Good machine program should make sure treatment gives the eligible work that accords with a design not only, should make the function of numerical control machine tool gets rational application and sufficient play at the same time. Numerical control machine tool is a kind of efficient automation equipment, the 2~3 of general accuracy machine tool of its efficiency prep above times, so, want to develop this one characteristic of numerical control machine tool adequately, must master its function, characteristic, use operation method adroitly, still must define treatment program correctly at the same time.
In process of treatment of numerical control machine tool, because treatment object is complex diversiform, especially the appearance of outline curve and position are Protean, add material different, batch is not coequal the influence of many sided element, when making treatment plan to specific spare parts, should undertake concrete analysis and distinction are treated, agile processing. Only such, ability makes the treatment plan that make sound, achieve Gao Hecheng of quality actor, efficiency thereby this low end.
After undertaking be mixinged seriously be analyticed carefully to machining craft, the general principle that makes treatment plan is first thick hind essence of life, first close hind far, first inside hind outside, block is least, course taking a knife is the shortest, as a result of the difference of scale of production, the treatment program to same part differs somewhat, should according to specific requirement, choose economy, sound craft plan.
Working procedure of 1, treatment differentiates
The spare parts is machined on numerical control machine tool, working procedure can compare concentration, outfit clip should complete whole process as far as possible. Machine photograph comparing with general accuracy machine tool, treatment working procedure differentiates the characteristic that has its oneself, commonly used working procedure differentiates the principle has the following two kinds.
The 1.1 principles that assure precision
Numerical control treatment asks working procedure is centered as far as possible. Often thick, finish machining places next finishing in outfit, be opposite to reduce heat to be out of shape with cutting force is out of shape the influence of precision of the appearance of workpiece, position, dimension precision and exterior surface roughness, answer to have thick, precision work apart. Countershaft kind or dish kind of spare parts, will everywhere first rough machining, take a few surplus precision work, will make sure exterior quality asks. In the meantime, to workpiece of a few casing, to assure the treatment precision of aperture, answer to machine the surface to machine aperture after that first.
The 1.2 principles that improve manufacturing efficiency
In numerical control treatment, change knife time to decrease, save the time that change a knife, should will need to use same after the treatment place that machines the knife is finished entirely, change another knife to machine other place again. Answer to reduce idle stroke as far as possible at the same time, with same when the many place knife treatment workpiece, answer to arrive at each to machine place with the shortest course.
Actual in, numerical control machines working procedure to want to ask to wait for a circumstance to consider integratedly according to the structural characteristic of specific spare parts, technology.
Those who machine a course is 2, affirmatory
In numerical control treatment, cutting tool (saying strictly is a knife dot) call treatment line relative to the athletic contrail at workpiece and direction. Namely cutting tool from to the knife the dot begins motion to rise, till end the method that machine program place passes, the method that includes cutting treatment and cutting tool introduce, return wait for blame cutting idle stroke. The factor that affects cutter track line is very much, material of technique, workpiece reachs his stiffness of precision of condition, treatment and requirement of exterior surface roughness, workpiece, mental allowance, the stiffness of cutting tool, durability reachs position, machine tool type and function, must assure what machine a course to be machined above all certainly the dimension precision of the spare parts and exterior quality, consider numeric computation next simple, course taking a knife as far as possible short, efficiency is more advanced.
Citing analysis studies numerical control machine tool machines the treatment line that the spare parts uses constantly below.
The treatment course with 2.1 conic cars is analysed
Outside the car on numerical control lathe conic, hypothesis is conic old way is D, trail is D, awl is long for L, the treatment course with conic car is shown 1 times like the graph.
Graph the treatment course with 1 conic car
The 1 that press a plan (A) course of cutting of a flight of stairs, 2 knives thick car, vehicle of last knife fine; Of 2 knives thick car eventually the knife is apart from S to want mathematical calculation, can similar triangle gets:
This kind machines a course, when thick car, amount of penetration of a cutting tool of cutting tool back is same, but when fine vehicle, amount of back penetration of a cutting tool is different; The course that at the same time cutting tool cutting moves is the shortest.
The 1 that press a plan (B) course of cutting of similar oblique line, when also wanting computational thick car eventually the knife is apart from S, same by similar triangle calculable:
Machine a course by this kind, the distance that cutting tool cutting moves is shorter.
The diagonal of the 1(c) that press a plan machines a course, needed to decide only carry penetration of a cutting tool on the back to measure Ap every time, and do not require calculation eventually the knife is apart from, process designing is convenient. But be in penetration of a cutting tool is being carried on the back to measure in cutting every time is change, and the course that cutting tool cutting moves is longer.
The treatment course of 2.2 cars circular arc is analysed
Apply G02 (or circular arc of G03) instruction car, if use one knife to machine circular arc, amounts of such penetration of a cutting tool are too large, hit a knife easily. So, when practical car circular arc, need much knife treatment, excise large much surplus first, what final ability car must need circular arc.
Research analyses car circular arc below course of commonly used treatment.
Graph the form of course of cutting of 2 circular arc
In the graph 2 in, a graph expresses to be homocentric circle type, b graph expresses to be circular arc waiting for diameter (different the centre of a circle) form, c graph expresses to be triangular form, d graph expresses to be echelon form. The cutting course of different form has different characteristic, understand their respective characteristic, be helpful for arranging its to take cutter track line reasonably. Analyse courses of afore-mentioned a few kinds of cutting now: Block number is homocentric circle type and type of circle waiting for diameter the least; Course taking a knife is the shortest for homocentric circle type, the others is ordinal for triangular echelon and type of circle waiting for diameter; Computation and process designing are the simplest to wait for diameter circle type (can use program loop function) , the others is ordinal for homocentric circle, triangle type and echelon form: Metallic excision leads force of highest, cutting to distributing the most reasonable for echelon form; Fine vehicle surplus is homocentric circle type equably.
Graph the car circular arc of course of cutting of 3 a flight of stairs
Graph the course of cutting of a flight of stairs of the 3 circular arc that it is a car. Namely first thick car becomes a flight of stairs, vehicle of last knife fine goes circular arc. This method is in after deciding every knife penetration of a cutting tool measures Ap, need mathematical calculation to give thick car eventually the knife is apart from S, beg circular arc and linear node namely. Distance of motion of cutting of this method cutting tool is shorter, but numeric computation is more numerous.
Graph circular arc of car of course of cutting of 4 homocentric circular arc
Graph the course of cutting of homocentric circular arc of the 4 circular arc that it is a car. Come with different radius circle namely turning, want place circular arc treatment to come out finally. This method is in decided every time after penetration of a cutting tool measures Ap, decide more easily to the start of circular arc of 90 ° , terminal coordinate, numeric calculation is simple, process designing is convenient, often use. But when the 4b that press a plan is machined, idle stroke time is longer.
Graph circular arc of car of course of cutting of law of 5 cars awl
Graph the course of cutting of car awl law of the 5 circular arc that it is a car. Namely first car conic, again car circular arc. But want to notice, of the start when Che Zhui and terminus affirmatory, if decide bad, damage possibly conic surface, leave surplus possibly also too greatly. If the graph is shown 5 times,determine a method, join OC hands in circular arc at D, cross D to nod the tangent AB of circular arc.
By geometrical relation CD=OC-OD= a day of =0.4148, this is the surplus of the biggest cutting when Che Zhui, namely when Che Zhui, treatment course cannot exceed AB line. Concern by graphic representation, can get AC=BC=0.5868, can decide the start when Che Zhui and terminus truly so. Become when R is not quite big, desirable AC=BC=0.5R. Computation of this method numerical value is more numerous, course of cutting tool cutting is short.
The graph introduces when 6 cutting whorl, derivative distance
The analysis that feed of the axial when whorl of 3, car is apart from
When car whorl, the feed of direction of whorl of cutting tool edge should rotate with workpiece main shaft the speed ratio that keeps strict concerns. Considering cutting tool from stop condition to arrive at designation feed speed or fall from designation feed rate to 0, drive system has to transfer surely process, along the treatment course length of axial feed, divide outside assuring to machine whorl length, still should increase δ 1 (2mm~5mm) cutting tool introduces distance and δ 2 (1mm~2mm) cutting tool cuts a distance, if pursue,6 are shown. When such coming that assure cutting whorl, rising fast after finishing, make cutting tool contacts workpiece, after cutting tool leaves work, fall again fast.
Milling of 4, outline machines the analysis of the course
To successive milling outline, when machining circular arc especially, should notice those who arrange good cutting tool to be cut, cut, should avoid to have sex as far as possible place repeat treatment, can appear otherwise apparent bounds trace. When the circle is being made outside using milling of means of circular arc interpolation, should arrange cutting tool from tangential enter circumferential milling treatment, after the treatment that make a circle ends, do not retreat a knife directly in place of point of tangency, and make cutting tool much move a paragraph of distance, direction of best edge tangent, when lest cancel cutting tool,be being compensated, cutting tool and workpiece face posture collide, cause workpiece to discard as useless. When the circular arc inside milling, also should abide by from tangential the principle that cuts, arrangement is cut, cut transfer circular arc, will rise inside the treatment precision of aperture surface and quality.
The analysis of course of 5, poriferous treatment
Taller to positional precision claimed accuracy aperture fastens treatment, the treatment that should note hole particularly is sequential arrangement, when arrangement is undeserved, take the backlash of edge reference axis likely, affect positional precision directly.