[step-manufacturing] 3/17 STEP-NC Conference Call on Probing Demonstration at Eastec

Sun Mar 13 16:25:23 EST 2005

> 
>Date: 3/17/05 Thursday
>
>Time: 2:00 -3:00 EST or 1:00-2:00 CST or 11am to 12:00 pm PST
>
>Dial in number: 425-717-7000 or 206-544-4444 or  866-350-0777
>
>Pass code: 21047#

All, there are two issues to discuss this week.

1. Spline implementation for CC1 data exchange

We need to decide what kinds of splines shall be supported in the CAM system translators and the CNC machine converter.

2. Probing demonstration at Eastec

There has been a considerable discussion on what kind(s) of probing to demonstrate at Eastec. The three options are:

a. Tool_probing
b. Workpiece_complete_probing
c. Workpiece_probing

Tool_probing is used to compute the actual diameter of the tool and set the tool diameter compensation registers. Workpiece_complete_probing is used to determine the actual position of the workpiece in the setup and set the workpiece coordinates compensation registers. Workpiece_probing is used to determine the actual location of a point on the surface of the workpiece and is used to determine the quality and accuracy of the finish.

After some discussion the consensus seems to be that giving a demonstration of workpiece_probing at Eastec will have the most value because it can make the in-process measurement of parts on the CNC much easier which in turns means that enterprises making high precision parts can spend less time moving their parts from the CNC to a CMM for in-process measurement and then back to the CNC for another pass of finish machining.

STEP Tools has started to prototype the data for workpiece_complete probing. The following definition was taken from the text of ISO 14649-10 page 53.

http://www.steptools.com/library/stepnc/tech_resources/FDIS_Feb2002_ISO14649_10.pdf

"Probing of a dimension with one axis movement. Probing tool movement starts at start_position in the direction "direction" towards the workpiece. When the probe tool touches the workpiece, the machine stops and the difference of expected_value and tool position is stored in the inherited attribute measured_offset."

The following is a AP-238 CC1 data set containing two workpiece_probing operations. Please note the following:

i. The probe operations go into the workplan at the same place as the workingsteps.
ii. The unique values of each probe operation are a start position and a measured_value/offset. The other parameters can be shared by many probing operations.
iii. In the data the measured_value has been set to an initial value of "999". The CNC converter will replace this with the value measured by the probe.
iv. The unit definitions (inches etc) have been set to NULL to make the data easier to read.

The concept is the CAM will write an AP-238 program describing the paths it wants machined and then the points it wants measured. The CNC converter will put the probe results as measured values into the data. The CAM will read the modified AP-238 file and use the measured_values to determine what additional finish operations (if any) are required and repeat the process by writing a new file with the new tool paths and the new points to be measured.

Here is the example data:

ISO-10303-21;
HEADER;
/* Generated by software containing ST-Developer
 * from STEP Tools, Inc. (www.steptools.com) 
 */

FILE_DESCRIPTION(
/* description */ ('ARM_SCHEMA: ap238_arm_schema'),
/* implementation_level */ '2;1');

FILE_NAME(
/* name */ 'probe_test',
/* time_stamp */ '2005-03-13T15:58:33-05:00',
/* author */ ('STEP-NC Maker'),
/* organization */ ('STEP Tools'),
/* preprocessor_version */ 'ST-DEVELOPER v11',
/* originating_system */ 'paper',
/* authorisation */ '');

FILE_SCHEMA (('INTEGRATED_CNC_SCHEMA'));
ENDSEC;

DATA;

/************************************************
 * Application object: PROJECT
 * ITS_ID: #11, #12 [Eastec]
 * MAIN_WORKPLAN: #11, #15, #17, #18, #20 [!]
 * ITS_WORKPIECES(1): #11, #15, #19, #23 [!]
 */
#11=PRODUCT_DEFINITION_FORMATION('1.0','Machining Project',#12);
#12=MACHINING_PROJECT('Eastec','AP-238 CC1',' ',(#13));
#13=PRODUCT_CONTEXT('drilling and milling',#14,'CNC Machining');
#14=APPLICATION_CONTEXT(
'Application protocol for the exchange of CNC data');
#15=PRODUCT_DEFINITION('Eastec','Project definition',#11,#16);
#16=PRODUCT_DEFINITION_CONTEXT(' ',#14,'Manufacturing');
#17=PROCESS_PRODUCT_ASSOCIATION('AP-238 CC1',' ',#15,#18);
#18=PRODUCT_DEFINITION_PROCESS('machining',' ',#20,' ');
#19=MACHINING_PROJECT_WORKPIECE_RELATIONSHIP('Eastec','workpiece',$,#15,
#23);

/************************************************
 * Application object: WORKPLAN
 * ITS_ID: #20 [probing demonstration]
 * ITS_ELEMENTS(1.0): #20, #21, #28 [!]
 * ITS_ELEMENTS(2.0): #20, #22, #58 [!]
 */
#20=MACHINING_WORKPLAN('probing demonstration','AP-238 CC2','','');
#21=MACHINING_PROCESS_SEQUENCE_RELATIONSHIP('NO NAME',' ',#20,#28,1.);
#22=MACHINING_PROCESS_SEQUENCE_RELATIONSHIP('NO NAME',' ',#20,#58,2.);

/************************************************
 * Application object: WORKPIECE
 * ITS_ID: #23 [Eastec workpiece]
 */
#23=PRODUCT_DEFINITION('Eastec workpiece','Workpiece definition',#24,#16);
#24=PRODUCT_DEFINITION_FORMATION('1.0','Workpiece',#25);
#25=PRODUCT('Eastec workpiece','AP-238 CC1',' ',(#13));

/************************************************
 * Application object: TOUCH_PROBE
 * ITS_ID: #26 [Rennishaw Best]
 * PROBE_LENGTH: #26, #27 [2.4]
 */
#26=REPRESENTATION('Rennishaw Best',(#27),$);
#27=(
LENGTH_MEASURE_WITH_UNIT()
MEASURE_REPRESENTATION_ITEM()
MEASURE_WITH_UNIT(NUMERIC_MEASURE(2.4),$)
REPRESENTATION_ITEM('probe length')
);

/************************************************
 * Application object: WORKPIECE_PROBING
 * ITS_ID: #28 [probe0]
 * START_POSITION: #28, #29, #30, #31, #32
 * MEASURED_VALUE: #28, #36, #37, #38, #39 [999]
 * EXPECTED_VALUE: #28, #40, #41, #42, #43 [1.5]
 * ITS_SECPLANE: #28, #44, #45, #46, #47
 * DIRECTION: #28, #50, #51, #52, #53
 * ITS_WORKPIECE: #28, #54, #55, #23 [!]
 * ITS_PROBE: #28, #56, #57, #26 [!]
 */
#28=MACHINING_TOUCH_PROBING('probe0','workpiece probing','','');
#29=ACTION_PROPERTY('start position','workpiece probing',#28);
#30=ACTION_PROPERTY_REPRESENTATION('start position','workpiece probing',
#29,#31);
#31=REPRESENTATION('start position',(#32),$);
#32=AXIS2_PLACEMENT_3D('y axis',#33,#34,#35);
#33=CARTESIAN_POINT('axis location',(0.,2.,3.));
#34=DIRECTION('Z direction',(0.,0.,1.));
#35=DIRECTION('Y direction',(0.,1.,0.));
#36=ACTION_PROPERTY('measured value','workpiece probing',#28);
#37=ACTION_PROPERTY_REPRESENTATION('measured value','workpiece probing',
#36,#38);
#38=REPRESENTATION('probe output',(#39),$);
#39=(
LENGTH_MEASURE_WITH_UNIT()
MEASURE_REPRESENTATION_ITEM()
MEASURE_WITH_UNIT(NUMERIC_MEASURE(999.),$)
REPRESENTATION_ITEM('probe0-measured-value')
);
#40=ACTION_PROPERTY('expected value','workpiece probing',#28);
#41=ACTION_PROPERTY_REPRESENTATION('expected value','workpiece probing',
#40,#42);
#42=REPRESENTATION('probe data',(#43),$);
#43=(
LENGTH_MEASURE_WITH_UNIT()
MEASURE_REPRESENTATION_ITEM()
MEASURE_WITH_UNIT(NUMERIC_MEASURE(1.5),$)
REPRESENTATION_ITEM('probe input')
);
#44=ACTION_PROPERTY('security plane','workpiece probing',#28);
#45=ACTION_PROPERTY_REPRESENTATION('security plane','workpiece probing',
#44,#46);
#46=REPRESENTATION('clearance plane',(#47),$);
#47=PLANE('security plane',#48);
#48=AXIS2_PLACEMENT_3D('security plane',#49,#34,#53);
#49=CARTESIAN_POINT('origin of security plane',(0.,0.,8.));
#50=ACTION_PROPERTY('direction','workpiece probing',#28);
#51=ACTION_PROPERTY_REPRESENTATION('direction','workpiece probing',#50,#52);
#52=REPRESENTATION('probe direction',(#53),$);
#53=DIRECTION('X direction',(1.,0.,0.));
#54=PRODUCT_DEFINITION_PROCESS('workpiece probing','workpiece probing',#28,
'');
#55=PROCESS_PRODUCT_ASSOCIATION('workpiece probing','workpiece probing',
#23,#54);
#56=ACTION_PROPERTY('probe','workpiece probing',#28);
#57=ACTION_PROPERTY_REPRESENTATION('probe','workpiece probing',#56,#26);

/************************************************
 * Application object: WORKPIECE_PROBING
 * ITS_ID: #58 [probe1]
 * START_POSITION: #58, #59, #60, #61, #62
 * MEASURED_VALUE: #58, #64, #65, #66, #67 [999]
 * EXPECTED_VALUE: #58, #68, #69, #42, #43 [1.5]
 * ITS_SECPLANE: #58, #70, #71, #46, #47
 * DIRECTION: #58, #72, #73, #52, #53
 * ITS_WORKPIECE: #58, #74, #75, #23 [!]
 * ITS_PROBE: #58, #76, #77, #26 [!]
 */
#58=MACHINING_TOUCH_PROBING('probe1','workpiece probing','','');
#59=ACTION_PROPERTY('start position','workpiece probing',#58);
#60=ACTION_PROPERTY_REPRESENTATION('start position','workpiece probing',
#59,#61);
#61=REPRESENTATION('start position',(#62),$);
#62=AXIS2_PLACEMENT_3D('y axis',#63,#34,#35);
#63=CARTESIAN_POINT('axis location',(10.,20.,30.));
#64=ACTION_PROPERTY('measured value','workpiece probing',#58);
#65=ACTION_PROPERTY_REPRESENTATION('measured value','workpiece probing',
#64,#66);
#66=REPRESENTATION('probe output',(#67),$);
#67=(
LENGTH_MEASURE_WITH_UNIT()
MEASURE_REPRESENTATION_ITEM()
MEASURE_WITH_UNIT(NUMERIC_MEASURE(999.),$)
REPRESENTATION_ITEM('probe1-measured-value')
);
#68=ACTION_PROPERTY('expected value','workpiece probing',#58);
#69=ACTION_PROPERTY_REPRESENTATION('expected value','workpiece probing',
#68,#42);
#70=ACTION_PROPERTY('security plane','workpiece probing',#58);
#71=ACTION_PROPERTY_REPRESENTATION('security plane','workpiece probing',
#70,#46);
#72=ACTION_PROPERTY('direction','workpiece probing',#58);
#73=ACTION_PROPERTY_REPRESENTATION('direction','workpiece probing',#72,#52);
#74=PRODUCT_DEFINITION_PROCESS('workpiece probing','workpiece probing',#58,
'');
#75=PROCESS_PRODUCT_ASSOCIATION('workpiece probing','workpiece probing',
#23,#74);
#76=ACTION_PROPERTY('probe','workpiece probing',#58);
#77=ACTION_PROPERTY_REPRESENTATION('probe','workpiece probing',#76,#26);

/************************************************
 * END OF APPLICATION OBJECT DESCRIPTIONS
 */
#78=APPLICATION_PROTOCOL_DEFINITION('Draft International Standard',
'integrated_cnc_schema',2004,#14);
ENDSEC;
END-ISO-10303-21;