially relative to the rotational body along the entire length of a blade, that is the incisions should extend exactly perpendicularly relative to the bent surface of the base plate.
The anchoring of the serrations in the base plate could, for example, by gluing or by a heat treatment of the base plate or by filling the spaces between the teeth of the serrations with a filler material while the serrations are properly inserted and in position in the incisions of the base plate.
Another possibility of anchoring the cutting blades in the base plate is provided by the invention in that the blades have anchoring hooks in the teeth of the back edge. Such blades are first formed into, a desired rotational configuration, for instance, by a pressure or hammering treatment, and then the anchoring hooks are forced into the incisions thus securing the blades in its base plate.
Although the present specification speaks mostly of cutting blades it is to be understood that the invention is not limited to cutting but includes any die stamping tools such as are used, for example, for grooving, slitting, perforating or any other manner of producing a contour or outline on a work material.
In order that the invention will be clearly understood it will now be described, by way of example, with reference to the accompanying drawings, wherein:
FIG. 1 is a perspective view of a rotational diecutting tool;
FIG. 2 shows a sectional view along the line II-II of FIG. 1;
FIG. 3 illustrates a front view of a bent cutting blade;
FIGS. 4 and it show side and front views of a cutting blade which is not bent;
FIGS. 5, 5a 6, 6a, 7 and 7a illustrate front and side views of yet other embodiments of cutting blades whereby the blade of FIG. 5 is not bent;
FIGS. 8 and 8a show side and front views of a blade having apertures therein throughout its length;
FIGS. 9, 9a and 912 show a blade with anchoring hooks in the I teeth of the serrations said hooks extending into the spaces between the teeth as shown in more detail in FIGS. 14, 14a, and Mb;
FIGS. 10, 10a and 10b illustrate anchoring hooks made by stamping, extending out of the teeth as shown in detain in FIGS. 15, 15a and 15b.
FIGS. Ill and 12 show perspective views for explaining the insertion of a blade into the base plate; and
FIG. 13 shows a sectional view of a blade as it is being inserted into the base plate,
FIGS. 14, Ma and 14b show the details of the blade of FIGS. 9, 9a and 9b FIGS. 15, l-5a and 1412 show the details of the blade of FIGS. 10,10a, and 10b.
FIGS. 1 and 2 show a rotational die stamping tool having a base plate I of suitable material which is bent to conform to the circumference of a stamping drum. Cutting blades 2 are inserted into the base plate along a desired contour or outline. The blades 2 bound areas 3 which correspond to the shapes or contours or configurations to be die stamped out of paper, fabric or the like.
The base plate may be made of any material which is suitable to assure a sufficient holding of the inserted blade. If necessary, the base plate may thus be made of aluminum, brass, or even of a suitablesteel. Further, suitable heat curable synthetic materials, hard papers or wood may be used to make the base plate. l-Iard polyvinyl chloride has been found suitable for most uses here involved.
The thickness of the base plate depends upon the required height or depth of the working blades. The larger the cutting depth will be the higher will be the height of the blades so that only a sufficiently thick base plate will prevent the bending down of the blades unless a very hard or strong base plate material, such as steel or the like is used.
Even where the rotational die stamping tool according to the invention is in the form of a grooving, slitting, perforating, corrugating or serrating blade, it is advantageous to secure these blades in the base plate in the same manner as described above. Such blades may, just as the cutting blades, be made of preformed band steel. The band steel will have the same strength as that used for making conventional plane die stamping tools. Such strength or width will be in the order of 0.5 millimeter to 2 millimeter, and mainly 0.7 millimeter to 1.0 millimeter. The ratio between the full height of a blade and its desired cutting depth will depend upon the material of which the base plate is made as well as upon the width of the blade.
The base plate 1 with the cutting blade 2 inserted therein, will be secured to a rotational cylinder (not shown). The material to be cut will be passed in suitable manner at constant speed under the cylinder and in contact therewith. Whereby the rotational stamping tool or cutting blade will roll over the material to cut out the desired shape or contour.
It is an important advantage of the invention that the necessary cutting pressure is substantially lower than for plane die stamping tools because due to the rotational cutting action it is now not necessary to press down simultaneously the entire blade configuration. Thus the pressure can now be concentrated along a line where the instantaneous cutting action takes place.
Yet another advantage is the substantially higher working speed of the present tools as compared to plane tools because no reciprocating tool motion is necessary. Thus the entire tool motion (rotation) is effective for the cutting operation and not just the down stroke as in prior art tools.
The material stamped out in the desired configurations will occupy a space or area 3 bounded by the cutting blades and will be removed in any suitable manner after a cutting run is completed. For example, well known pushout members may be inserted into the areas 3, for example, foam rubber pads will facilitate the pushout function.
Where the cutting blades do not extend in parallel to the longitudinal axis of the rotational cylinder, it is necessary to conform the blade to the arc corresponding to the surface of the cylinder to which the blade is attached through its base plate. Such conforming of the blades to the rotationed body would cause tensile forces in the cutting area of a blade and compressional forces in the back edge of the blade. The invention obviates this difficulty and greatly facilitates the bending necessary for such conforming by providing the back edges of the blades with serrations.
Such serrations include spacings 6 between adjacent teeth. The spacings provide sufficient flexibility in the areas which otherwise would be subject to compressional forces and thus the bending is made possible at all. The shape of the teeth may vary as desired, for instance, as shown in FIGS. 3 to a. In the embodiment of FIG. 4 the spacings 6 are relatively wide as compared to the width of teeth 5. Contrary thereto the spacings shown in FIG. 6 are of relatively narrow width. Where the spacings 6 have a squared straight line boundary as shown in FIG. 7, their width can be still smaller, this will depend upon the amount of bending required for conforming the blades to the surface of the supporting rotational body.
It has been found that especially desirable bending conditions are realized if the teeth are formed as show in FIGS. 4, 5, 9 and 10 whereas good stress distribution is accomplished with serrations having spacings such as shown in 5 and 7 to 10. In any event the bending is greatly facilitated by the serrations as taught by this invention.
FIG. 8 shows that the spacings 6 between teeth 5 are bounded by straight lines and are relatively narrow. To still further improve the bending characteristics of the blades, apertures S are provided in the blades between the cutting edge and the serrated back edge.
FIG. 9 illustrates a serration in which the teeth 5 have anchoring hooks 7 which protrude alternately from the side of the teeth which faces an adjacent tooth. The hooks may point up and down in alternating fashion. The hooks may be completely within the plane defined by the blade or they may protrude from such plane in alternate fashion as shown in FIG. I
9a in more detail.
FIG. 10 shows a modification of the hooks 7 in that the hooks protrude in alternate fashion from one or the other surface ofa plane defined by the blade.
The method of making a die stamping tool according to the invention will now be explained with reference to FIGS. 11 to 13.
One or more curved base plates 10 having an inner radius of curvature corresponding to the outer radius of a pressure roller (not shown) may be suitably attached to such roller.
First incisions 11 are made in the surface of the base plate,
such incisions 11 corresponding to the pattern, shape, contour or configuration to be cut out of a material, for example, carton blanks. The incisions ought to extend radially into the base plate at all points along the length of the incisions. This may be accomplished, for instance, with a special jigsaw the saw blade of which is guided in such a manner that the saw blade will always extend at a right angle to the curvature (radially). However, it is also possible to make the incisions in any other suitable manner, for example, by a heat treatment of the base plate or by using other suitable tools.
The incisions 11 may extend completely through the base plate 10 whereby the areas bounded by the incision are prevented from falling out of the base plate by means of bridging members.
The incisions may also be made in the form of a series of cuts of relatively short length or holes whereby the length of such cuts or holes will depend upon the size of the teeth of the blades to be inserted therein.
A working blade previously made of band steel will now be inserted into the contour of the incisions 11. Such insertion may be accomplished by hammering, pressing or rolling or a combination thereof.
The cutting blades l2 will be bend or shaped in space as they are being inserted to follow the curve of the base plate so that at any particular point the blades extend perpendicularly to the curved surface of the base plate 10 that is, the blades will protrude radially relative to the center axis 14 of the base plate 10.
As shown in FIG. 11 the blade 12 has been inserted up to the point 13.
After the insertion of the blades in the prepared incisions the spacings between the teeth 5 may be closed, for example, by a heat treatment of the material of the base plate or by filling such spaces with a suitable glue so that the blades will be securely held in the base plate. Instead or in addition the surfaces of the incisions may be coated, either prior or during the insertion, with a suitable glue which, after hardening, will hold the blades in the base plate. No gluing is necessary with anchoring hooks but hooks and gluing and/or heat treatment may be used in combination.
The hooks alone will hold the blades in the base plate with sufficient strength so that a closing or filling of the spaces is not absolutely necessary. However, gluing etc. may be used as additional strengthening means, particularly where the base plate is relatively thin or where a relatively high cutting depth IS necessary.
Stress relief bores 15 may be provided adjacent the incision in any known manner.
It is preferable to attach the base plate to a curved work support which is rotatable about a vertical axis.
It is to be understood that the invention is not limited to the particular embodiments and features described and shown but also comprises any modifications with the scope of the appended claims.
I. in a rotational die stamping tool having a preformed base plate conforming to the surface of a rotational body and a working blade means held in slots in said base plate said working blade means defining a plane and having a working edge protruding above the surface of the base plate as well as a serrated back edge with teeth anchored in said slots of the base plate, the improvement comprising anchoring hooks forming part of at least some of said teeth, said anchoring hooks having a downward slant to form a downwardly pointed surface for facilitating the insertion of the serrated back edge of the blade means into said slots, said anchoring hooks further having an upwardly facing surface for facilitating the anchoring of the blade means in said slots.
2. The rotational die stamping tool according to claim 1, wherein said anchoring hooks protrude out of said plane