SU1352453A1 - System for extreme regulation of vibration amplitude on metal-cutting machine with sliding spindle - Google Patents

Abstract

The invention can be used in managing the processes of roughing and semi-finishing on milling and boring machines with a retractable spindle. The purpose of the invention is to increase the reliability of operation, speed and expansion of the scope of the system. The goal is achieved by taking into account the restrictions on the feed rate and spindle speed, forming a smooth change in the cutting speed, eliminating the system yaw around the mode with a given amplitude of vibrations due to synchronization of the system with tool beats, generating control signals and signals proportional to the amplitude of vibrations, taking into account spindle ratios. To do this, the system containing the stabilization circuit of the power parameter, the unit of permissible vibration amplitude, two storage devices, the search cycle forming unit, the switch, two comparison elements, the spindle speed regulator, the extremum sensor, the threshold element, the And element, the spindle speed limiting unit are entered , amplitude detector, strobe signal generation unit, extremum sensor signal converter, spindle extension sensor, and low pass filter. 1 hp f-ly, 4. Il.

Description

The invention relates to automation, in particular to automatic control and regulation, in particular to systems of extreme regulation, and can be applied in adaptive control of machine tools |

The purpose of the invention is to increase reliability and speed and expand the scope of application of systems

FIG. 1 is a functional diagram of the system for the extreme regulation of the amplitude of vibrations on a cutting machine with a sliding spindle in FIG. 2 - fuktsional-extremum sensor signal converter circuit; in fig. 3 - functionalities of the gate signal forming unit; in fig. 4 is a functional block diagram of the formation of a search for a command generator.

The system contains a speed controller 1 which determines the cutting speed, a power parameter setting device 2, a reference element 3, a feed controller 4, a feed drive 5, a control object 6, a main motion drive 7, a feed restriction unit 8, an extremum sensor 9, a sensor .10 power parameter, unit 11 permissible vibration level, second comparison element 12, switch

13, the low-pass filter 14, the threshold-g with the output of the RS-flip-flop 48. The output of the ele.

The element 15, the element 16, the search cycle forming unit 17, the third comparison element 18, the first 19 and second 20 memories, the spindle speed regulator 21, the adder 22, the spindle speed limiting block 23, the spindle extension sensor 24, the transducer 25, an amplitude detector 26 and a strobe signal generation unit 27.

Blocks 1, 2, 3, 4, 5, 7, 8, 10, and 22 form a contour 28 of stabilizing the cutting parameter.

Inverter 25 includes a serially-controlled control bandpass filter 29 and an amplifier 30 with an adjustable gain factor.

Unit 27 consists of a series-connected detector 31, a low-pass filter 32, and a level reference comparator 33. A predetermined voltage level is applied to the second input of the comparator 33. Comparator 33 output

Ment 47 is connected to the input of the pulse distributor 49. The first two outputs of the distributor 49 are connected to the second input of the switch 13.

40 The third output of the distributor 49 is connected to the first input of the element 18. The R input of the RS flip-flop 5G is connected to the first output of the distributor 49 and the first input of the element OR 51. The output

dc trigger 50 is connected to the second input of the element 16. The fourth output of the distributor 49 is connected to the S-input of the trigger 50 and the second input of the OR 51 element. The trigger output 48 is connected to the second input of the element 47 and S-input of the RS-flip-flop 52. The trigger output 52 is connected to the first input of the SHS-NOT 53 element. The output of the OR 51 element is connected to the R-input of the trigger 52 and the second input of the OR-.NE 53 element. The output of the element 53 is connected to the S-input of the trigger 48.

The controller 4 and block B control the travel speed.

50

55

connected to the first input of a clocked driver 34. The output of the driver 34 is connected to the trigger input

35 and the input element OR 36. The second input element 36 is associated with the output element AND 37. The first input element 37 is connected with the trigger output 35. The first, second and third codes of the generator 38 pulses are connected respectively to the second input of the imaging unit 34, S-input trigger 35 and the second input of the PI element.

The first inputs of the sample-storage nodes 39 and 40 are connected. The outputs of nodes 39 and 40 are connected respectively to the first and second inputs of the comparator 41, the output of the comparator 41 through the driver 42 is connected to the R-input

RS-flip-flop 43 and the first input element YA1Sh 44. The second input element 44 is connected to the output of the element 45. The output of the trigger 43 is connected to the first input of the element I. The fourth, fifth, sixth, seventh and second outputs of the generator 38 are connected respectively to the second inputs nodes 39 and 40, the third input of the comparator 41, the S-input of the trigger 43 and the second input

element I.

Block 17 includes a pulse generator 46, the output of which is connected to the first input of the element OR-g NOT 47. The second input of the element 47 is connected

with the output of RS-flip-flop 48. Elec.

Ment 47 is connected to the input of the pulse distributor 49. The first two outputs of the distributor 49 are connected to the second input of the switch 13.

The third output of the distributor 49 is connected to the first input of the element 18. The R input of the RS flip-flop 5G is connected to the first output of the distributor 49 and the first input of the element OR 51. The output

trigger 50 is connected to the second input of the element 16. The fourth output of the distributor 49 is connected to the S input of the trigger 50 and the second input of the OR element 51. The trigger output 48 is connected to the second input of the element 47 and the S input of the RS flip-flop 52. The trigger output 52 is connected to the first input of the element SH-NOT 53. The output of the element OR 51 is connected to the R-input of the trigger 52 and the second input of the element OR-.NE 53. The output of the element 53 is connected to the S-input of the trigger 48.

The controller 4 and block B control the travel speed.

The machine tool in the proportional-integral (PI) control mode, taking into account the limitation on the maximum node movement speed (S "o | (.), which is primarily determined by the durability of the tool and the capabilities of the feed drive itself.

 The values of the maximum allowable feed rate per tooth () are supplied to the corresponding inputs of block 8 from the system console or from the memory block of the CNC Unit, the number of teeth (Z) of the tool corresponds to the technological program of processing the part, from the drive input 7 a signal about the spindle speed (p), and from the sensor 24 there is a signal about the magnitude of the spindle advance (k.), where L is the magnitude of the spindle extension.

With an increase in the length of the cantilever part of the spindle assembly, the value of the maximum allowable feed rate decreases, which is ensured by the introduction. signal from the spindle extension sensor. The reduction in the permissible feed rate is determined by the limitation on the vibration resistance of the machine. With an increase in the cantilever part of the spindle assembly, the rigidity decreases, the natural frequency and damping of the machine – tool – part system, more precisely, its weakest link — the spindle device.

The value of the maximum allowable movement speed of the node is calculated by the formula:

mmax o max. L ..c ZKP ,,

The controller 21 controls the spindle rotation speed in the PI control mode in accordance with the control signal that comes from element 18. The control in this mode occurs at the moments when the resolution signal comes from element 16. When the amplitude of vibration decreases below the magnitudes A of the signal from element 16 short-circuits the regulator and the signal from the regulator smoothly returns to zero due to the output filter.

The values of the maximum permissible spindle speeds are fed to the corresponding inputs of the block 23 from the system console or from the memory block (

min max

) In accordance with

the technological program for processing the part (i.e., material of the workpiece, cutter and cutting conditions), from the setpoint

1, the set spindle speed (rp) is received, and the voltage from the sensor 24 is proportional to the spindle triggering (). The value of the minimum allowable speed

The spindle, taking into account the extension of the spindle assembly, is determined by the formula:

 L nU

P

min

0

5 The system works as follows.

After the tool has come into contact with the part and the cutting has begun, vibrations may occur, fixed by sensor 9. At the time t, the amplitude of vibrations is analyzed, as it is greater than A, the system performs a trial change of the cutting speed according to the pi law up to the time t. B

5, moment tj is analyzed by the amplitude of vibrations and compared with the amplitude of vibrations measured at time t,. If U A A (t) - A (t,) O, then the output signal of the regulator 21 is inverted according to an aperiodic law, thereby avoiding strikes on the cutter. Thus, on the interval, the system moves in the opposite direction.

5 from the minimum direction. By changing the direction of motion in the interval ,, the system analyzes the amplitude of vibrations at time t and changes the number of spindle revolutions in accordance with the input signal. Comparing the amplitudes of vibrations at times C and uA A (t) - A (t), O, the system continues to move to the minimum of the amplitudes of vibrations in the same direction.

five

At the moment tg the amplitude of vibrations

becomes less than the threshold value, and element 16 removes the signal. Allowing the system to move to a minimum from the regulator 21. Thus, the system establishes the necessary cutting speed, which provides a predetermined amplitude of vibrations. At the time tfl, if the vibration amplitude is less than a predetermined value A, the element 15, through element 16, sends a command to the controller 21, which ensures a smooth return of the cutting speed to the target value. In case of over 51

At a given level of the amplitude of vibrations Ad, the process of searching for an extremum is repeated.

When setting up the system (taking into account the inertia of cutting), it is possible to analyze the amplitudes of vibrations not at successive envelope peaks, but through hectares of intervals, i.e. skip m maximal amplitudes —and compare A; with A; ,

Block 23 takes into account the constraints on the maximum and minimum number of constraints (processing conditions, the corresponding material, the selected tool), taking into account the spindle extension.

The cutting power condition stabilization circuit 28 (for example, cutting power or torque on the spindle) maintains the corresponding power parameter at a given level (based on the processing technology). At the moment of insertion of the tool into the workpiece, a signal appears at the output of sensor 10, which on element 3 is compared with the signal produced by ad sensor 2. According to the result of comparing these signals, controller 4 changes the feed to maintain a predetermined value of the power parameter (M) In block 8, the feed restriction takes into account the change in the number of spindle revolutions and the extension of the spindle assembly, as well as the technological possibilities of processing.

Claims (2)

1. Extreme vibration amplitude control system on a cutting spindle machine tool containing a speed controller, serially connected force parameter generator, reference element, feed regulator and feed drive connected by an output to the first input of the control object, the second input of which is connected to the main drive output the motion, the input of which is connected to the first input of the feed restriction unit connected by the output to the control input of the feed regulator, the first output of the object is regulated connected to the input extremum sensor, the second output controlling the object through the sensor circuit coupled to a second parameter input 524536. the comparison element, the output of the setpoint permissible vibration level is connected through the second comparison element to the inputs of the switch and low-pass filter connected by the output through the threshold element to the first input of the AND element, the second input of the switch is connected to the first output Q block forming the search cycle, the second output of which is connected to the first input of the third comparison element, the second and third inputs of which are under-. They are connected respectively to the outputs 15 of the first and second storage devices, the third output of the search cycle formation block is connected to the second input of the element I, the output of which is connected to the first input of the spindle speed regulator 20 connected to the output of the third element comparison, and the first and second outputs of the switch are connected respectively to the inputs of the first and 25 of the second memory devices, which is associated with the fact that, in order to increase the reliability of the operation, speed and expansion of the system application area, 30 adder, spindle speed limiting unit, spindle extension probe connected in series, transducer, amplitude detector and gating signal generation unit, the spindle extension probe input connected to the third output of the control object, the second converter input connected to the extremum sensor output and the output to the second the input of the gate forming unit, the first input of which is connected to the second input of the second reference element, the first output of the gate generating unit The alov is connected to the input of the search cycle forming unit, and the second output is connected to the second input of the amplitude detector, the output of the spindle speed controller is connected to the first input of the spindle speed limiting unit, the second and third inputs of which are connected respectively to the outputs of the speed limiter and the spindle extension sensor, the output of the spindle speed limiter is connected via an adder to the input of the main motion drive, the second input of the adder is connected to the OUTPUT of the speed setter, and the second input of the feed limiting unit 35 40 45 50 55 chi - with the output of the spindle advance sensor. 2. The system of claim 1, wherein the converter comprises a series-connected controlled band-pass filter and an amplifier with adjustable gain, the first input of the converter being the first input of the controlled band-pass filter, the second input of which is connected to the second input of the amplifier. - with adjustable gain factor and a second converter input, the output of which is an amplifier output with adjustable gain factor. F1 / &, 9 G Editor L.Pcholinsk ( Compiled by P. Kudr vtsev Tehred A. Kravchuk Proofreader G, Reshetnik Order 5565/47 Circulation 863 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 . iti6.27 Y figure 2