Classifications

• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B19/00—Programme-control systems
  • G05B19/02—Programme-control systems electric
  • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
  • G05B19/19—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
  • G05B19/40—Open loop systems, e.g. using stepping motor
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B19/00—Programme-control systems
  • G05B19/02—Programme-control systems electric
  • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
  • G05B19/41—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path
  • G05B19/4103—Digital interpolation
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/33—Director till display
  • G05B2219/33099—Computer numerical control [CNC]; Software control [SWC]
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/33—Director till display
  • G05B2219/33182—Uart, serial datatransmission, modem
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/34—Director, elements to supervisory
  • G05B2219/34087—Enter at fixed periods distances in counter for each axis, pulse distribution
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/34—Director, elements to supervisory
  • G05B2219/34098—Slope fitting, fairing contour, curve fitting, transition
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/34—Director, elements to supervisory
  • G05B2219/34187—Any angle, slope
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/34—Director, elements to supervisory
  • G05B2219/34215—Microprocessor
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/35—Nc in input of data, input till input file format
  • G05B2219/35439—Keys or buttons
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/36—Nc in input of data, input key till input tape
  • G05B2219/36383—Manual input combined with input from computer or tape

Definitions

• This invention relates to forming contours, and more particularly to forming contours either of straight line and/or curvilinear form, utilising a computer numerical control system (C N C system).
• C N C system computer numerical control system
• the invention is particularly applicable to the machining of contours, although the invention also has other applications, such as, the drawing or scribing of lines on metal plate or sheet material, including fabrics, prior to cutting operations, or in relation to the preparation of drawings including the preparation of contour maps.
• Background Art The application of C N C systems to machine tools in particular has significantly advanced the machining of shapes, particularly shapes which are not of circular or straight line forms which are normally quickly and accurately accomplished using conventional machine tools.
• the simplest method of applying a C N C system is to use incremental drives, such as stepping motors, which rotate the leadscrews of a machine tool by fixed increments corresponding to the outward pulses from a computer.
• Each counter counts a predetermined number of input pulses such that the ratios of the numbers of input pulses is equal to the ratios of the inverses of the numbers of increments relevant to the component of the contour or segment in the directions of the related drives with which the component is associated, and the respective counter only initiates the feeding of a drive pulse to that motor when the predetermined number of input pulses have been counted, whereafter the counter recommences counting the continuous feed of input pulses.
• a relatively high number of input pulses can be broken down into a relatively small number of drive pulses to be computed for each incremental drive, and the incremental drives are only required to advance over a constant predetermined distance per drive pulse.
• the speed of advance or travel can be easily kept constant, or even, varied if necessary, to reduce acceleration caused by changes in direction of travel when the contour changes from one straight configured segment to another straight configured segment forming a small part of a contour of curvilinear configuration, or between a straight section and a curvilinear section of a contour having both straight and curvilinear sections forming parts thereof.
• the invention may therefore envisage a method of controlling an apparatus for forming a straight configured contour, or a straight configured segment forming part of a curvilinear contour, and having co-ordinates in at least two directions, said apparatus incorporating a work piece support, a contour forming means, incremental drives to effect relative movement between said support and said contour forming means in said directions, said method comprising the steps of; (a) determining the components of said contour or segment in said directions as a number of increments of length equal to a predetermined distance, (b) providing a continuous feed of input pulses,
• the invention may also envisage a control system adapted for association with an apparatus for forming a straight configured contour, or a straight configured segment forming part of a curvilinear contour, and having co-ordinates in at least two directions, said apparatus being of the type comprising a work piece support, a contour forming means, incremental drives to effect relative movement between said support and said contour forming means in said directions, said control system being adapted to deliver drive pulses to said incremental drives, and comprising means to continuously receive input pulses, means to continuously count, in respect of each said direction, a predetermined number of input pulses in accordance with the ratio of the inverses of a number of increments of predetermined distance making up the components of said contour or segment in said directions, means for, in use, feeding
• the contour forming means takes the form of a drawing or scribing implement carried by the apparatus and may be controlled to draw or scribe a line of the contour required, whilst, in the case of an apparatus to machine contours, that is, a machine tool, the contour forming means is a material removing means, such as a milling cutter, grinding wheel or other machining or cutting device, including an oxy-acetylene cutting unit, and in respect of which either the tool head is controlled to move in the required directions, or the workpiece support is controlled to move in the required directions.
• a material removing means such as a milling cutter, grinding wheel or other machining or cutting device, including an oxy-acetylene cutting unit
• Figure 1 is a perspective view of a conventional milling machine to which, in this embodiment, the invention is applied,
• Figure 2 is a representation of an arc in a single orthogonal plane for the purposes of explaining the basic concept of the present invention
• Figure 3 is a representation of the same arc in a plane inclined to be orthogonal plane
• Figure 4 is a representation of the same arc in a plane inclined to all of the orthogonal planes
• Figure 5 is a schematic block diagram of the basic system in accordance with the present invention as adapted to form or cut a circular arc in a plane inclined to all of the orthogonal planes.
• FIG. 6 is a block diagram of the basic requirements of the control system for this preferred form of the invention.
• FIG. 7 is a detailed circuit diagram of the power supply circuit for the stepping motors
• FIG 8 is a detailed circuit diagram for the operator controls.
• FIG. 9 is a detailed circuit diagram of the connections for the stepping motor circuits
• Figure 10 is a detailed circuit diagram for the respective motor control boards
• Figure 11 is a detailed circuit diagram for the respective motor drive boards.
• Figure 12 is a flow chart of the basic programming requirements for the micro-processor Figure 13 is a flow chart of the requirements of initial programming step
• Figure 14 is a flow chart of the requirements of the input and load programming steps
• Figure 15 is a flow chart of the programming requirements for the translation of geometrical parameters into a table as required by the load routine
• Figure 16 is a flow chart of the prograiming requirements for simulating three counters with the internal registers of the micro-processor, Best Mode for Carrying Out the Invention
• FIG. 1 of the drawings there is illustrated a perspective view of a conventional milling machine, gene ⁇ rally designated as 100, and to which this preferred embodiment of the invention is applied.
• the milling machine basically comprises a machine table assembly 101 having an upper table 102, the upper surface of which provides a work support surface 103 on which a work piece is to be supported and which is caused to move transversely of the machine, along an axis designated by X, by means of a lead screw 104 which in turn is intermittently driven by a stepping motor M in response to electrical drive pulses delivered to the motor from a micro-processor controlled motor drive circuit.
• the upper table is in turn supported on a lower support 106, which is caused to move in a direction perpendicular to the X axis, and along an axis designated by Y, by means of a lead screw 105 which in turn is intermittently driven by a stepping motor M Y in response to electrical drive pulses delivered to the motor from a motor drive circuit therefor which is under the control of a micro-processor.
• the machine further incorporates a conventional milling cutter 107 suspended over the machine table in a conventional chuck arrangement 108 which in turn is rotatably driven by a cutter drive, motor 109.
• the arrangement also incorporates an automatic drive 110 for raising and lowering the drive assembly for the milling cutter, in a direction or axis designated as Z, by means of a stepping motor M Z in response to electrical drive pulses delivered to the motor from a motor drive circuit therefor which may be under the control of the microprocessor, or may be manually actuated.
• the machine shown in Figure 1, and described above, is a conventional arrangement for a machine of this type and to which a conventional C N C system may be applied for the stepping motors to rotate the lead screws of the machine tool by fixed increments in response to drive pulses and under the control of a. micro-processor.
• the controller divides it into elemental intervals, usually 0.1 degree for large radii and 1.0 degree for small radii, and it generates a straight path mid-way between the straight chords and the straight tangents of the elemental arcs.
• chords is sufficiently accrrate for elemental intervals less than 2.0 degrees.
• Pd/ ⁇ X and Pd/ ⁇ Y are the numbers of input pulses to be counted by the X and Y axis counters, respectively, before they send pulses to their corresponding motors.
• R To change the arc radius from unity to any value R, all that is necessary is to arrange for the counters to move to their next numbers after PR input pulses instead of after P pulses.
• aR is the distance travelled and bPR is the time taken, where a is a constant and b is the input pulse period; Therefore the speed of travel is a/bP. It is independent of the arc radius, and can be varied by changing the input pulse frequency. Arcs or straight lines and arcs can be joined smoothly by fixing the initial inclination of one to match the final inclination of its predecessor.
• An arc can be generated in any plane.
• Fig. 3 of the drawings take an arc of unit radius contained by a plane which makes an angle ⁇ with the XY plane and is perpendicular to the YZ plane.
• the radius of the arc makes an angle ⁇ degrees with the intersection of the inclined plane and the XY plane.
• the distances to be travelled in the X, Y and Z directions, respectively are:
• the controller sends equally-spaced pulses to the X, Y and Z motors such that the distances ⁇ X, ⁇ Y and ⁇ Z are moved simultaneously.
• the operation is similar to arc generation in an orthogonal plane except that an additional counter is used. It is provided with Pd/ ⁇ Z values and it initiates pulses for the Z motor.
• a more general case is an arc on a plane which is inclined to all orthogonal planes.
• ⁇ X 0.00175 ⁇ - cos ⁇ sin ( ⁇ + 0.05) + cos ⁇ sin ⁇ cos ( ⁇ + 0.05) ⁇
• ⁇ X, ⁇ Y and ⁇ Z are the components of an elemental line in the orthogonal directions
• d is the step size per motor pulse
• P is the number of input pulses chosen to be fed to the counters for one line
• the counters are supplied with the numbers Pd/ ⁇ X, Pd/ ⁇ Y and Pd/ ⁇ Z for each line. The operation is then similar to the generation of an arc of unit radius. If the elemental lines are not of equal length, then for constant speed of travel, P must be made proportional to the length of the line for each element.
• FIG. 5 is a schematic diagram in block form of a system in accordance with the present invention adapted to form or cut a circular arc in a plane inclined to all orthogonal planes, that is, requiring movements in three orthogonal directions.
• a pulse generator 1 feeds input pulses to three counters 2, 3 and 4, which in turn direct drive pulses to stepping motors M X , M Y and M Z respectively for the X, Y and Z axes.
• the input pulses from the pulse generator are also fed to a main counter 8 which in turn feeds intermediate pulses to counters 2, 3 and 4 to alter the value of the number of input pulses each of those counters is to receive before feeding a drive pulse to the respective stepping motor.
• the counters 2, 3 and 4 count pulses received from the pulse generator 1 and each time they receive Pd/ ⁇ X, Pd/ ⁇ Y and Pd/ ⁇ Z pulses, respectively, they send a drive pulse to the respective stepping motors M X , M Y and M Z .
• P is the number of pulses chosen to be fed to the counters for an elemental interval, typically 0.1 degree, of a circular arc of unit radius
• d is the step size
• ⁇ X, ⁇ Y and ⁇ Z are the orthogonal movements required for an elemental interval.
• Counter 8 simultaneously counts the pulses from the pulse generator 1 and each time it has received PR pulses, where R is a value related to the radius of the arc to be formed or cut, the counter 8 sends a pulse to counters 2, 3 and 4 causing those counters to adjust the number of Pd/ ⁇ X, Pd/ ⁇ Y and Pd/ ⁇ Z input pulses they are to receive before delivering a drive pulse to their respective stepping motors.
• the coupling between the S B C and the keyboard is achieved by an RS-232C D-type connector in which the pins 4, 6 and 14 of the J3 connector of the S B C is coupled to pins 2, 3 and 7 of the RS-232C connector and thus to the keyboard. Pins 8 and 10 of the J3 connector are coupled together.
• the S B C is in turn coupled to motor control boards for each of the stepping motors to achieve motor control as to be later described. Via the keyboard the operator supplies details of the shape of the contour to be formed and the speed at which it is to be formed in accordance with programs also to be later described.
• the keyboard unit further incorporates a printing device which records the input details as they are forwarded to the computer.
• the computer as identified and programmed receives the input details and converts them to two (in the case of two dimensional contours) or three (in the case of three dimensional contours) sets of control pulses appropriate for the two, or three, orthogonal movements in the machine tool to be controlled.
• the computer in turn provides control pulses to motor control boards corresponding to each stepping motor M X , M Y and M Z .
• the basic circuit requirem.ents are shown for the main power supply which provides power to the respective motor drive boards (MDB'S) for each stepping motor, the details of which are shown in Figure 11, via the pin connectors as indicated, and also the stepping motors via the 7-pin cannon connectors at the pin connections as indicated.
• the mains power also supplies a cooling fan for the unit as illustrated, and a rectified 5VD.C. supply to motor control boards (MCB'S), the details of which are shown in Figure 10 of the drawings.
• the mains power supply is also coupled, via a suitable 12VD.C. regulated power supply, opto electrics, T.T.L.
• Figure 8 of the drawings shows the details of the main control panel and the connections therein for actuating automatic and manual selection and select functions for the stepping motors as well as lamps indicating selection of manual or automatic function for each of the stepping motors, and in respect of which only the connections to the MCB and the MDB for the X-axis motor M X are shown for the sake of simplicity of illustration.
• Both the MCB and MDB pin connections from the mains power supply, and also for the control panel and the computer via the cannon plug type DA-15P will be evident from Figure 8, with reference to Figure 7. It will be appreciated that similar connections will be facilitated for the MCB'S and MDB'S for the Y and Z axis motors M Y and M Z .
• pins 8, 6 and 14 of the cannon plug connector are coupled to pins 48, 4 and 1 respectively of the connector identified as J1 on the computer.
• the respective pin connections for the connection between the MCB and the MDB are also shown in Figure 8.
• FIGs 10 and 11 of the drawings show the details of the individual MCB'S and MDB'S which are coupled, at the pin connections indicated, to each other, and to the control panel switchs and lamps, and the computer, as shown in Figure 8.
• Each MCB incorporates a stepping motor driving controller identified as PMM8713 as supplied by Sanyo Denki Co. Ltd. of Japan.
• the MCB'S receive control pulses from the computer, or alternatively receive manually actuated pulses from the control panel, and subsequently convert the control pulses into motor mode control pulses which are then supplied to the respective MDB'S.
• the MDB'S which receive the motor mode control pulses from the MCB'S amplify them to motor drive pulses which are subsequently supplied to the respective stepping motors M X , M Y and M Z via the 7-pin cannon connections shown in Figures 7 and 9.
• the manual controls on the control panel enable the operator to select whether the control pulses for the motors M X , M Y and M Z will be supplied from the computer or from the manual control board itself. When the latter is selected, the operator is able to control the number of pulses to each motor and to choose the direction or sign of the resulting movement of the particular machine axis to which the respective motors are coupled.
• Figure 12 of the drawings represents a flow chart of the programmed information to be supplied to the computer, which in the case of this embodiment involves programming for movement in the X and Y axes via motors M X and M Y , with movement in the Z axis via motor M Z , if required, being accomplished by manual control of the appropriate functions of the control panel and as previously discussed.
• the initial programming step is followed by INPUT (interfacing with the monitor for the input routine) and LOAD (storing of the input geometrical data) programming according to the information set down in Figure 14.
• INPUT interface with the monitor for the input routine
• LOAD storing of the input geometrical data
• CONGEN transformation of geometrical input parameters into a table from the input routine
• This section of the program can also be readily prepared by a programmer.
• the system can also be applied to rotational motion such as the rotation of a work piece or of a machine head about one or more axes.

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• Engineering & Computer Science (AREA)
• Human Computer Interaction (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Automation & Control Theory (AREA)
• Computing Systems (AREA)
• Theoretical Computer Science (AREA)
• Numerical Control (AREA)

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Citations (7)

• 1981
  • 1981-11-24 JP JP56503630A patent/JPS57501801A/ja active Pending
  • 1981-11-24 WO PCT/AU1981/000168 patent/WO1982001947A1/en not_active Ceased

Patent Citations (7)

Non-Patent Citations (1)

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