An Introduction to Grinding Machine Control Systems John Moruzzi AMTReL An Introduction to Grinding...

An Introduction to Grinding Machine Control Systems

John MoruzziAMTReL


Director of Studies: Dr Michael Morgan

Personal Introduction

John MoruzziBSc Electrical Engineering & Electronics University of Leeds

MSC Computational & Statistical Modelling University of Liverpool

Known AMTReL since early 90’s

Software engineering Aerospace / AvionicsManufacturing / Machine ToolsOMR / OCR Applications

Electrical installation Commercial / IndustrialTechnical sales / support Grinding machine process

control(Balance Systems)


AMTReL Jones & Shipman 1300X

• Universal grinding machine• External and Internal wheelheads• SAMM control (Servo Assisted Manual Machine)• Prototype machine based on Format 15 model• Built circa 1994, modified 2001• Closed control system – Industrial PC / MS-DOS


Used for previous AMTReL projects/PhD’s

Adaptive control (Y Chen)Open CNC Interface (C Statham)

High speed Internal grindingIndustry co-operations (Timken, Lucas, …)Fluid delivery methods, nozzle designAE monitoring Dressing tool control (fluid coupling)

Objectives

MachineRe-commission hardware

Move axesReplace workhead drive

Modifications to wiringDisable hardware limitations

Remove original control panel

Implement simplified control panel

Interface external devices

Control systemInitial “desktop” PC control :

ISA bus motion control cardISA bus Digital I/O cardStandard mouse / keyboard / monitor

Initial softwareWindows 2000 (XP), Visual BasicProgramming familiarityAxis configurationAxis movementsSimple grinding cyclesSimple cycle programmingSimple IO features


Machine Tool Axes

Cylindrical (Universal) grinding machine

Z axis - horizontal (table)positioning of workpiece for grinding

X axis - radial (wheelfeed / infeed)application of wheel for grinding

C axis - workpiece rotation (workhead)fixed between headstock and tailstock

Surface grinding machine

X axis - horizontal (table)oscillation of workpiece for grinding

Y axis - vertical (“downfeed”)application of wheel for grinding

Z axis - workpiece incremental translation (saddle) clamped to table


Axis positioning and control

Position measurementEncoder

linear scale or rotary2 quadrature pulsetrainsMarker / Zero pulsedistance moved and direction

ConfigurationScaling (pulses / rev, pulses / mm)Thread pitch

LimitsAxis overtravel switches / signals (+ve, –ve)

Axis movementMotion control hardware

Position target, move speedPosition feedback (speed)Speed reference signal

Servo driveSpeed reference input (DC +/- 10V)Motor power output (DC / AC)Scaling, Trim, Offsets

Servo motorResolver feedback (speed)

Ballscrew


Wheelspeed and Workspeed

WheelspeedRotational speed (RPM) Surface speed (m/sec)

Fixed on simple machines , can be changed with gearing / pulleysVariable on more sophisticated machines, can be adjusted for “constant speed” machining

WorkspeedRotational speed (RPM) Surface speed (m/sec)

Variable on most grinding machinesControlled by operator / programOpen-loop motor drive control


N.B. Relationship between wheel speed and workpiece speed crucial to the grinding process

Common grinding cycles

Dressing Single point “diamond” dressing:Wheel rotating (surface speed vc )Wheel traverses past diamond tip (crossfeed velocity vf)

Wheel infeeds an increment (infeed amount ad)Repeat until wheel surface fully dressed

Plunge grinding Workpiece / table positioned relative to wheelWheel and workpiece rotating (vc and vw)Wheel infeed at Rapid speed to start position (dia)Wheel infeed at Coarse feed to Fine Feed start position (dia)Wheel infeed at Fine feed to Final Size position (dia)Sparkout or Dwell with no infeed

Traverse grinding Workpiece / table set to oscillate across wheel to wheelWheel and workpiece rotating (vc and vw)Wheel infeed by Rapid increments to start position (dia)Wheel infeed by Coarse increments to Fine Feed start position (dia)Wheel infeed at Fine feed to Final Size position (dia)Sparkout passes of wheel with no infeed


Cycle programming - 1

CNC part-programming

Sequence of instruction lines or “blocks”

M-codes functional commands

G-codes movement commands

Canned cycles complex operations(machine specific)

M-codesM02 End of ProgramM03 Spindle on (CW rotation)M05 Spindle StopM07 Coolant on (flood)M09 Coolant off

G-codesG00 Rapid positioning G01 Linear interpolationG28 Return to home position

Canned cycles (J & S Series 10)G86 Traverse GrindingG88 Plunge Grinding

G88 X25.4 Z50.000 D0.50 A0.010 B0.02 C0.0005 P25.5 J25.410 S10 Q0


Cycle programming - 2

Plunge cycle

Go to Z start pos: <Enter>Go to X size pos: <Enter>Go to X start pos: <Enter> Go to X finefeed pos: <Enter>

Program X coarse feedrate <Enter>Program X fine feedrate <Enter>

Program Sparkout time <Enter>

Traverse cycle

Go to Z right pos: <Enter>Go to Z left pos: <Enter>Go to X size pos: <Enter>Go to X start pos: <Enter> Go to X finefeed pos: <Enter>

Program X coarse increment <Enter>Program X fine increment <Enter>Program sparkout passes <Enter>

Set Z traverse speed


Guided / Teaching process Manually move to position, save values Enter / adjust values (keypad, buttons)

Architecture of a CNC system

Main Control

Executor Scheduling, program execution, monitoring

IO routines HMI, programming, Digital, Bus

Safety Machine logic

Cycle management Sequencing, monitoring

Motion Control Axis movements, motors

Process optimisation

In-process Gauging Diameter, Shoulder

Touch Detection AE, PowerWheel balancing Auto / ManualProbing


Adaptive / Intelligent Control

Adaptive strategy Parameter modificationSelection strategy Rule / Case basedProcess models & rules Kinematic, ComplianceDatabase Learning strategy, data

Jones & Shipman Ultramat

Left-Hand operator panelManual/ Automatic modeOperation selection – Dress / Plunge / TraverseProgram upload / downloadLinked cycle select

Z axis DRO, MPG and scale settingFeedrate Override switchKey enable

Cycle interrupt / repeatTraverse hold / dwell

Z axis reverse / jog

E-stop buttonControl On button


Jones & Shipman Ultramat

Right-hand control panel• X axis DRO, MPG and scale setting• Wheelguard raise, Workhead airlift & unclamp• Gauge apply, Dresser raise • Coolant On/Off, Wheel On/Off, Workhead

On/Off• Cycle Start/Stop


“Easy” Touch screen• Program / cycle selection• Data entry• Numeric keypad• Navigation• Operator information• Machine setup

Machine control comparison


J&S Ultramat – Fanuc

Processor moduleAxis / workhead drivesIO interfacing modulesEthernet / RS232 / USB

J&S 1300X – CT, bespoke

2 x Axis drives1 x workhead driveIO interfacing with terminal blocks3-phase / 1 phase transformers

Current control hardware – 1300X

4 x Axis encoder inputsX axis, Z axis positionX axis, Z axis MPG commands

3 (4) Axis speed control outputsX axis, Z axis speedWorkhead (C axis) speed

48 Opto-isolated digital IO18 inputs (24)8 outputs (24)

RS-232 interfacepanel display data (out)panel control commands (in)


Industrial PC caseMotion control cardDigital IO cardCPU cardPower supply

Servo Motion control


Motion controlKv : Derivative Gain

Speeddem = (Posmodel –Posactual)x Kv

ServoDrive

Servo Motor

Encoder Transmission

SpeeddemPosactual

VelactualVeldemand

Posdemand

Deva 004 : X, Z axis setup Z axis

PITCH = -10.0000 MAXVOLT = 3000 (2150)COUNT = 10000.0000 MAXSPEED = 60

MAXACCEL = 60GAIN KV = 15

SPEED = 25

X axis

PITCH = -5.0000 MAXVOLT = -3000 (-3850)COUNT = 10000.0000 MAXSPEED = 60GEARING = 1:1.29 MAXACCEL = 60

GAIN KV = 45SPEED = 50


Initial software


Process / Cycle parameters

AxisX0DatumPosition As DoubleXHomePosition As DoubleXZeroPosition As DoubleXAbsolute As Double

Z0DatumPosition As DoubleZRevDatumPosition As DoubleZHomePosition As DoubleZAbsolute As Double


PlungePlungeCoarseInfeed As Double PlungeFineInfeed As DoublePlungeFineDia As DoublePlungeStartDia As DoublePlungeSizeDia As DoublePlungeDwell As Double

TraverseXCoarseInc As DoubleXFineInc As DoubleTraverseZFeed As DoubleTraverseStartDia As DoubleTraverseFineDia As DoubleTraverseSizeDia As DoubleZ0Dwell As DoubleZRevDwell As DoubleTraversePasses

MotiondblXMovespeed As Double dblXRapid As Double dblXCoarseFeed As DoubledblXFineFeed As DoubledblXInfeed As DoubledblXInfeedRate As DoubleintXDwell as Integer

dblXStartPosition As DoubledblXFinePosition As DoubledblXSizePosition As Double

dblZReversePositionL As DoubledblZReversePositionR As DoubledblZStartPosition As Double

intFROSetting As IntegerblnFeedHold As Boolean

New Components

• Workhead servo drive• Industrial PC • Motion control card• Touchscreen monitor• Console switches / lamps• Cabling / connectors


Progress

So far.....

Reactivation of machine toolMinor electrical modifications

Development software with “old” hardware

Familiarity with motion control package

Implementation of simple cycles

Axis configuration and movement

Specification and ordering of equipment

Initial interface design

Next steps....

Commissioning of workhead drive

Axis movement via MPGs: Incremental Rapid

Digital IO Equipment control

Axis limits etc.

PCI motion card Cabling

Control panel

Initial demonstration software


And finally...

Thank you.....


An Introduction to Grinding Machine Control Systems John Moruzzi AMTReL An Introduction to Grinding...

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