SU1196812A1 - Device for limiting torque of power nut-driver - Google Patents

Abstract

A DEVICE FOR RESTRICTING THE WRINKING TORQUE WRITER, containing a rotational speed sensor and a torque sensorj connected by outputs to the inputs of the first multiplication unit and the second multiplication unit connected to the input of the differentiating element, sequentially connected actuator and control valve installed on the compressed supply line air to the drive of the wrench, characterized in that, in order to improve the accuracy of the device, it introduced two analog-digital converter, two triggers, two switches, three registers, computing unit, constant input block, two comparison elements, three AND elements, pulse generator, pulse shaper, key, digital-to-analog converter, pulse counter and analog adder connected by the first input to the direct output of the second trigger, to the first input of the second element AND, the control of 4. the input of the pulse counter, to the first control inputs of the first and second switches and to the first control input of the computing unit associated with the second control input with the second control inputs of the first and second switches, with the forward output of the first trigger, with the second inputs the first and second elements And, with a single input of the second trigger and with a control input of the key, the information input of the computing unit is connected to the output of the first commutator, torus, and the output with the information input of the second switch, connected by the first and second information outputs to the information inputs 4 of the first and second register, respectively, and the third information outputs to the information inputs of the third register connected by outputs to the input of a digital-analog converter connected to the second input of the analog adder, connected to the third input to the output of the first multiplication unit, and the output to the 00 information input of the key and to the input of the pulse former connected to the first control input of the primary Comparison element associated with the output with the zero input of the first trigger, the second control input with the output of the first And element, the first information input with the output of the first register, and the second information input with the output of the second analog-digital converter and the first information input of the first switch connected by the second information input to the output

Description

the first analog-to-digital converter and the third information input to the output of the input unit of constants connected to the bus inputs; input of the device constants; bus The device start is connected to the single input of the first trigger, with the information input of the pulse counter; associated with the output of the pulse generator, the first information outputs of the counter with the departures TpeTb lb of the And element, and the second information outputs — with the first information inputs of the second comparison element connected by the second information 6812

the inputs to the outputs of the second register, the output to the zero input of the second trigger, the first control input to the output of the third element I, and the second control input to the output of the second element I, the inverse output of the second trigger I, the key output is connected to the actuator input, the output of the differentiating element is connected to the input of the first analog-digital converter, and the input of the second analog-to-digital converter i is connected to the output of the second multiplication unit.

The invention relates to devices for limiting the torque (KM) on the spindle of screw-closing devices with a pneumatic actuator, which are expedient to use when equipping wrenches designed to tighten bolted connections with a given W in products of the transport engineering, while the wrenches can be filled for manual or stationary use, and also in the form of units for automatic means of assembly.

The purpose of the invention is to improve the accuracy of the device.

Figure 1 shows the block diagram of the device; figure 2 - timing diagram of the devices.

The device contains a control valve 1, a wrench drive 2, a rotational speed sensor 3, a torque sensor 4, a first multiplication unit 5, an analog adder 6, a second multiplication unit 7, a differentiating element 8, a first 9 and a second 10 analog-digital converters, a first switch 11, block 12 input constants, computing unit 13, second switch 14, first 15, second 16 and third 17 registers, first 18 and second 19 comparison elements, digital-to-analog converter 20, pulse counter 21, pulse generator 22, third And 23 shaped spruce pulses 24, the key 25, executive

mechanism 26, first 27 and second 28

triggers, the first 29 and second 30 elements And, the bus 31 input constants, input 32 Start the device.

The device works as follows.

in a way.

When applied to a power supply device at the direct outputs. Triggers 27 and 28 are set to logical zeros. In this case, the key 25 is closed and the actuating element 26 (for which an amplifier can be used) maintains the closed state of the valve 1 standing on the compressed air line.

In this initial state, the counter 21 is set to the initial (zero) state, at the outputs of the And 23, 29 and 30 elements, the zero-levels prohibiting the operation of the elements 18 and 19 of the comparison. Their outputs are also zero levels. In the initial state, the bus 31 in the block 12 input constants are entered constant

the values characterizing the parameters of the process of tightening the nuts: I is the magnitude of the moment of inertia of the rotating parts of the wrench mechanism, M is the magnitude of the torque, P is the pressure of the rotating air; the magnitude of the torque with which the flow should be (then the connection i co is the frequency of rotation of the wrench; Uj, is the coefficient determined from the ratios

ABOUT

, (T) - coefficient

R

) of

produced

ratios m

 - C00jq p- full rotation angle o

the start of the advancement of the nut on the free part of the bolt shank before the start of the tightening of the nut.

Additionally, the frequency value CJ J is entered at which the bolted joint is scheduled to be tightened. The number corresponding to the frequency co, after entering it into the input unit 12, the constants passes through the switches 11 and 14, the computing unit 13 into the register 17 and is converted into an analog form in the converter 20.

The device and the wrench are turned on by applying a signal to input 32. In this case, the direct output of the trigger 27 is logical 1, the state of the trigger 28 changes (the logical output 1 appears logical 1). At the same time at the output of the element I 30 on vHit

permissive

I 1

the signal from the output element And 23 to the input element 19 of the comparison. The signal 1 is fed to one input of the adder 6. At the same time, a signal 1 is produced at its output, a passage through the switch 25 (opens at 1 at its control input) and through an actuator 26, which fully opens the control valve 1. At the same time, the actuator 2 The wrench is supplied with a maximum pressure of 7, Drive 2 is driven to rotate, and the outputs of blocks 5 and 7 of the multiplication (in the role of which large-scale amplifiers can be used) generate signals corresponding to torque M and rotation frequency O, respectively.

The signal corresponding to the value of M, having passed through the converter 10 in the digital code, goes through the switch 11 to the computing unit 13. The signal w goes to the adder 6. When the signal passes at the direct output of the trigger 23

196812

from O to 1, the pulse counter 21 starts counting the pulses supplied from the generator of 22 pulses,

In the described mode, the frequency of rotation of the wrench with varies during the transition process from 1 in to the steady-state maximum value. At a frequency of rotation of 10, the torque developed to move the nut along the free part of the bolt shank has an approximately constant value of M ,. J5 Computational highlight of this mode (on the direct outputs of both triggers 1) solves

ABOUT),

ffo

l ax LLn 2AL

0.9; (1)

-T-so

2t-mn

WH /, I P -

olVoKC fn

The results of the calculation through the switch .14 are entered into register 16. Comparison element 19 does not compare time t, counted by counter 21 with calculated value t, until signal 1 comes from the output of AND 23 to its control input. P1 interval of time from 1 at the direct output of trigger 28 until the appearance of 1 on. the output element And 23 is chosen longer duration of the transition process in setting the frequency of rotation with when the wrench is turned on, but much shorter time t.

The signal at the output of the adder 6 in this mode is described by the expression

U6 and, d, .K.,., - yi, „, Kei, k, bK-bcovV (2) -w- .Ke 1,

where ujg, and uj. - signals at the output of the trigger 28,

digital to analogue converter 20 and multiplication unit 5, respectively, K and K are coefficients

the gain of the adder 6, defined by different inputs, Kb-, 6

In this mode, the control valve 1 is fully open until

until the number ti, calculate it. in the computing unit 13 and emitted into the register 16, it does not compare with the number t, counted by the counter 21 pulses. At the output of the comparison element 19, a signal 1, changing the state of the trigger 28 at the direct output of the trigger 28 (the signal O appears), is detected.

Under these conditions (at the direct output of the trigger 28 O, and at the direct output of the trigger 27 1), the device starts working in a new mode. At that, the counter 21 is set to the initial state, the operation of the element 19 is prohibited, since the output signal O, TA 30 appears iia the output of the element 29 and the signal allowing the signal from the output of the imager 24 to the input of the comparison element 18. In the computing unit 13, the calculation of the expression (1) is stopped. Through the switch 11 to the block 13, the speed of the torque change in time dli is output from the output of the converter 9 in the digital code.

In this mode, the output signal

dt summator 6 is described by the expression derived from (2),

b VS

(3)

 K. (Q, -U).

At the beginning of this mode, At the same time, Ug 0. A negative signal, having passed through key 25, is fed to i actuator 26, after rapid closing of valve 1. In this mode, computing unit 13 solves the expression

., - l1m- b (, ()

(L

Oh about

- the torque at which the pressure must be disconnected so that the bolt connection is bypassed with the specified torque

- stiffness characteristic of the bolted joint. on h describes the expression (JM HALL ((1m (

.. .It

When valve 1 is closed (when Ug, 0), the rotational speed of the spindle CO decreases until it reaches the value of CO, do. At the same time, the signal at the output of the adder 6 becomes equal to

(6)

TO,

0

U W, Ug

Positive signal U,

jg, pass) without key 25 and execute through key 25 and actuator 26, causes the control valve 1 to partially open. As a result, the frequency of rotation of the wrench spindle stabilizes

CO, OILSO ,. . (7)

When a positive signal Ug appears, the shaper of 24 pulses (which can be made in the form of a one-shot) is applied to the control input of the element. 18 Comparison signal 1, {allowing comparison of the current value of torque M, received from converter 10 with the calculated value taken from register 15.

In view of (5) and (7), expression (4) takes the form

(eight)

1, I s about L

 these processes occur during the movement of the nut along the free part of the bolt shank.

dM

0 - and dt ° "

m m.; gpg -li, i-i and-,

At the beginning of the tightening of the bolt joint, the stabilization of the rotation frequency continues (due to further opening of the control valve 1), the torque M increases (M Mts), and

the value will melt

and decreases

dt

In the moment

estimated value of M

one

the equality M) M is executed by comparison circuit 18, by applying signal 1 to trigger 27. At the same time, the signal O is set at the direct output of trigger 27, the key 25, the control valve 1 is closed, and the tightening of the bolt connection is continued due to the kinetic energy accumulated in the rotating

parts of the wrench, until the torque reaches Ml.

 In this mode (the signals O on the direct outputs of both triggers), the devices return to the initial conditions described, while maintaining the previously entered constants.

The proposed device for limiting torque allows to increase the accuracy and expand the range of the obtained maximum torque values by pre-switching off the wrench at the time when the current torque value reaches the value defined by the expression (8), which calculates the kinetic energy accumulated in the wrench. In the known device, the magnitude of the kinetic energy is not studied, therefore reloading occurs.

Expansion of the range of maximum values obtained provides 1968128

c in the proposed device due to the fact that by the time the nut is tightened, the wrench is suitable with low kinetic energy (rotational speed CJ |), which is provided by pressure control taking into account information about the dimensions of the free part of the bolt. At the same time, the advancement of the nut for the most part of the free length of the bolt is performed at maximum speed, which increases the productivity.

No known device size information.

15 of the free part of the bolt, therefore, even in the process of moving the nut through it, the pressure is switched by the valve, working in the On / Off mode. As a result

20, the time taken to pass through the free part of the nut increases, and by the time the nut is tightened, the wrench does not fit with minimized kinetic energy.

Claims (1)

DEVICE FOR LIMITING THE TORQUE OF A WRENCH, comprising a rotational speed sensor and a torque sensor, connected by outputs to the inputs of a first multiplication unit and a second multiplication unit, connected by an output to an input of a differentiating element, serially connected to an actuator and a control valve mounted on a compressed supply line air to the wrench drive, characterized in that, in order to improve the accuracy of the device, two analog-to-digital converters are introduced into it switch, two triggers, two switches, three registers, a computational unit, a constant input unit, two comparison elements, three AND elements, a pulse generator, a pulse shaper, a key, a digital-to-analog converter, a pulse counter and an analog adder connected to the direct output of the second by the first input trigger to the first input of the second AND element, which controls. the pulse counter input, to the first control inputs of the first and second switches and to the first control input of the computing unit connected by the second control input with the second control inputs: direct inputs of the first and second switches, with direct output of the first trigger, with second inputs of the first and second elements , with a single input of the second trigger and with a control input of the key, an information input, the computing unit is connected to the output of the first commutator, torus, and the output is connected to the information input of the second switch, the first and second information outputs to the information inputs of the first and second register, respectively, and the third information outputs to the information inputs of the third register, · connected by the outputs to the input of the digital-to-analog converter, connected by the output to the second input of the analog adder, connected by the third input to the output of the first multiplication unit and the output to the information input of the key and to the input of the pulse shaper connected by the output to the first control input of the first comparison element associated with the output with the zero input of the first trigger, the second control input with the output of the first AND element, the first information input with the output of the first register, and the second information input with the output of the second analog-to-digital converter and with the first information input of the first switch connected to the second information input to the output of the first analog-to-digital converter, and the third information input - to the output of the constant input unit connected by the inputs to the bus Enter device constants, bus Start oystva connected to a single input of the first flip-flop, the data input of the pulse counter; connected with the output of the pulse generator, the first information outputs of the counter ₍ with the outputs of the third element And, and the second information outputs - with the first information inputs of the second comparison element connected by the second information inputs 1196812 to the outputs of the second register, the output - to the zero input of the second trigger, the first control input to the output of the third AND element, and the second control input to the output of the second AND element, the inverse output of the second trigger is connected to the first input of the first AND element, the key output is connected to by the input of the actuator, the output of the differentiating element is connected to the input of the first analog-to-digital converter, and the input of the second analog-to-digital converter is connected to the output of the second multiplication unit.