Get the means of craft information from inside CAD graph

We Selected One Of The Methods To Test It Practically.

Key Words: The ceaseless development of technology of CAD of 　 of foreword of CAD; Processing Information;get1 and perfect, the description that makes its reach a part to the product is more and more adjacent at reality, 2 dimension CAD already was achieved to the description of product and spare parts and exceeded the level of artificial design. Since 80 time end, our country imported many worlds' top-ranking CAD/CAM software, these software are built in national economy medium, dogging in the job that science and technology of stimulative our country of trend of development of international advanced technique progresses, had outstanding effect. But medium and small businesses of our country majority still uses hundred thousands of yuan to go up even without ability 1 million yuan of CAD software, what personnel of major project technology basically uses still is AutoCAD this kind of low-cost software, accumulate the project technology data that come down is 2 dimension form for the most part. Although having the manufacturer of advanced CAD/CAM software, because stage a cycle of songs in a traditional opera is insufficient, still also use " two legs " the method that walk. The article will set out from general CAD software, research gets the means that processes craft information from inside CAD graph data, and the choice undertakes more detailed experiment sex studies one kind among them. To CAPP of implementation of medium and small businesses, computer manufacturing management provides reference. The expression of information of the craft in 2 　 CAD because the method machines manufacturing need, hope to enough treatment craft information can be contained in the data of CAD, if dimension reachs its precision, form the geometrical precision requirement such as surface roughness of tolerancepublic errand, surface, material, heat treatment, assemble wait for technical requirement. To achieve the goal with CAD compositive information, a kind of popular method is, add relevant craft information when tectonic feature, the neuter form that uses a level is described like STEP standard [1] . The computer of our country most medium and small businesses is versed in Cheng is designed, finish with AutoCAD software design namely. In AutoCAD record or description process craft information, will come true with 3 kinds of forms, namely " TEXT " or " MTEXT " (text tags a form) , " DIMENSION " (dimension tags a form) and " ATTRIB " (attribute form) , among them " TEXT " or " MTEXT " the form is relatively simple, "DIMENSION " the form is relatively complex, with respect to its data format undertakes an analysis below [2, 3] . There are the dimension that a linear level tags and its noncombatant duty on the blueprint paper of CAD suppose, if plan institute is shown, its are basic dimension is: 15mm, next deviation are: - 0.

011mm, deviation is on: - 0.

006mm. Watch 1 reach a table the 2 DXF that showed this measure respectively state form and IGES represent a form. Chart level tags dimension denotive to using DXF document dimension, watch 1 listed only crucial part. Group code 0 represent an attempt yuan type, group cost " TEXT " express to be text; Group code 8 state graph layer name is " 0 " layer; Group code the 1 measure that expresses to tag. Process craft information to getting among them and character, the most important group code is " 0 " and " 1 " . Should find group code above all the group cost of 0 is " TEXT " graph yuan, next again from group code 1 in get next basic measure, deviation or on deviation (if express 1 in add black italics) . Express 000TEXTTEXTTEXT888000666BYBLOCKBYBLOCKBYBLOCK62626200010101016 of format of file of 1 　 DXF.

6917.

54517.

520202014.

9114.

78415.

0363030300.

00.

00.

04040400.

180.

180.

1811115.

000-0.

011-0.

00672727211111111117.

06517.

90517.

90521212115.

014.

87415.

1263131310.

00.

00.

0737373222 　 are denotive to using IGES document dimension, express the 2 parts that listed we are interested only, add black italics to be respectively among them next basic measure, deviation or on deviation. Express format of file of 2 　 IGES 212, 3, 6, 0.

75, 0.

18, 1, , 0.

0, 0, 0, 1.

669D1, 1.

491D1, 0.

0, 6H15.

000, 6, 1P00000010.

72, 0.

18, 1, , 0.

0, 0, 0, 1.

7545D1, 1.

4784D1, 0.

0, 6H - 0.

011, 6, 0.

81, 0.

18, 1P00000021, , 0.

0, 0, 0, 1.

75D1, 1.

5036D1, 0.

0, 6H - 0.

0061P0000003 　 is additional, still have a kind of commonly used data presentation form, namely form of memory of AutoCAD database object, be close to on its format at DXF format, store with the form of the watch. The AutoCAD database of on one example stores the format is: (- 1.

<Entity Name:60000022) pursues yuan renown; (0.

"DIMENSION " ) pursue yuan of type; (2.

"*D0 " ) anonymous a name; (1.

"" ) the dimension that keys in by the user tags text value to wait. In this groups of data, the most important is group code 0 with group code the group of 1 is worth. By group code the group of 0 is worth " DIMENSION " , whether can find dimension to tag a graph certainly yuan, by group code 1 can numerate directly tagging basic measure value. In this exemple, the basic measure when tagging is worth the automatic measured value that chose AutoCAD, because of this group code the group cost of 1 is empty. To using " TEXT " , " MTEXT " (text tags a form) or " ATTRIB " (attribute form) record or the condition that describe treatment craft information, format of memory of its AutoCAD database is relatively simple, they have a common characteristic, be in namely group code 1 hind follow corresponding news directly. The 3 meanses that get craft information from inside CAD 3.

The choice of 1 method is analysed by above knowable, get treatment craft information from inside the graph of CAD, can come true with two kinds of methods. The first kind is those who leave a line to get way, can pass the processing of pair of STEP, DXF or IGES format file namely, get concerned treatment craft information. Although the format difference of these 3 kinds of standards is very big, but independent at CAD, information can be handled in other environment. The 2nd kind gets way for on-line, do not exit AutoCAD namely, get concerned treatment craft information from inside memory of its database object directly. STEP of hang on of the first kind of means, DXF reachs the not lack fidelity changeover of IGES, can lose information otherwise; When getting information additionally relatively blind, can get entirely only, cannot get selectively; Handle real time intuitionistic sex is poor. The 2nd kind of means can issue ground of intuitionistic real time to get data in AutoCAD; From theoretic tell, the information that always tags on blueprint can be gotten; Still can undertake the purposeful, news that has a choice is gotten additionally. 3.

The itself of AutoCAD of executive research 　 of 2 plan contains AutoLISP user to develop a tool, LISP language has very strong symbol processing and watch processing function, it is the powerful tool that builds expert system. (1) is gotten " TEXT " , " MTEXT " or " ATTRIB " pursue yuan of medium numerical value get " TEXT " , " MTEXT " (text tags a form) or " ATTRIB " (attribute form) the processes craft information programming of record or description, set Namet to be hypostatic name among them. (Setq Ent (entget Namet)) ; Get graph metadata 　 (If (equal (cdr (assco 0 Ent)) " TEXT " ) whether is; differentiate text 　 (Setq Datum (cdr (assco 1 Ent)))) ; If be,be data of text criterion extraction " MTEX " or " ATTRIB " , pursue with its the name replaces yuan of kind in the program " TEXT " can. (2) is gotten " DIMENSION " pursue yuan of medium numerical value to " DIMENSION " formal tagging a kind of circumstance is, when dimension is tagged the user keyed in measure value, its data is worth even if follow in group code the 1 group cost from the back; Another kind of circumstance is, when dimension is tagged the user affirmed measure measured value, criterion the 1 group cost from the back is group code empty (" " ) , its data is worth with " anonymous piece " the form is implicit in " DIMENSION " graph yuan in. Anonymous piece structure and general cake literary composition are different, cannot use search " INSERT " graph yuan methodological visit. Get with " DIMENSION " the method that the form tags dimension data has 3 kinds: Collect a magic art directly, the dimension that its tag is keyed in by the user, can use get group code directly the 1 group cost from the back obtains data; "Scamper leaves " extraction law, use first " EXPLODE " command, make " DIMENSION " the dimension that the form tags pursues yuan " scamper leaves " , dissension becomes single figure yuan, next this dimension, deviation reach this time base on the data of deviation becomes " TEXT " formal graph yuan, get again next " TEXT " pursue yuan of group code 1 the group from the back is worth and obtain data; The visit is anonymous an extraction law, use Tlbserach function to get enter anonymous piece passageway, recycle Entnext function is gotten anonymous a medium each stature plan yuan, from " TEXT " child graph yuan get group code 1 the group from the back is worth and obtain data. The first kind of method is conditional extraction law, have bigger limitation. The 2nd kind of method is simpler, can with " TEXT " tag means to unite processing; Its defect was to destroy former " DIMENSION " tagging structure, and " anonymous piece " " scamper leaves " the memory amount that will increase part drawing, can revise to the following graph especially bring very big trouble. For example, average to size is tagged and character, "Scamper leaves " hind, the borderline of dimension line, dimension, arrowhead plan that will make independence yuan hypostatic. Process designing of the 3rd kind of method is more complex, but protected former " DIMENSION " tagging structure, dimension data still is pressed anonymous piece structural means stores, got data information already, did not increase memory to measure again, it is a better method. With the 3rd kind of method (use Tlbserach function) the gets craft information order of the work out is as follows: (　 of 　 of 　 of 　 of 　 of 　 of 　 of Setq Ent (car(entsel))) ; Choice dimension tags a graph yuan, win a figure yuan renown (Setq Entt (entget Ent ' (" ACAD " ) ) ) 　 of 　 of 　 of 　 　 　 ; Win a figure yuan define table (　 of 　 of 　 of 　 of 　 of 　 of Setq Named (cdr (assoc 2 Entt))) ; Get anonymous piece piece renown (Setq Head (tblsearch " BLOCK " 　 of 　 of 　 of 　 of Named)) 　 　 ; Take out a head news (　 of 　 of 　 of 　 of 　 of 　 of Setq Entname (cdr (assoc-2 Head))) ; Take out piece in the first stature plan yuan renown (　 of While (/=entname Nil) ; If have child graph yuan continue (　 of 　 of 　 of 　 of 　 of 　 of Setq Ent (entget Entname)) ; Take out a neutron to pursue yuan define table (If (equal(cdr (assco 0 Ent)) " TEXT " ) 　 of 　 of 　 of 　 　 　 ; Whether does differentiate pursue for article notebook yuan of 　 (Progn 　 ; If be article notebook to pursue yuan continue 　 (　 of 　 of 　 of 　 of 　 of 　 of Setq Datuml(cdr(assco 1 Ent))) ; Extraction text is numeric (dimension is numeric) 　 　 (　 of 　 of 　 of 　 of 　 of 　 of Setq Entname(entnext Entname)) ; Take out the next child pursue yuan of renown 　 (　 of 　 of 　 of 　 of 　 of 　 of Setq Ent (entget Entname)) ; Take out child graph yuan define table 　 (If (equal(cdr(assco 0 Ent)) " TEXT " ) 　 of 　 of 　 of 　 　 　 ; Whether does differentiate pursue for article notebook yuan of 　 　 (Progn 　 ; If be article notebook to pursue yuan continue 　 　 (　 of 　 of 　 of 　 of 　 of 　 of Setq Datum2(cdr(assco 1 Ent))) ; Extraction text is numeric (next deviation) 　 　 　 (　 of 　 of 　 of 　 of 　 of 　 of Setq Entname(entnext Entname)) ; Reassume gives the next child pursue yuan of renown 　 　 (　 of 　 of 　 of 　 of 　 of 　 of Setq Ent (entget Entname)) ; Take out child graph yuan 　 of define table 　 (If(equal(cdr(assco 0 Ent)) " TEXT " ) 　 of 　 of 　 of 　 　 　 ; Whether to pursue for article notebook yuan of 　 　 　 (　 of 　 of 　 of 　 of 　 of 　 of Setq Datum3(cdr(assco 1 Ent))) ; Yes, extract text numerical value (on deviation) 　 of 　 　 　 ) 　 ; 　 of 　 of 　 of 　 of end of the deviation on extraction) 　 　 　 ) 　 ; The deviation below extraction ends 　 ) 　 ) 　 ; Extraction measure numerical value ends (　 of 　 of 　 of 　 of 　 of 　 of Setq Entname(entnext Entname))) ; Take out the next child pursue yuan of renown 　 (of 3) dimension precision what dimension precision built in changing a function automatically to study originally is automatic change a function. When undertaking CAPP, the accuracy class that what people cares more is dimension is not particular numerical value. According to the regulation of standard public errand of our country, what we built dimension precision is automatic change functional module. This module uses AutoLISP language design, can move below AutoCAD environment, go to the lavatory to realized CAPP to offer. 4 last words article thrash out go up in the foundation of data of former CAD graph, get the means that processes craft information, chose on-line to get means to undertake study from which. Particular executive test had on AutoCAD software, found out the need in carrying out to settle the crucial point of the problem, treatment is gotten in data of existing CAD technology for the factory craft information, make existing technology data gets be usinged adequately, implementation CAPP provided very good reference. CNC Milling CNC Machining