Numerical control lathe executes all sorts of cutting treatment continuously normally, the before one cutting tool when tool carrier is changing a knife can produce difference between position of point of a knife and the cutting tool position that change newly, cutting tool installation also is put in error, cutting tool to wear away to wait for an error with radius of circular arc of point of a knife, if do not use cutting tool to compensate a function to give,compensate, do not give the part that accords with design demand figure with respect to cutting. In addition, reasonable use cutting tool compensation to still can simplify process designing. The cutting tool compensation of numerical control lathe can be divided it is two kinds, namely compensation of cutting tool position and compensation of cutting tool radius.
Position of 1 cutting tool is compensated
In machining a process, if use many cutting tool, take position of tool carrier center to regard process designing as origin normally, namely with tool carrier center! For the initial drop of the program, if the graph is shown 1 times, and cutting tool moves actually orbit is worth control by compensation of cutting tool position. By the graph 1 (A) visible, compensation of cutting tool position includes cutting tool geometry to compensation is worth and wear away compensation cost.
Graph compensation of position of 1 cutting tool
Because be put in the deflection quantity of two kinds of forms, so compensation of cutting tool position uses two kinds of methods, a kind of method is compensation is worth and wear away geometry compensation cost parts set location deposits compensation cost, its format is:
Another kind of method is measure geometrical deflection and wear away deflection quantity adds up to compensation, if pursue (B) be shown, its format is:
Total compensation is worth location number to have two effect, an action is the compensation cost that chooses correspondence of cutting tool date, carry out cutting tool position to compensate a function; Another action is when location number 00 when can cancel positional compensation, for example T0100, express expunction + the compensation value with date current cutting tool. Graph 2 show positional compensatory effect, graph the process designing trochoid that 2 medium solid line are dot of A of tool carrier center, dotted line is the actual trochoid that the A when executive position is compensated nods, the compensation cost of axis of the azimuth of actual contrail and X, Z is concerned, its program is:
N010 G00 X10 Z-10 T0202;
N020 G01 Z-30;
N030 X20 Z-40 T0200;
Graph position of 2 cutting tool compensates action
Structure of cutting tool of system of numerical control lathe is shown 3 times like the graph, graph 3 in P is fictitious point of a knife, s is the centre of a circle of knife head circular arc, r is knife head radius, a is tool carrier reference point.
Graph structure of 3 lathe tool
The reference point of lathe is tool carrier center, so compensation of cutting tool position needs from beginning to end. Compensation of cutting tool position is to use the changeover between contrail of center of circular arc of implementation point of a knife and tool carrier reference point, corresponding figure 3 in the changeover between A and S, but actually we cannot be measured directly the distance vector between these two center, and can measure only fictitious point of a knife! With the distance between $ of tool carrier reference point.
For handy for the purpose of, might as well R=0 of radius of hypothesis knife head, the coordinate that can use measurement unit of cutting tool length to measure a fictitious point of a knife to nod P to wear reference point relative to Yu Dao at this moment and, in stocking cutting tool parameter to express.
In type: — , P of fictitious point of a knife nods coordinate;
(X, z) — , the coordinate of A of tool carrier reference point.
Draw up formula of computation of compensatory of cutting tool position is very easily so far
The coordinate of P of point of a knife of the hypothesis in type nods coordinate to machine spare parts contrail namely actually, can obtain from inside numerical control machine program. Right now, type of classics of contrail of spare parts outline (2) after compensation, can come true namely through controlling A of tool carrier reference point.
To the graph 3 in R ≠ the circumstance of 0, when undertaking cutting tool position is compensated, not only the compensation that needs to consider radius of knife head circular arc, and the installation way that considers cutting tool even (specific see 2.2) .
Radius of 2 cutting tool is compensated
When work out machine program, it is commonly regarding point of a knife is one is nodded, however actually point of a knife has circular arc, inside cutting aperture, outside when circle and end panel, circular arc of point of a knife does not affect treatment dimension and figure, but when cutting cone and circular arc, meet those who bring about cutting tool walk orbit and process designing contrail not photograph be identical, and one need a value. Graph 4 state circular arc point of a knife has radius compensation and the contrail when be being compensated without radius. Can see from inside the graph, when using process designing of P of fictitious point of a knife, if contrail of center of cutting tool circular arc pursues 4 in double dot underlines place to show, the error of outline appearance existence that cutting tool processes orbit and work requirement actually, error size and R of circular arc radius are concerned. If use process designing of center of cutting tool circular arc to use the contrail of center of circular arc of the cutting tool when radius compensates a function,be a graph 4 medium fine solid line, treatment contrail and the outline that workpiece asks are equal.
Graph point of a knife of 4 circular arc has radius compensation and the contrail when be being compensated without radius
Because the installation of lathe tool and geometrical form are more complex, make through a few respects below elaborate further.
The trend of P of 2.1 hypothesises point of a knife is firm
The azimuth of center of opposite circular arc of P of point of a knife of fictitious lathe tool and direction of cutting tool shift are concerned, it affects circular arc lathe tool to amend computational result directly. Graph 5 it is azimuth of point of a knife of hypothesis of circular arc lathe tool and code. Can see from inside the graph, the azimuth of P of point of a knife has 8 kinds, use 1~8 respectively 8 numbers code expresses, set at the same time, when point of a knife takes place of circular arc center, code is 0 or 9, understandable compensate to do not have circular arc.
Graph azimuth of point of a knife of hypothesis of lathe tool of 5 circular arc and code
Compensation of radius of 2.2 circular arc and positional compensatory concern
If according to A of tool carrier center the dot regards process designing as initial drop, take no account of compensation of circular arc radius, criterion lathe tool compensates a value in X axis and Z axis according to the graph 1 (B) what show a method to decide. Want to consider compensation of lathe tool position already, want to consider compensation of circular arc radius again, right now lathe tool is compensated in the position of X axis and Z axis the value can show a method 6 times to decide according to the graph, and in putting the value of R of circular arc radius of cutting tool corresponding location, when treatment numerical control device undertakes circular arc radius is compensated automatically. In the compensates date correspondence location in T of cutting tool code, deposit a group of data: The length of axis of X axis Z compensates a value, cost of compensation of circular arc radius and azimuth of fictitious point of a knife (0~9) . When the operation, in the location that can input 4 data of each cutting tool cutting tool to compensate date correspondence respectively, can realize automatic compensation (watch 1) .
Graph compensation of position of lathe tool of 6 circular arc
Express 1 cutting tool to compensate a value
Radius of 2.3 circular arc compensates orbit automatically
Whether is cutting tool radius compensated and use why to plant means compensation, dictate by G medium G40, G41, G42 decides:
G40 — , compensation of cutting tool radius cancels, after using this statement namely, make instruction of G41, G42 invalid.
G41 — , left compensation of cutting tool radius, look along way of cutting tool movement namely, cutting tool is located in the compensation of cutting tool radius when workpiece is left.
G42 — , right compensation of cutting tool radius, look along way of cutting tool movement namely, the cutting tool radius when cutting tool is located in on the right side of workpiece is compensated.
Graph 7 it is process of compensation of the cutting tool when radius of use circular arc is compensated.
Graph 7 in block format of cutting tool compensatory is:
G40__ ; Eliminate compensation;
G41__ ; Radius compensates initiative block;
Graph 7 cutting tool compensate a process
From the graph 7 can see, in initiative block, cutting tool increases compensation cost gradually in mobile process. After ending when initiative block, center of cutting tool circular arc stays on the vertical line that program set coordinate orders, the distance is radius compensation cost.
The cutting tool when lathe of 3 numerical control does not have cutting tool radius to compensate a function compensates computation
When numerical control lathe compensates a function without cutting tool radius, when lathe tool of the head that use a circle processes work, be about to seek compensation of radius of solution cutting tool with calculative method.
3.1 machine cone by process designing of fictitious point of a knife
If the graph is shown 8 times, if AB of outline of workpiece of edge of fictitious point of a knife is mobile, namely with AB coincide, press AB dimension process designing, inevitable generation pursues 8 (A) in ABCD remain error. Because this presses a plan 8 (B) be shown, make the cutting site of lathe tool changes to AB, move along AB, can avoid rudimental error thereby, but at this moment contrail of fictitious point of a knife and outline differred in Z direction △ Z.
In type: R is radius of cutting tool circular arc; θ is cone bevel.
Because this can press the coordinate of contrail of fictitious point of a knife to be worth process designing directly, give in X direction and Z direction compensation △ Z can.
Graph knife of 8 cars cone compensates sketch map
3.2 machine circular arc by process designing of fictitious point of a knife
When surface of turning circular arc, the circumstance that if the graph is shown 9 times,can appear. Graph 9 (A) the convex arc that is R for turning radius, as a result of the existence of P, criterion the circular arc appearance that the circular arc contrail that dot of # of point of a knife walks along is not work place requirement. Its the centre of a circle is ” ” , radius is ” R+r ” , right now process designing personnel still undertakes process designing by dot of P of fictitious point of a knife, take no account of the influence of radius of circular arc of point of a knife, but before the requirement is machined, the value should fill to go up in the knife Z to with X to add R of a compensation respectively. Manage together, in cutting sunken circular arc, if pursue 9 (B) when, be in X to with Z to decrease R of a compensation respectively.
Graph filling sketch map of knife of 9 cars circular arc
3.3 press process designing of contrail of center of circular arc of point of a knife
The graph shows a part 10 times is formed by 3 paragraphs of convex arc and sunken circular arc, 3 paragraphs of when can show with dotted line place at this moment equidistant lines undertake process designing, namely
Round radius is round radius for round radius, the terminal coordinate of 3 paragraphs of circular arc by equidistant relation of point of tangency is gotten. Process designing of this kind of method is more intuitionistic, often be used.
Graph 10 press process designing of center of circular arc of point of a knife
4 last words
Cutting tool compensates functional action to basically change a course in Yu Jian, press the outline dimension process designing of the spare parts namely. Before treatment, handlers measures actual cutting tool length, radius and affirmatory compensation sign, input numerical control system as cutting tool compensating parameter, because change knife or cutting tool to wear away,make when bringing parameter of cutting tool dimension to change, although illuminate,use original program, still can machine a spare parts that asks accord with dimension however. In addition, cutting tool compensates a function to still can satisfy a few special requirements of process designing and treatment craft.