WO2008017159A1 - Steel rule cutting die and ejection strip - Google Patents

Abstract

A multi-cavity steel rule cutting die has adjacent cavities that are tightly nested together. A baseboard is produced with a first series of slots adapted to receive a first cutting element, and a second series of slots adapted to receive a second cutting element. The slots in each series are separated by bridges which are longer than the slots. When viewed along a line between two adjacent cavities, a slot of the first series is located between and spaced from two adjacent slots of the second series while the bridges associated with adjacent cavities overlap each other in a region of the baseboard. A scrap material ejector comprising one or more bendable portions is described and may be used to eject scrap material from an area between two adjacent die cavities.

Description

TITLE: STEEL RULE CUTTING DIE AND EJECTION STRIP

[0001] For the United States of America, this is an application claiming the benefit under 35 USC 119(e) of US Application Serial Number 60/821 ,900 filed on August 9, 2006 and US Application Serial Number 60/886,034 filed on January 22, 2007 both of which are incorporated herein, in their entirety, by this reference to them.

FIELD

[0002] This specification relates generally to steel rule cutting dies, methods of making them, or to a device for ejecting scrap material from between adjacent lengths of rule in a die.

BACKGROUND

[0003] The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art. [0004] Steel rule cutting dies may be used in countless applications, including cutting cardboard boxes, garments, composites, plastics, and material used in automotive interior trim (i.e., head liners, head rests, seats, door panels, trunk liners and the like). Steel rule cutting dies are particularly advantageous in the repetitive cutting of a specific shape. [0005] A steel rule cutting die generally includes a baseboard and at least one length of steel rule (or knife) affixed thereto. The rule is typically a piece of band steel that has a sharpened cutting edge and is bent to form a closed loop which defines a cavity (i.e., the shape to be cut out of the material to be processed). The loop of rule may be called a cutting element or a cavity. The cutting element can be affixed to the baseboard by screws (removably affixed), through slots or kerfs in the baseboard (fixed-in-place), or by other such means. The dies are used together with a cutting press that forces them against and into a stack of material in order to cut the material. Multiple layers of material can be cut with one pressing operation. A single die will often include a plurality of cavities, so that multiple pieces can be cut during a single pass through the press. It is desirable to have multiple cavities on a single die positioned together in an efficient configuration in an effort to minimize scrap material. [0006] The cutting process generally involves a die being pressed onto and into the material to separate the material into useful pieces and scrap material. The useful pieces within the cavities may be removed for subsequent processing. The scrap material that is disposed in-between adjacent cavities needs to be stripped from the die and then may be discarded. The die is preferably able to withstand many passes through the press.

[0007] When cutting elements are fixed in place, the slots or kerfs in the baseboard are separated by short (relative to the slots) bridges to keep the part of the baseboard inside the cutting element attached to the rest of the baseboard. The edge of the rule opposite the cutting edge is notched to clear the bridges so that the cutting element may be inserted into the slots. U.S. Patent Nos. 4,543,862; 4,694,719; 4,852,439; 5,129,295; and, 5,676,032 describe fixed in place dies and are incorporated herein in their entirety for, among other things, their further description of die technology, for example as shown and discussed in relation to Figures 18 and 20 of U.S. Patent No. 5,676,032, although the claims of this patent are not limited by any statements in those patents. A die with removably affixed cavities is shown in US Patent No. 6,233,809 which is incorporated herein in its entirety by this reference to it although the claims of this patent are not limited by any statement in that patent.

INTRODUCTION

[0008] The following introduction is intended to introduce the reader to this specification but not to define any invention. One or more inventions may reside in a combination or sub-combination of the apparatus elements or process steps described below or in other parts of this document. The inventor does not waive or disclaim his rights to any invention or inventions disclosed in this specification merely by not describing such other invention or inventions in the claims.

[0009] The inventor has attempted to reduce the minimum spacing between the cutting edges of adjacent cutting elements attached to a baseboard, for example to 3 mm or less or to 1 mm or less. In doing so, the inventor has encountered various difficulties. One difficulty is that scrap material pushed into the space between adjacent cutting elements is difficult to remove. Another difficulty when using fixed in place dies is that, according to conventional practice, the bridges associated with adjacent cutting elements are located side by side so as to provide a part of the baseboard extending between the insides of adjacent cavities. The slots for adjacent cavities are therefore also located generally side by side. However, when an attempt is made to space adjacent cavities at a small spacing, the strips of baseboard between the slots of adjacent cavities are very thin or may disappear entirely in some places, depending on the spacing between adjacent cavities and the distance between the cutting edge of the cavity and the outside of the rule. The resulting thin strips of baseboard are weak and may break when the cavity is inserted or later in use. Further, after a slot for a first cavity is cut, there is very little material to support a tool, such as a router bit, cutting an adjacent slot for an adjacent cavity and so the tool may deflect into the first cut slot. This may leave no baseboard material to prevent adjacent cavities from touching each other.

[0010] One aspect of a die described in this specification relates to a multi-cavity fixed in place steel rule cutting die having a baseboard with a first series of slots adapted to receive a first cutting element, and a second series of slots adapted to receive a second cutting element. Bridges between the slots may be longer than the slots. For example the bridges may be about 30 mm or more or 40 mm or more in length or up to about 55 mm in length while the slots may be shorter than the bridges by about 20 mm or more, or the slots may be about 40 mm or less or 26 mm or less in length. When viewed along a path or line on the baseboard between two cavities, a slot of the first - A -

series is located across from a bridge of the second series, or between two consecutive slots of the second series. For example, the slots of the first series and the slots in the second series may be alternately positioned and spaced along the path. Each slot of the first series may be spaced in the direction of the path from each slot of the second series, for example by 10 mm or more or by 25% of the length of a bridge or more, such that there is no overlap between adjacent slots along the path but an overlap between adjacent bridges. This results in a slot having a section of baseboard extending from both sides of the slot to a distance greater than a spacing between adjacent cavities.

[0011] Another aspect of a die or a scrap material ejector described in this specification relates to preventing the build-up of scrap material formed in-between adjacent cavities. A scrap material ejector may comprise a resilient member which may be placed in a space between adjacent cavities. When the die is pressed into the material, the scrap material formed in- between adjacent cavities will be forced against the resilient member of the scrap material ejector. As the die is removed from the material, the resilient member will spring back to its original state causing the scrap material disposed in-between adjacent cavities to be ejected therefrom. The scrap material ejector may comprise a band of resilient material stretched between two end pieces and may be used, for example, with fixed in place or removably affixed cavities.

[0012] Another scrap material ejector described in this specification comprises a rigid but resilient member which may be placed in a space between adjacent cavities. The ejector may be free-standing in such a space. The ejector has a scrap material bearing surface or surfaces and a bendable area. When pressed, the bendable area bends or curves. When the press force is released, the bendable area returns to its original shape to eject the scrap. The ejector may be, for example, cut from a sheet material, such as of poly or another plastic. The bendable area may have a region that is within 60 degrees of vertical when in use. [0013] In other aspects, this specification describes one or more methods for making a die, for example a die as described above.

[0014] Additional features, advantages, and embodiments of one or more inventions may be set forth or apparent from consideration of the following detailed description, drawings and claims. Moreover, it is to be understood that both the foregoing summary of the invention and the following detailed description provide examples or further explanation without limiting the scope of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS [0015] Figure 1 is a photograph illustrating a baseboard for a die; and

[0016] Figure 2 is a photograph illustrating a set of cavity elements on the baseboard of Figure 1 with scrap material ejectors between two pairs of adjacent cutting elements.

[0017] Figure 3 shows various alternate profiles for various alternate scrap material ejectors.

[0018] Figures 4 and 5 show a sample bendable ejector in an initial and bent state.

DETAILED DESCRIPTION

[0019] Various apparatuses or processes will be described below to provide an example of an embodiment of each claimed invention. No embodiment described below limits any claimed invention and any claimed invention may cover processes or apparatuses that are not described below. The claimed inventions are not limited to apparatuses or processes having all of the features of any one apparatus or process described below or to features common to multiple or all of the apparatuses described below. It is possible that an apparatus or process described below is not an embodiment of any claimed invention. The applicants, inventors and owners reserve all rights in any invention disclosed in an apparatus or process described below that is not claimed in this document and do not abandon, disclaim or dedicate to the public any such invention by its disclosure in this document. [0020] Referring now to the Figures wherein like reference numerals designate corresponding parts throughout the views, Figures 1-2 illustrate a steel rule cutting die, generally designated 20.

[0021] As shown in Figure 2, steel rule cutting die 20 includes a baseboard 22 on which a plurality of cutting elements 24 may be affixed. Cutting elements 24 may be made of a single piece of metal bent into a predetermined shape, or of multiple pieces of metal, as would be apparent to a skilled artisan. The closed loop of a cutting element 24 will be hereinafter designated cavity 26. Cutting element 24 may include a top edge 28 having a sharpened cutting edge formed thereon, and a bottom edge 30 which is adapted to be mounted into the baseboard 22. Top edge 28 of cutting element 24 may be offset towards the outside of the cavity 26 or at the outer edge of the cavity 26. A scrap material ejector shown generally at 32 may include a resilient member 34 and two end pieces 36, 36. [0022] As shown in Figure 1 , baseboard 22 may have slots positioned to permit adjacent cavities 26 to be placed side by side with a minimum gap between their respective cutting edges of, for example, about 3 mm or less or about 1 mm or less. The baseboard 22 includes a first series of slots 38 adapted to receive a first cutting element 24, and a second series of slots 40 adapted to receive a second cutting element 24. The slots 38, 40 are separated along the perimeter of their respective cavities 26 by bridges. The bridges may be longer than the slots 38, 40. For example, the bridges in Figure 1 are about 50 mm in length while the slots are about 30-40 mm in length. The cutting elements 24 may include mounting legs (not shown) formed by removing material to clean the bridges. The mounting legs are shaped and sized to fit into the slots provided in the baseboard 22. The cutting elements 24 may be held in the slots, for example, by friction or by a fastener applied through lugs attached to the cutting elements 24. The slots of the first series 38 and the slots of the second series 40 are alternately positioned and spaced from each other along a path between adjacent cavities in a region, shown generally at 42 of the baseboard 22, for example a region in which the adjacent cavities 26 are generally closely spaced or a region containing a point at which adjacent cavities 26 are spaced at or about a minimum spacing. The slots of the first series 38 and the slots of the second series 40 are unaligned in the region 42 such that the mounting legs of the first cutting element 24 and the second cutting element 24 will not be directly across from each other or such that the bridges of the adjacent cavities 26 overlap each other. As shown in Figure 1 , each slot of the first series 38 is spaced from each slot of the second series 40 along a path on the surface of the baseboard 22 between the two adjacent cavities 26 in the region 42, for example by a distance of 5 mm or more.

[0023] The design of steel rule cutting die 20, as described above, enables placements of cavities 26 to be very close to each other. Specifically, cavities 26 may be placed in a nested configuration with their cutting edges as close as 3 mm or less or 1.5 mm or less or 1 mm or less. Outer surfaces of adjacent cavities 26 may be in touching engagement with each other. Despite this close spacing, baseboard material extends from the side of each slot 38, 40 to a distance greater than this spacing, for example 10 mm or more. The close spacing may be used only in one or more regions of the baseboard 22, for example those regions where the placement between cavities determines the length of a marker being cut. In other areas of the baseboard 22, spacing between adjacent cavities may not be critical to the efficiency of material usage and may be increased. Optionally, the slots 38, 40 and bridges may be arranged as described above in other regions such that a consistent length, or range of lengths, of slots 38, 40 and bridges can be used throughout the die 20.

[0024] Baseboard 22 may be made of a hardwood such as birch, beech, or maple, for example, or may be made of a metal, plastic or composite. Wood, however, beneficially provides good friction against a steel cutting element 24. Cutting elements 24 may be made of a metal such as steel and the like. Slots 38 may be formed, for example, by a router, laser or saw. The lengths of the slots 38, 40 and bridges may be generally constant, or within predetermined ranges, throughout the die 20.

[0025] A scrap material ejector 32 may be placed in and occupy some or all of the space between adjacent cavities 26. When the die 20 is pressed into the material, the scrap material formed in-between adjacent cavities 26 will be forced against the resilient member 34 of the scrap material ejector 32. As the die 20 is removed from the material, the resilient member 34 will spring back to its original state causing the scrap material disposed in-between adjacent cavities 26 to be ejected there from. [0026] The scrap material ejector 32 may include a resilient member 34 and two end pieces 36, 36. The resilient member 34 may be a strap, of a width similar to the height of the portion of the cutting elements 24 above the baseboards 22, and made from, for example, gum rubber or another type of rubber or resilient material. Alternately, the resilient member 34 may be a cord or line of resilient material located near the top edge 28 of a cavity 26. The two end pieces 36, 36 may be, for example, red ejection rubber blocks or blocks of another type of rubber or resilient material, or a spring or other compressible item. The scrap material ejector 32 is stretched and inserted into the gap between adjacent cavities 26 of the die 20. The two end pieces 36, 36 rest against the corners of the cutting elements 24 or may be affixed to the baseboard 22. The thin resilient member 32 is kept tight by the two end pieces 36, 36 and in tension which aids in ejecting the scrap material out of the space in-between the cavities 26. The scrap material ejector 32 may be used in dies other than the fixed in place die of Figures 1 and 2, for example with a die with removably affixed cavities. The end pieces 36, 36 may themselves assist in ejecting scrap material from the areas of the die 20 that they occupy.

[0027] Figures 3 to 5 show an alternate scrap material ejector 50 which may be used to eject scrap from between adjacent cavities, for example adjacent cavities fixed in place or removably affixed cavities, for example spaced at 3 mm or less, 1.5 mm or less or 1 mm or less, for example having sections of knife that are generally parallel to each other or spaced by not more than 3 mm over a distance of 10 cm or more. The alternate scrap material ejector 50 is cut from a sheet of a rigid but bendable material such as a polycarbonate or other plastic to a profile including a scrap material bearing surface 52 and a bendable area 54. Bendable area 54 may include one or more sections having an edge at an angle more than 10 degrees but less than 60 degrees from vertical when in use or between 30 degrees and 80 degrees from the scrap material bearing surface. The sheet of material and ejector may have a thickness of 1 mm or less or equal to or less than the minimum spacing between adjacent cavities and a height equal to or less than the height of the cavities that it will be used with. For example, the ejector 50 may have a height of 35 mm or 38 mm and a thickness of between or including about 0.030" and 0.080". Figure 4 shows an ejector 50a in an initial state. Figure 5 shows the ejector 50a with simulated force of a die pushing on it and the bendable portion 54 bent. In use, the ejector 50 is inserted in a space between two adjacent cavities in which it may be free-standing or held more nearly vertical by shims.

[0028] Although particular embodiments of one or more inventions have been described in detail herein with reference to the accompanying drawings, it is to be understood that each claimed invention is not limited to those particular embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of any invention as defined in the appended claims.

Claims

CLAIMS:We claim:

1. A baseboard for a die, comprising: a) a first series of slots; and b) a second series of slots, the slots of the second series and the slots in the first series being alternately positioned along a path in the baseboard, wherein each slot is spaced from each adjacent slot along the path such that there is no overlap between adjacent slots in the longitudinal direction.

2. A baseboard for a die, comprising: a) a first series of slots adapted to receive a first cutting element; and b) a second series of slots separated by bridges longer than the slots of the first series of slots and adapted to receive a second cutting element, the second cutting element being adjacent to the first cutting element over at least a region of the baseboard, a bridge of the second series in the region being positioned adjacent, and extending beyond both ends of a slot of the first series of slots.

3. A method for producing a baseboard for use in a die, the method comprising: a) providing the baseboard; b) forming a plurality of slots spaced by bridges along the perimeter of a plurality of cavity shapes in the baseboard; wherein each slot has baseboard material extending from both of its sides to a distance of at least 5 mm in a region of the baseboard in which the perimeter at least two of the cavity shapes are spaced 3 mm or less apart from each other.

4. A scrap ejector comprising a resilient member and two end pieces.

5. A method of placing a scrap ejector according to claim 4 in a die comprising steps of stretching the resilient member, inserting the stretched resilient member into a gap between two cavities of the die and placing the end pieces such that they abut parts of the cavities on either side of the gap and keep the resilient member in the gap and under tension.

6. A baseboard for a die having slots and bridges following the shape of multiple cavities, the bridges being longer than the slots, the slots associated with a cavity being located adjacent the bridges associated with another cavity in a region of the baseboard.

7. A method of making a die comprising forming slots in a baseboard according to claims 1 , 2 or 6.

8. The method of claim 7 further comprising forming cavities of a cutting element, removing material from a non-cutting side of the cutting element to form mounting legs and inserting the legs into the slots.

9. The method according to claim 7 or 8 further comprising inserting a scrap ejector comprising one or more bendable sections between adjacent cutting elements.

10. A scrap ejector comprising one or more bendable sections.

11. The ejector of claim 10 wherein the bendable section(s) bend in a plane of the ejector.

12. The ejector of claim 10 or 11 wherein the bendable portion(s) have an edge oriented between 30 and 80 degrees from a scrap material bearing surface.

13. The ejector of any of claims 10 to 12 made in the form of a shaped sheet or plate of a rigid but resilient material.

14. A die comprising two adjacent cutting elements and an ejector according to any of claims 10 to 12 placed between them.

15. A die according to claim 14 wherein the cutting elements are removably affixed to a baseboard.

16. A die according to claim 14 wherein the cutting elements are fixed-in- place on a baseboard.