SU1154062A1 - Arrangement for protecting rod-type tool - Google Patents

Abstract

A DEVICE FOR PROTECTION OF A POWER TOOL, containing two electromagnetic sensors installed at the tool surface, an information processing unit containing a differentiating element connected by inputs to the outputs of the sensors, and an output to the control system l Lazy cutting modes, characterized in reliability of protection, the information processing unit is equipped with a time-angle converter, and the device has a speed sensor, the output of which is connected to the input of the time-angle converter, a multiplication unit, In this case, the delay and the comparator, while the electromagnetic sensors are connected to the input of the time converter - an angle, the output of which is connected directly and through a differentiating element to the multiplication unit, which is connected directly and through the delay element to the comparator, output eaten about to

Description

The invention relates to machine tool tiltings and can be used in machine tools when performing deep hole machining operations to protect the core tool (drill, tap, reamer) from breakage.

A device for protecting a rod tool is known, which controls the angle of unwinding of the tool according to the discrepancy between the magnetic marks synchronously recorded before processing on the non-working part of the tool and above the maximum allowable unwinding angle controls the feed amount. The device contains two electromagnetic sensors in the form of a reader. magnetic heads, two synchronously recorded on the non-working part of the tool annular tracks of mechanical marks, a processing unit. information connected to the sensors and containing a differentiating element, the output of the information processing unit is connected to the control system of the tool feed drive lj.

However, in the known device short-term impulse overloads of the tool are not recorded, for example, due to the presence of uneven hardness of the material of the part, which can cause destructive unwinding of the tool. In addition, the device is characterized by low speed, since the time to reach the unwinding angle of the limit value during tool overload can be significant. This causes insufficient reliability. the method of protecting the core tool and the device implementing this method.

The purpose of the invention is improving the reliability of protection.

The goal is achieved by the fact that, in a device for protecting a rod tool, containing two electromagnetic sensors installed at the tool surface, an information processing unit containing a differentiator 1C1 and a connected element to the outputs of the sensors, and an output to the control system with cutting modes equipped with a time-to-angle converter, and a device with a speed sensor, the output of which is connected to the input of the time-to-converter, a multiplier, a delay element and a comparator ,

the electromagnetic sensors are connected to the input of the time-angle converter, the output of which is connected directly and through a differentiating element to the multiplication unit, which is connected by the output. directly and through a delay element to the comparator, output connected to the cutting mode control system.

FIG. 1 shows a family of curves 9 (and) of the distribution of the unwinding angle 9 of the rod tool along the length E of its working part at various depths h L

(L is the length of the working part of the tool), the graph of the change of the spin angle 0, measured by the sensors installed at the ends of the working part of the tool, from the depth of

h (movement along the abode curve is right), as well as a graph of the change in the derivative d Q / dh of the rate of change of the spin angle 9 along the depth of the buried part h of the tool,

in fig. 2 is a block diagram of a device as applied to a deep hole drilling operation.

The device contains the workpiece 1, drill 2, magnetic

tags 3 and 4, respectively, on the non-working and working parts of the drill 2, electromagnetic sensors 5 and 6, made in the form of reading magnetic heads, which are connected

 the functional time converter 7 is an angle to which the rotational speed sensor 8 is also connected. Output of converter 7 directly and through differential

element 9 is connected to the inputs of the multiplication unit 10, the output of which is connected to the inputs of the two-threshold comparator 11 directly and through the delay element 12. The output of the comparator 11 is connected to the control system of the feed drive 13.

The core tool protection is as follows (as applied to the deep hole drilling operation).

When deepened into part 1, the twist drill 2 is subjected to the effect of the torque moment Mcr,

3

From the moment of force of resistance to cutting and the moment of force of friction of shavings and drill 2 against the wall of the hole of the MTP.

Mkr, MC. + Mtr.

With an increase in the depth of h of the drill 2, the moment of friction forces Mtr. Continuously increases, therefore the load on the drill 2 and the process increases. The angle of untwisting of the drill bit 2 as h deepens increases and is, depending on several main factors, (10-30) 10 rad / mm. Maximum. The measuring range of the unwinding angle 9 is possible when measuring the divergence of marks 3 and 4 at the beginning and at the end of the non-buried working part of the drill 2. At the same time, the sensitivity of the protection device is high. The measured angle in with this arrangement of the read information varies monotonically in accordance with the curve a bcJe.

The derivative d 0 / dh monotonously varies - the rate of change 0 A similar view with a stable feed of the drill 2 has the dependence d Q / dt - the change in time of the controlled unwinding angle.

If the load on the tool exceeds the allowable, for example, when the axial stiffness of the AIDS system is insufficient, due to the struts between the drill 2 and part 1, due to the uneven hardness of the part, then the breaking point of the drill 2 may be destructive. h) and 6 (t). The moment of kink in the curve b (h), the point C - (Fig. 1) corresponds to the jump U of the derivative d b / dh and d 0 / dt. This feature, which does not appear when the instrument is operated without overloading, is used as a sign of overloading the instrument to protect it. To detune from the initial processing time, when the derivatives of d 9 / dh, d Q / dt also increase abruptly, they control the production of 6-d9 / dt. Then at t

 O, 0 O, e .ii 0. d t

Pulsed electrical signals: from the outputs of sensors 5 and 6, when untwisting the drill 2, do not coincide in

624

of time. The time shift At is converted in the functional transducer 7 time-angle to the measured unwinding angle 9 by multiplying t by the signal from the sensor 8 of the rotation speed of the drill 2, proportional to the spindle speed 8 and t-n. A signal 9 is fed to the inputs of multiplication unit 10 directly from the output of converter 7 and a signal d S, / dt through differentiating element 9. A jump in the derivative d S / dt (production - 8 d & d) is detected in comparator 11 , to the inputs of which a 6-d Q / dt signal is applied directly and through a delay element 12 shifting this side in the lateral direction by a time t (setpoint). So in comparator 11

comparison of two adjacent values of d 9 / dt. With a monotonic change in the de / dt (t) dependence, any two values shifted by t differ slightly. Difference

these values do not exceed the threshold of the comparator 11, the output of the comparator 11 is no signal. With a change in the signal E d b / dt, the output of the comparator 11 almost instantly appears a signal arriving on the drive control system 13, reducing the feed.

Example. Workable

material - steel 18X2H4VA with a hardness of IKS 22-28. Depth of drilling is 24 mm, four-diameter drill bit. D 1.65 mm, material RBM5, feed rate 0.01–0.05 mm / rev, 7–15 kg; Mtp ,.

1.5 kgm -Use magnetic heads from permallo 80HXS. During processing, up to 5 actuations of the device are recorded to reduce the feed from 0.03 to 0.01 mm / rev, which eliminates tool breakage.

The proposed rod tool protection device allows high-speed determination of

tool overload mode and give a signal to the feed regulation. This increases the durability of the tool, dramatically reduces the failure of drills, taps, reamers, i.e. increases the efficiency of metal processing.

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Claims (1)

DEVICE FOR PROTECTING A ROD TOOL, comprising two electromagnetic sensors installed at the tool surface, an information processing unit containing a differentiating element connected by inputs to the sensor outputs and an output to a cutting mode control system, characterized in that, in order to increase the reliability of protection , the information processing unit is equipped with a time-angle converter, and the device is equipped with a speed sensor, the output of which is connected to the input of the time-angle converter, a multiplication unit, a delay element and a comparator, wherein the electromagnetic sensors connected to the input of inverter time-angle whose output is connected directly and via a differentiating element to the multiplication unit, whose output is connected directly and through the _L element za- 5 Derzhko to a comparator, the output to the connected mode control system cutting.