GB2069889A - Machine tool control - Google Patents

Machine tool control Download PDF

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Publication number
GB2069889A
GB2069889A GB8105597A GB8105597A GB2069889A GB 2069889 A GB2069889 A GB 2069889A GB 8105597 A GB8105597 A GB 8105597A GB 8105597 A GB8105597 A GB 8105597A GB 2069889 A GB2069889 A GB 2069889A
Authority
GB
United Kingdom
Prior art keywords
axis
workpiece
traverse
axis traverse
control
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8105597A
Other versions
GB2069889B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mercer Nairne & Co Ltd
Original Assignee
Mercer Nairne & Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mercer Nairne & Co Ltd filed Critical Mercer Nairne & Co Ltd
Priority to US06/299,293 priority Critical patent/US4471676A/en
Publication of GB2069889A publication Critical patent/GB2069889A/en
Application granted granted Critical
Publication of GB2069889B publication Critical patent/GB2069889B/en
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D5/00—Bending sheet metal along straight lines, e.g. to form simple curves
    • B21D5/004—Bending sheet metal along straight lines, e.g. to form simple curves with program control
    • 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
    • G05B19/401—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 control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes
    • G05B19/4015—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 control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes going to a reference at the beginning of machine cycle, e.g. for calibration
    • 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
    • G05B19/406—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 monitoring or safety
    • G05B19/4061—Avoiding collision or forbidden zones
    • 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
    • G05B2219/45—Nc applications
    • G05B2219/45143—Press-brake, bending machine
    • 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
    • G05B2219/49—Nc machine tool, till multiple
    • G05B2219/49144—Limit movement on an axis by setting limits

Landscapes

  • Engineering & Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Mechanical Engineering (AREA)
  • Punching Or Piercing (AREA)

Abstract

A method fo sensing the position of a workpiece clamp 8 on a workpiece positioning assembly of a computer-controlled machine tool such as a turret punch press including an X-axis traverse, a Y-axis traverse and, a workpiece support 7 movable along the X-axis traverse and carrying the workpiece support. The method consists of the steps of providing a datum position on the X-axis for the control, providing a datum position on the Y-axis for the control, providing a datum position on the turret for the control, moving the member to the datum position on the X-axis at the beginning of each operating sequence, registering movement of the member along the X-axis traverse, moving the member passed sensor means 12 to identify for the control the position of the member relative to the datum position on the X-axis. Apparatus for carrying out the method is also provided. <IMAGE>

Description

SPECIFICATION Machine tool including workpiece clamp sensor This invention relates to a computer controlled machine tool including a workpiece clamp sensor for preventing the workpiece clamp from being punched, milled or the like.
On a machine tool such as a punch press the workpiece, e.g. a sheet of metal, is moved on X and Y axes by means of a workpiece positioning assembly. The assembly comprises a Y-axis traverse fixed to the frame, a movable X-axis traverse carried by the Y-axis traverse, and, movable along the X-axis traverse, a workpiece carriage having two or more workpiece clamps for holding the workpiece and supporting it for movement relative to the punching head.
Workpiece clamp sensors are used to prevent the punching head actually punching the clamp when punching near the edge of the sheet.
At present the sensing arrangement, on a turret punch press for example may consist of a sensor on the Y-axis and two separate sensors on the X-axis operative once the Y-axis sensor is actuated and arranged to be triggered by upstanding plates on the clamps themselves. The computer control is then operative to create a dead area for each clamp when the associated plate triggers a sensor; the dead area being the same for each punch station and therefore large enough to accommodate the largest punch size. However such an arrangement means that an unnecessarily large dead area is created in many cases.
An object of the present invention is to provide an improved arrangement for sensing the position of a workpiece clamp.
According to the present invention there is provided a method for sensing the position of a member such as a workpiece clamp on a workpiece positioning assembly of a computercontrolled machine tool including an X-axis traverse, a Y-axis traverse and, a workpiece support movable along the X-axis traverse, the workpiece clamp being positioned on the workpiece support, the method comprising the steps of (a) providing a datum position on the Xaxis for the control, (b) registering movement of the member along the X-axis traverse, and (c) before operation, moving the member passed sensor means to identify for the control the position of the member relative to the datum position on the X-axis.
The method preferably also includes, between steps (a) and step (c), the additional step (d) of moving the member to the datum position on the X-axis at the beginning of each operating sequence. According to another aspect of the invention there is provided a method of sensing the position of the or each workpiece clamp on a workpiece positioning assembly of a computercontrolled turret punch press including an X-axis traverse, a Y-axis traverse and, a workpiece support movable along the X-axis traverse, the or each workpiece clamp being positioned on the workpiece support, the method comprising the steps of providing a datum position on the X-axis for the control, providing a datum position on the Y-axis for the control, providing a datum position on the turret for the control, registering movement of the workpiece support along the X-axis traverse, providing sensor means on the X-axis traverse, and moving the or each workpiece clamp passed the sensor means to identify for the control the postion of the member relative to the datum position on the X-axis traverse, the control then being operative to follow the position of the or each workpiece clamp and to create a dead area about a workpiece clamp of a size determined by the punch station indexed relative to the turret datum when the workpiece clamp is in the vicinity of the punch station.
According to another aspect of the invention there is provided a computer controlled machine tool comprising a control, a working head, a workpiece positioning assembly for moving a workpiece relative to the working head and including an X-axis traverse, a Y-axis traverse, a workpiece support movable along the X-axis traverse, and a workpiece clamping assembly on the support for holding a workpiece, a datum position on the X-axis traverse, and sensor means for sensing and computing the position of the workpiece clamping assembly relative to the datum position on the X-axis traverse, the control means, at the start of each operating sequence, being operative to pass the workpiece clamp assembly passed the sensor means to identify the position of the workpiece clamp assembly.
Preferably there are two clamps and the sensor means is operable to provide information whereby the control can know the actual positions of the workpiece clamps.
The movement of the workpiece support along the X-axis traverse is registered by means of a feedback from the operating DC servo motor drive to the control and movement of the X-axis traverse along the Y-axis traverse is similarly recorded. The control computes these signals by determining the speed of rotation of the respective electric drives so that, with a driven lead screw of predetermined pitch the movement of the respective part can be exactly calculated.
The invention will now be described by way of example with reference to the accompanying diagrammmatic drawings in which: Figure 1 is a diagrammatic front view of a punch press; Figure 2 is a diagrammatic plan view of a turret of a punch press; Figure 3 is a sectional side elevation of the X-axis traverse in more detail: Figure 4 is a plan view a clamp mounting member; Figure 5 is a section on 5-5 in Figure 4; Figures 6a and 6b are a side elevation and plan view of a preferred form of sensor actuator; and Figure 7 is an underneath plan view of a preferred form of sensor.
In Figure 1 a punch press has a C-shaped frame 1 consisting of an upper limb 2 and a lower limb 3 which define a throat 4. Secured to the lower limb 3 are horizontally-spaced bearing rails 5 of the Y-axis traverse which support the X-axis traverse 6 for movement in the direction of the throat 4. Movable along the X-axis traverse is a workpiece carriage 7 having two spaced workpiece clamps 8 which can be selectively positioned as desired on the carriage 7 according to the workpiece being supported. With computercontrolled machines it is necessary at the start of an operation to tell the computer the starting position and therefore a datum position for the X-axis traverse is shown at 9. In addition, a datum position is provided for the computer control C for the Y-axis traverse and also for the turret position.
However, instead of having two sensors positioned on the X-axis and one on the Y-axis as before, a single sensor 12 is provided suitably midway between the ends of the X-axis traverse: the position of the sensor being fixed and recorded by the computer control.
Referring now to Figures 3 to 7 which show the sensing arrangement in more detail it will be seen that the X-axis traverse 6 comprises an elongate rigid beam 13 supporting a single bearing rail 14 and a driven lead screw 1 5. The workpiece carriage 7 is supported on the bearing rail 14 and is in driving connection with the lead screw 1 5 for movement along the traverse. The sensor 12 is mounted on the underside of a mounting bracket 1 6 rigidly secured to the beam 13.
The sensor 12 is a proximity switch having an active face 1 7 and is operative to transmit a signal via cable 8 to a control C on sensing one of sensor actuators 1 9 carried by the workpiece clamp assemblies 8. The sensor actuators 1 9 are secured one to the top of each clamp mounting plate 20, by screws passing through base slots 21 in holes 22 in the mounting plate 20. In Figures 3,4 and 5 the clamps themselves are not shown for clarity but the mounting plates 20 each support a clamp details of which are given in a co-pending application No. 8011933 to which reference is directed.
A clamp is received between side arms 23 of the respective mounting plate 20 and may be moved along the workpiece carriage 7 by the dovetail groove 24 and rollers 25 cooperating with a corresponding surface (not shown) on the front face of the workpiece carriage 7. The clamp mounting plates 20 are locked in position by locking screws (not shown) which pass through holes 26 in each side arm 23. The distance between the top of the sensor actuators 1 9 and the sensor 12 as they pass below is suitably about 3 to 4 mm.
Preferably, as shown in Figures 4 and 5, the clamp mounting plates 20 each include a further single proximity switch 27 for detecting loosening of the adjacent locking screw in the side arm 23.
The computer programme is arranged so that, before an operation can begin, the workpiece carriage must move past the sensor 12, preferably to the other end of the beam, so that the positions of the clamps can be computed. Alternatively, the sensor may be used to check the position of the clamps relative to the datum with respect to information fed into the control by the operator.
Therefore, at any time, the computer control always knows the position of the clamps and accordingly there should be no inadvertent punching of the clamps. As the computer now knows the position of workpiece clamps the dead area may be created automatically of a size according to the punch station indexed e.g. T1 and T2 thereby creating a smaller dead area for a smaller punch than for a larger punch: movement of the workpiece carriage along the X-axis traverse or the X-axis traverse along the Y-axis traverse being registered by means of a feed back from the respective operating DC servo motor drive to the control C.
The system of the present invention, although described by way of example with reference to a punching machine, may be used on other machine tools. The sensor may be arranged only to check the position of the clamps at the beginning of the operation or continually during a programme cycle.

Claims (11)

1. A method for sensing the position of a member such as a workpiece clamp on a workpiece positioning assembly of a computercontrolled machine tool including an X-axis traverse, a Y-axis traverse and, a workpiece support movable along the X-axis traverse, the workpiece clamp being positioned on the workpiece support, the method comprising the steps of (a) providing a datum position on the X-axis for the control, (b) registering movement of the member along the X-axis traverse, and (c) before operation, moving the member passed sensor means to identify for the control the position of the member relative to the datum position on the X-axis.
2. A method for sensing the position of a member such as a workpiece clamp according to claim 1 comprising between step (a) and step (c), the additional step (d) of moving the member to the datum position on the X-axis at the beginning of each operating sequence.
3. A method of sensing the position of a workpiece clamp relative to the working head of a machine tool according to claim 1 or 2 comprising the additional steps of (e) providing a datum position on the Y-axis for the control, (f) recording the position of the machine tool head relative to the datum positions, and (g) registering movement of X-axis traverse on the Y-axis traverse.
4. A method of sensing the position of the or each workpiece clamp on a workpiece positioning assembly of a computer-controlled turret punch press including an X-axis traverse, a Y-axis traverse and, a workpiece support movable along the X-axis traverse, the or each workpiece clamp being positioned on the workpiece support, the method comprising the steps of providing a datum position on the X-axis for the control, providing a datum position on the Y-axis for the control, providing a datum position on the turret for the control, registering movement of the workpiece support along the X-axis traverse, providing sensor means on the X-axis traverse, and moving the or each workpiece clamp passed the sensor means to identify for the control the position of the member relative to the datum position on the X-axis traverse, the control then being operative to follow the position of the or each workpiece clamp and to create a dead area about a workpiece clamp of a size determined by the punch station indexed relative to the turret datum when the workpiece clamp is in the vicinity of the punch station.
5. A computer controlled machine tool comprising a control, a working head, a workpiece positioning assembly for moving a workpiece relative to the working head and including an X-axis traverse, a Y-traverse, a workpiece support movable along the X-axis traverse, and a workpiece clamping assembly on the support for holding a workpiece, a datum position on the X-axis traverse, and sensor means for sensing and computing the position of the workpiece clamping assembly relative to the datum position on the X-axis traverse, the control means, at the start of each operating sequence, being operative to pass the workpiece clamp assembly passed the sensor means to identify the position of the workpiece clamp assembly.
6. A computer controlled machine tool according to claim 5 comprising a datum position on the Y-axis, and means for registering movement of the X-axis traverse on the Y-axis traverse.
7. A computer controlled machine tool according to claim 6 comprising electric drive means for driving the workpiece support along the X-axis traverse, and electric drive means for driving the X-axis traverse along the Y-axis traverse.
8. A computer controlled machine tool according to claim 7 wherein the sensor means comprises a sensor on the X-axis traverse, an actuator on the workpiece clamping assembly, and means for registering movement of the workpiece support along the X-axis traverse.
9. A computer controlled machine tool according to claim 8 wherein the means for registering movement of the X-axis traverse on the Y-axis traverse and the means for registering movement of the workpiece support along the X-axis traverse comprises means registering the speed of rotation of the respective electric drive means.
10. A computer controlled machine tool substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
11. A method of sensing the position of a member such as a workpiece clamp on a workpiece positioning assembly of a computer-controlled machine tool substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
GB8105597A 1980-02-22 1981-02-23 Machine tool control Expired GB2069889B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US06/299,293 US4471676A (en) 1981-02-23 1981-09-03 Machine tool including workpiece clamp sensor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8006027 1980-02-22

Publications (2)

Publication Number Publication Date
GB2069889A true GB2069889A (en) 1981-09-03
GB2069889B GB2069889B (en) 1983-03-23

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ID=10511583

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Application Number Title Priority Date Filing Date
GB8105597A Expired GB2069889B (en) 1980-02-22 1981-02-23 Machine tool control

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0529239A2 (en) * 1991-07-04 1993-03-03 Mitsubishi Denki Kabushiki Kaisha Numerical control unit with position counter control and display
GB2381770A (en) * 2001-11-09 2003-05-14 Tradewise Engineering Ltd Punching machine work piece holding and positioning means

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60247421A (en) * 1984-05-24 1985-12-07 Fanuc Ltd Device for preventing collision of work holder and tool in numerical control for turret punch press

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0529239A2 (en) * 1991-07-04 1993-03-03 Mitsubishi Denki Kabushiki Kaisha Numerical control unit with position counter control and display
EP0529239A3 (en) * 1991-07-04 1993-08-11 Mitsubishi Denki Kabushiki Kaisha Numerical control unit with position counter control and display
US5734573A (en) * 1991-07-04 1998-03-31 Mitsubishi Denki Kabushiki Kaisha Numerical control unit with position counter control and display
GB2381770A (en) * 2001-11-09 2003-05-14 Tradewise Engineering Ltd Punching machine work piece holding and positioning means
GB2381770B (en) * 2001-11-09 2004-12-15 Tradewise Engineering Ltd Punching machine

Also Published As

Publication number Publication date
GB2069889B (en) 1983-03-23

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee