SU1231485A1 - Device for automatic checking and controlling of process for cutting by means of numerically controlled machine tool - Google Patents

Abstract

The invention relates to the field of mechanical engineering and allows to expand the functionality by generating control signals taking into account the magnitude of the extension of the spindle assembly and the parameters of the mandrel and to improve the accuracy of measurement of vibrations in the cutting zone. B in accordance with the parameters of the selected tool and the signal of the spindle advancement sensor, taking into account the data of the memory block through the communication unit with the machine, generates signals on the transducer amplitude of the vibration amplitude and the conversion component of the cutting forces. Signals proportional to the amplitude of vibrations A of the spindle assembly and the magnitude of the torque M on the spindle shaft are amplified. In the control unit, the signals are compared with the maximum allowable values A, M, M,. If the amplitude vibration A of the spindle assembly in the cutting zone is either exceeded by a pull point M on the spindle shaft, or the torque ramp up rate of the corresponding limit values, the control unit performs emergency braking of the feed drive. If the signal from the control unit through the communication unit enters the processor within a specified period of time, the processor, through the communication unit with the machine, sends a signal to the second input. The control unit is set to exit the tool from the workpiece, thereby preventing the quality of the workpiece from deteriorating. When cutting, if the amplitude of vibrations A of the spindle assembly in the cutting zone, the magnitude of the torque M at the spindle and the rate of increase of the torque M are less than the corresponding maximum permissible values A, M, M, then the information about the amplitude of vibrations A and the magnitude of the torque enters the processor, where it is compared with the optimal values stored in the memory unit, and the control signals are changed, which are fed to the drive inputs and through the communication unit with the machine in order to optimize the cutting process, 3 hp. f-ly, 4 silt, 1 tab. i (L N9 00 4 :: 00 ate

Description

The invention relates to mechanical engineering and can be used in controlling roughing and semi-finishing processes on CNC milling machines.

The purpose of the invention is to expand the functionality of the device by generating control signals taking into account the spindle device spacing and mandrel parameters and increasing the accuracy of measuring vibrations in the cutting zone.

Fig. „1 shows the functional diagram of the device for automatic control and monitoring of the process of relays on CNC machines; in fig. 2 - the same, with the disclosure of the performance of individual blocks; in fig. 3 is a schematic diagram of a logic element; in fig. 4 is a timing diagram of the operation of the spindle vibration conversion unit.

A device for automatically monitoring and controlling the cutting process on CNC machines contains a standard CNC 1 device, including a processor 2, a memory block 3, a communication block 4 with a machine, an analog-to-digital converter 5.

The device; for automatic control and control of the cutting process on CNC machines, also contains a control unit 6, a feed drive 7, a main motion drive 8, a control and control object 9, a component of measuring cutting force components 10, a conversion unit 11 comprising x cutting forces, vibration amplitude conversion unit 12, spindle extension sensor 13. The control unit 6 contains a logic element 14, comparison elements 15-17, rectifiers 18-20, diode limiters 21-23, OR 24, differentiation unit 25. The conversion unit 11 comprised ush 1x of cutting forces 26 and an adjustable gain amplifier 27.

Amplitude amplitude conversion unit 12 includes a controllable bandpass filter 28, a variable gain amplifier 29, a detector 30, a first low pass filter 31, a variable selection component 32, a differentiation unit 33, a first comparator 34 zero level, first rectified 0

0

five

five

35 40 45

50 55

the driver 35, the first diode stop 36, the first driver 37, the first element 38, the second zero level comparator 39, the second rectifier 40, the second diode stop 41, the second driver 42, RS-flip-flop 43, the third comparator 44 , the third rectifier 45, the third diode limiter 46, the second element And 47, the third driver 48, the amplitude detector 49, the second low-pass filter 50, the sample-storage node 51.

Logic element 14 contains operational amplifiers 52 and 53, the first switching element 54 with contacts 54 and 545, the second switching element 55 with contact 55, resistors 56 - 61,

FIG. Figure 2 shows the maximum allowable and current amplitudes of vibrations of Hell and A., the maximum allowable and current torques of M and M on the spindle, the maximum allowable and current values of the rate of increase of the torque of M and M on the spindle.

On. Fig. 4, the signals at output 1 are indicated as follows: a - block 10; b - filter 28; in - detector 30; g - filter 31; d - node 32; e - node 33; W - limiter 36; 3 —former 37; and - limiter 41; Kg shaper 42; l - limiter 46; m - element 47; n - shaper 48; o - trigger 43; p - element 38; p - detector 49; c - filter 50; t - node 51,

The 2C42 device is used as a CNC device.

Processor 2 and memory block 3 are Electronics-60 computer units included in 2C42.

Block 4 — Block Interface of communication with the machine; ADC - ADC adaptive control; The information exchange channels of processor 2 with blocks 3, 4 and 5 are the internal channels of the 2C42 device.

The component 10 for measuring the component cutting forces includes sensors for the radial and tangential components c: sh1 cut placed on the respective organs of the machine.

On the relevant bodies of the object 9 control and management of metal. The radial component of the cutting machine, namely, in the pockets of the hydrostatic bearing, has sensors of the radial component of the cutting force. As sensors

With the diagonal component of the cutting force, inductive pressure sensors DC-10 can be used, embedded in the pockets of the hydrostatic bearing or vibration sensors D-13, located on the sleeve fitted on the outer ring of the front bearing of the spindle assembly, oriented in the radial direction. The sensor of the tangential component of the cutting force on milling and boring machines can serve as a torque sensor, made taking into account the tool radius.

Unit 10 also contains a sinusoidal voltage generator for power supply of inductive pressure sensors DD-10 and preamplifiers of sensor signals.

The first output of block 10 (the output of the second preamplifier) - the tangential component - is connected to the first input of the block 11 of the conversion of the component cutting forces

The second output of the unit 10 (the output of one of the pre-amplifiers) is a radial component connected to the first input of the spindle vibration conversion unit 12.

 The sensor 13 of the spindle extension: is installed in such a way that its individual elements are placed on the movable and fixed organs of the machine in accordance with their functional purpose.

As a spindle extension sensor, any cyclic sensor can be used in conjunction with. a converter (e.g. inductoxin, selsyn, rotary transformer).

The spindle vibration conversion unit 12 is a signal extraction and conversion unit proportional to the amplitude of the spindle vibrations.

The logical element 14 of block 6 with zero signals JJax at its inputs II and III has a transmission coefficient equal to one. At occurrence of the signal unit at the input II coefficient

transmission of a logic element 14 of Sta-50 vii with spindle assembly parameters

and chisel frame (stiffness and demounting).

equal to (-1).

The band-pass filter 28 of the 125UP voltage controlled unit provides for the separation of the signal at a frequency close to the natural frequency of the specific 55 device. The band-pass filter frequency is determined by the control voltage.

- five . ABOUT .

 520

25

thirty

.

45

35

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The device works as follows.

Before the start of a given technological operation, the signals of the corresponding maximum permissible values from the memory block 3 by the processor 2 through the communication unit A with the machine are fed to the first inputs of the corresponding elements 15-17 of block 6.

Before embedding, the amplitude of vibrations A is insignificant and much less than the maximum permissible value A specified in block 3 of the CNC memory and fed through processor 2 to the output of block 4. The torque of m on the spindle and the rate of increase of torque M are much lower than the maximum permissible corresponding values

MO and M.

The values of the maximum permissible values of A, MO and MO for this technological operation are stored in memory block 3.

For a given control technology program, a tool is selected from the tool magazine of a machine of the type machining center. Instrument parameters are stored in memory block 3.

In accordance with the parameters of the selected tool and the signal of the spindle insertion sensor 12, the processor 2, taking into account the data of the memory block 3, via the communication unit 4 with the machine, generates signals to the inputs III of the filter 28 and the amplifier 29 of the block 12 and the amplifier 27 of the block 11 (FIG. 2).

The signal (Fig. 4a) from the sensor of the radial component of the cutting force of the block 10 goes to the band-driven filter 28 of the block 12. The parameters of this filter change when the spindle moves or when the mandrel is replaced. The filter 28 is thus adjusted to its own bending frequency spindle assembly. After the filter, the signal (Fig. 4iS) is fed to the amplifier 29, where the signal is scaled to 40

vii with spindle assembly parameters

and chisel frame (stiffness and damping).

FIG. 4c shows a diagram of the formation of a signal at the output of block 12, which is proportional to the maximum amplitude of the vibrations of the spindle assembly.

The most important elements of block 12 are the amplitude (peak) detector 49 and the sample-storage node 51. The mplit detector 49 is designed to store the extreme values of the input signal (Fig. 46). As 5 increases the input voltage (input 1, figo 4B), it is monitored by the output voltage (FIG. 4p) 5, and when the input signal decreases, the amplitude detector goes into storage mode and remembers the previous maximum value of the input voltage. This voltage is held at the output of the detector (Fig. 4p) or until a larger signal is received at the input 1 5 (Fig. 46), W1I before the reset command (input II, fig. 4d;).

The sampling-storage node in the sampling mode (in the presence of a signal at input IIj of Fig. 4k) repeats input signal 1 (Fig. 4c) at the output (Fig. 4m) and then on command (in the absence of a signal at input II) remembers its instantaneous value and goes into storage mode (Fig. 4t). The detector 30 performs one half-period rectification (FIG. 46). Filter 31 performs (Fig. 4d) low-pass filtering (0.2-15 Hz), eliminating the high-frequency component of the spectrum (80-30-50 Hz), due to the natural frequency of the spindle and mandrel system ..

The node 32 selects the variable component of the signal (Fig. 45), and the node 33 performs a rather accurate 35 signal differentiation (Fig. 4e). At the output of the diode limiter 36 (Fig. A signal is generated, the amplitude of which has the magnitude necessary for working with discrete 40 integrated circuits. (IC), for example, 5 V - 1 for the IC 155 series. Shaper 37 on the trailing edge of the signal gives a short pulse given the duration (fig.4z) required for the peak detector 49 to operate while reducing the amplitude of the input signal of block 12. The limiter 41, like 36, generates a signal for the operation of discrete ICs (fig. 4i) .50 Shaper 42 on the trailing edge of the signal limiter 41 outputs are short th pulse of the required duration (Fig. 4k), which sets the RS-flip-flop 43 to state 1 and controls the operation of the node 51 (Fig. 4o). At the output of the limiter 46, a signal (Fig. 4l) of a given amplitude is generated

(for IC 155 series 5 V) if the input signal of block 12 currently exceeds the maximum amplitude of the signal at the input of block 12 at the previous recording time in node 51 (you can compare Fig. 4, and 4t). At the output of the element 47, a signal is formed (Fig. 4m), on the leading edge of which the driver 48 produces a short pulse (Fig. 4n), which sets the RS flip-flop 43 to the state O (Fig. 4o). At the output of element 38, a signal appears (Fig 4p) in the case of a coincidence of units at its inputs. Such a phenomenon occurs when the maximum amplitude of the input signal of block 12 decreases. Filter 50 is necessary in order to smooth out the spike caused by the operation of detector 49 while reducing the input signal of block 12 (Fig. 4c). The signal from the torque sensor of the block 10, proportional to the tangential component of the cutting force (torque on the spindle), is processed by the filter 26 of the block 11 (the noise associated with the electric pickup of the wheel speed bar and t, e) is eliminated and scaled by the amplifier 27 block 11 (Fig. 2), taking into account the cantilever part of the spindle-mandrel system. As this system changes, the maximum permissible value of the tangential component of the cutting force (torque) due to the vibration resistance of the machine also changes (as the spindle increases, the maximum permissible value decreases and the gain of the amplifier 27 increases).

In block 6, the signals generated in blocks 11 and 12 are compared with the maximum permissible values of M,

about

Md n Hell. When the amplitude of vibrations of the spindle assembly in the cutting zone or the torque M on the spindle shaft, or the growth rate M of the torque of the corresponding limit values is increased, a logical signal appears at the output of the OR element 24 and is applied to the logic element 14 that performs emergency braking feed drive. If the signal from the element 27 through the communication unit 4 enters the processor 2 within a specified period of time, the processor 2 through the communication unit 4

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The signal (on the second Task of the control unit 6) on the tool from the workpiece, thereby preventing deterioration of the quality of the paged product.

Logical element 14 Avlaine in the table.

chi pho si og et xp vy va va te me ct 5 de zu in that ru k ni fe SP

T.

The transmission coefficient of the logic element 14

-one

-one

After the tool is removed from the workpiece, a tool change process is carried out. When cutting, if the amplitude of vibrations A of the spindle assembly in the cutting zone, the magnitude of the torque M at the spindle and the rate of increase of the torque M are less than the corresponding maximum allowable values Ad, Md, M, then information about the amplitude of vibrations A and the magnitude of torque M enters through the analog-to-digital converter 5 to the processor 2, where it is compared with the optimal values for a given technological operation, stored in memory block 3, and the control signals are changed, which are sent to the inputs p ivodov 6 and 7 through the communication unit 4 to the machine in order to optimize the cutting process. At the input of the drive 7, the signal enters through block 6 (this is the first entry of the Task). When the signal proportional to the tangential component of the cutting force exceeds the optimum value, a signal is generated that reduces the reference signal supplied to the input of the drive 7 taking into account the limitation on the maximum feed rate. The last logical operation is carried out in processor 2 with the help of block 3 of

50 of the spindle assembly and parameters of the refraction and increase in the accuracy of vibration measurement in the cutting zone, the control unit as well as the conversion components of the component forces are cut in it

This is where the maximum feed value for this technological 55 "and the amplitude of spindle vibrations and operation is stored.

advancement sensor: spindle, with the first group of inputs The task of the control unit is connected to the outputs of the unit

In the case when the signal is proportional to the maximum amplitude of the vibration

exceeds the optimal value, a change in the control signal at the output of the drive 8 is formed taking into account the restrictions on the cutting speed. Consideration of these restrictions, the values of which are stored in the memory block 3 of the CNC Unit 1, is performed in the processor 2. The block 6 thus constructed provides the maximum speed required to protect the elements of the AIDS system on CNC machines of the CNC type. The device allows to take into account the change of the cantilever part of the spindle-mandrel system, more accurately and reliably generate a signal characterizing the amplitude of vibrations of the cutting tool in the cutting zone, more accurately determine the tool breakage time, which together leads to an increase in the quality of the cutting process, tool life and the effectiveness of the protection of elements of the AIDS system.

The invention can find application in all milling and boring machines with a numerical control device such as CNC, as well as in machine-modules built on the basis of the machines of this group.

Claims (3)

1. A device for automatic control and management of the cutting process 35 on CNC machines, containing a processor connected to the communication channel with the memory unit and the communication unit with the machine and connected by inputs to the analog-digital 40 transducer, feed drives and main movement organoz. machine tool, as well as a component measurement unit, including radial and tangential component sensors 45 cutting forces, characterized in that, in order to extend the functionality by generating control signals taking into account the magnitude of the movement 50 of the spindle assembly and parameters of the mandrel and increasing the accuracy of measuring vibrations in the cutting zone, a control unit is introduced into it, as well as blocks for converting the component cutting forces 55 "and the vibration amplitudes of the spindle and "And and the vibration amplitude of the spindle and advancement sensor: spindle, with the first group of inputs The task of the control unit is connected to the outputs of the unit and the second 1 con block group connection with the machine, inputs The current state of the trolley is connected to the outputs of the spindle vibration transducer units and the component cutting forces, respectively, the first output of the control unit is connected to the feed drive, and the second to the input of the communication unit with the machine, the first inputs of the vibration amplitude conversion units and the component cutting forces are connected to the outputs of the measuring unit: yu: c cutting forces, the second and third inputs of these blocks are connected respectively to each other, and the third inputs of these blocks are connected to the communication unit with the machine The spindle extension outflow sensor is connected to the first input of the analog-digital converter and the second inputs of the conversion unit of vibration and component slaughter forces, besides the inputs of the current state of the control unit are connected to the second inputs of the analog-digital converter, and the main motion drive is connected to communication unit with the machine. 2. An apparatus according to claim 1, characterized in that the amplitude-amplitude conversion unit is designed as a series-connected controlled bandpass filter amplifier with an adjustable gain factor, a detector, a first low-pass filter, a variable component node, a differentiation unit, the first a zero level comparator, a first rectifier, a first diode limiter, and a first shaper, and also contains a second zero level comparator, a third zero level comparator, two l, two diode limiters, three drivers, two elements, AND, RS trigger, amplitude detector, second low-pass filter, sampling-storage unit, and the detector output is connected to the first input of the amplitude detector, the output of the first driver is connected to the first input of the first element And, the output of which is connected to the second input of the amplitude detector, and the output of the variable component component of the signal through the second zero level comparator connected in series, the second rectifier, the second diode limiter and the second oh form ten 15 20 25 31485 The rover is connected to the S-input of the RS-flip-flop, the output of which is connected to the second-1 input of the first element AND, besides the output of the first low-pass filter is connected to the first input of the third comparator, the output of which through the third diode limiter, the second element And and the third driver are connected to the R-BXO-house RS-flip-flop, the output of the second diode limiter g is connected to the second input of the second element And, and the output of the amplitude detector is connected to the input of the second low-pass filter, which is connected to the first input of the sampling-storage unit and is the output of a vibration amplitude conversion unit, the output of the second shaper is connected to the second input of the sampling-storage unit, the output of which is connected to the second input of the third comparator is the first input of a vibration amplitude conversion unit, the second and third inputs of which are the second and third inputs of a band-pass controlled filter, connected respectively to the second and third inputs of the amplifier with Rui gain coefficient. 3. The device of Claim 1, which is that the conversion unit of the component cutting forces comprises a series-connected low-pass filter and an amplifier with an adjustable gain factor, the input of the low-pass filter being the first input of the conversion part block cutting forces, the second and third inputs of the amplifier with an adjustable gain factor are respectively the second and third inputs of the conversion unit of the component cutting forces, the output of which is the output of the amplifier with an adjustable coefficient gain ratio. 4, a device according to claim 1, characterized in that the control unit comprises a logic element, an OR element, a differentiation node, and three groups of elements, each of which consists of a series-connected comparison element, a rectifier and a diode limiter,. the output of which is connected to 35 40 45 50 55 П123 the input of the OR element, the first and second inputs of the logic element are the corresponding inputs of the first group of inputs of the control unit, the output of the logic element is the first output of the control unit, the third input of the logic element is connected to the output of the OR element and the second output of the control unit comparison items 485 12 connected to the remaining inputs of the first group of inputs of the control unit, the second inputs of the first and second comparison elements are connected to the corresponding inputs of the second group of inputs of the control unit, the second input of the second comparison element is connected through the differentiation node to the second input of the third comparison element. Inputs Quest t  current state SnoSbi „jaSctntji 1 DTl Otit orW