Patent Application
20070039436
This specification describes one or more inventions that may relate to one or more of die cutting, steel rule or cavity dies, vacuum pre-compression in die cutting and roller presses.
The following background description is not an admission that any apparatus or method discussed below is prior art or part of the knowledge of people skilled in the art in any country.
U.S. Pat. No. 4,960,019 describes a stationary steel rule cutting die for cutting a fixed pattern in each of a plurality of stacked compressible material layers according to the shape of the steel rule die and including a vacuum system for reducing the stacked height of the compressible material layers prior to cutting. The die assembly includes an enclosure comprising an upper wall and collapsible side walls extending downwardly from the upper wall. A rigid annular structure is secured to the lower edge of the collapsible side walls. The enclosure is positioned over the stacked compressible material layers with an annular sealing surface defined on the lower peripheral edges of the rigid annular structure coacting with an upwardly facing, closed loop sealing surface defined on the steel rule cutting die to define a sealed chamber from which air is exhausted through the rigid annular structure to collapse the side walls of the enclosure and compress the material layers prior to cutting.
In U.S. Pat. No. 6,233,809, a cutting knife assembly has a baseboard with a generally planar surface. A cutting knife is detachably connected to the baseboard. The cutting knife extends in a perpendicular direction to the baseboard. The cutting knife circumscribes a knife cavity on the baseboard. At least one elongated cross member is affixed to the cutting knife and extends across the knife cavity. The cross member is mounted to the baseboard by a removable fastener. The cutting knife may then be easily removed from the baseboard and resecured.
U.S. Pat. Nos. 4,960,019 and 6,233,809 are incorporated herein, in their entirety, by this reference to them.
It is an object of an invention described herein to improve on, or at least provide a useful alternative to, the prior art. It is another object of an invention described herein to provide a process or apparatus for cutting a material. The following summary is intended to introduce the reader to one or more of the inventions but not to define any invention. An invention may reside in any combination of one or more apparatus elements or process steps selected from the set of all apparatus elements and process steps described in any part of this document.
The inventors have observed that there is a need for a cost efficient method and apparatus for cutting low to medium quantities of material with high accuracy and material utilization, for example to produce automotive upholstery pieces for small manufacturers or limited production vehicles. Low to medium quantities may be, for example, the parts required in one material, for example cloth fabric or a vinyl laminate, for the interior of 1 to 20 automobiles. Some low volume work is being performed on machines that have some form of a computer controlled cutting head moving over a stationary sheet of material on a table. While these machines may be cost effective, the quality of the cut pieces is not as good as what may be obtained with dies. Some leather cutting is done by a roller press process. In this type of process, a sheet of leather is placed on a cutting pad which is a board made of a material, such as polypropylene, which is rigid enough to create a surface which can be cut against but soft enough to allow edges of the knives of dies to penetrate into it. Die cavities are placed on the leather by workers trained to get a good quantity and quality of cut pieces from irregularly shaped leather stock. This assembly is then sent through a roller press to cut the leather. While the cost of the roller press is sufficiently low for use in leather cutting, the process is not cost effective for cloth or vinyl work because the rate of production is comparatively low when compared to rates of production for cloth or vinyl cutting. Achieving higher throughput would require placing more layers of material under the dies with each pass. However, particularly with multiple layers of material, the rollers move or stretch the material as it is being cut causing the parts to grow in one direction or generally be inaccurately cut.
High volume automotive interiors are generally cut using steel rule type dies, cutting many layers of materials simultaneously in large presses. This process provides high quality parts, but the cost of a large press can only be recovered in high volume situations.
A process or apparatus described herein deals with these issues, in brief, by using a vacuum to compress multiple sheets of material against a set of dies before or while passing the material and dies through a roller press. The vacuum makes the die and material assembly more stable as it passes through the rollers and allows multiple layers to be cut accurately. Stability of the die and material assembly may be further enhanced by making the dies from narrow knife stock to create a low die and further optionally by installing braces vertically in some locations. Output may be further enhanced by placing the dies very close together or touching each other which is facilitated by using offset bevel steel for the knives of the die and removably mounting one or more dies to a die board which also aids in removing scrap pieces. Further optionally, in places where dies touch each other, parts of the outside side walls of the adjacent cavities may be ground to or near the point of the knife. Further optionally, the material and dies may be further pre-compressed by passing them through the roller press with the rollers set to a compressing, rather than cutting, separation distance. The process or apparatus thus provides a way to economically cut low to medium volumes of material accurately and economically or other uses or benefits, particularly where the same roller press can also be used part time for leather cutting.
In one aspect, an apparatus has a plurality of cavity dies attached to a die board. The dies and die board may be installed into, or be part of, an enclosure. The enclosure has or contains a cutting pad on the opposite side of the dies from the die board. The enclosure also has collapsible side walls and room for sheets of material, for example 1 to 6 sheets of material, to be placed in the enclosure between the dies and the cutting pad. A vacuum system can be attached in communication with the interior of the enclosure to create a vacuum in the enclosure, thus drawing the cutting pad and die board together and compressing any material between the dies and the cutting pad. The enclosure may be fed through a roller press to press the cutting pad against the dies so as to cut the material. One or more of the dies may have a brace or base plate through which it is attached to the baseboard. The dies may have offset bevel steel knives made of knife stock having a width of 32 mm or less or 20 mm or less, such that the die is 32 mm or less or 20 mm or less tall. One or more of the dies may be attached to the baseboard with quick release fasteners. The dies may be spaced from 0-1 mm apart from each other.
In another aspect, a process is described for producing pieces of material cut to a pattern from one or more, for example 1 to 6, sheets of material using cutting dies. The cutting dies are mounted on a die board in a pattern fitting within the perimeter of the sheets of material. The dies may touch adjacent dies or be spaced apart by 1 mm or less from adjacent dies at least along the controlling length or width of a nest or marker of dies. Sheets of material are placed on the dies. A cutting pad is placed over the sheets of material. The cutting pad is forced towards the die board, for example by a vacuum, to compress the sheets of material against the dies. The die board, dies, sheets of material and cutting pad are then passed through a roller press which forces the cutting pad into contact against the dies to cut the sheets of material. Optionally, one or more of the dies may be removed from the die board after cutting to assist in removing scraps of material from between adjacent dies. Further optionally, the sheets of material may be passed through the roller press to further pre-compress the material before cutting.
In other aspects, a quick release fastener, a die assembly with releasable dies and processes for mounting or removing dies or removing scrap from between dies are disclosed.
One or more embodiments of one or more inventions will be described below with reference to the following figures.
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.
Referring to part A of
Cutting pad 14 is made of a material, such as polypropylene, which is rigid enough to create a surface which may be cut against but soft enough to allow the dies 18 to penetrate it slightly. Die board 16 may be of any material, for example high density plastic, wood, or steel, suitable for transferring pressure from a press to the dies 18. Optionally, cutting pad 14 may comprise two pads placed against each other in parallel. An outer pad is not penetrated by the dies 18 and so ensures that a seal or vacuum can be maintained. An inner pad is affixed to the underside of the outer pad, for example by adhesive tape or threaded fasteners. After many cuts, the inner pad may become eroded and need to be replaced. At such time, the inner pad is removed from the outer pad and replaced by a new inner pad.
Sides 20 may be of a rubber covered fabric or other flexible but generally gas impermeable material. Base plate 22 may be steel. Seals 24 may be fastened or bonded to sides 20 and attach to base plate 22, for example magnetically, to enclose and seal a plenum 26 including space between the press board 14 and the die board 16. An outlet 28 through a side 20 allows the plenum 26 to be connected to a vacuum source 30, for example a vacuum pump, through hose 31. Vacuum pump 30 is operable to create a partial vacuum in plenum 26 causing enclosure 12 to partially collapse and move press board 14 and die board 16 together to compress sheets of material 32 against dies 18 as shown in part B of
Optionally, assembly 10 can be passed through the roller press 34 in multiple passes to either further pre-compress the sheets of material 32 or to cut the sheets of material 32 in multiple passes. For example, during a first pass in a first direction, the rollers 38 may be set at a separation distance that further compresses the sheets of material 32 but does not cut them. The vacuum pump 30 may be on during this first pass such that there is only a limited rebound of the sheets of material 32 after the first pass, if any. The rollers 38 may then be moved closer together and the assembly passed through the rollers 38 a second time, optionally in a reverse direction. This second pass may cut the sheets of material 32. For example, 6 plies of a fabric material might initially have a thickness of 35 to 40 mm when placed on the dies 18. When the assembly 10 is assembled and vacuum source 30 turned on, the sheets of material 32 may compress, depending on the material, to for example 12 to 35 mm. A first pass through the roller press 34 with roller 38 set at a separation distance, less than the height of the assembly 10 but large enough to not cut the sheets of material 32, may result in the sheets of material 32 having a thickness of 80 percent or less, or 60 percent or less, of their thickness before this pass, that is their thickness under vacuum alone. Stacks of a lesser number of sheets of material 32 involve correspondingly lesser thicknesses. The vacuum source may be left on continuously from before the first pass through roller press 34, whether it is a cutting or compressing pass, until the sheets of material 32 have been fully cut.
One or more dies 18 may also be fastened to die board 16 with quick release fittings 60. As shown in
The knife 50 of die 18 may be relatively short compared to dies used in other applications. For example, knife 50 may be 32 mm tall or less or 20 mm tall or less, for example about 19 or 20 mm. The inventors have found that taller knives 50 are not necessary for economical low to medium volume cutting and may flex and so produce less accurate cut pieces in the method and apparatus of the invention. Knife edge 52 is offset to the outside of dies 18. With this offset, and the short knife 50 being used to cut a limited, for example 6 or less, number of sheets, dies 18 can be placed very close together, for example at spacings of 1 mm or less or even touching at points of tangency with neighbouring dies 18. Such small spacing may be required only between those dies 18 located along the controlling length or width of a set of dies 18. Where die 18 spacing can be increased without increasing the length or width of a set of dies, a larger spacing may be used to reduce stress on the dies 18 and make scrap removal easier. Optionally, in places where adjacent dies 18 touch each other, the outside of the dies 18 may be ground down or otherwise removed to, or near to, knife edge 52 to reduce or remove the bevel on the outside of knife edge 52. This allows parts of two adjacent dies 18 to be placed next to each other so as to create, in effect, a section of thick blade with a knife edge 52 in its center serving two adjacent dies 18.
The small spacing along the controlling width or length, even compared to a slightly larger 3 mm spacing, produces a great reduction in scrap wastage. However, scrap pieces may be forced tightly into small inter die areas 70, particularly if marker notches 72 in knife 50 angle into an inter die area 70. Removing scrap from these areas is facilitated by attaching one or more dies 18 with the quick release fittings 60. The quick release fittings 60 allow these dies 18 to be quickly removed between cuts, as shown in
As shown in
The description above was of a sample embodiment or embodiments of one or more claims and not intended to limit or define the invention of any claim which may be carried out in various alternate embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2,513,158 | Jul 2005 | CA | national |
This application claims the benefit under 35 USC 119(e) of U.S. Application Ser. No. 60/701,995 filed Jul. 25, 2005 and claims priority to Canadian Application Serial No. 2,513,158 filed Jul. 25, 2005. U.S. Application Ser. No. 60/701,995 and Canadian Application Serial No. 2,513,158 are incorporated herein, in their entirety, by this reference to them.
| Number | Date | Country | |
|---|---|---|---|
| 60701995 | Jul 2005 | US |
