WO2022118345A1

WO2022118345A1 - Optimised cnc wire cutting method

Info

Publication number: WO2022118345A1
Application number: PCT/IN2021/051140
Authority: WO
Inventors: Viswesh SRINIVASAN
Original assignee: Srinivasan Viswesh
Priority date: 2020-12-06
Filing date: 2021-12-06
Publication date: 2022-06-09

Abstract

This invention relates to the field of CNC wire cutting. This invention proposes an intelligent cutting method (tool path), which results in reduced cutting time and reduced material wastage using Common Line cutting method, combined with honey comb nesting, particularly for pipe shape cutting in foam, used in insulation applications. Common Line method for cutting half pipe shapes with U and L joint is also proposed in this invention.

Description

“OPTIMISED CNC WIRE CUTTING METHOD”

FIELD OF INVENTION

[001] This invention relates to the field of CNC wire cutting. This invention proposes an intelligent cutting method (tool path), which results in reduced cutting time and reduced material wastage, specifically for cutting pipe shapes, used in insulation applications.

[002] The present application is based on, and claims priority from an Indian Application Number 202041048668 filed on 6^th December, 2020, and an Indian Application Number 202141023644 filed on 27th May, 2021, the disclosure of which is hereby incorporated by reference herein.

BACKGROUND OF INVENTION

[003] In CNC wire cutting process, non-optimal tool path can cause increased cutting time and material wastage. Drawing the tool path manually for each size can be a time consuming process.

[004] Hence there is a need to develop a method of cutting which minimizes the cutting time and material wastage. There is also a need for developing an automatic method of generating this tool path, without manual laborious process.

OBJECT OF INVENTION

[005] The principal object of this invention is to develop an innovative manufacturing method (tool path), which results in reduced cutting time and reduced material wastage. [006] Another objective is to develop an automatic method of generating this tool path, without manual laborious process, for any given object size.

[007] 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

[008] 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:

[009] FIG. 1 depicts a typical pipe cutting path.

[0010] FIG. 2 depicts another typical pipe cutting path.

[0011] FIG. 3 depicts the proposed Common Line (CL) pipe cutting path.

[0012] FIG 4 depicts the proposed Common Line (CL) pipe cutting path for pipe-in-pipe scenario.

[0013] FIG 5 depicts the proposed Pipe cutting CL path for U-joint pipe

[0014] FIG 6 depicts the proposed Pipe cutting CL path for U-joint pipe-in-pipe

[0015] FIG 7 depicts the proposed Pipe cutting CL path for L-joint pipe [0016] FIG 8 depicts the proposed Pipe cutting CL path for L-joint pipe-in-pipe.

[0017] FIG 9. Pipe cutting path with proposed AU nesting

[0018] FIG 10. Pipe cutting path with proposed AU nesting

[0019] FIG 11 : Pipe cutting non-chain pathl with proposed AU nesting [0020] FIG 12: Pipe cutting chain pathl with proposed AU nesting

[0021] FIG 13. Pipe cutting path for Ujoint

[0022] FIG 14. Pipe cutting path for L joint

[0023] FIG 15. Pipe cutting path with Lead-In-Out at OD

[0024] FIG 16. Pipe cutting path with comer loop at ID [0025] FIG 17: Pipe cutting chain pathl with proposed A nesting

DETAILED DESCRIPTION OF INVENTION

[0026] 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 pipe insulation shapes in foam material, any other application 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.

[0027] The embodiments herein describe an innovative manufacturing method and tool path, which results in lesser cutting time and reduced material wastage. Referring now to the drawings, and more particularly to FIGS. 1 through 17, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.

[0028] FIG 1 shows a typical tool path for pipe profile cutting. The travel path 103 from one pipe to next pipe is very long (~= Pipe Outer diameter) and is an unproductive cut, which unnecessarily increases cutting time. The travel path 104 from one pipe to next pipe is very long (~= PI*Pipe Outer diameter/2) and is an unproductive cut, which unnecessarily increases cutting time. [0029] FIG 2 shows another typical tool path for pipe profile cutting. The travel path 112 from one pipe to next pipe is very long (~= Pipe Outer diameter/2) and is an unproductive cut, which unnecessarily increases cutting time.

[0030] In FIG 3, CD is the Inner Diameter (ID) of the half pipe and BG is the Outer Diameter (OD) after tool radius compensation has been applied. BCFDGHB is the shape of the half pipe after tool radius compensation (Outside offset) has been applied to the shape of the half pipe.

[0031] FIG 3 shows the proposed optimized tool path of this invention: ABCDECFDGHBIGJ which results in fabrication of two half pipes, where the lines BC and DG are common between the 2 half pipes, which results in reduced overall cutting time.

[0032] In another embodiment the cutting path is chosen as ABCFDECFDGHBIGJ which ensures the ID of the pipe stays as a full circle, instead of two half circles.

[0033] FIG 4 shows the proposed optimized tool path when cutting multiple pipe sizes with one pipe inside another pipe. Shape C1D1G1E1H1J1C1 and shape C1D1F1E1H1I1C1 are the outside offset shape of half pipe (121) by tool radius. Shape B1C1J1H1K1L1B1 and shape B1C1I1H1K1M1B1 are the outside offset shape of half pipe (122) by tool radius.

[0034] D1E1 is ID of pipe 121. C1H1 is OD of pipe 121 and ID of pipe 122. B1K1 is OD of pipe 122.

[0035] FIG 4 shows the proposed optimized tool path when cutting multiple pipe sizes with one pipe inside another pipe: A1B1C1D1E1F1D1G1E1H1J1C1I1H1K1L1B1M1K1N1, which results in fabrication of two numbers of half pipe 121 and two numbers of half pipe 122.

[0036] In another embodiment the cutting path is chosen as A1B1C1D1G1E1F1D1G1E1H1J1C1I1H1K1L1B1M1K1N1 which ensures the ID of the pipe 121 stays as a full circle, instead of two half circles.

[0037] The path is chosen such that the top half K1L1B1 od pipe 122 is cut first before the bottom half B1M1K1 of pipe 122, with the rest of the inner pipes can be in any one of top half first or bottom half first.

[0038] Similar tool path logic can be extended for multiple nested pipes, with diameter lines being common for top and bottom half pipes and OD of smaller pipe being common line to ID of the next bigger pipe, with the top half of the outer most cut before cutting the bottom half.

[0039] FIG 5 shows the proposed optimized tool path for U joint pipes: A2B2U1C2D2E2C2F2D2U2G2H2B2I2G2J2, resulting in fabrication of two half pipes with desired U joint.

[0040] FIG 6 shows the proposed optimized tool path for U joint pipes, when cutting multiple pipe sizes with one pipe inside another pipe: A3B3U3C3U1D3E3F3D3G3E3U2H3J3C3I3H3U4K3L3B3M3K3N3, resulting in fabrication of four half pipes with desired U joints.

[0041] FIG 7 shows the proposed optimized tool path for L joint pipes: A4B4C4D4E4F4G4I4F4H4G4J4K4L4M4C4N4L4O4, resulting in fabrication of two half pipes with desired L joint.

[0042] FIG 8 shows the proposed optimized tool path for L joint pipes, when cutting multiple pipe sizes with one pipe inside another pipe: A5B5C5D5E5F5G5H5I5J5H5K5I5L5M5N5O5E5P5N5Q5R5S5T5B5U5S5V5, resulting in fabrication of four half pipes with desired L joints.

[0043]

[0044] The desired pipe shape if first offsetted to compensate for cutting tool diameter. The Common-Line path of FIG 3,4 etc. are generated using the already offsetted shape.

[0045] Pipes for insulation etc. have to be cut in so many different sizes. Manually drawing the tool path will be very laborious job. This invention proposes an automatic method of generating the tool path as explained in Fig 3, Fig 4, Fig 5, Fig 6, Fig 7, Fig 8. ( method 710)

[0046] FIG 2 shows a typical tool path for pipe profile cutting. It consists of pipe-sectors arranged like Alphabet C and hence called C-nesting.

[0047] But this nesting involves wastage near the ID zone 113. This also involves extra cut lines 112, as the cutting wire has to travel from one pipe to another, which increases cutting time.

[0048] FIG 9 shows an improved nesting arrangement. In this, pipes are arranged in A orientation 201 (Inverted U) and U orientation (202) in alternative rows.

[0049] The ending leg (203) of a U pipe and starting leg (204) of next U pipe are inserted into the gap 205 at the Inner Diameter (ID) of the top row pipe in A orientation, as shown in FIG 3.

[0050] The distance dl (206) between A-pipe (201) and U-pipe (202) is mathematically computed using standard trigonometric laws.

[0051] After nesting, the optimal cutting tool path needs to be determined by computing. FIG 4 shows one possible cutting path, where A-pipe (201) is cut along path a-b-c-d-e-f-a and then wire is moved to start point al of next A-pipe, without intersecting with any of the arranged pipes.

[0052] The U-pipes (202) are cut along the path m-n-o-p-q-r-m and then travel to start point of next U-pipe ml, without intersecting with any of the arranged pipes.

[0053] But in this cutting path, the travel from “a to al” and “m to ml” are extra cut lines, which unnecessarily increases the cutting time.

[0054] Hence there is a need to develop a more efficient cutting path, which takes minimal cutting time.

[0055] FIG 12 shows proposed improved cutting path in this invention. In this new path, first the Outer Diameter (OD) of all the A-pipes are cut, as shown by red line from E1-E2-E3-E4-E5-E6-E7. Then ID of all the A-pipes in the top row are cut along the path E7-F1-F2-F3-F4-F5-F6-F7-F8-E1. Then ID of all the U-pipes in the next bottom U-row are cut along the path G1-G2-G3-G4-G5-G6-G7-G8-G9-G10- Gl l. Then OD of all the U-pipes in the same U-row are cut along the path Gl l-Hl- H2-H3-H4-H5-G1.

[0056] The above path is repeated for alternate A & U rows. In this proposed path, extra travel paths from one pipe to next pipe is minimized, resulting in reduced cutting time.

[0057] 180 deg pipe sector is shown as an example. The proposed path is applicable even for pipe sectors like 120 deg, 90 deg etc.

[0058] FIG 13 shows an arrangement, where the pipe joints are U joints (601, 602), which still gives the same nesting efficiency and cutting time savings from the proposed path, (method 913) [0059] FIG 14 shows an arrangement, where the pipe joints are L joints (701, 702), which still gives the same nesting efficiency and cutting time savings from the proposed path, (method 914)

[0060] FIG 15 shows the method 910 of OD cutting path with lead-in lead-out path (E1-E2-I1 -12-13 -I4-E4). This gives time for the wire, which may be lagging due to cutting force, to catch up with the CNC co-ordinates, which will avoid shape defects at sharp turns.

[0061] FIG 16 also shows method 911 of cutting tool path with the corner loop path 901. This gives time for the wire, which may be lagging due to cutting force, to catch up with the CNC co-ordinates, which will avoid shape defects at sharp turns.

[0062] The distance dl (206) may be recomputed if corner loops 901 are used ( method 912)

[0063] FIG 17 shows full A-nesting. The chain path proposed in this invention is also applicable for this nesting. le. Cut OD of all the pipes in the top row, then cut ID of all the pipes in the same row on the return path etc. (method 915)

[0064] Pipes for insulation etc. have to be cut in so many different sizes. Manually drawing the tool path will be very laborious job. This invention proposes an automatic method of generating the tool path as explained in this invention. ( method 916)

[0065] 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.

Claims

We Claim:

1) Method 100 of cutting half pipe sections 101, 102, where the tool path is such that some portions of the geometry are shared between two half pipes such as ABCDECFDGHBIGJ, which results in two half pipes, where the shape BCFDGHB and BCEDGIB are the shapes obtained by offsetting in outside direction of regular half pipe shapes, by cutting tool radius for compensation.

2) Method 200 of claim 1, where the cutting path is ABCFDECFDGHBIGJ, which ensures the ID of the pipe stays as a full circle, without getting cut in to two half circles.

3) Method 300 of cutting multiple nested half pipe sections, in small pipe inside large pipe mode, where D1E1 is the ID of pipe 121 and C1H1 is the OD of pipe 121 and ID of pipe 122 and B1K1 is OD of pipe 122, with shape C1D1G1E1H1J1C1 and C1D1F1E1H1I1C1 being offsetted shape of half pipe 121, and Shape B1C1J1H1K1L1B1 and shape B1C1I1H1K1M1B1 being the outside offset shape of half pipe (122), with the proposed cutting path A1B1C1D1E1F1D1G1E1H1J1C1I1H1K1L1B1M1K1N1, fabricating four half pipes.

4) Method 400 of claim2, where the cutting path is A1B1C1D1G1E1F1D1G1E1H1J1C1I1H1K1L1B1M1K1N1, which ensures the ID of the pipe stays as a full circle, without getting cut in to two half circles.

5) Method of claim3, where the cutting of top half K1L1B1 is done before cutting bottom half B1M1K1, with the rest of the inner pipes can be in one of top first or bottom first. ) Method of cutting half pipe shapes with U joints Ul, U2, with path A2B2U1C2D2E2C2F2D2U2G2H2B2I2G2J2, resulting in fabrication of two half pipes with desired U joint. ) Method 500 of cutting half pipes of claim 6, with multiple nested pipes, cutting along path A3B3U3C3U1D3E3F3D3G3E3U2H3J3C3I3H3U4K3L3B3M3K3N3, resulting in fabrication of four half pipes with desired U joints. ) Method 600 of cutting half pipe shapes with L joints LI 1, LI 2, with path A4B4C4D4E4F4G4I4F4H4G4J4K4L4M4C4N4L4O4, resulting in fabrication of two half pipes with desired L joint. ) Method 700 of cutting half pipes of claim 8, with multiple nested pipes, cutting along path A5B5C5D5E5F5G5H5I5J5H5K5I5L5M5N5O5E5P5N5Q5R5S5T5B5U5S5 V5, resulting in fabrication of four half pipes with desired L joints. 0) Method 710 of automatically generating the cutting tool path methods proposed in claims 1 to claim 9. 1) Method 800 of nesting pipe sectors, with pipes arranged in A-config (201) in odd rows starting from top and U-config (202) in even rows, where distance 206 between the rows is automatically computed, such that legs 203, 204 of the U-pipe can go in to ID zone 205 of the A-pipe. 2) Method 900 of automatic cutting path generation for pipes arranged as in method 100 of claim 1, such that OD of all the top row A-config (201) pipes are cut (path E1-E2-E3-E4-E5-E6-E7 ), followed by ID of all the top row pipes ( path E7-F1-F2-F3-F4-F5-F6-F7-F8-E1), followed by ID of all U-config pipes in next row ( path G1-G2-G3-G4-G5-G6-G7-G8-G9-G10-G11), followed by OD of all the U-config pipes ( path G11-H1-H2-H3-H4-H5-G1). This cutting path is repeated for subsequent A-U-A-U rows.

13) Method 910 of creating tool path of claim2, where the lead-in lead-out path II- 12-13 -14 is added to avoid wire lag shape defects at the sharp corners.

14) Method 911 of creating tool path of claim2, where the corner loop path 901 is added for pipe ID corners, to avoid wire lag shape defects at the sharp corners.

15) Method 912 of recomputing the inter-row distance 206, to accommodate corner-loop 901 proposed in claim 4. 16) Method 913 of creating tool path of claim2, where the pipe joint can be U shaped joint 601, 602.

17) Method 914 of creating tool path of claim2, where the pipe joint can be L shaped joint 701, 702.

18) Method 915 of chain cutting of pipes as proposed in claim2 applied all rows in A-orientation instead if alternating A-U-A-U rows.

19) Method 916 of automatically generating the cutting tool path methods proposed in claims 11 to claim 18.