JPS58114840A - Correcting system of pitch error in machine tool - Google Patents

Abstract

PURPOSE:To enable to do with small memory capacity and to facilitate the change of parameters by a method wherein the errors in shaft feed motion are approximated with straight lines and the intersections and gradients of said straight lines are memorized in the form of parameters, based upon which the correction is performed. CONSTITUTION:Amounts of feed of X-axis necessary for generating the error of a predetermined unit length, for example of one micrometer, for the respective error characteristic curves l1-l4 are determined as pitches P1-P4. Let CR1, CR2 and CR3 denote the bent points of the curves l1-l4 and further let break point positions BP1-BP3 be the amounts of feed of X-axis corresponding to said bent points CR1, CR2 and CR3. In addition, let SP be the starting point serving as an origin for correction and SL be the stroke limit of the range of correction. The gradients and the positions of intersections of the curves l1- l4 are determined so that the intervals of blocksI-IV multiply integrally as against the pitches P1-P4 and memorized together with the starting point SP as a supplementary table. At the break points BP1-BP3, the judgement of correction is made from the change of the gradients of the characteristic curves before and after the point to be corrected so as not to produce error.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pitch-difference compensation method for compensating for a difference of 1 m in the same direction as the direction of movement of the axis of a machine tool by ×I.

A cutlery is used to carry and move a machine tool such as a machine tool that carries out machining. Production of Ichinoseki etc. of the Cabinet 1
Difference, cut during machining 81. Differences in kneading occur due to deformation due to force, simple ζ, and other factors, but it is impossible for Komachi to eliminate the kneading difference due to bending, and there is a certain limit to machining accuracy.

In recent years, with the development of t/Tsukuda control (iNc) 轡σ's electronic honjin branch technique and jt* control technology, it has become "J 肚, ζσ) to control 欬-like-ga with precision". The function of the control technology is that the oil-cooled tube glaze can be fed in 1 minute.
In order to do the IIt trick, there is l*, which corrects the Japanese and vertical posture of the machine. However, although it is not impossible to produce a table of 81 stocks with a tpi of lfi or higher, in practice the production cost is high (too much and uneconomical, and the cutting force and It is difficult to manufacture something based on thermal deformation (which also takes into account the complicated deformation of the mechanical system).

For this reason, as a method to finish the machine itself with high precision, we continuously measure the deviation of the sliding table etc. from the clay P9'r mourning path, and the resulting By feedback, the I control command is corrected to satisfy the required previous layer (5 methods have been proposed. However, this correction method requires complicated measurement methods and processing of measured values. (・Due to the 5 problems, the reality is that nothing practical has been realized.Also, the error for the axis movement amount is discretely added -1 in advance to obtain a correction table, A method has been proposed in which the corresponding error cover is read out from the correction table when the position is set.For example, the difference in the same direction as the movement direction (actual deviation from position)
), as shown in the ig1 diagram, when the X-axis position and the corresponding difference X' are sequentially changed, the error data corresponding to the position C1 For example, when the X-axis position l1
When the device is at
) II child (・C is the misrun data X ・Akita is added to the command value to stop the vehicle.
In the θ・Karu correction method, if the error cover is thick (・If the stroke of the child axis movement is long, the correction tape Y・ becomes large (・・One drawback is that the correction table If you control the size and make -f small, there will be a rough correction (・ and (・tsuta defect ρ)).

Therefore, the target is the above-mentioned yl saku point (and cylinder). I plan on offering it.

1 I will explain this detail below.

This invention relates to the pitch-travel support system used in earthworks, and determines the error in the same direction as the direction of subsequent movement of the shaft of the f-sharpening machine in the same direction as lil-1, An error characteristic curve of linear approximation is calculated from this measurement error data, and a breakpoint position indicating the position of the axis corresponding to the bending point of the error characteristic curve and a breakpoint position that is an integer fraction of the interval between the breakpoint positions and a predetermined unit. The amount of movement of the axis for the length error is stored as the pitch of each linear slope of the one-difference curved line, and the movement of the axis is calculated at a predetermined value each time the axis passes through a correction point corresponding to the pitch. In addition to making corrections per unit length, when passing each breakpoint position, changes in the slope of the characteristic curve tightening of the front bale are observed to determine whether or not to make corrections to avoid increasing errors. It is something. That is, in the present invention, first, a linear approximation one-difference curve 11141-12-13-14 as shown in FIG. 2 is obtained from the X-axis measurement-difference data as shown in FIG. In this case, each difference measurement curve 11 calculates the amount of movement on the
~ ] 4 pitches p1 to p4 are determined. And the adjacent error characteristics--11 and! The bending point of 2 is C11-
The bending point of koji 12 and 13 is 2, - the difference is %! ! While taking the bending points of 1l13 and 14 as CR3,
The moving amounts of the X axis corresponding to these bending points OLI to CkL3 are respectively set as break point positions WIBP1 to BP3, the starting point serving as the origin of correction is set as SP, and the stroke limit of the correction range is set as SL. Therefore, block between the starting point SP and breakpoint m & HPI■, and block the space between breakpoints fullIHP1 and BF2■
, block ■ between break point position @BP2 and BF2, block IV between break point position @B)'3 and stroke limit SL, and valley block I~
The pitches are adjusted to 1Iill so that the intervals 1 to ' are exactly divisible by the corresponding pitches p1 to p4. In other words, the intervals between blocks ■ to ■ are the corresponding pinches p1 to p4, respectively.
The slopes and intersection points of KwA difference meters #11 to 14 are set so that the connection times the error characteristic -1 determined in this way.
Break point position of 7111-14 [BP1-HP3
And the pitches p1 to p4 of each block I NIV are stored in memories M1 to M9 along with the starting point SP in a corresponding relationship as shown in FIG.
Store it as a correction table.

Based on the block position data stored in the correction table and the pitch data of that section, in this invention, when moving within the same block, a correction of 1# is performed every time the block moves by the pitch Ik determined by the block. When moving to another block, look at the change in the slope of the characteristic curve before and after, and decide whether to make corrections or not to avoid an increase in error. A correction of 1μ is made each time the pitch amount is shifted.The state of this correction method will be explained with reference to the diagram in Fig. 4. In this example, the block ■ corresponding to the error characteristic curve % sex curve 14K corresponding block ■
It shows the movement between. Therefore, since the pitch in block mK is p3 and the pitch in block IV is p4, in this invention, when moving within block m, the correction point CM31 is set for every pitch pitch 3.
, (3J↓,... and when moving within one block ■, a correction point CM41 is set for every pitch pitch 4,
CM42,... is determined, and each time the correction point passes, 1μ
Make corrections. For example, the XsO dust location is Xl, and the command value causes the position f11X2 in the same block m.
Considering the case where the correction point CM33 and (3
32, the correction points CM feather and 0M32 are each corrected by 1 μ.

In this case, the detection of whether there is a correction point (Jd33, 0M32) is performed by comparing the correction point one before the current position (the correction point with the largest position among the correction points smaller than the current position) and the current position. It is determined whether the difference is greater than the pitch p3. Therefore, the position −“Xl to X2
When moving to the previous correction point (CM34), when the X-axis reaches the correction point CM33, it is memorized as the current position.
) is the pitch p3, so the correction point is 1μ at 1 field.
(・By adding 11T-f of the previous correction point to CM33 for the current position, when the X-axis reaches the correction point CM32 in four ways, 1# correction is made at the correction point CM32. You can do anything.

Next, if we consider the case of moving from position Now, perform the same correction as described above. That is, break point positions HPI to HP3, start point S
Since P and stroke limit SL are stored in memo I) M1 to M4, it is possible to monitor which block the X-axis position is currently in, and for block m, as described above (correction point CM, 0M32 and CM31 are corrected by 1μ. Then, when passing the correction point CM31 and reaching the breakpoint position [BF2K, the current position is recognized as the breakpoint position BP3, so this breakpoint position *In BP3, it is decided whether to perform the correction or not. In the case of Fig. 4, the signs of the slopes of the front and rear characteristic curves are different, so
Don't make any corrections (・. However, when you pass the breakpoint position @B) '3, record the previous correction point that should be memorized from CM 31 to BF2, and change the pitch from this breakpoint position 1iBP3. When the X-axis moves by p4, a correction of 1 μ is performed at the correction point CM41. After that, the correction will be made within block ■.

Then, the same correction is made at the correction point CM42, and
The axis is delayed within the error range of 1μ to the command value setting X3.

In addition, here we have explained the case of moving from the lower block ■ to the upper fill block ■, but the same applies to the case of moving from the upper side to the lower 111 block, and in this case too, the previous block in the monarchy A new correction point is determined based on the correction point.

In addition, in the example of FIG.
The interval between the position where and the break point position HP3 is an integer multiple of the respective pitches p3 and p4, but it is not necessarily necessary to double the integer in this way, and the interval between the break point positions It is sufficient if the pitch is an integral multiple of the valley pitch.

Here, we will explain the specific correction method using the flowchart shown in FIG.

First, when a correction operation is started (step 81), it is determined whether the correction table as shown in FIG. 3 is correct (step 82). In this case, it is necessary to judge whether the break point positions etc. are arranged in descending order.If it is correct or not, it is returned, and if it is correct, it is returned in the lbj period (W point If synchronization is established, check which block the & machine is currently stopping at and set it in register 1 as memory (step S3).
. In this example, the machine is stopped at block (2), so "3" is set in register 1. Finally, after confirming whether or not it is within the stroke register LSL (step S5), the contents of registers 2 and 3 are set to "0", and the contents r3J of register 1 are transferred to register 4. At step 86), the pitch (p3 in this example) of the register 4 stored in the register 5 (m in this example) is set and its sign is determined (step 87). If the pitch is 0, it is left as is; if it is positive, register 3 is set to "1" (step S8); if it is negative, the pitch of register 5 is converted to an absolute value and made positive, and "-1" indicating dog in register 3
is set (step 89). In this example pitch p3
Since is positive, "1" is set in register 3. In this way, when Jj:, jA in register 5 is determined, the correction point immediately before the current position - (this IIJ) is stored in register b.
Then set Q. ]34) Step 81O), set the break point position of the previous block [HPP (Kono example -
(-&i LiF2) Subtract the command position (ilXN (X2. It becomes $1 routine A to the block, and the ω match VC below O is I in the register 40 (“3” in this example).
Add IJ to find the block of F-11 (■ in this example) (step 812), then subtract the command position
1 (step 5lj).

If the difference is greater than or equal to 0 (in the case of command position
For X2), m” - movement within the block
(Assuming that, the movement routine within the block as described below is as follows.) Then, V is the breakpoint position of the block corresponding to the current position, and the breakpoint position of the block one block above the current position. It is determined whether the commanded position is within the current block, an upper block, or a lower block from the large/J% between the break point position of the block and the current position.

Therefore, when moving to a movement routine within the same block, such as when a command position @X2 is given to the current position X1, the command position (in this example, X) is first set in the register 7, and Register 7 that stores this command position
The previous correction point CM34 is stored from (step 814) by subtracting register 6 and the difference is set as the content of register 7, and it is determined whether the difference is positive (step 815). .

If the difference is negative, subtract register 3 from register 2 and set the difference in register 2, and subtract register 5 from register 6 and set the difference in register 6. Step 816L If the difference in the register 7 is pressure, the process moves to the next step 817. Therefore, in this case, the value of register 7 becomes positive.
Subtract the contents of register 5 that stores the pitch (p3) of the block from the contents of register 7 that stores the difference with m34, set the difference in register 7, and check whether it is negative or not. investigate. If the difference is positive or 0, the content of register 2 is "0" and the content of register 3 is ! [I.J.
At the same time, the contents 1cM34J of register 6 and the contents "p3" of register 5 are added and the added value is set in register 6 (step 819). As a result, the register 2 that accumulates the correction amount
The content of becomes rlJ, and the previous correction point for the current position is updated from CM34 to CM33. The above operation will be repeated until the contents of register 7 become negative, so at the time register 7 becomes negative, register 2 will eventually store the correction amount for moving from position @X1 to X2. Then, the register 6 stores the correction point CM3t immediately before the position wtX2 and stores it (・
It becomes K. In this way, if the judgment in step 818 is negative, the register 6 adds one more step S to the previous correction point CM32 with respect to the current position is set in register 2, and this corrected value is used as the axis command value (step 821). Therefore, in this example, the command is such that the command value X2 is subtracted by IJ v2 times.

On the other hand, when the command position is set to X, the routine moves from step 813 to the upper block. step 840).

Then, ``1'' is added to register 1 storing the dust block number (r3J in this example) to make it ``4'' (step 841), and this block (■ in this example) is breakpoint position BP (BF2 in this example)
) is set in register 6, and the contents of register 4 are set to "4" corresponding to the updated block (step 542). Next, the pitch (in this example, p) of the block (■ in this example) stored in register 4 is stored in register 5.
4) and determine whether it is positive or negative (step 543
) is positive, it indicates positive in register 8 (step 844), and in your case, the pitch in register 5 is converted to a PM value and made positive, and
indicates a negative value and sets ↑ "-1" (step 545).

If it is 0, set it to 0 (step 844A).
). In this example, pitch p4 is negative, so register 8
"1-1" is set. Then, in step 54, it is determined whether the signs of register 3 and register 8 have changed.
6) If there has been a change, the process jumps to step 849 and determines whether the correction in the new block has been completed without repeating the correction process. If the break point position HP3 has not been completed, add the register 6 storing the break point position HP3 and the register 5 storing the pitch p4, and set the added value in the register 6 (step 848), register 2. The contents of register 8 are added to the contents of register 8, and the contents of register 2 are added.
(step 847). In this example, since the register 8Kr-IJ is set, the contents of the register 2 become [-1], and the above process is repeated until the correction in the new block is completed. Note that if the signs of register 3 and register 8 are the same and do not change, the process of step 847 is performed, so that the contents of register 8 are added to register 2 to perform correction. When the correction within the new block is thus completed, the processes from step 820 described above are executed. Therefore, the contents of register 2 in this case are subtraction correction at correction point CM, 33, supplementary correction points CM41 and CM4.
Since K is set to perform additive correction in each step 2,
In total, one subtraction correction is performed from position X1 to position X.

Furthermore, the routine to move to the lower block is shown in Figure 5)
As shown in , the principle is exactly the same, except that the operation is the opposite of that for moving to the upper block.

As described above, according to the correction method of this invention, the error in the movement of the axis is approximated by a straight line, and the intersection point and perpendicular slope are stored as parameters, and correction is performed based on this, so it takes a long time. It has the advantage that the memory capacity is small relative to the amount of movement, and parameters can be easily changed.

Note that although the above description has been made regarding the correction of the X axis, similar corrections can be made for other axes as well. Further, although the wA difference of one tone is used to determine the pitch of each error characteristic curve edge, the unit length can be arbitrarily determined.

[Brief explanation of the drawing]

Fig. 1 is an error graph showing the #j constant of the error in the same direction X' as the movement direction with respect to the movement amount of the machine tool's X axis, and Fig. 2 is a diagram showing an example of the 14M characteristic curve according to the present invention.
FIG. 3 is a diagram showing an example of a correction table according to the present invention;
FIG. 4 is a diagram for explaining the principle of the correction method according to the present invention, and FIG. - Distance measurement curve, SP...starting point, SL
...Stroke limit, BPI~HP3...Break voice/to position, M1~M9...Memory.

Claims (1)

[Claims] The error in the direction of movement and in all four directions relative to the amount of movement of the axis of the machine tool is sequentially measured, and an error characteristic curve of linear approximation is obtained from this measured difference data, corresponding to the bending point of the above-mentioned difference characteristic curve. a breakpoint position indicating the position of the axis to
The pitch with which the violet is the linear slope of the lIl difference characteristic curve is set aside by 1, and with respect to the movement of the axis, the predetermined unit length is In addition to making corrections using
Bisona force correction force type for work 1 illusion, which is characterized by the ability to judge whether or not to perform correction so as not to increase errors.