Support bed for sheet material cut by a fluid jet

Abstract

A bed for supporting sheet material during cutting by means of a high velocity fluid cutting jet is comprised of a laminated structure which permits the fluid cutting jet to pass through the material and the structure into a fluid collection chamber. The laminated structure prevents reflected fluid from the jet in the chamber from bouncing back against the sheet material. The laminated structure is comprised of an upper layer and a lower layer of barrier material and an intermediate layer formed from a fusible material such as tar, putty or similar substances.

Description

BACKGROUND OF THE INVENTION

The present invention relates to apparatus for cutting sheet material by means of a high velocity fluid cutting jet and, more particularly, it is concerned with a support bed on which the sheet material is held as the fluid jet cuts through the material.

While the cutting of sheet material by means of a fluid jet is well known, disposal of the jet thereafter presents some difficulties especially if the jet moves to various locations over the sheet material during the cutting operation.

Apparatus for cutting sheet material by means of a high velocity fluid cutting jet is disclosed in a copending application Ser. No. 488,158 filed July 12, 1974 and entitled FLUID CUTTING JET RECEIVER filed by Gerber et al, and having the same Assignee as the present application. In the copending application, a fluid jet receiver is positioned on the side of a layup of sheet material opposite a jet nozzle and is provided with an inlet that registers with the fluid cutting jet as it exits from the sheet material. The receiver moves with the jet or is constructed in such a manner that the inlet always remains in registry with the jet to disperse the jet in a deflection chamber and prevent the sheet material from being wetted by back-splatter and vapor. The energy levels of high velocity fluid cutting jets frequently reach many horsepower and, therefore, the jet receiver is designed to dissipate such energy without creating excessive backsplatter that could wet the bottom layer or layers of the sheet material and possibly ruin the material. Accordingly, the jet receiver in the copending application includes a specially designed jet deflection chamber which confines the jet and its fluid until the energy has been dissipated.

The present invention relates to a support bed that is constructed in such a manner that the cutting jet is prevented from rebounding against the sheet material after cutting and without utilizing a jet deflection chamber such as that disclosed in the referenced application.

Accordingly, it is a general object of the present invention to disclose a support bed on which sheet material may be cut without being subjected to backsplatter from a high velocity fluid cutting jet.

SUMMARY OF THE INVENTION

The present invention resides in a bed for supporting sheet material to be cut with a high velocity fluid cutting jet. The bed is comprised of a laminated structure on which the sheet material is laid and which allows a fluid cutting jet to pass from the sheet material into a fluid collecting chamber but prevents the fluid from reaching the sheet material on rebound.

The laminated structure has an upper layer, a lower layer spaced from and underlying the upper layer and intermediate layer. The upper layer usually defines the support surface on which the sheet material is spread and is formed from a barrier material such as paper, plastic sheet material or the like. The lower layer is also formed from a barrier material similar to or the same as that forming the upper layer.

The intermediate layer is formed from a severable and self-healing material that can be penetrated by the high velocity jet. The self-healing material may be a tar, putty or fusible plastic material which flows together after the jet has moved to another location. The laminated structure may then be used in numerous cutting operations without being destroyed by repeated cutting.

The barrier material of the upper and lower layers holds the self-healing material in a generally planar configuration and separates the generally tacky, self-healing material from the sheet material above and the supporting means in the bed below. Furthermore, the barrier material of the lower layer in the laminated structure resists backsplatter created by the jet as it impinges on the base of the fluid collection chamber in the bed and, thereby, prevents the sheet material from being wetted. A lower layer made of paper or plastic sheet material allows the jet to pass from the sheet material into a collection chamber without allowing backsplatter to reach the sheet material, because the high energy density of the jet needed for cutting is substantially reduced as the jet impinges on the base of the collection chamber and is dispersed in a random fashion.

The laminated structure, accordingly, has the ability to allow the fluid jet to pass into a fluid collection chamber from cut sheet material but prevents the fluid from reaching the material on rebound.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cutting apparatus having a fluid cutting nozzle and the support bed of the present invention.

FIG. 2 is a fragmentary cross-sectional view of the support bed in one embodiment of the present invention.

FIG. 3 is a fragmentary cross-sectional view of the support bed in another embodiment of the present invention

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a cutting apparatus, generally designated 10, having a fluid jet nozzle 12 which produces a high-velocity, fluid cutting jet J for cutting materials such as woven and non-woven fabrics, plastics, leather and similar limp sheet materials. The apparatus 10 includes a support table having a bed 14 on which the material is spread during a cutting operation. Generally the material is positioned in a multi-ply layup such as the layup L shown on the bed 14. It is also possible, however, to cut single plies of sheet material with the apparatus.

The fluid nozzle 12 produces a high-velocity, fluid cutting jet J which may have a diameter ranging between 0.004 inches and 0.010 inches and a velocity between 1,000 and 3,000 feet per second. Such a jet is capable of producing a contoured cut through a multi-ply layup when the nozzle 12 is translated relative to the material. Therefore, multiple pattern pieces can be cut from a layup by translating the nozzle and, correspondingly, the jet J along predefined cutting paths P at the perimeter of the pattern pieces.

For this reason, the nozzle 12 is mounted on a system of carriages which move parallel to the layup L in the illustrated X and Y coordinate directions. An X-carriage 20 is mounted on gear racks 22 extending longitudinally along each side of the support bed 14 for moving the nozzle back and forth over the layup in the X-coordinate direction. A Y-carriage 24 is mounted on the X-carriage 20 by means of a guide rail 26 and a lead screw 28 for movement relative to the layup and the X-carriage 20 in the illustrated Y-coordinate direction. Composite motions of the X- and Y-carriages translate the nozzle 12 to any desired coordinate over the layup.

An X-drive motor 30 mounted on the carriage 20 rotates pinions (not shown) engaging the two gear racks 22 for controlling the movement of the nozzle 12 in the X-coordinate direction. A Y-drive motor 32 mounted on the carriage 20 rotates the lead screw 28 to position the Y-carriage 24 and the nozzle in the Y-coordinate direction. Both the X-and Y-drive motors are operated by a control computer (not shown) which derives specific commands for tracking given cutting paths or pattern pieces from a cutting program tape. Programmed numerical controls for positioning two-axis carriage mechanisms are well known in the art and require no further description for understanding the present invention.

A combined reservoir and pump 40 are mounted at one end of the X-carriage 20 and are connected by means of a flexible high-pressure hose 42 to a hydraulic intensifier 44 mounted on the Y-carriage 24. The pump 40 pressurizes a fluid, generally water, in the reservoir, to a pressure of approximately 3,000 psi before it is transmitted through the hose 42 to the intensifier 44. In the intensifier, the pressure of the fluid is boosted to a nozzle pressure in the range of 10,000 to 100,000 psi, and the highly pressurized fluid is then delivered to the nozzle 12 which produces the cutting jet J.

Turning more specifically to the present invention, the support bed 14 defines a surface 50 on which the material is spread for cutting, and the bed also protects the material from backsplatter produced by the cutting jet J after the jet penetrates into the bed.

One embodiment of the support bed 14 is shown in the cross-sectional view of FIG. 2. The bed is comprised of a laminated structure 60 and a fluid collection chamber 62 formed between the laminated structure, the floor or base 64 of the bed and the peripheral bed wall 66. The base 64 includes a drain 68 through which spent fluid from the jet J is removed for disposal or recirculation through the pump 40.

The collection chamber 62 is filled with a plurality of elongated members extending in a closely packed array upwardly from the base 64 to the lower side of the laminated structure 60. In one form of the invention, the elongated members are metal pins 70 having their lower ends imbedded in the base 64 and having their free, upper ends lying in a common plane. The laminated structure 60 rests on top of the pins within the peripheral wall 66. Of course, the metal pins 70 anchored in the base 64 of the bed could be replaced by bristled mats having the free ends of the bristles lying in a common plane.

The laminated structure 60 has at least three layers, the upper layer 72 usually defining the support surface for the layup L. The layer 72 is formed from a barrier material such as a heavy paper, tagboard or a plastic sheet material. One plastic suitable for the present invention is a hardened plastic marketed under the trademark "FORMICA".

The lower layer 74 of the laminated structure 60 is also formed from a barrier material such as a heavy paper, tagboard or plastic which can resist the concentrated pressure applied to the material by the upper ends of the pins 70 when a layup is resting on the structure 60.

The terms "upper" and "lower" are used in this application for identification and should not be interpreted to limit the invention to support beds in which the laminated structure 60 is held in a horizontal position.

The upper and lower layers 72 and 74 also serve the function of holding the intermediate layer 76 in a planar configuration therebetween. The material forming the intermediate layer 76 is a self-healing material that is readily severed by the fluid cutting jet J as it exits from the lower side of the layup L. The material may be any one of a number of fusible materials which are highly plastic in the temperature range between 40.degree. and 120.degree. F. Semi-fluid materials such as tar or putty which display properties of both fluids and solids may be used. Another suitable product is sold under the trademark "SILLY PUTTY". All of these materials behave as highly viscous fluids which fuse or "melt" together at room temperatures, after they are separated. Due to this property, they are referred to in a support bed of a cutting apparatus as self-healing in that cuts produced in the materials by a fluid cutting jet close a brief time after the jet has moved to another region of the bed. A great number of cuts through the sheet material do not destroy the laminate 60 and, therefore, it is non-disposable.

From the above, it will be understood that the upper and lower layers 72 and 74 are formed from a barrier material less plastic or flexible and hence more rigid than the self-healing material in order to hold the intermediate layer 76 in a planar configuration. Furthermore, since tar and putty has a tacky texture, the layers 72 and 74 prevent the intermediate layer from adhering to either the sheet material in the layup or the metal pins 70 in the chamber 62.

The laminated structure 60 cooperates with the fluid cutting jet during a cutting operation in the following manner. As the jet J exists from the bottom ply of the layup L, it penetrates through all three layers 72, 74 and 76 of the laminated structure and enters the collection chamber 62. Unless the jet is immediately dispursed by a metal pin 70, the jet strikes the upwardly facing reflecting surface of the base 64 of the bed and bounces upwardly toward the lower layer 74 in a diffused spray as illustrated in FIG. 2. The energy density of the rebounding fluid is substantially reduced from that which obtains in the incident jet at the base 64 because of the fluid diffusion. Therefore, the rebounding fluid does not continue upwardly through the barrier material forming the lower layer 74 but, instead, is deflected downwardly again toward the base 64. The fluid continues to bounce back and forth between the base 64 and the layer 74 until the energy is substantially expended. The fluid then gravitates toward the drain 68 for disposal or recycling.

Accordingly, the sheet material forming the layup L is cut by the fluid cutting jet J issuing from the nozzle 12 but backsplatter from the jet in the chamber 62 is prevented from reaching the fabric material and wetting it. Furthermore, the energy of the jet is dissipated in a relatively confined space below the support surface of the bed 14.

FIG. 3 illustrates a further embodiment of the support bed 14 similar to that shown in FIG. 2. In FIG. 3 the laminated structure 60 is the same as that illustrated and described in FIG. 2 and hence it carries the same reference numerals. The structure 60, however, is supported upon a honeycomb structure comprised of a plurality of hexagonal cells 90. The cells extend through the fluid collecting chamber from the base 64 upwardly to the layer 74 and hold the laminated structure 60 in place between the peripheral wall 66 of the bed 14. The cells 90 are closed at their bottom ends by the base 64 and are open at their upper ends to admit the fluid jet passing through the laminated structure 60.

The dissipation of the fluid jet in the embodiment of FIG. 3 is substantially the same as that described above in connection with FIG. 2. The barrier material of the lower layer 74 prevents backsplatter from reaching the layup. Spent fluid from the jet flows to the drain 68 through drain ports or holes (not shown) in the bottom ends of the cells 90. Accordingly, sheet material forming a layup is cut by the fluid jet J without receiving backsplatter and the energy of the jet is dissipated in a confined collecting chamber within the bottom of the bed 14.

While the present invention has been described in several preferred embodiments, it should be understood that further modifications and substitutions can be had without departing from the spirit of the invention. For example, it is contemplated that the laminated structure disclosed may also be used on a cutting table comprised of a pair of conveyors placed in end-to-end relationship to form a throatway between the conveyors for receiving a fluid cutting jet. The conveyors translate the sheet material beingn cut in one coordinate direction back and forth under the jet. The laminated structure 60 is positioned between the conveyors and the sheet material and serves the same protective functions as those described above in connection with FIGS. 2 and 3. Fusible materials and barrier materials other than those specifically mentioned above may also be used provided that the self-healing and protective functions respectively are performed. Accordingly, the present invention has been described in a preferred embodiment by way of illustration rather than limitation.

Claims

I claim:

1. In combination in a cutting apparatus having a high velocity fluid cutting jet issuing from a nozzle translated in parallel relationship relative to and above sheet material in a cutting operation, an improved bed for supporting sheet material under the jet comprising:

a laminated structure penetrable by the jet and having:

an upper layer defining a support surface on which the sheet material is spread;

a lower layer spaced from and underlying the upper layer; and

an intermediate layer between the upper and lower layers and formed from a severable and self-healing material,

the upper and lower layers being formed from a barrier material for holding the self-healing material of the intermediate layer in place between the upper and lower layers; and

means disposed below the laminated structure and defining a fluid collection chamber for receiving the spent fluid from the jet.

2. A combination as defined in claim 1 wherein:

the upper layer and the lower layer of the laminated structure are more rigid than the intermediate layer.

3. A combination as defined in claim 1 wherein:

the intermediate layer of the laminated structure is formed from a material more plastic than the material of the upper or lower layers.

4. A combination as defined in claim 1 wherein:

the intermediate layer of the laminated structure is formed from a fusible material.

5. A combination as defined in claim 4 wherein the fusible material is tar.

6. A combination as defined in claim 4 wherein the fusible material is a viscous, semi-fluid material.

7. A combination as defined in claim 1 wherein the upper layer of the laminated structure is formed from a material selected from the group consisting of paper, tagboard and hardened plastic sheet material.

8. A combination as defined in claim 1 wherein the lower layer of the laminated structure is formed from a material selected from the group consisting of paper, tagboard and hardened plastic.

9. A combination as defined in claim 1 further including:

a fluid permeable, mechanical support means underlying the lower layer of the laminated structure for holding the laminated structure in a predetermined support plane above the fluid collection chamber.

10. A combination as defined in claim 9 wherein:

the mechanical support means includes a honeycomb structure having parallel cells extending upwardly toward the lower layer and having the ends of the cells adjacent the lower layer open.

11. A combination as defined in claim 10 wherein the means defining the fluid collection chamber further includes:

a base underlying the honeycomb structure and covering the ends of the cells opposite the open ends.

12. A combination as defined in claim 9 wherein:

the mechanical support means and the means defining the fluid collection chamber include a base and an array of elongated members extending upwardly from the base toward the lower layer of the laminated structure, the upper ends of the members being free and lying substantially in a common plane.

13. A combination as defined in claim 12 wherein the elongated members are metal pins.

14. In combination in a cutting machine having a jet nozzle which moves relative to sheet material and produces a high velocity fluid cutting jet for penetrating the sheet material along predefined cutting paths in a cutting operation, an improved bed for supporting the sheet material as the material is cut by the high velocity fluid cutting jet comprising:

a base having a hard, reflective surface for reflecting an impinging fluid cutting jet; and

a penetrable, laminated, planar structure supported in spaced and generally parallel relationship from the reflective surface of the base to define a collecting chamber between the reflective surface and the confronting surface of the planar structure, and defining a support surface for the sheet material to be cut by the jet on the side of the planar structure opposite said confronting surface, the structure being comprised of two outer layers and at least one interposed intermediate layer, the intermediate layer being comprised of a self-healing, plastic and viscous material and each of the outer layers being a layer of material more rigid than the viscous material for capturing and holding the viscous material between the outer layers whereby the fluid cutting jet may cut through sheet material on the support surface and penetrate through the laminated structure into the collecting chamber, and the self-healing material in the laminated structure closes the cut made by the jet as the jet is moved along the predefined cutting paths.

15. A combination as defined in claim 14 wherein the outer layers of the planar structure are formed from a material selected from the group consisting of paper, tagboard and hardened plastic.