SU1204368A1 - Method and apparatus for controlling the grinding cycle - Google Patents

Abstract

1. A method of controlling grinding when operating in a cycle that includes rough and finishing grinding and dimensional nursing with switching the feed values as an allowance function, characterized in that, in order to improve the accuracy and quality of the workpiece, the value of the allowance for finishing grinding is set directly proportional to the energy expended by the main electric drive of the machine to remove the control allowance at the predukitsev stage, and the value of the allowance for dimensional care is set inversely proportional to flax of energy expended by the main electric drive of the machine for removal of the allowance at the preceding stages. 2. A grinding control device, operating in a cycle, comprising a controlled power converter connected to a cross feed motor 1 and an active power sensor connected in series, a memory unit and an adder, characterized in that the allowance sensor connected to the first device is inserted into the device the second, third and fourth null organs, the control allowance master, associated with the second input of the first null organ, the nursing allowance sensor, connected with the second input of the third null organ, integrating the device whose input is connected to the adder, the first output through the executive closing contact of the first null organ to the input of the first entered functional converter, and the second output through the executive closing contact of the third null organ to the input of the second entered functional converter, and the output of the first functional the converter is connected to the second input of the second null organ, the output of the second functional converter is connected to the second input of the fourth null organ, the sensor roughing feed speed connected through sequentially connected executive disconnecting contacts of the third and second zero organs to the first input of the controlled power converter, finisher feed rate adjuster connected through the sequentially operating disconnecting contact of the third zero authority and executive closing contact of the second zero - an organ with a second input of the control converter, and a setter for rapid retraction of the support connected through (L N3 O 4: about 9d e

Description

fourth-body executive make contact with third

The invention relates to mechanical engineering and machine tool construction and can be used in the automation of internal grinding, circular grinding and chute grinding machines,

The purpose of the invention is to increase the accuracy and quality of workpieces by taking into account the cutting ability of the grinding wheel and the size of the initial allowance of the part.

FIG. 1, a depicts graphs of changes in feed rates within a single part machining cycle; in fig. 1.6-graphs of grinding power change within a part processing cycle; in fig. 1, c — graphs of changes in the current allowance within a single part machining cycle; in fig. 2 is a functional diagram of the device for automatic control of the diametral size and cutting mode during plunge mortise.

The control of the energy expended by the main electric drive is carried out in a known manner by measuring the current cutting power, memorizing it and subtracting the idling loss power in the spindle group of the machine. The resulting differential power P3 is then integrated in time, which determines the value of the energy expended in the various stages of the workpiece:

Q. PU; . "Ib

about .

where is T.

. and Tj is the time for removal of control and total (for rough and finishing processing) allowances, respectively.

With the help of the Q and Qg energy control, it is possible to purposefully control the grinding mode: through the finishing allowance, and through the allowance for nursing).

1204368

input controlled power converter.

This can be seen in graphs (Figs. 1-3), which take into account two perturbing influences characteristic of the grinding process: variations in the initial allowance of part S (Fig. 1a) ranging from up to 8, and the cutting ability of the grinding wheel, about which can be judged by the power, which is spent on chiffing (Fig. 16), with a range from maximum (P) to minimum (P). The time dependences of V (t), .Pij (t), and S (t) are given for the four possible extreme combinations of the two specified disturbing influences and are indicated: the maximum initial allowance and sharp cutting sections of the outer circle - S, the minimum initial allowance and the dull circle - MH, maximum initial allowance and blunted circle - 5 - minimum initial allowance and sharp cutting circle - MO.

Using as a technological parameter the active power of grinding Rc and the energy levels caused by it for the removal of predetermined allowances allows you to simultaneously control the most important parameters of the workpiece

and the conditions of its processing.

The method closely relates the two most important technological parameters — the current allowance of the part S and the energy Q or Qp expended on the removal of this allowance, which makes it possible to combine the advantages given by the joint use of these parameters.

By way of grinding control

in order to increase the accuracy of parts manufacturing during the processing cycle of each part, the removed allowance is redistributed to the draft () and to the finishing (Sj (Qn))

grinding and care 5ts (pp) depending on the energy levels Q to and Q, respectively, spent on removing the control allowance () and the allowance (). Adjustments allowances SjCQ) and

, (Qc)

produced, respectively, at the end of the roughing stage and at the nursing stage; This gives us the ability to react flexibly to a change in the processing conditions, changing in the processing cycle of each part the moments of transition from rough to fine, as well as the value of allowance for nursing.

At the beginning, the measurement of active power and the subsequent calculation of the energy Q expended on processing the test allowance is made. As a result, the optimal (based on minimum machine time and temperature conditions) value for fine grinding is determined, which is just proportional to the Q value. The greater the Q energy expended to remove the control allowance, the earlier the switching occurs. cross feed speeds from rough to fair. This, in turn, allows stabilizing the parameters of the workpiece and, to a certain extent, the temperature of the part before the end of the machining cycle.

The most responsible from the point of view of achieving the accuracy of the part, as well as its quality parameters (shape, part geometry, surface roughness) is the final stage of treatment - nursing. The amount of nursing allowance is inversely proportional to the Q energy expended in all previous stages of machining the part. This makes it possible to determine, with the highest possible accuracy, the magnitude l Sf of the linear expansion of the part due to its heating during processing, which is then automatically compensated by a device implementing the method.

In all cases, the treatment is stopped at the value of the allowance L8, the early value of the temperature expansion. As can be seen from FIG. 1, the magnitude of this allowance LZ varies greatly from each other depending on the initial allowance of the part 5c and the state of the cutting ability of the spindle wheel. In particular, the numerical values of this allowance are FOR-cutting circle with pain. . "- | Wn

shom l s ° and small

 s; °

primary

allowances of parts and for a blunted circle, respectively, with a large dZts and small initial allowances. Consider the grinding process by

The proposed method for combining properties (8d). Draft feed Vj with a large initial allowance S (starts at time T (curve 1 in Fig. 1a). During the rough treatment, the steady-state power value for the cutting circle will reach P (curve 2 in Fig. 16). At some ( pre-established) control stock S, (curve 3 on

5 of FIG. 1c) the result of measuring the energy consumed by the time point Tk on the removal of this allowance (S S) is equal to:

0,

0

0

five

0

0

/ iMdtc

,four

C i

five

If you don’t take into account current power fluctuations if the function P (j, (t) is smooth, then this energy will be equal to:

Q k PL, (T, -Tj).

depending on the value of Q y, the value of the allowance for finishing is determined directly proportional to the energy

5 (9,) ,,

where C and P are the coefficients that, other things being equal, determine the line for limiting the intensity of metal removal by prizhogam. ..

When the allowance S is reached (Fig. 1c, curve 3), the feed is switched from rough V to finishing Vc (fig.-la, curve 1). From the moment of time T (Fig. 1a, curve 1), the processing of the part at the feed speed is started, at which the steady value of the cutting power reaches the value of Py (Fig. 16, curve 2). With a predetermined and fixed allowance S (Fig. 1c, curve 3), the net flow is stopped and from the time point T (Fig. 1) the nursing process begins, i.e. removal of allowance due to the energy of elastic deformation. By the same moment of time, the result of measuring the total energy expended and removing the allowance

(nto, 7). imero:

with(

Sc

If the function PjjCt) is assumed to be smooth, then:

. ()

depending on the value of Q set the value of the allowance for nursing, inversely proportional to the energy QC:

S4 (Qc) 83- bS, q J,

where C ,, m are the coefficients that determine numerically, other things being equal, the temperature error due to the linear expansion of the workpiece bS.

The command to stop grinding is formed with an allowance S (FIG. 1, curve 3) at time T. When the part reaches the nominal ambient temperature after processing, due to the lead in size & 5 °, the size of the workpiece) takes the nominal value and the allowance becomes equal.

If now during the operation of the machine, the cutting ability of the grinding wheel deteriorates and reaches the limiting value (), then the process of changing the cutting power will be represented by curve 4 in Fig. 16

Accordingly, the steady value of the cutting power will be equal to

s

and switching speeds with v,

01

1) occurs0

on Vp (curve 5 in fig

with a larger allowance of 32 (Fig. 1c, 35 curve -6), with a slightly smaller time T, but with a larger value of the expended energy Q ,. Processing at the stage of the final supply will proceed at the steady-state power R. - (Fig. 16, curve 4).

After finishing

WITH

nursing begins at tl, which, depending on the expenditure

yg

45

The energy QC will end at the current allowance of 8. (FIG. 16, curve 6) at the time Too.

If parts are received for processing, with a minimum initial SK allowance, or, then the process begins.

time ment T C (curve 7 and 8 in Fig. 1). With a sharp-cutting wheel, the cutting power varies according to curve 9, with blunting, to curve 10 (Fig. 1 b), v reaches the maximum values of RS, and P, respectively. In this case, the control allowance (Zsdkts-W) (in Fig. 1c, curves 11 and 12) and COOT45

50

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The corresponding energy expended by the machine on its removal will be significantly less than in the above considered cases with a large part allowance.

Lei S,

Accordingly, smaller values of allowances for finishing processing will be established at acute cutting S (curve 12 in Fig. 1c) and

25

thirty

five

five

 (curve 12 on Lig.

 M E

blunted S (Fig. 1c, curve 11) 10 circles, as well as allowances for nursing (Fig. 1c, curve 12) and S j, (curve 11).

Between curves 3 and 6 and 11 and 12 (fit. 1c) of the limiting values of S (t) 15, there are two areas in which the allowance is set for finishing (13–16) and for nursing (17–20).

FIG. 2 shows a device 20 implementing the proposed method.

The device comprises a driving motor 21, a spindle of the pantheral circle 22, a support 23 with an electric motor 24 of transverse feeding,. connected to a controlled power converter 25, an active power sensor 26, a memory device 27, and an adder 28. In addition, the device comprises speed control devices 29 and 30, respectively, draft and finishing feeds, current allowance sensor 31, four zero-organs 32-35, : ass: pilot 36 control allowance, setting control 37 of allowance for nursing, setting control 38 of the rapid removal of the port, an integrating device 39 and two functional converters 40 and 41. The sensor 31 of the current allowance is connected to the first inputs of the zero-organs 32-35. Setting control .36 control A new p) trigger is connected to the second input of the first null organ 32. The nursing allowance unit 37 is connected to the second input of the third null organ 34. The output cf of the mmator 28 is connected to the input of the integrating device 39. The first output of the integrating device 39 is through an executive closing device The contact 42 of the first zero-body 32 is connected to the input of the first functional converter 40, the second output of the integrating device 39 is connected through the executive circuit to the contact 43 of the third zero-switch 34 to the input of the second functional unit the developer 41, ьг the course of the first functional transform 5

0

The receiver 40 is connected to the input of the second zero-body 33. The output of the second functional converter 41 is connected to the input of the fourth zero-body 35. The unit 29 of the speed of the draft feed is connected through serially connected executive disconnecting contacts 44 and 45 of the second and third 34 zero-organs to the first input of the controlled power converter 25. A finisher speed setting device 30 is connected in series through the disconnecting contact 46 of the third 34 zero-organ and the closing contact 47 of the second null-organ 33 is connected to the second input of the controlled power converter 25. Unit 38 for rapid retraction of the caliper through the closing executive contact 48 of the fourth zero-body 35 is connected to the third input of the controlled power converter 25.

The device works in the following way.

The control of the current allowance S of the workpiece 49 is carried out by the sensor 31. The signal from its output is fed to the inputs of a set of null organs 32-35 that form discrete commands for controlling the grinding cycle's duty cycle1. The null organs 32 and 34 are matched at fixed values of the allowances S and Sj (Fig. 1c), which are predetermined by the operator using the set points 36 and 37, respectively. The null organs 33 and 35 are controlled by functional transducers 40 and 41, respectively. When processing the work 49, the drive motor 21 draws power from the network, the current value of which is measured by power sensor 26. The signal from the Power sensor 26 enters the memory device 27, which stores the value of the idling loss power P. Adder 28 provides a signal proportional to the cutting power:, P.,

u

-PC, - IAC

1204368S

At the output of the adder 28 is enabled integrating device 39, which calculates the value of the energy,: spent on removal of metal for

specific time span: t

t.

.

to

ts

0

,

five

0

five

This energy is calculated and measured in a single part machining cycle for two minutes.

The first time is when the sensor 3 allowance 31 and the setpoint 36 of the control allowance fix the achievement of the value of the control allowance S, and the integrating device 39 calculates the energy value O and sends a signal proportional to O 1C to the input of the function converter 40. In turn, the function converter 40 converts the signal coming from the integrating device 39. into the signal that determines the value of the allowance for finishing:

5g (Rk) s.d

The signal S.2 (Q, t) determines the moment of the operation of the null organ 33.

The second time energy is measured when the sensor 31 and the setpoint adjuster 37 fix the achievement of the value of the control allowance S (Fig. 1c). The integrator 39 calculates the value of the energy Q spent on removing the allowance at the previous processing steps. A signal proportional to Q is fed to the input of the functional converter 41, which converts the signal from the integrating device 39, into a signal, which determines the value of nursing allowance:

 S4 (Qc) S., - c, q.

The signal S (Qg) determines the moment of the operation of the null organ 35. The trigger of the null organ 35 means the termination of the nursing stage and the grinding wheel 22 is quickly retracted from the part 49.

V va

B l-

(ABOUT ";

FIG. f

LL5 / I

  jgdSn

Editor A. Revin

Compiled by A. Semenov Tehred T. Tulik

Order 8464/12 Circulation 768 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch PPP Patent, Uzhgorod, st. Project.na, 4

Proofreader. Cherni

Claims (2)

1. The method of controlling grinding when working in a cycle that includes rough and fine grinding and dimensional nursing with switching feed values in the stock function, characterized in that, in order to improve the accuracy and quality of the machined parts, the size of the allowance for finish grinding is set directly proportional to the value the energy expended by the main electric drive of the machine to remove the control allowance at the previous stage, and the amount of allowance for dimensional nursing is set inversely proportional to rgii spent by the main electric drive of the machine for removal at start-up in the previous stages. 2. The grinding control device during operation in a cycle, comprising a controlled power converter connected to transverse electric motors, and therefore connected by an active power sensor, a memory unit and an adder, characterized in that an allowance sensor connected to the first and second is introduced into the device, the third and fourth null organs, control allowance master associated with the second input of the first zero organ, nursing allowance master associated with the second input of the third null organ integrating devices , the input of which is connected to the adder, the first output through the executive closing contact of the first zero-organ - with the input of the first input functional converter, and the second output through the executive closing contact of the third zero-organ - with the input of the second input functional converter, and the output of the first functional converter is connected to the second input of the second zero-organ, the output of the second functional transducer is connected to the second input of the fourth zero-organ, the roughing speed adjuster under Achi, connected through series-connected executive opening contacts of the third and second zero-organ to the first input of the controlled power converter, a fine feed speed controller, connected through series-connected executive opening contact of the third zero-organ and executive closing contact of the second zero-organ to the second input of the control converter, and the master quick-release caliper, connected through the executive closing contact of the fourth zero-organ with the third <2043 68 input of a controlled power converter.