| JPS6272005 | CONTROL METHOD FOR ROBOT |
| JPH03217912 | DEVICE FOR RETURNING TO ORIGIN |
| WO/1988/006752 | NUMERICAL CONTROL METHOD CAPABLE OF VARIABLY SETTING POSITIONING PRECISION |
| WO2019038785A1 | 2019-02-28 |
| CLAIMS 1) An automatic CNC multi -wire cutting machine 100 with inter- wire distance adjustment automatic system, with multiple parallel wires 101, held on both ends by springs 102, with each spring hooked to slider plate 105, 105 A on either side of the wire 101, which is sliding on guide rod 104, 104A on either side of the wire, where a camera sensor 107 is attached to each of the slider plate 105 or 105 A or both, to view along the wire length, to measure wire deflection, by viewing a bead 109 hanging on the wire 101 on one or both end of the wire 101. 2) An automatic inter- wire adjustment system 100, of claim 1 where the bead 109 is electrically illuminated, by battery or by using the current, voltage being supplied to the wire 101. 3) An automatic inter-wire adjustment system 100, of claim 1 , where the end 102B of the spring 102, where wire 101 is connected to the spring, is given a specific color or attached with an illuminated bead , so it is easy for the camera 107 to detect the end position 102B of the spring with respect to the bead 109, to detect wire breakage and non-uniform spring tension across the multiple wires 101. 4) An automatic inter-wire adjustment system 100, of claim 1, where an actuator 106 which moves front back on axis 115 towards and away from the slider 105, to catch and move and position the sliders along axis 114 along the guide rod 104, with each of the slider 105 having embedded target object 110 with slender tip HOB, which can be detected by a sensor 111 which is mounted adjacent to the actuator 106. 5) An automatic inter-wire adjustment system 100, of claim 1, where the sensor 111 moving on axis 114, but not moving on axis 115, thus the sensor 111 able to detect the object 110, 110B in the sliders both in the extended and retracted position of actuator 106. 6) An automatic inter-wire adjustment system 100, of claim 1, programmed to detect positions of each slider 105 along the guide rod 104 using sensor 111, to catch and alert operator on faulty scenarios. |
[001] Multiple parallel wires are used for cutting extruded shapes from raw material. In such system, the distance between wires need to be adjusted, based on size of parts being cut. Also wire deflects because of cutting force, causing dimension errors. This invention proposes an innovative automation method, which solves the above two problems. Also wire tension on all the wires needs to be maintained constant. This invention proposes an innovative automation method, which detects possible errors during wire pitch adjustments.
[002] The present application is based on, and claims priority from an Indian Application Number 202041036958 filed on 27th August, 2020, and an Indian Application Number 202041040420 filed on 18th September, 2020, the disclosure of which is hereby incorporated by reference herein.
BACKGROUND OF INVENTION
[003] Multiple parallel wires are used for cutting extruded shapes from raw material. In such system, the distance between wires need to be adjusted precisely, based on size of parts being cut. Also wire deflects because of cutting force, causing dimension errors. This invention proposes an innovative automation method, which solves the above two problems.
[004] In such multi-string system, wire tension by spring stretch can become non- uniform due to operator errors. Also unintended errors can occur during string pitch adjustment. [005] Hence there is a need to develop an innovative automation method, which solves the above two problems.
OBJECT OF INVENTION
[006] The principal object of this invention is to develop an innovative automation method which achieves inter-wire distance adjustment and robust wire deflection measurement simultaneously.
[007] Another object of this invention is to develop an innovative automation method which achieves robust error-free inter-wire distance adjustment and also detects non-uniformity in spring tension among multiple wires simultaneously.
[008] 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
[009] 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:
[0010] FIG. 1 Proposed auto string attachment with camera
[0011] FIG. 2 Multiwire cutting system. [0012] FIG. 3 Proposed auto string attachment with smart slider with sensor
[0013] FIG. 4 Multi -Wire cutting system: Slider catcher correct engagement.
[0014] FIG. 5 Multi-Wire cutting system: Slider catcher fault2
[0015] FIG. 6 Multi-Wire cutting system: Slider catcher fault3
DETAILED DESCRIPTION OF INVENTION
[0016] 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 designs in EPS, EPE foam material using heated wire, 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. [0017] The embodiments herein describe an automatic Multi string/wire cutting system. Referring now to the drawings, and more particularly to FIGS. 1 through 6, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0018] Fig 1 shows a CNC wire cutting system 100, with cutting wire 101, held by springs 102 on both ends of wire. The springs are hooked to slider plate 105.
[0019] The CNC wire cutting system 100 typically has multiple such wires in parallel, cutting parts simultaneously from a block of material.
[0020] Each wire has its own springs (102) and slider plates (105) on both end of wire. [0021] The slider plate 105 is free to slide on the guiding rod 104. The guiding rod can be circular or non-circular.
[0022] The wire is resting on the grooves of a grooved/teethed rod 103 on either side.
[0023] 106 is an electric or pneumatic actuator which can grip the slider plate 105 and slide it along the guide rod 104 and position it at desired position, to achieve to correct inter-wire distance adjustment.
[0024] The grooved rod 103 will retract back to a retracted position, thus releasing the wires from its grooves, thus allowing the wires to slide freely up-down along with the slider plate 105. After wires are adjusted to correct position, the grooved rod 103 will come back to the position as shown in FIGI, to catch the wires in its grooves.
[0025] When cutting material with wire, the wire can deflect because of cutting force. Such excess wire deflection can cause dimension defects in the part being cut.
[0026] Hence it is necessary to sense the wire deflection and slow-down or speedup the machine cutting speed, to minimize the part defects and also achieve maximum productivity, both at the same time.
[0027] In PCT PCT/IN2018/050540, a method of measuring wire deflection is explained, where a colored bead is applied on the wire and a camera collinear to the wire, viewing along the length of the wire to measure the bead deflection, which is a measure of the wire deflection. [0028] However, when multiple wires are present in the system, and also when the wire position is changing frequently, it is challenging to position the wire nearly colinear and parallel to the wire. Setup time for such precise adjustments can be challenging and time consuming.
[0029] This invention proposes a simple innovative method to enable precise positioning of the camera sensor to measure wire deflection precisely for each wire in the system.
[0030] Fig 1 shows a camera sensor 107, attached to the slider 105, by a plate 108. The camera position is such that it is nearly colinear and parallel to the wire, viewing along the length of the wire.
[0031] 109 is a bead attached to the wire 101. The bead can be circular washer or flanged washer, with the face of the washer or flange given a specific color like red, which is not easily present in the background and which camera can easily identify. The bead has a hole in the center through which wire 101 is passed.
[0032] The bead can also be conical shape 110 as show in Fig 1.
[0033] Each slider plate 105 of each wire in the multi -wire cutting system 100 is provided with a camera attachment 107, as shown in Fig 1.
[0034] When the actuator 106 slides the slider 105 to set wire position, the camera will also slide with the slider and wire, thus retaining its relative position with respect to the wire.
[0035] The plates 105, 108 can be separate or an integral path. [0036] The proposed system achieves two simultaneous functions needed for multiwire material cutting system. (A) automatic inter-wire distance adjustment. (B) automatic measurement of wire deflection of every individual wire.
[0037] The wire deflection data is used to either control the cutting speed or the cutting power of the wire. In hot wire cutting system, power can be increased by sending more current through the wire. In abrasive wire system, power can be increased by increasing the wire speed (pulley RPM).
[0038] The bead can also be an illuminated bead, to make it easy for the camera to detect it. The power for illuminating the bead can be from a battery or can be drawn from the current energy passing through the wire.
[0039] Camera can be wired or wireless. Camera can also have an optional on-board image processing CPU.
[0040] The tip 102B of the spring is also given a unique colour, which the camera 107 can see and measure the tip position of the spring. Colour can be given by paint or by attaching a coloured or illuminated bead to the tip 102B.
[0041] When wire 101 breaks, the spring will compress and the tip 102B will retract and move away from the camera view. This can be detected by camera to alert operator and CNC control system.
[0042] It is also desirable to have uniform spring tension in all the wires in a multi wire CNC cutting system.
[0043] The camera 107 can measure the spring tip 102B position with respect to the teethed rod 103 and give an alert to operator if spring stretch is excessive or inadequate in a particular wire. [0044] In multi wire cutting system, the slider 105 position along the guide rod 104 is adjusted by the actuator 106.
[0045] The retractable arm 106B of the actuator engages with the tapered tip 105B of the slider.
[0046] Referring to figures 4, 5, 6: figure 4 shows correct engagement of the actuator with the slider. Figures 5 and 6 shows faulty engagement of the actuator with the slider (fault2, fault3).
[0047] It is essential that the auto string adjustment system has the sensors and intelligence to detect these faults.
[0048] It is essential to keep low friction between 104 and 105 for smooth adjustment of the sliders. Also, during slider adjustments, the teethed rod 103 is in retracted position, causing the tension in the springs 102 to reduce, which reduces friction between 104 and 105. This can cause the slider to shift position (fault4) by gravity force, when there is vibration in the machine.
[0049] Slider can also slide down when a cutting wire gets cut (fault5), causing zero spring tension and hence lowering friction between 104 and 105.
[0050] Hence there is a need to inspect the slider positions, post pitch adjustment, as well as before every cut, to avoid rejection of output cut parts.
[0051] This invention proposes a simple sensor and target arrangement, which results in an economic and robust method of detecting all the faults (fault2, fault3, fault4, fault5), with the same sensor. [0052] 110 is a target object attached to the extended slider plate 108. This can be a metal or magnet or a coloured or illuminated bead or a reflective sticker, as per the need of the sensor 111.
[0053] 110B is the optional tip of the target object 110, of slender size.
[0054] 111 is a sensor to detect target object 110. The sensor I l l is mounted such that it is independent of the front/ back motion of the actuator tip 106B, but moves up/down along the Z-axis (114) with the actuator 106.
[0055] The target object 110 is also at an offset distance 113 from the zone on the slider, where the actuator 106B engages.
[0056] Such an arrangement ensures the sensor 111 can sense the object 110, HOB in both retracted and extended positions of 106B. Fault2, Fault3 occurs in extended position of 106B. Fault4, faults occurs in retracted position of 106B.Thus this intelligent arrangement of sensors, target object enables to detect multiple faults with same arrangement.
[0057] To find fault4 and faults, the sensor 111 and actuator 106 is slowly moved along the Z axis (which is the axis used to move the sliders), finding the position of each target object 110, HOB in each of the slider 105, 105A on both sides of the wire 101.
[0058] Standard edge finding sequence: fast move -> retract ->slow move: can be used to find the object locations more accurately.
[0059] The parallelism of 105, 105 A can also be checked by the sensors, thus ensuring wire parallelism. [0060] The sensor 111 can be one of standard object detection sensors like magnetic read switch, conductive sensor, LASER sensor, camera sensor etc. these sensors are given as example and any other object detection sensor can be used.
[0061] 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.