FIELD OF INVENTION

[001] This invention is related to a user-friendly device for cutting designs in edges and middle of a foam. The present specification is based on and claims priority from an Indian Provisional application number 202041010639 filed on 12 ^th March 2020, the disclosure of which is incorporated herein.

BACKGROUND OF INVENTION

[002] It is often required to cut designs in edges and middle of the foam. Typically, V-shaped (chamfer cut) or curved V-shaped (fillet cut) or any other complex profiles need to be cut.

[003] Also bending a thick wire to required shapes is challenging and needs special tools.

[004] Cutting such V-shaped designs on a CNC machine requires complicated tools and 4-axis CNC control. However, 4-axis CNC usage is complex, expensive and needs advanced operator skills.

[005] Hence there is a need to develop a simple, user-friendly design cutting device in foam.

OBJECT OF INVENTION [006] The principal object of this invention is to develop a user-friendly device for cutting edge chamfer, fillet, profile designs etc. in foam edges. [007] Another objective of this invention is to develop a method of cutting curved shapes using straight wires itself.

[008] Another objective of this invention is to develop a user-friendly device that can also cut V-chamfer, fillet etc. designs in middle of the foam also, with varying depth, producing true 3D aesthetic designs.

[009] Another objective is to develop a tool which can achieve designs cutting in foam entirely on a CNC.

[0010] Another objective is to develop intelligent sensing devices to measure depth of cut, so it can be maintained constant, irrespective of work-piece height variations.

[0011] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF FIGURES

[0012] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:

[0013] FIG. 1 depicts the proposed foam edge cutting device.

[0014] FIG. 1A depicts the proposed foam edge cutting device, top view.

[0015] Fig 2 depicts the frame for fixing multiple straight wires to form a curved edge.

[0016] Fig 3 depicts the multiple straight wires to form a curved edge.

[0017] Fig 4 depicts the multiple straight wires to form a curved edge.

[0018] Fig.5 depicts a frame for cutting full spherical objects.

[0019] Fig.6 depicts sample edge cuts. [0020] FIG 7 depicts the proposed foam edge cutting device with rolling edge.

[0021] FIG 8 depicts the proposed foam edge cutting device (middle of foam also).

[0022] FIG 9 depicts sample design to be cut in foam.

[0023] FIG 10 depicts sample design to be cut in middle of foam. [0024] FIG 11 depicts a cutting tool for CNC design cutting.

[0025] FIG 12 depicts a height sensor to measure depth of cut.

[0026] FIG 13 depicts a LASER based height sensor to measure depth of cut. DETAILED DESCRIPTION OF INVENTION

[0027] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. For example, it should be noted that while some embodiments are explained with respect to cutting of foam with heated wire, any other application like material, tool, may also incorporate the subject matter of the invention with little or no modifications. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein. [0028] The embodiments herein describe an intelligent device for cutting edge designs like chamfer, fillet is foam material. Referring now to the drawings, and more particularly to FIGS. 1 through 13, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments. [0029] FIG 9 shows a typical foam piece 401, whose edges need to be chamfered, filleted etc. In fig4, the shape is a donut shape with two concentric circles.

[0030] After 2D profile cutting, the edges of the foam are sharp and square as shown by edge 406 in FIG9. [0031] Edges 404, 405 are the filleted edges to be achieved in the foam.

[0032] FIG 1 shows the proposed edge cutting device. It consists of base-board 102, on which the foam 101 to be cut is placed. 103 is a mechanical butting edge to butt the foam 101 when cutting. 103 is not hot, so it won’t cut the foam edge. [0033] 104 is an actively heated resistance wire like NiChrome wire, fitted to a L- frame consisting of vertical leg 106 and horizontal leg 105, locked to base board 102, consisting of a butting edge 103, with no other obstruction other than the vertical pole 106 and edge 103 protmding out of the base board 102, hence user can freely slide material 101 on base board 102 without any obstruction. [0034] The cutting wire 104 will cut the foam, when the foam is slid by the user along its perimeter, while butting the foam to the edge 103. The edge 103 is optional, instead user can butt the foam edge on the vertical leg 106 itself, but edge 103 is shorter compared to leg 106 and hence less friction will be faced when butted on 103 compared to 106. Also the butting edges 103, 106 are chamfered or filleted to enable smooth sliding of the foam on these edges. The wire 104 can be straight for chamfer effect or curved for fillet effect or bent to any other profile shapes, for desired edge shape on foam to be cut.

[0035] 106 is the vertical leg of the support piece 105. Slots 107, 108 are for adjusting the wire angle. 109 is a power-supply, to heat the wire 104. 110 are bush legs for the base board 102. [0036] Fig 1A shows the top view of the proposed device in FIG 1.

[0037] The cutting wire 104 can be straight for chamfer effect. The wire 104 can be curved for fillet cuts. [0038] However, it is challenging to bend a thick wire to desired curved shape. It needs special wire bending tools and also has challenges like spring back effects etc.

[0039] This invention proposes an intelligent cutting method by which a combination of straight wires itself can be used to cut curve of desired shape. [0040] Fig 2 shows the Curved shape cutting machine 1200, with L- shaped frame with Vertical leg 1201 and Horizontal leg 1202, similar to the legs 106,105 in FIG1. On each leg, holes 1203,1204 are made at known periodic interval, where the bolts 1206, 1207 are fixed. Or the holes 1203, 1204 can be continuous forming a slot.

[0041] Now the cutting wires 1210 are stringed around the bolts 1206, 1207 forming the desired curved cutting edge 1211. Both extruded and revolved curved shapes can be cut using the obtained cutting edge 1211. A spring is used at one or both end of the wire 1210 to maintain it straight under tension. Care is also taken to ensure the wires 1210, 1210a, 1210b don’t touch each other, by making them non co-planar, by winding them on different threads of the bolts 1206, 1207. Optionally the wires can be covered with thin insulation, so they don’t short if they touch each other.

[0042] Optionally a constant current power supply is used to power the wires 1210, 1210a etc. so current is maintained in case of an accidental short between the wires.

[0043] The wires 1210, 1210a, 1201b etc. can be in electrical parallel connection or a series connection. Mechanically also, they can be multiple parallel wires or a single long wire winding criss-cross on the bolts 1206, 1207 etc.

[0044] For cutting extruded curved shapes, a butting face 1208 is useful for pushing the material straight by butting on the face 1208. [0045] For cutting revolved curved shapes, on the topside of the Horizontal leg 1202 a series of holes 1205 are made for fixing the pin 1212, such that the pin 1212 acts as the pivoting centre and the material is revolved around the pin to obtain a hemispherical cut. Now the material is flipped and again revolved around the pin 1211 such that a complete spherical cut is done. In another embodiment a shaft of rotating motor can be fixed in hole 1205 instead of pin 1212, such that the material will be automatically rotated by the motor.

[0046] The L- shaped frame can be replaced with C-shaped frame 1300 with three legs 1301, 1302, 1303 as shown in the Fig 5, such that a single rotation can produce a complete sphere or other revolved shapes of cross-section 1304.

[0047] These mentioned L-shaped and C-shaped frames are fixed on a base plate for easy holding of material during cutting.

[0048] A chart is given to the user, mentioning the hole locations where the straight wire 1210, 1210a, 1210b etc. ends must be placed to get the desired curve 1211. [0049] An automatic method of generating the end locations of the wires 1210,

1201a, 1201b etc. and number of wires needed to achieve the desired curve 1211 is also proposed in this invention. The end points are found by drawing tangent lines to the curve 1211 and getting the intersections points of the tangents with the vertical and horizontal legs 1201, 1202 of the L-frame of the edge cutting device. [0050] FIG6 shows the material before and after edge cutting (extruded cutting) using the proposed device. FIG6 shows a straight edge, but even a curved edge shape like S can be edge cut using the proposed device. First 2D cut the S-shape. Then move along the curved edges of S, by always butting the face on 1208. [0051] The butting edge 103, can optionally be a bearing outer race, as shown in

FIG 7.

[0052] The inner race is locked to the base board 102, by a solid or hollow shaft bolt 204. [0053] This provides a smooth rolling edge, making it easy to slide the foam on the butting edge for reference.

[0054] For achieving chamfer cutting, user butts/presses the foam 101 on to the edge 103 and slides the foam along the perimeter of the edge, from start to end.

[0055] The same device can be used for chamfering inner edges also (example: ID of the donut shape in FIG 9.), since there are no obstructions on the base board 102, other than the central support piece 106, the foam can be slid freely without obstruction.

[0056] Sometimes it is also necessary to engrave chamfer edged designs in the middle of the foam, where there is no cut butting edge available. The depth of the engraved design also to be varied. For example, in FIG 10, Depth of cut at 502 is deeper and becomes shallower as it approaches 503 point at edge of the design. This is called Vcarving design.

[0057] Such a design engraving is very difficult to achieve in a CNC machine and needs complex 4-axis motion control and programming.

[0058] A simpler alternative is proposed in this invention, as shown in FIG 8. [0059] FIG 8 consists of a V-shaped bent hotwire tool, which is actively heated, with cutting edges 302 and 302A. Edge 302A is optional or can also be at a different angle compared to 302. [0060] It also consists of a not actively heated, relatively cold protrusion 303, with a radiused ball-nose bottom.

[0061] The entire V-shaped cutting edge is fixed on plate 305, which in turn is free to slide up/down along a straight motion guide 306. [0062] 306 is in turn fixed on a static mechanical frame with top horizontal frame

308 and vertical frames 309, 309 A. This frame is in turn fixed to the ground/base-board 310.

[0063] 311 is an optional stopper, which can be used for edge chamfer cutting in the same setup. [0064] First, the design as shown in FIG 10 is cut in a 3 -axis CNC machine, with both 2D shape and 3D depth information, using a cylindrical tool (hot knife or rotating end mill). After this, the piece looks as shown in FIG 10 left side. Here the design is cut such that depth of cut is more at 502 and gradually decreases (to near zero) at 503.

[0065] Now this piece is taken to the chamfer device shown in FIG 8. [0066] The protrusion 303 is first placed in the groove to be chamfered and heat is turned ON.

[0067] Then operator slowly sides the foam along the curve 502-503. As the foam is slid in XY, the pin 303 rests on the bottom of the groove and floats up/down as per the depth information in the groove, as cut by the CNC machine in the previous step. In this example, depth is deep at 502 and shallow at 503. As the tool floats up, the dimension of the chamfered edge also reduces, thus producing the desired design effect as shown in FIG 10 right side. [0068] The optional stopper 311 also enables edge chamfering in this same device. But in this setup, the frame legs 309, 309A is a constraint, which limits the size of the foam that can be edge chamfered. Hence for pure edge chamfering application, device shown in FIG 1 is advantageous. [0069] FIG 11 shows a new CNC cutting tool for achieving the desired engraving in a 3-acis XYZ CNC machine. It consists of hot-knife 601, with two V-shaped cutting edges 602, 603. The V-shaped edges are free to rotate about 601, thus free to align to the direction of cut. 601, 602, 603 are actively heated. As lip ring arrangement can be optionally used to heat the swiveling edges 602, 603. [0070] It also consists of a non-heating “plough” edge 604, which is at 90 degrees angle from the V edges 602 & 603 as shown in top-view of the device in FIG 6. This non-heating edge forces the V to be perpendicular to the direction of cut.

[0071] The plough edge 604 is always at 90 degrees from the cutting edges 602 & 603, but can float up/down with respect to the cutting edges 602, 603. So that the plough is always scratching on the surface of the foam when cutting.

[0072] Such a tool achieves complex design engraving at both edge and middle of the foam.

[0073] In one embodiment, the V-edges 602, 603, 604 are also allowed to float on the 601 edge up & down. A sensor connected to this floating tool detects the position along Z-direction with respect to the knife 601, which is rigidly held to the Z-axis of the CNC machine. This position information can be used by the CNC controller, to ensure constant depth of cut, irrespective of workpiece height variations. [0074] Similar floating device 703 connected to a position sensor, can be used on U-shaped scooping device 702, as shown in FIG 12, thus ensuring constant depth of the scooping, for applications like packaging etc. 704 is optional floating sensor on opposite leg of the scoop. [0075] FIG 13 shows a CNC machine fitted with a 3D height sensor consisting of

LASER point light source 804, camera 802 looking down on to the sheet 801 being cut. 802 is the cutting tool (hot knife, scoop, drill bit, end mill etc.) cutting the raw material 801 at a depth of cut 805. Such a sensor can robustly detect workpiece height variations. This sensed distance can be given as feedback to the CNC controller to maintain a constant depth of cut 805.

[0076] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.