perm filename PROP2[1,VDS] blob sn#080049 filedate 1974-01-02 generic text, type T, neo UTF8
00300				December 31, 1973
00600		The  automated  machine  shop.     Two  possible routes, both
00700	viable, one a lot more ambitious than the other. The  more  immediate
00800	sort  of  automated machine shop- the interactive machine shop.   The
00900	more ambitious type of shop- the completely automated shop.   I  will
01000	discuss my thinking on these two proposal alternatives.
01200		The interactive machine shop.
01400		Presently,  most prototype machining is done manually with no
01500	numerically controlled machines being employed.    The  prime  reason
01600	given  is  not economics, but the fact that the machinist must really
01700	be there to make the first part.  N.C.  machine  programming  methods
01800	today  require  an  average  of  3  rounds  of  iteration  to  make a
01900	successful part.  Thus, for short runs, the N.C.  machine-programming
02000	debugging  operation  offsets  the  advantages  of the machine's high
02100	speed and errorless machining ability.
02200		Generally,  programming of these N.C. machines is not done by
02300	the machine operator, but by a programmer who usually happens  to  be
02400	either  an engineer, or an ex-machinist who has had special training.
02500	The operation works like so.   The shop recieves  a  print  from  the
02600	engineering department.  The foreman looks the print over and decides
02700	how to make the part.  If the quantities are  large  enough,  he  may
02800	decide  that  n.c.   machining may be the best way.  In this case, he
02900	will turn the drawing over to a programmer  who  will  use  either  a
03000	Flexowriter,  or in larger establishments a mini-computer and the APT
03100	programming language to create a program tape for the n.c. machine. A
03200	part  will  be  attempted.  Only in rare cases will the first part be
03300	completely successful, as even the best programmeers have  difficulty
03400	n picking the proper machining speeds for all cuts, or accounting for
03500	part or tool deflection, or insuring that no interferences  occur  in
03600	the  cutting sequence.  In just about every case, the programmer ends
03700	up watching the first and second and thrid part goo thru the  machine
03800	while  making  corrections  to the program. Frequently as many as ten
03900	iterations are required to successfully make a part.
04100		My first proposal is for a more interactive approach to  this
04200	machining operation, involving more computer use with a standard n.c.
04300	machine.   Here is what I envision.  Think of the  following  layout.
04400	You  have  a  prototype machine shop- execpt it is equipped with n.c.
04500	machine tools (in addition or instead of the  conventional  manuallly
04600	controlled  tools).    A  computer  terminal  from  a large timeshare
04700	computer also is in the shop.  In addition there is a machinist. This
04800	fellow  may  not  be  too  skilled  a programmer, but merely a person
04900	capable of taking instructions and making judgements  about  what  is
05000	good  machining practice, and who also knows what his machines can do
05100	and what they can't do.
05200			In the full blown version of this interactive shop, a
05300	part gets designed by an engineer  sitting  in  front  of  a  display
05400	console.  Here  he has the ability to manipulate geometric shapes and
05500	call in subroutines of fixed configurations, to create a  part  which
05600	he  then  wishes  to  make.   Maybe  he will design a complete device
05700	consisting of several parts, some  purchased,  some  made,  and  some
05800	modified  pruchased  parts.   Each part can be detailed separately on
05900	the screen, and then dimensioned so that it will fit into  the  whole
06000	system,  using  a computer aided dimensioning system which would have
06100	knowledge of  standard  machining  tolerances,  and  practices.   The
06200	program  would  also  have  knowledge  of  other constraints, such as
06300	dimensions or shapes  of  purchased  components  which  fit  into  th
06400	system.    By  making several passes at the program and reviewing the
06500	finalized assembly and dimensioned drawings, the engineer can operate
06600	interactively  with  the  computer  to  produce a system with all the
06700	proper component tolerances,  dimensions,  and  configurations  which
06800	satisfies him, and also represent a reasonable machining task.
07000		Next,  the  engineer  "sends"  the layout and drawings to the
07100	machine shop.  This means that the computer makes up a machining tape
07200	per  the design drawings, and supplies a list of required material to
07300	the shop.   Here the machinist has a say of  what  the  shop  has  in
07400	stock, and what kinds of jigs and fixtures to hold the parts the shop
07500	may have.    His input is  back  to  the  computer  in  the  form  of
07600	answering questions put to the shop by the computer.  These questions
07700	await simple replies, such as the stock dimension, or the location of
07800	a  corner  of  the  stock  or  part on the mill table, or the size of
07900	cutters available.  Based on this information and a built in program,
08000	the  computer  creates a first pass n.c. tape. The machinist, who may
08100	have a reference set of drawings at hand so that he can spot  obvious
08200	errors, sets up the machine per the instructions, and then starts the
08300	operation.   Rough cuts are performed and unless the  operator  notes
08400	any  fatal  errors, the machining sequence proceeds with the computer
08500	giving the machine AND the operator new  instructions  from  time  to
08600	time.    Feedback  from the operator is accepted and computer updates
08700	in the machining operation are  made  as  needed.   Typical  feedback
08800	information will be in the form of answers to various questions posed
08900	by the computer- such as cutting speed ok? or can  I  take  a  deeper
09000	cut?,  etc.  The  response  will  be in the form of simple Y and N or
09100	number type answers.   Requests for dimension measurement may come as
09200	the  part  nears  the  finished  dimensions.   Here the computer will
09300	request that the operator measure the thickness of  a  part,  or  the
09400	diameter of a bore, or the taper of an edge.  The data is fed back to
09500	the computer and serves to update the program to accomodate  for  the
09600	particular  errors  inherent  in  the machine, or the setup.  Furthur
09700	instructions such as requesting a statement of the surface finish, or
09800	requesting  that  an  edge  be deburred, or requests that a cutter be
09900	changed, or that a hole be hand tapped, or even that the operator  do
10000	a  particularly  sensitive cut where extra careful observation of the
10100	cutting operation may be required.  These commands would all come  to
10200	the  operator through the remote trminal which could be a teletype or
10300	similar device..
10500			In a more advanced sort  of  system,  the  data  link
10600	between machine and computer could be improved with the incorporation
10700	of  direct  force  feedback,  so  that  cutter  forces,   or   cutter
10800	temperature  could be fedback to the computer.   Even sounds and some
10900	special purpose sensor outputs could be used to furthur  improve  the
11000	speed and accuracy of the prototype machining operation.
11200		This  completes  an  outline  of a proposed development of an
11300	interactive prototype and short run machine shop.  I  consider  it  a
11400	very  realistice  type  of  proposal.  Several parts of this proposal
11500	could be implemented quickly right here at Stanford.  I  have  talked
11600	to  some  of the people in the Department of Chemistry, and they have
11700	expressed interest  in  a  project  of  this  sort.   Their  shop  is
11800	presently  just  about the best shop on campus, but it lacks any n.c.
11900	machines. In fact, I doubt that there are any n.c.  machine tools  at
12000	Stanford  University,  with  the  possible  execption  of  SLAC. With
12100	machine shop costs of $12 per hour  and  up,  it  appears  that  this
12200	interactive  approach  is  a viable way to speed up the production of
12300	prototype and short run production parts, at a large savings in cost.
12400	Back  to  the Chemistry Dept. Besides having the best shop on campus,
12500	(machines and facilities), they also have some of  the  most  capable
12600	machinists, one of whom is a trained operator of n.c.  equipment from
12700	a previous postion at Hewlett-Packard.     Because  of  this  quality
12800	shop,  the  Chemistry  Dept.   has  a  very positive attitude towards
12900	acquisition of new equipment and thus there are funds  available  for
13000	the  purchase  of  an  n.c.  milling machine(for example).  Here is a
13100	really good chance for  several  graduate  theses,  in  the  Computer
13200	Science , Mechanical Engineering and Interdepartmental Fields.