The economy to common lathe numerical control is transformed, when considering overall design plan, the principle that should follow is: Below the future that asks in contented design, to the machine tool alter should as far as possible little, in order to reduce cost.
One, the numerical control of lathe is transformed
1, principle of job of numerical control machine tool and composition
1) principle of job of numerical control machine tool:
When numerical control machine tool machines a spare parts, should weave above all the machine program of the spare parts, this is the working instruction of numerical control machine tool. Input machine program numerical control device, control a machine tool by numerical control device again advocate athletic change, case stop, if clamp of exchange of cutting tool choice, workpiece loosens and the direction that feed moves, speed and displacement quantity and other cool lubricant, close wait for a movement, make cutting tool and workpiece and other assist the sets according to machine program order with firm device, contrail and parameter to have the job, machine a spare parts that accords with a requirement thereby.
2) the composition of numerical control machine tool:
Numerical control machine tool basically is mixed by device of control medium, numerical control, servo the 4 parts composition such as machine tool noumenon, following plan institute show its composition block diagram:
2, design content and task
Common lathe (C618) numerical control transforms design content to include: Overall program is decided really and the test and verify, design that machinery transforms a part is calculated (the design that includes system of fore-and-aft, transverse feed and computation) , advocate movement is voluntary the design of circuit of control of electromotor of timing of gearshift principle and the design that the system of machine tool transmission after transforming pursues, machine tool, electromagnetism. .
This design task is right C618 center lathe undertakes counting accusing to change transforming, implementation personal computer turns control to the numerical control of lathe. Use personal computer to undertake to the system of fore-and-aft, transverse feed of lathe the number is controlled, want to achieve unit of fore-and-aft the least movement to be 0.01 / pulse, pulse of 0.005 / of unit of transverse the least movement, advocate motion should implement automatic speed change, tool carrier should transform the automatic dislocation tool carrier of automata, want can automatic cutting whorl.
3, the design of numerical control part is transformed
1) way of movement of numerical control system is decided really
Numerical control system can divide by its motion contrail for: Order position control system, successive control system. System of dot position control asks to control cutting tool to move from only a bit more additional position, and do not impose control to athletic contrail in principle. Successive control system can be opposite two or the displacement of direction of two above coordinate has strict uninterrupted control. Because C618 lathe wants to machine complex outline spare parts, so system of this personal computer numerical control uses successive control system.
2) the design of servo feed system is transformed
The servo feed system of numerical control machine tool is pressed have detect without the position and feedback can be divided for servo of open loop servo, half closed circuit, closed circuit servo.
The advantage of closed-loop control plan is the machine tool precision that can achieve become reconciled, can compensate all sorts of errors in mechanical transmission system, remove the clearance, interference effect to machining precision. But his structure difficulty of complex, technology big, mode and maintenance difficulty, cost is high.
System of half closed-loop control because timing range is wide, overload capability is strong, use feedback control again, because this function far excel enters the open loop of electromotor drive with the pace,control a system. But, use half closed-loop control its mode wants than open loop complex, there also should be the characteristic of its oneself on the design, technical difficulty is greater.
Open loop does not have positional controller and feedback circuitry in control system, the precision of open loop system is accordingly poorer, but its structure is simple, adjust easily, so commonly used ask at precision not tall circumstance.
The foreword on the course is compared, the demand of cause treatment precision of the C618 lathe that transforms as a result of place is not high, so the decision uses open loop to control a system.
3) the hardware circuit design of numerical control system
Numerical control system is by hardware and software two parts are comprised, hardware is the base that controls a system, the stand or fall of function affects the character of service of system of integral numerical control directly.
The design program of numerical control device has normally:
● is OK and all him design is made
● can use veneer machine or STD module or labour accuse machine change make
● can choose off-the-peg numerical control device to make a few suit change alter
Transform in the economy of general accuracy machine tool numerical control in, because the first kind of design is periodic longer and wasteful, at the same time quality also is hard to assure. The 2nd kind more wasteful. So not curricular design will adopt plan of the 3rd bell.