Patent Application
20110167972
The present invention relates to foam cutting apparatus and methods. In particular, the present invention relates to foam cutting apparatus and methods for use in cutting closed cell foam products. However, the apparatus and methods could also be used in respect of other compressible foam products.
In the foam product manufacturing industry, foam products are cut to a desired shape in a number of different ways. Complex shapes often require multiple pieces of foam to be individually cut and then bonded together to form the complex shape.
One method of producing integral complex shapes in a consistent manner involves compression cutting, which is used to cut foam products out of foam blocks or sheets. The foam is compressed between two surfaces, typically between a support surface and a template or between a roller and a moving template.
As the foam is compressed between the two surfaces, the foam expands into recesses in the template and consequently, different portions of the foam product undergo different degrees of compression, depending on the depth of recesses in the template. This creates a varying compression profile in the foam product. A cutting tool is then used to cut the foam adjacent to the template. Accordingly, as the foam product is cut, the varying compression profile in the foam product creates a cutting profile that generally reflects the shape of the template.
An alternative method of cutting shaped foam products is protrusion cutting, in which the foam is compressed between a support surface and a template having an opening rather than a recess, so that a portion of the foam protrudes through the opening. As with the compression cutting process, a varying compression profile is created in the foam product. A cutting tool is then used to cut away the portion of the foam that protrudes through the opening. Accordingly, as the foam product is cut, the varying compression profile in the foam product creates a cutting profile that produces a smooth curved surface.
Foam products generally have an open cell structure, meaning that the pores formed in the foam product are interconnected and allow the passage of air from one pore to the next. However, it is possible to produce foam products having a closed cell structure, meaning that the pores formed in the foam product are not interconnected, preventing the passage of air between pores.
The compressive strength of the foam product varies greatly between open and closed cell structures and closed cell foam products display certain characteristics that are advantageous over open cell foam products in certain applications. One such characteristic is the ability of closed cell foams to provide a seal.
One advantage of the protrusion cutting process is that the portion of foam that results in the cut foam product is not subjected to the same extreme compressive forces as the foam in the compression cutting process. The extreme compressive forces in compression cutting can rupture the pores in a closed cell foam and compromise the closed cell nature of the foam. Further, the compressive forces required for compression cutting a closed cell foam are much greater than for an open cell foam and as a result, some compression cutting machines have difficulty processing closed cell foam. Further, as the compressive forces required for compression cutting are much greater than for protrusion cutting, this can limit the maximum density of foam materials that can be cut to produce high definition foam products.
However, protrusion cutting does not allow a foam product to be cut with a central aperture. In order to cut a foam product with an internal aperture, the aperture needs to be separately cut after the protrusion cutting operation. Using traditional aperture cutting techniques, it is not possible to produce a foam product with a curved profile adjacent to the aperture and traditional techniques typically result in internal apertures having steep walls, sharp edges and a rough finish.
Compression cutting and protrusion cutting generally work well with low density open cell foam material, producing consistent cut foam products with uniformly smooth surfaces.
However, when closed cell foam is used, the process often results in foam products having an inconsistent, non-uniform surface profile, product to product.
Investigations revealed that in the protrusion cutting process, the compression of the foam product between the support surface and the template often results in small pockets of air being trapped between the closed cell foam and the support surface. Similarly, in the compression cutting process, small pockets of air get trapped between the closed cell foam and the template.
Accordingly, it is generally not possible to produce consistent, high-definition, multi-contoured foam products from closed cell foam using existing traditional protrusion cutting or compression cutting techniques.
It is an object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages, or to provide a useful alternative.
In a first aspect, the present invention provides a compression cutting apparatus for cutting a closed-cell foam product comprising:
Preferably, the apparatus further comprises a vacuum device in fluid communication with the air vents, the vacuum device being adapted to apply a suction force to the vents.
Optionally, the vents are arranged in a matrix of evenly spaced vents.
Preferably, the vents are holes having a diameter of between about 0.5 mm and 3 mm.
In a preferred embodiment, the apparatus further comprises fasteners for fastening the template to the support surface.
Optionally, the apparatus further comprises an auxiliary plate smaller than the opening and adapted to be arranged within the opening to compress the foam product between the auxiliary plate and the support surface.
Optionally, the apparatus further comprises a shim adapted to be secured to the support surface within the opening between the support surface and the foam product to further protrude a portion of the foam product through the opening.
In a second aspect, the present invention provides a method of compression cutting a closed cell foam product, said method including the steps of:
In a preferred embodiment, the method further comprises the step of:
Preferably, the method further comprises the step of:
In a third aspect, the present invention provides a compression cutting apparatus for cutting a closed-cell foam product comprising:
In a preferred embodiment, the compression belt and cutting tool are stationary and the template is movable along the support surface.
In a fourth aspect, the present invention provides a method of compression cutting a closed cell foam product, said method including the steps of:
In a fifth aspect, the present invention provides a protrusion cutting apparatus for cutting a foam product comprising:
In a preferred embodiment, the auxiliary plate is adapted to compress the foam product between the auxiliary plate and the support surface.
Preferably, the auxiliary plate is a shim adapted to be secured to the support surface between the foam product and the support surface.
Optionally, the apparatus further comprises one or more air vents formed in the support surface to allow air trapped between the compressed foam product and the support surface to escape.
In a sixth aspect, the present invention provides a method of compression cutting a foam product, said method including the steps of:
In one preferred embodiment, the auxiliary plate is movable relative to the support plate to compress the foam product between the support surface and the auxiliary plate.
In an alternative embodiment, the auxiliary plate is a shim secured to the support surface between the foam product and the support surface to further protrude a portion of the foam product through the opening.
Preferably, the method further comprises the step of:
A preferred embodiment of the invention will now be described by way of specific example with reference to the accompanying drawings, in which:
Prior to cutting, the foam product 12 is compressed between the inner surface 13 of the template 14 and the support surface 16, resulting in the configuration shown in
As shown in
Similarly, when a closed cell foam product is cut using compression cutting, the compression of the foam product between the template and the compression surface often results in bubbles or small pockets of air being trapped between the foam product and the template. These small pockets of air create inconsistencies in the compression of the foam product and as a result cause inconsistencies in the profile of the cut foam product.
The support surface 36 includes a plurality of air vents 40 extending through the support surface 36. These air vents 40 allow any air trapped between the support surface 36 and the foam product 32 to escape through the support surface 36. The air vents 40 are typically circular holes and have a diameter of between about 0.5 mm and 3 mm. Fasteners 42, such as bolts or clamps, are typically used to secure the template 34 to the support surface 36. A vacuum source can be connected to the air vents 40 to assist in venting trapped air from between the support surface 36 and the foam product 32.
In operation, the foam product 52 is mounted on the template 60 at the upstream end 56 of the support surface 54. Together the foam product 52 and the template 60 are fed downstream towards the compression belt 64 in the direction of Arrow B. As the foam product 52 contacts the compression belt 64, it is gradually compressed into the recess 62 of the template 60. As the template 60 passes to the downstream side of the compression belt 64, the cutting tool 66 cuts the foam product 52.
During compression of the foam product 52 into the recess 62 of the template 60, any air that is trapped between the foam product 52 and the template 60 is able to escape via the air vents 68 provided in the template 60.
A vacuum source can be provided in fluid communication with the air vents 68 to apply a suction force to the air vents 68. This helps to evacuate air trapped between the foam product 52 and the template 60 and also serves to help suck the foam product 52 into the recess 62.
This prevents the formation of bubbles between the foam product 52 and the template 60 and consequently, a more consistent and uniform cut foam product 70 results from the cutting operation.
A further advantageous feature of the apparatus is that much smaller tolerances of the finished foam product can be achieved.
The cutting tool 90 is used to cut away the portion of the foam product 82 that projects above the template 84. As shown in
As in the earlier embodiments discussed above, the support surface 86 may include air vents to evacuate air from between the foam product 82 and the support surface 86.
By employing this apparatus, it is possible to produce a foam product having an internal aperture via a single compression cutting process. Further, it is possible to produce a foam product having a surface that curves smoothly into the internal aperture, rather than the rough surface and sharp edges that result from die cutting a hole in the foam product.
The cutting tool 120 is used to cut away the portion of the foam product 112 that projects above the template 114. The cut foam product 130 that results has a profiled outer surface with a raised section 132 corresponding to the positioning of the shim 122. In this way, the shims 122 can be used to create a cut foam product 130 with a complex contoured surface.
As in the earlier embodiments discussed above, the support surface 116 may include air vents to evacuate air from between the foam product 112 and the support surface 116.
The aforementioned apparatus and techniques allow high-definition multi-contoured shapes to be cut from both closed cell and open cell foam products. The ability to produce high-definition multi-contoured shapes from closed cell foams has a wide range of applications in the use of closed cell foam products in, for example, sealing functions.
Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008904769 | Sep 2008 | AU | national |
| 2008904778 | Sep 2008 | AU | national |
| 2008905526 | Oct 2008 | AU | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/AU09/01150 | 9/3/2009 | WO | 00 | 3/2/2011 |
