JPS6288548A - Temperature compensating device for cutting machine tool - Google Patents

Abstract

PURPOSE:To aim at enhancing the working efficiency and availability factor of an automatic cutting machine tool, by automatically compensating and controlling thermal displacement in accordance with a compensating value which is calculated in accordance with a count number obtained by counting a cycle rest time during rest of the machine tool or an operating time. CONSTITUTION:When continuous operation of a machine tool is stopped, a stop signal is taken into an AND gate 18 which is opened in accordance with a count number and a continuous operation stopping signal taken thereinto, and the time tau of the count value is taken into a computing section 19 which receives a parameter XO for a saturating displacement value and the resultant parameter P of parameters PF, PN delivered from coinciding circuits 14, 15. The computing section 19 computes a compensating value in accordance with the parameters XO, P and the time tau, and as a result, compensates and controls a motor 7 in accordance with the thus obtained compensating value X by means of an interpolator 7b. With this arrangement, it is possible to prevent the worker from purposely measuring the compensating value, and therefore, it is possible to enhance the working efficiency and availability factor of the machine tool as an automatic machine tool.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects changes in machining dimensions from multiple data files such as duty (short-time displacement) and spindle rotation speed (long-term displacement) in turning machine tools. The present invention relates to a temperature correction device for a turning machine tool that is expressed as an approximate function and provides a dimensional correction amount when the machine is restarted after stopping.

[Conventional technology]

Generally, after starting a turning machine tool and starting machining, the temperature of the tool rest and headstock increases over time, and after about 8 hours, the temperature-induced displacement saturates to a constant value. It is known to do.

For example, if the machine is stopped during a lunch break or setup change, and then restarted, it may be difficult to accurately determine the amount of correction for thermal displacement depending on the length of time the machine is stopped, and it may be difficult to accurately determine the amount of correction for thermal displacement by measuring it each time. It was corrected and reworked.

[Problem that the invention seeks to solve]

However, as mentioned above, when stopping and restarting a machine, measurements must be taken each time to accurately correct the amount of correction, which results in poor processing efficiency as an automatic machine and is a factor that hinders productivity. Ta.

The purpose of the present invention has been proposed in order to solve the problem in view of the above circumstances, and it is an object of the present invention to mathematically calculate the thermal change curve due to the time-dependent changes in the characteristics possessed by the machine, that is, the duty of the tool post and the displacement of the headstock. A turning machine tool that improves machining efficiency by counting the cycle down time or operating time when the machine is stopped, and automatically imports and corrects the dimensional correction amount when restarting the cycle based on the counted number. An object of the present invention is to provide a temperature correction device.

[Means and effects for solving the problems] The present invention is a temperature correction device for correcting thermal displacement that occurs during machining with a turning machine tool. an input/output device that inputs/outputs parameters such as the assigned duty, a machining information program memory that stores machining information programs, a spindle rotation duty data file that stores parameters for each spindle rotation duty, and a turret. The X-axis feed duty data file in which the parameters are stored for each X-axis feed duty, and the machining information program stored in the memory are run to determine the spindle rotation duty and X-axis feed for each machining. The duty is calculated, and the calculated spindle rotation duty and X-axis feed duty are compared with the spindle rotation duty and X-transport duty stored in the spindle rotation duty data file and the X-axis feed duty data file, respectively. A matching circuit, a synthetic parameter P that is a combination of parameters taken out when matching occurs in the matching circuit, and a preset saturation displacement 11X.

and a first calculation means that calculates the correction amount of X=Xo (1-e-'τ) from the time τ after the start of machining, and a first calculation means that calculates the correction amount of X=Xo (1-e-'τ) from the time τ after the start of machining, and a a second calculation means that calculates the displacement amount during rework from the synthesized parameter pv, the preset saturation displacement amount XO, and the time τ1 from when the machine stops until the rework is performed as X'=Xoe−'τ'; and,
The displacement amount X" obtained by the second calculation means is calculated by setting the time τ'' as XO(1,
-P(r'+ΔT')) and a third calculating means for performing Te correction.

By employing the temperature correction device of the present invention, the correction amount X can be automatically adjusted when reprocessing is performed after the machine is stopped.

Re-processing is performed with correction control.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

+1) First, the basic principle of the present invention will be explained.

After starting the turning machine tool and starting machining, the temperature of the tool rest and head stock increases over time, and after about 8 hours, the thermal displacement due to temperature saturates to a constant value. The thermal displacement curve that changes with the passage of time is shown in FIG. 2(A), and the thermal displacement curve changes depending on the number of rotations of the main shaft, for example. Further, if the machine is once stopped after saturating with the thermal displacement curve shown in FIG. 2(A), cooling will occur with a different thermal displacement curve as time passes. In reality, this curve X changes while drawing a curve like a two-dot chain line every time the vehicle stops on the curve X. FIG. 2(B) is a model drawing of the general heating curve and cooling curve of this thermal displacement.

In Figure 2 (B), the horizontal axis represents time (cycle).

The vertical axis shows the amount of thermal displacement. Curve X is a heating curve, and curve
is the cooling curve.

The respective curves x and x' can generally be expressed by the following equations.

x=xo (1-1'τ) When the machine is stopped in this saturated state, the amount of thermal displacement decreases over time according to curve X@, and returns to its original state in about 8 hours.

For example, in Figure 2 (B), the saturation of the curve
Stop the machine at point A in the closed state, and from point A τ'
When machining is restarted from point B where the machining is cooled according to curve X° until machining is restarted from point B after the waiting time, the amount of thermal displacement does not necessarily change according to curve X and machining is performed.

Therefore, as a result of experiments based on past experience, the present inventors found that the amount of displacement of point B on curve X' and the amount of displacement of curve X at point B
Calculate the time (τ) at point C of curve X when the amount of displacement becomes equal to It can be processed smoothly.

That is, one hour is determined from x=X", that is, XO(1-8-'τ)=Xoe-". Here, Xo is the displacement at saturation (duty function), P is a coefficient giving the slope of the curve (duty gap, and τ is the separation time (cycle number).
o*P and Pl are determined in advance from empirical values for each spindle rotational speed N and are filed in a data file as shown in FIG. 2(C).

The data on the thermal displacement over time on the spindle side and the tool rest side, which are filed in the data file shown in FIG. 2(C), are measured in the state shown in FIG. 3.

FIG. 3 is a plan view of the turning machine tool. In FIG. 3, a spindle 101 is rotatably supported on a spindle head 100. As shown in FIG. A chuck 102 is attached to the main shaft 101, and a test bar W is inserted into the chuck 102 for measurement.

Turret tool rest 104 is supported by a housing, which housing 103 is mounted on the cross slide.

Furthermore, a tool holder 105 into which a tool T is inserted is attached to the turret head. Cross slide is saddle 1
It is placed on 06. Thus, the saddle 106 is guided by the guide 107 and moved in the Z-axis direction, and the cross slide is guided by the guide 108 and moved in the X-axis direction.

One side end of the guide 107 is used as a reference surface, a measuring device is temporarily fixed to the reference surface using a magnet 109, etc., and the measuring device's probe is brought into contact with the end surface of the tool T or the test bar W to measure the workpiece. Data affecting the amount of displacement on the spindle side i and the turret side are measured using dial gauges 11Qa and 110b for each type of tool and machining conditions of each tool, etc., and the above curves x and x are obtained.
The coefficients P and P' of ' are calculated in advance and stored in the data file shown in FIG. 2(C).

(2) Next, a specific configuration of the present invention will be explained based on FIG. 1.

FIG. 1 is a control block diagram illustrating the present invention in detail.

In FIG. 1, various data are input in advance to a CNC 1 from a keyboard with a screen 2 via an input/output circuit 2a.

A machining information program for each workpiece is stored in a machining information program memory 3.

In the spindle rotation duty data file 4, parameters P N + P N' for each duty DIIDtlD31...D■, which have been determined empirically, have already been filed. Also, X-axis feed duty data file 5
Similarly to the spindle rotation duty data file 4, each duty D 2. D z, D 3. ...I)F+
The parameters P F + P F 1 for P F + P F 1 are filed.

The main shaft motor 6 is connected to a drive unit 6a, and further connected to the CPUI via an input/output device 6c.

A motor 7 for moving the turret is connected to an amplifier 7a,
Furthermore, it is connected to the CPUI via an interpolator 7b. The position feed received by the interpolator 7b is fed back to the motor 7 and controlled.

For example, when machining each workpiece, the machining information program
The processing information program stored in the memory 3 is once run, and the total feed amount Fi and the total displacement amount Xi are calculated by the calculation unit 8.
Then, the total time H is obtained by performing the calculation process H-1ΣXi/Fil. On the other hand, each displacement f
iXi is taken into the arithmetic unit 9 and arithmetic processing of L2ΣXi is performed to obtain the total displacement amount.

The total time H and total displacement measured by the calculation units 8 and 9 are taken into the calculation unit 10, and the calculation process of DF=L/H is performed, and the duty D is calculated.
, is temporarily stored in the memory 11.

The total rotation speed Ni of the spindle rotation speed N and the time τi are taken into the calculation unit 12, and the calculation process of DH=ΣN i Xτi is performed, and the duty D is stored in the memory 1.
3 is temporarily stored.

When the duty D stored in the memory 11 and the duty I)rt stored in the X-axis feed duty data file 5 are taken into the coincidence circuit 14, and the duty D and DFi match, the parameter P F
+P F 1 is output.

Further, the duty D8 stored in the memory 13 and the data DNi stored in the spindle rotation duty data file 4 are taken into the matching circuit 15, and the data D, DH! If they match, the parameters Pn, P'
n is output.

When machining is started according to the machining information program stored in the machining information program memory 3, a continuous operation start signal (hereinafter referred to as a start signal) is taken into the AND gate 16. Furthermore, AND gate 1 is activated by the status signal.
6 is opened and counted by the counter 17. The count value counted by the counter 17 is the AND gate 18
be taken in. When the continuous operation of the machine is stopped, a stop signal is input to the AND gate 18. and·
The AND gate 18 is opened by the count value taken into the gate 18 and a continuous operation stop signal (hereinafter referred to as a stop signal), and the time τ of the count value is taken into the calculation section 19. The calculation unit 19 receives the saturation displacement parameter Xo and the parameter PF output from the coincidence circuit 14.15.
, PM are taken into the calculation unit 19, respectively. The arithmetic unit 19 performs the arithmetic process x=xo (t-e-'τ) based on the parameters Xo, P, and time τ, and uses the corrected correction amount X as a result to calculate Correction control of the motor 7 is performed.

When the machine is operated for 8 hours, for example, and then stopped during a break, a stop signal is input to the AND gate 20. The status signal causes AND gate 20 to open and counter 21 to count. The time T2 of the count number counted by the 8H counter 21 is taken into the comparators 22 and 23.

A comparator 22 compares T with a preset time, for example, 8 hours (Hl) after the machine is stopped, and if T<H, the data is taken into the AND gate 24.

Also, a start signal is taken into the AND gate 24. Thus, the AND gate 24 is opened by the start signal and the time r that satisfies the condition T2<H8. Next, when the time r after the machine has stopped is taken into the calculating section 25, the parameter XO and the parameter P'F which have already been taken are retrieved.

By the synthesis parameter P' of pFo, X'=Xoe-Pr
The arithmetic processing is performed, and further x=x', that is, Xo
The time is calculated from (1-e-'τ) = X oe-PF τ', and the τ'' time is taken into the calculating section 26. The calculating section 26 calculates the preset correction time △τ゛° and the time τ''. ′ is added. (τ″+△
τ”) time into the calculation unit 19, x+ a= X□
A calculation process of (le-(r''+AT''l) is performed. Correction control of the motor 7 is performed via the interpolator 7b based on the correction t x + obtained by the calculation process.

Compare the 12 hours taken into the comparator 23 with the time H8 after the machine stopped, and if T z > Hm, the machine itself has completely cooled down, so the calculation section 27 calculates -O is processed and sent to the interpolator 7b, where the motor 7 is controlled.

(3) The operation of the present invention will be explained based on the flowchart of FIG.

In Fig. 4, first start the machine at stage 0. ■
In step 1, the data DN of the spindle rotation duty is inputted from the screen keyboard 2 and is filed in the spindle rotation duty data file 4. In the 0th stage, the X-axis duty data DF is similarly inputted from the screen keyboard 2 and inputted into the X-axis feed duty data file 5. Next, in the 0th stage, it is determined whether or not to stop the machine. If the machine is not stopped, the process proceeds to the 0th stage, and the calculation unit 19 calculates the correction amount X for each time.
The arithmetic processing of X=Xo (1-e''de τ) is continued.

When a decision is made at the 0th stage to stop the machine, the count is reset at the 0th stage. Next, at the 0th stage, the counter 21 starts counting the time τ'. At the 0th stage, it is determined whether a cycle start is to be performed or not, and if the cycle start is not to be performed, the counter 21 is reset.

When it is determined at the 0th stage that a cycle start is to be performed, the comparators 22 and 23 at the 0th stage compare whether 8 hours have elapsed. If 8 hours have not elapsed in the 0th stage, the calculation unit 25 calculates the time correction amount in the 1st stage: X'=Xoe −
A calculation process of deg j is performed to obtain the correction amount x'. In the 0th stage, the correction amount x=xo (1-e-rr') of the calculation unit 19 is made to sequentially count the time.

Compare whether or not x-x” at the 0th stage, X≠X1
In the case of , it is returned to the stage before the 0th stage and fed back until it becomes
The arithmetic processing of (τ11+Δτ″) is performed.

At the 0th stage, the time (τ″+△τ″) processed by the 0th stage is substituted into τ of the calculation unit 19, and X,
= X 0 (1-6-P(r'+, a?'')) The correction amount X1 is obtained by the calculation process, and the correction amount X1 is calculated in the 0th stage.

The motor 7 is corrected and controlled via the interpolator 7b using the correction amount as an external tool correction input.

Note that if 8 hours have not elapsed in the 0th stage, the process proceeds to the 0th stage X, and the correction amount calculated in the 0th stage is the 0th stage X.
In the 0th stage, the motor 7 is corrected and controlled via the interpolator 7b as an external correction amount.

Effect C] The present invention counts the cycle stop time or operating time when the machine is stopped by formulating the displacement curve of the experimental values of the duty of the tool rest and the displacement of the headstock, which are characteristics possessed by the machine, The amount of dimensional correction at the time of restarting the cycle is calculated based on the count number, and the correction is automatically controlled based on the amount of correction, so there is no need for the operator to take the trouble to measure the amount of correction.

Therefore, as an automatic machine, the processing efficiency is improved by several orders of magnitude compared to the conventional machine, and the operating rate is also improved.

[Brief explanation of drawings]

FIG. 1 is a control block diagram illustrating the present invention in detail. FIG. 2(A) is a diagram showing the amount of displacement with respect to time for each spindle rotation speed. FIG. 2(B) is a diagram showing a heating curve and a cooling curve of a thermal displacement position with respect to time to explain the basic principle of the present invention. FIG. 2(C) is a data file of parameters associated with the spindle rotation speed used in the present invention. FIG. 3 is a plan view of a turning machine tool for explaining displacement measurement. FIG. 4 is a flowchart illustrating the present invention in detail. 1...CNC2...Keyboard with screen 3...Machining information program memory 4...Spindle rotation duty data file 5...X
Axis feed duty data file 7...Motor
7b Interpolator 14.15... Matching circuit 1, 7.21... Counter 19.25.26.27... Arithmetic unit Patent applicant Hitachi Seiki Co., Ltd. Figure 2 (A) Figure 2 (B ) Fang 2 (C) Figure 3 Figure 4

Claims (1)

[Claims] An input/output device that inputs and outputs parameters such as preset duty, a machining information program memory that stores a machining information program, and a spindle rotation device that stores parameters for each spindle rotation duty. The main axis rotation for each machining is performed by running the duty data file, the X-axis feed duty data file in which parameters are filed for each X-axis feed duty of the tool post, and the machining information program stored in the machining information program memory. The duty and the X-axis feed duty are calculated, and the calculated spindle rotation duty and Synthesis parameter P, which is a combination of the matching circuits to be compared and the parameters taken out when matching in the matching circuits, the preset saturation displacement amount X_0, and the time τ after the start of machining
The first step to calculate the correction amount of X_0(1-e^-^p^τ)
and a synthetic parameter P' which is obtained by combining the parameters retrieved when the matching circuit matches when the machine is stopped and reworked, the preset saturation displacement amount X_0, and the time τ from when the machine is stopped until rework is performed. A second calculating means calculates the displacement amount at the time of re-machining from ' by X'=X_0e^-^p^τ', and the displacement amount
Time τ″ is calculated as X, and correction time Δτ″ is added (τ″+Δτ″) Correction amount due to time
A temperature correction device for a turning machine tool, comprising a third calculating means for correcting by ^τ^''^)), and performing re-processing by performing correction control using a correction amount of X_1 after the machine is stopped.