Current, breed of numerical control machine tool is already basic and all ready, norms is various, already had 400 according to not complete count many breed norms. Can undertake classified according to a variety of principles. But Baconian rise, common is the following face 4 kinds of methods will classify.
1, classify by craft utility
(1) machine tool of ordinary numerical control. This kind of machine tool and sort of traditional general purpose machine tool are same, the car that has numerical control, mill, boring, auger, grinder is waited a moment, and avery kind of has a lot of variety again, have in numerical control milling machine for example establish mill, lie mill, tool mill, Long Menxi. The craft possibility of this kind of machine tool and general purpose machine tool are similar, what what differ is the spare parts that it can process complex form.
(2) machine tool of numerical control machining center. This kind of machine tool rises in the development on the foundation of machine tool of ordinary numerical control. It is add on machine tool of ordinary numerical control assemble a knife library (can accommodate 10-100 many cutting tool) the numerical control machine tool that trades knife unit automatically with a kind of tape that trade knife unit automatically and makes (say multitask ordinal accuses machine tool or boring again, customarily abbreviation is machining center — Machining Center) , this makes numerical control machine tool is mixed further to automation efficient change directional development.
Is the distinction of machine tool of numerical control machining center and machine tool of ordinary numerical control: ? Device of numerical control of? of sunken have diarrhoea of witch of the Huaihe River of ぜ can control a machine tool to change automatically cutting tool, machine a face to finish mill automatically each to workpiece continuously (car) , boring, auger, the multitask foreword treatment such as bore with a reamer and tap. This kind of machine tool is given priority to with boring mill mostly, basically use treatment casing part. It and phase of general numerical control machine tool are like next advantages than providing:
① reduces number of machine tool stage, facilitating management, want a machine tool to be able to complete full treatment only to the spare parts of multitask foreword, can reduce the stocks of semi-manufactured goods;
② should hold clip only as a result of workpiece, because because install the fixed position error that cause for many times,this decreased, can rely on machine tool precision to assure to machine quality;
③ working procedure is centered, reduced auxiliary time, improved productivity;
④ installs clip to be able to complete treatment of much talk working procedure last time in a machine tool as a result of the spare parts, reduced the amount of special class clamping apparatus greatly so, shortened further production plans time.
Still have a kind of machining center additionally, rise in the development on lathe foundation, with the axis kind the spare parts is main treatment object. Divide outside can undertaking turning, boring, still can have place of the random on end panel and week face auger cut, milling and tap treatment. This kind of machining center also sets knife warehouse, can install 4-12 cutting tool, customarily call this kind of machine tool turning center (TC: Turning Center) .
Graph the numerical control treatment of linkage of 1 5 axes
(3) machine tool of much coordinate numerical control. Have the part of some of complex form, use the numerical control machine tool of 3 coordinate to still cannot be machined, the treatment that is like spare parts of curved surface of airscrew, plane, the treatment of synthetic motion ability that needs 3 above coordinate gives place want form. Appeared then the numerical control machine tool of much coordinate, its characteristic is number of axle of pilot of numerical control device more, machine tool structure is more complex also, its coordinate number of axle depends on normally the craft requirement that machines a spare parts. Commonly used now is 4, 5, the numerical control machine tool of 6 coordinate. Graph the 1 numerical control that is 5 axes linkage machines sketch map. At this moment, x, y, z3 of the circumgyrate of coordinate and revolving stage, cutting tool it is OK to swing at the same time linkage, in order to machine kind of spare parts such as wing.
2, the athletic contrail classification that presses numerical control machine tool
According to the contrail that can move relatively between pilot cutting tool and workpiece, can separate numerical control machine tool machine tool of numerical control of the position control that it is a dot, aspect machine tool of machine tool of linear control numerical control, outline control numerical control. Show cent to narrate as follows:
(1) machine tool of numerical control of dot position control. The numerical control device of this kind of machine tool can control part of machine tool shift only from a position (dot) accurately shift arrives another position (nod) , control the coordinate cost of journey terminus only namely, do not undertake in mobile process any cutting are machined, as to the two shift between relevant point speed reachs a course to depend on productivity. Have to be on the foundation of exact location as far as possible tall productivity, so two-phase involves the shift between the dot is first be close to new position with moving quickly, fall next fast 1-3 class, those who make is slow dot of fast approach fixed position, in order to assure precision of its fixed position.
Punching machine of drilling machine of boring machine of coordinate of main numerical control, numerical control, numerical control and numerical control measure this kind of machine tool machine,
(2) choose a machine tool of linear control numerical control. When this kind of machine tool works, should control two-phase to close the position between the dot not only (be apart from) namely, control two-phase to close the floating rate between the dot and line even (namely orbit) . Its course is general comprise by the straight line segment with each axes parallel. It and the distinction that choose machine tool of position control numerical control depend on: When the mobile component of the machine tool is mobile, can the direction along a reference axis (popularly is OK also undertake cutting along 45 ° diagonal, but cannot the linear cutting along aleatoric slope) undertake cutting is machined, and the numerical control machine tool that its assist a function to compare bit of position control is much, for example, should increase treatment of feed of control of main shaft rotate speed, loop, cutting tool to choose to wait for a function.
This kind of machine tool basically has milling machine of boring of lathe of simple and easy numerical control, numerical control and numerical control machining center to wait. Corresponding numerical control unit says to order a linear control equipment.
(3) outline controls numerical control machine tool. The control equipment of this kind of machine tool can be opposite two at the same time or the reference axis of two above has successive control. Add man-hour to want to control start and terminus not only, dominate the speed of every bits in whole treatment process and niche even, make the machine tool machines the part that gives the complex appearance that accords with blueprint requirement. Its auxiliary function also is compared all ready.
This kind of machine tool basically has grinder of milling machine of numerical control lathe, numerical control, numerical control and report to machine a machine tool to wait. Its corresponding numerical control unit says it is outline control equipment (or continuous control equipment) .
3, the control means classification that presses servo
Numerical control machine tool according to right controlled the quantity has without detect feedback device can be divided for open loop and closed circuit two kinds. In closed circuit system, the position that puts according to measurement unit can be its cent again complete closed circuit and half closed circuit two kinds. On the foundation of open loop system, still developed system of compensation of a kind of open loop numerical control.
Graph 2 open loop control systematic block diagram
The flow that numerical control device issues signal is one-way, so problem of nonexistent system stability. Also the one-way flow as a result of signal, it is not made to the real position of component of machine tool shift examine, precision of machine tool treatment is not so tall, its precision basically depends on the function of servo. Working process is: The data of the input allocates an instruction pulse through operation of numerical control unit, through servo orgnaization (servo component often enters electric machinery for the pace) make be accused workbench is mobile.
Job of this kind of machine tool compares stable, response rapid, debug convenient, maintenance simple, but its control precision to be restricted. It applies to the machine tool of medium, small-sized numerical control of general requirement.
(Machine tool of 2) closed-loop control numerical control. Because open loop controls the demand of machine tool of nicety of precision short of and large machine tool, must detect so its real work place, for this, increase on machine tool of numerical control of open loop control detect feedback device, always detect in treatment the position of component of machine tool shift, the positional conform to that makes institute of plant of the sum numerical control asks closes, with period achieve very tall treatment precision.
Block diagram of closed-loop control system is shown 3 times like the graph. The A in the graph measures component for speed, c measures component for the position. When statement cost sends positional comparator, be like workbench to do not have shift right now, do not have feedback quantity, dictate the value makes servo electric machinery rotational, through A general speed feedback signal sends speed to dominate circuit, through C general workbench actual displacement measures feedback to go back, with the instruction in positional comparator the value undertakes comparative, undertake controlling with relative poor value, when till need a value,be being eliminated till, realize the exact location of workbench finally. The advantage of this kind of machine tool is precision tall, rate is rapid, but debug and maintenance is more complex. Its key is systematic stability, must give to stability when the design so take seriously enoughly.
Graph block diagram of system of 3 closed-loop control
(3) is OK and general. Flexibility and adaptability are consequently strong, also facilitate batch is produced, modular soft, hardware, raised systematic quality and dependability. So, machine tool of contemporary numerical control uses CNC device. Machine tool of numerical control of half closed-loop control. The composition of system of half closed-loop control is shown 4 times like the graph.
Graph block diagram of system of 4 half closed-loop control
Means of this kind of control does not undertake checking metrical to the real position of workbench, pass however measure component with contact of servo electric machinery, if measure fast dynamo A and photoelectricity code dish of B(or rotate transformer) wait to detect secondhand the corner that gives servo electric machinery, push the actual displacement of cipher out workbench to measure, graph block diagram of system of 4 half closed-loop control uses this value and statement cost to undertake comparative, the value that use difference will realize control. From the graph 5 can see, because workbench did not include completely to be inside control loop, say consequently for half closed-loop control. Means of this kind of control uprights between open loop and closed circuit, precision is tall without closed circuit, debug more convenient than closed circuit however.
(Machine tool of compensation of 4) open loop numerical control. Rise 3 kinds of afore-mentioned characteristics that control fashion centrally selectively, can form the plan of mixed control. This is the subject that people studies for years in machine tool of large numerical control, already became reality now. Because, machine tool of large numerical control, need is so tall that need much feed speed mixes return rate, need quite tall precision again. If use the control of complete closed circuit only, all park controls catenary of machine tool drive and workbench in link, the element is very complex, although installation debugs much classics setbacks, difficult still and heavy. For escape these contradict, can use mixed control means. In specific plan it can divide again for two kinds of forms: It is open loop compensation; It is half closed circuit compensation. Here tries machine tool of numerical control of open loop compensation control to introduce only.
Graph the 5 compositive block diagram that are means of open loop compensation control. Its characteristic is: Main control chooses a pace to control servo orgnaization into the open loop of electric machinery, add circuit of a corrective servo. The feedback signal that measures component through installing the linear displacement on workbench comes the error of corrective and mechanical system.
Graph block diagram of compensation of 5 open loop control
4, classify by numerical control device
If numerical control machine tool realizes device of numerical control of pilot of function of numerical control logic to divide by its, have hard line () numerical control and flexible cord () numerical control two kinds.
(1) hard line numerical control (weigh ordinary numerical control, namely NC) . The function such as operation of the input of system of this kind of numerical control, interpolation, control all wait for parts of an apparatus to come true by integrated circuit or discrete element. Generally speaking, numerical control machine tool is different, its control circuit to also differ, systematic versatility is accordingly poorer, because its are comprised by hardware entirely, function and flexibility are so poorer also. This kind of system applies more extensively before in 70 time.
(2) flexible cord numerical control (weigh computerized numerical control or personal computer numerical control again, namely CNC or MNC) . This kind of system is used medium, large-scale reach VLSI to form CNC unit, or comprise with personal computer and special and compositive chip, main numerical control function comes true almost completely by software, to different numerical control machine tool, simply weaves different software can come true, and hardware is almost OK and general. Flexibility and adaptability are consequently strong, also facilitate batch is produced, modular soft, hardware, raised systematic quality and dependability. So, machine tool of contemporary numerical control uses CNC device.