SU1355468A1 - Method of monitoring the dressing of grinding wheel with diamond - Google Patents

Abstract

The invention relates to abrasive machining and can be used in control systems of devices for dressing a circle of grinding machines. The purpose of the invention is to improve the quality of grinding, as well as the durability of the wheel and diamond, by excluding noise and noise from the vibration sensor and generating unambiguous discrete signals or commands to control the machine cycle. For this, low frequencies up to 10-30 kHz are filtered out from the signal of the vibration sensor and the continuity of the output signal is monitored. The command to stop editing is formed on the condition that the maximum signal breaks correspond to the permissible magnitude of the surface defects of the circle. When the diamond leaves the straightening area, the output signal is blocked. If necessary, editing is carried out in several passes, and the depth of editing for each pass is set taking into account specific conditions, in particular, the cost of the tool and the time required for editing. An edit mode is possible in which, after the diamond touches the circle, a passage is made along the generatrix with a minimum depth of removal and, when a passage with a zero value of the output signal is detected during this passage, the diamond is brought to the middle of this portion and brought to the circle until it touches, but no more than the maximum possible depth of dressing, and repeat passes until the elimination of defects exceeding the allowable ones. 2 hp ff, 8 ill. (C (L SO sd ate O5 00

Description

The invention relates to abrasive machining and can be used in control systems of devices for dressing a circle of grinding machines.

The purpose of the invention is to improve the quality of grinding, as well as the durability of the wheel and diamond, by excluding noise and noise from the vibration sensor and generating unambiguous discrete signals or commands to control the machine cycle.

FIG. 1 shows a method for controlling the straightening of a straight circle wheel on a universal circular grinding machine; in fig. 2 is a block diagram of a circle editing control; in fig. 3 - electrical signals of the block diagram at the initial stage of editing; in fig. 4 - the same, at an intermediate stage of editing; in fig. 5 - the same, at the time of the end of the edit; in fig. 6 - time diagram of the integrator output signal at various frequencies of the vibration sensor signal; in fig. 7 is a method for controlling the grinding process; in fig. 8 is a section A-A in FIG. 7

Grinding headstock 1 (Fig. 1), flooring and grinding wheel 2, is movable in the direction of arrows 3 (feed to the dressing). Table 4, moving along the generatrix 2 (arrows 5) carries the holder 6 with the right tool (diamond) 7, as well as the vibration sensor 8, which perceives oscillations of the diamond 7. A screw with a handwheel 9 is provided for adjusting the position of the diamond 9. Table 4 also carries sensors 10 and 11 locks with screws 12 and 13 adjusting their position, interacting with the flag 15 installed on the frame 14. Elements 10-15 block the output signal when diamond 7 exits beyond the straightening area, which eliminates false commands at the ends of the stroke. Feed grinding headstock 1 on the diamond 7 is provided with a screw 16 with a flywheel 17.

Circle 2 is edited by supplying the grinding wheel 1 with screw 16 until diamond 7 touches circle 2 and additionally to the depth of dressing and passage of diamond along the circle profile provided by the movement of the table 4. During editing, the vibration sensor 8 generates a signal that, if there are 2 defects on the wheel the type of recess 18 is interrupted.

The block diagram of the circle editing control (Fig. 2) shows amplifier 19 connected with sensors 8, 10 and 11, block 20, which converts the amplified signal of the vibration sensor into square pulses of the same amplitude, pulse width controller 21, which generates pulses of the same (adjustable ) duration; an integrator 22 that converts a sequence of pulses into a voltage level, depending on the duration of the pulses, the pauses between them and their number for a given time interval;

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a threshold device 23, triggered by an increase in the voltage level at its input to the magnitude of the trigger threshold; an output device (block) 24; a visual or acoustic indication unit 25, which allows to evaluate the performance of the system; the drive control unit 26, the drive 27 for the lateral movement of the grinding headstock and the drive 28 for the longitudinal movement of the table.

The signal at the output of the block 24 appears only when the signal frequency of the vibration sensor 8, and hence the frequency of the following rectangular pulses at the input of the integrator 22 reaches the tuning frequency set by the regulator 21 of the pulse duration, i.e. low frequencies of up to 10-30 kHz are filtered, which eliminates interference (noise) associated with the machine vibrations caused by the operation of its nodes. This is achieved due to the fact that at a selected duration of rectangular pulses at the input of the integrator 22, the voltage at its output is determined by the pulse frequency and the number of them (5-10).

The method is carried out as follows.

From the electrical circuit of the machine, the control unit 26 receives a command to start, editing the circle. The control unit commands the actuator 27 to move the wheelhead 1 with the pitch wheel 2 in the direction of the diamond 7 by an amount equal to the removal from the abrasive wheel in one pass. Then, the control unit 26 commands the actuator 28 to move the table 4 with the diamond mounted diamond 7 with it along the generator of the circle 2 (for example, from right to left). After the diamond 7 has reached the right edge of the circle 2, the sensor 11 is triggered, which, through control block 26, turns on amplifier 19. The vibration sensor U, after amplification in block 19, is converted in block 20 to rectangular unipolar pulses, is limited in amplitude and is fed to the regulator 21 input pulse duration, from the output of which the pulses t / 2 are fed to the input of the integrator 22. The output voltage f / C of the integrator 22 rises to the magnitude of the response voltage (/ "of the threshold device 23, which turns on the output device 24, to the output the closure of which are t / 4 pulses (Fig. 3-5).

The timing charts in FIG. 3-5 are marked:

and - the output electrical signal from the vibration sensor 8;

/ 2 - output signal from the controller 21 duration. Pulses;

b C - the output signal from the integrator 22;

U is the signal from the output device 24;

Un is the trigger voltage level of the threshold device 23;

t - time

In the timing diagram of FIG. 6 marked:

(Uz is the voltage at the output of the integrator 22;

/ is the pulse frequency at the input of the integrator 22, corresponding to the frequency of the vibration sensor signals;

LJn is the trigger voltage level of the threshold device 23;

/ - time

At the selected trigger voltage level Un (Fig. 6) of the threshold device 23 (as, for example, in the above case) at kHz, the Of signal at frequencies / less than 10 kHz does not reach the specified trigger voltage U, therefore, the output device 24 does not output input signal).

Bundles of high-frequency pulses U and output pulses t / 4 appear only when the diamond 7 touches circle 2. In the initial stage of editing (first pass), the pulse frequency U is low (Fig. 3). When the diamond 7 reaches the left edge of the circle, the sensor 10 through the control unit 26 switches off the amplifier 19 and the control unit issues commands to reverse the table 4 to the initial right position. At the command of the control unit 26, the grinding headstock 1 moves again towards the diamond 7 by an amount equal to the removal from the abrasive wheel in a single pass, and the editing cycle repeats as described. In the intermediate editing stage, the pulse frequency L / 4 increases (Fig. 4). With a fully straightened circle, the signal U at the output of block 24 becomes continuous (Fig. 5), after which the control block 26 issues a command to the machine control circuit about the end of the straightening. At the same time, a signal (/ 4 is supplied to the display unit 25.

The device according to the proposed method can be adjusted to work in several different modes.

Example 1. Diamond is brought to the grinding wheel before the contact, which is visually determined by the display unit 25 (for example, the lamp is lit), the required depth of dressing is set, and the run is corrected in a single pass. During this passage, the continuity of the light bulb is visually monitored. If the light is burning intermittently, the diamond feed and dressing are repeated until a continuous signal is received.

Example 2. The circle is edited in a fully automatic mode by the command "Start of editing, formed in the electrical circuit of the machine and entering the control block 26. The editing cycle until the approach of the diamond 7 to the right edge of the circle is similar to that described in the first pass. During the first pass, the continuity of the output signal is evaluated.

along the edge of the circle. If there are local drops on the circle (signal), then on command from the control unit 26 of the control table 4 with the diamond holder installed and the diamond 7 stops in the middle of this section. An additional command is given to feed the grinding wheel to the contact with the diamond (in the middle of this area), but the supply of the wheel is limited, its value does not exceed the maximum possible depth

0 removal from the abrasive wheel in one pass. Editing is carried out, as a rule, in one following pass, thus saving editing time, as well as reducing diamond wear. If necessary, for additional quality straightening, another additional pass is made, giving the working surface of the wheel the required quality.

Example 3. The straight signal duration is measured by direct editing in a single pass, when grinding

0 the circle is filled with full and high quality. This time is stored and used as a reference for comparison in subsequent dressing cycles.

1. For an ideal quality of editing, the cycle is considered finished when this time is reached.

2. If minor defects are allowed on the surface of the circle, which cause the output signal to disappear for a while, then the cycle is considered to be finished if

Q is the maximum value of the time of any signal pause and the total time of these pauses does not exceed the pre-set values.

In these cases, there is no need for sensors that block the output signal.

The method may also be feasible in monitoring and controlling the grinding process.

When machining (figs. 7 and 8) with a grinding wheel 2, product 29, installed, for example, in centers 30 and 31 of the headstock product 32 and tailstock 33, mounted on a machine 4, the vibration sensor 8 is placed, for example, on quills 34 of the tailstock 33. The control equipment remains the same (Fig. 2).

The differences in methods are reduced to the conditioned nature of the processes carried out at a given 5 moment (editing of a circle or grinding) by a set of input commands and output commands or signals.

When implementing the method for controlling the grinding process of the product, in control block 26, instead of a command for editing circle 0, a command is entered at the beginning of the grinding cycle.

The control unit commands the actuator 27 to move the grinding pedestal 5 (Fig. 7) with the rotating wheel 2 in the direction of the product 29 and the actuator 28 (Fig. 2) for reciprocating movement of the table 4 with the mounted

product 29. When the circle 2 interacts with the product, the vibration sensor 8 generates a signal, which, as described above, is converted by the one shown in FIG. 2 by a circuit to the output command or signal of the block 26 and (or) to the signal (visual or acoustic) of the display block 25. In the grinding process, various parameters can be monitored. At the same time, after excluding a low frequency from the signal, the relative duration of the signal during the time interval equal to at least the product turnover duration is controlled (relative duration (for example, in percentage) - the ratio of the contact time between a circle and the product during a given time interval to the value of the specified interval - characterizes discontinuity of the circle contact with the product). The output signals or commands are formed differentially, taking into account the relative duration of the signal and the difference between the current and final (specified) dimensions of the product (Fig. 8).

At the moment of the first contact of the circle with the product, the signal "Touch and (or) the command to activate the rough feed is generated. If the workpiece has a uniform allowance (when the workpiece cannot be obtained (despite the "soft mode) to get a suitable product (circuit 37 in Fig. 8), before the end of the feed cycle, the signal" Scrap and / or a command to stop 5 processing and installation of the new billet.

During nursing, the signal, which at the time of switching from the finishing feed to nursing is continuous, becomes intermittent and disappears at the end of nursing. At this moment, the signal "Processing is finished."

Claims (3)

1. A method for controlling grinding of a grinding wheel with a diamond, including measuring the vibration of the diamond holder with a vibration sensor and forming a command to stop editing, characterized in that, in order to improve the quality of grinding, low frequencies up to 10-30 kHz are eliminated from the vibration sensor signal and controlling the discontinuity of the output signal, which characterizes the contact of the diamond with a circle, and, at the same time, the straightening is stopped after the signal reaches a maximum permissible length of 35 in FIG. 8), then removing the unevenness of 25, determined by the requirements of This occurs relatively quickly and the relative duration of the output signal increases accordingly. In this case, are formed in accordance with a predetermined design mode of processing in a circle. 2. A method according to claim 1, characterized in that it additionally controls the total duration of the signal breaks during the successive switching commands for 30 passes of al.maz on the profile of the circle and the right- semi-finishing, finishing feed and on the vy-ku are stopped after reaching the specified life. total duration. If the stock allowance is less equal (contour 36 in FIG. 8), then relate-3. A method according to claim 1, characterized in that the signal duration is increased, which, in order to increase productivity, is slower, there is a danger of rejection 35 after the diamond touches the circle to the product, due to the deformation of the workpiece, the passage along the profile with mini-rough grinding occurs ( the depth of removal, and at the time of the discovery of some inheritance). In this case, in order to prevent this passage of the section with a zero rejection rotation, the switching command on the output signal value outputs a diamond with a semi-finish or finishing form - “in the middle of this section and brought to It is run ahead of time, this allows processing to be carried out in a more “soft mode” and a suitable product can be obtained from the defective workpiece. g circle to the touch, but no more than the maximum possible depth of dressing, and repeat passes until the elimination of defects exceeding the allowable ones. / /five circle. 3. The method according to claim 1, characterized in that, in order to increase productivity, after the diamond touches the circle, a passage is made along the generatrix with a minimum depth of removal, and when this section of the output signal is detected during this passage, the output t diamond in the middle of this site and brings t to circle to the touch, but no more than the maximum possible depth of dressing, and repeat passes until the elimination of defects exceeding the allowable ones. / srig1 The „„ traffic jam or „1 achopo embedding Output signal or signal dzig.2 Z / 71 from U-. Ur  P l UL  four Fiez Vi Fig4 2 Vs Un Sh z phi5.5 / Jr7l / V / / tr tz 57. U / LU // / -JA / Z, J ffff C f FC5.6 srig.V Editor M. Petrova Order 5464/17 Compiled by A. Semenov Tehred I. VeresKorrektor A. Obruchar Circulation 715 Subscription VNIIPI USSR State Committee do inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, i. Uzhgorod, st. Project, 4