perm filename PROP3[1,VDS] blob sn#080050
filedate 1974-01-02 generic text, type T, neo UTF8
00100 A DISSERTAION PROPOSAL
00300 December 31, 1973
00500 A continuation of Prop2.
00800 The totally automated machine shop.
01000 The concept of the totally automated machine shop was brought
01100 up in Prop1. This earlier discussion outlined some of my thinking
01200 regarding the possibilities of developing a completely automated
01300 machine shop in which the operator would be a computer and a
01400 mechanical arm. The input would be an interactively created design
01500 and the output a finished part or eventually a product manufactured
01600 to the description created by the designer.
01800 As a starting point, I will give a brief description of how I
01900 see the general prupose shop working. First lets look at the layout.
02000 Imagine that we have a large timeshare computer, and a high data rate
02100 link to a machine shop. In this shop are a number of machines all
02200 n.c. type or else powered such that either electrical switching or at
02300 the most low mechanical forces are required to make them perform all
02400 tasks. They are all located in known locations, and each has a well
02500 stocked accessory holder. A stock room with a good supply of stock
02600 material is near the tools. This stock is stored so that it can be
02700 removed and placed in a shear or saw very easily by a manipulator.
02800 Besides these machines there exists one or more mechanical
02900 manipulators which can move around to all of the machines and perform
03000 various operational tasks on these machines, just as a human operator
03100 does. The machines, the manipulators, and the associated
03200 accessory and sensing devices are all interfaced to the computer so
03300 that they are directly controlled (thru a mini-computer if
03600 Now lets look at a typical sequence of operation. An
03700 engineer sits down at a graphics display console. His task is to
03800 create a working device of some sort. This device is part of a
03900 system. There are several parts to the device, some purchased,
04000 others made from purchased stock, and still others modifications of
04100 purchased completed components. These parts must all fit together
04200 and operate as a device, and the device must operate properly in the
04300 completed system. Using GEOMED or a similar interactive
04400 display-graphics program, the engineer can reate shapes and structure
04500 on his console and manipulate these developed bodies at will. As
04600 engineer are generally rather realism oriented people, the graphics
04700 program will probably be oriented to display shapes and forms in a
04800 manner which is easily interpreted by the design engineer. A
04900 library of pruchased component dimensions and specifications along
05000 with standard engineering dimensions and details can also be called
05100 by the designer or directly by the computer, as would be the case
05200 when placing screw holes, or selecting screw or shaft sizes.
05400 Assume that the design is done, the designer looks over what
05500 he has created on the screen and sees that everything is correct; the
05600 program has picked the proper screws, has matched up all the bolt
05700 patterns properly, and has chosen the right tolerances. Now a
05800 manufacturing operations program can be called in. This gives the
05900 operator a list of the proposed machining operations and a list of
06000 the stock required, and the estimated time and cost. A breakdown
06100 gives the details, so that the designer can change dimensions or
06200 specifications to reduce costs, or get around difficult or impossible
06300 operations. Once this iterative operation is completed, the required
06400 setup list and stock list is compared with the shop inventory. If
06500 they are complete, the machining can begin.
06700 Following the computer generated sequence commands the
06800 machining operations are performed. The individual machines are
06900 directly controlled by the computer using position feedback and
07000 feedback from permanently mounted motor current and temperature
07100 sensors, force sensors, etc. Setting up each machine, changing
07200 tools, and transferring material are the mechanical manipulators.
07300 These arms serve the same purpose as the human operator in the
07400 typical n.c. machine shop. In addition, they provide the computer
07500 with a device for positioning measuring instruments, checking on
07600 surface finishes, and making all the necessary observations that are
07700 required of a human macchine operator. This information is fed
07800 directly back the computer for updating of the machining sequences.
07900 In this way, the shop need not be a very precisely set up layout.
08000 Real machines setup almost casually can be used in such a situation
08100 where feedback is sufficient.
08300 The task is complete when the finished parts are delivered to
08400 the output box, just like line printer output. Possibly, even
08500 assembled into a complete assembly, properly inspected, tested,
08600 documented and certified.
08800 Certainly, the development and execution of a complete,
08900 general purpose system such as has just been described is no
09000 overnight task. A number of man years effort is involved, both in
09100 the programming and the engineering of such a system. The execution
09200 of such a problem is beyond the cope of a single PhD thesis
09300 dissertation, but a thorough study of the problems and approach to
09400 such a project may very well be a good thesis topic. But, as an
09500 alternative to a paper study of such a general purpose completely
09600 automatic system, it seems reasonable to attempt the development of a
09700 special purpose automatic shop as a more realistic initial goal.
09800 What follows are some thoughts on a special purpose completely
09900 automated shop.
10100 The automated sheet metal shop.
10300 Prototype sheet metal parts are very expensive relative to
10400 production quantities. As an example, it is frequent to find that
10500 the cost of just two of a kind is only 5% more than the initial one
10600 piece. Why is this so. Well, there has never been much automating of
10700 sheetmetal processes, other than blanking and stamping which are
10800 restricted to large production runs. Other than n.c. punches and
10900 n.c. stops on hand fed shears, there are no other really automatic
11000 machines used in this field. It has been considered a hard to
11100 automate field, because of the types of machines used and the need to
11200 do a lot of manipulating of the material which can frequently be
11300 large floppy sheets, of varying thicknesses, yield strength, and
11400 stock dimension.