JPS63271505A - Position interpolating method for numerical controller - Google Patents

Abstract

PURPOSE:To increase the feed speed of a tool up to its maximum by composing a fine block so that a shape error is within a permissible error quantity range. CONSTITUTION:A block of axial movement command data, specially, a fine block is composed so that its error is within the permissible error quantity range specified by an operator, and a new path is generated before a movement quantity per unit time is found from data commanded in a machining program. Namely, when the fine block is composed by a position interpolation part 241, two processes, i.e. the removal (primary composition) 241a of an extremely fine block for determining whether or not the composition is performed according to the movement quantity of the fine block and the composition (secondary composition) 241b of a fine block for determining whether or not a new path is employed by generating the new path and comparing the path with a command path are carried out. Consequently, fast machining is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a position interpolation method in a numerical control (hereinafter referred to as NC) machine tool when performing high-speed machining.

(Technical Background and Problems to be Solved) The feed rate of a tool when machining with an NC machine tool is a unit determined from the axis movement command data SD and feed rate command data VD commanded in the machining program 110. It is expressed in iTM moved per hour.

￥S5 is a block diagram schematically showing a conventional NC device for controlling the above-mentioned NC machine tool, and includes a program input section 120 into which a machining program 11G is input manually, and a machining program read out from the program input section 120. 11
Axis movement command data SO and auxiliary movement command (S,
T, M command) program interpreter 130 that separates data
It has

Furthermore, a function generation unit 140 that calculates a movement amount TM per unit time based on the axis movement command data SD and the feed speed command data vO read from the program interpretation unit 130;
An axis control section 150 that controls the tool using the movement ffiTM per unit time read from the function generation section 1110 is provided.

To explain the operation of the above-mentioned NC device, when a machining program 110 is manually entered into the program input section 120 via a paper tape or the like, the program interpretation section 130 reads out the machining program 110 from the program input section 120, and The movement command data SD and the auxiliary operation command (S, T, M, command) data are separated. and,
The function generation unit 14G calculates the movement amount TM per unit time based on the axis movement command data SO and the feed speed command data VD read from the program interpretation unit 130, and calculates the movement amount TM per unit time.
0 reads the movement amount TM per unit time from the function generator 140 and controls the tool.

Here, in order to move each axis eight times according to the shape based on the axis movement command data SD, the movement amount OM for each block commanded to the machining program 110 and the movement amount TM per unit time are as follows. The relationship is expressed by equation (1).

[IMkTM...(1) By the way, when performing rough machining, for example, it is better to shorten the machining time than to reduce the amount of error in the machined shape, even if the amount of error in the machined shape becomes somewhat large. It may be desired. However, 1N 9) J ffi small block (
In a machining program in which a series of microblocks (hereinafter referred to as microblocks) are made, the movement fiBM for each block is extremely small, so from the relationship in equation (1) above, the movement fiT per unit time is
There was a drawback that M could not be increased.

Also, ignoring equation (1) above, the movement iT per unit time is
If M is increased, each axis of the tool will not move according to the shape based on the axis movement command data SO, so there is a problem that it is not possible to process the tool into an accurate shape.

(Object of the Invention) The wood invention was made in view of the above-mentioned circumstances, and the object of the present invention is to provide an NC device that can perform high-speed machining by suppressing the tolerance amount of machining shape within a certain amount. An object of the present invention is to provide a position interpolation method.

(Means for Solving the Problems) The invention relates to a position interpolation method in an NC device that performs position interpolation of continuous minute blocks instructed by a machining program in an NC device that controls an NG machine tool.
The above object of the present invention is to synthesize the continuous micro blocks according to a predetermined calculation formula to create a path that can suppress the shape error of the workpiece within a certain amount and increase the feed rate of the tool. achieved.

(Function of the Invention) The present invention is designed to ensure that blocks of axis movement command data, especially minute blocks, fall within the tolerance amount specified by the operator before calculating the movement amount per unit time from the data commanded in the machining program. The above blocks are combined to create a new route.

(Embodiment of the Invention) FIG. 1 is a block diagram showing an embodiment of a device for realizing the position interpolation method according to the present invention, corresponding to FIG.
A function generation unit 240, which is composed of a position interpolation unit 241 that synthesizes micro blocks with respect to the command shape of the machining program 110, and a speed interpolation unit 242 that calculates the movement i+ITM per unit time, is different from the conventional function generation unit 140. is provided instead.

The method of synthesizing minute blocks in the position interpolation unit 241 includes removal of extremely minute blocks (first synthesis) in which it is determined whether or not to synthesize based on the amount of movement of the minute blocks.
There are two processes: 1a and minute block synthesis (secondary synthesis) 241b, which generates a new route in advance and compares the new route with the commanded route to determine whether to adopt the new route. , and a case where one of these two processes is used or a case where both are used together can be considered, but here, a case where both are used in combination will be explained with reference to the flowchart of FIG. 2.

First, remove extremely small blocks (first synthesis) 2
To explain the processing of 41a, the program interpreter 1
Step S1) to read one block from the axis movement command data SO read from 30, and its movement it dr. ,
To find the command point C1+l (Xl+I
+yl+l+Zl++) and command point C+ of the previous block
(X+, Y+, Z+) is substituted into the following equation (2) (step S2).

d+++='X+++-X"V+++-V+"-"7・
(2) Then, it is checked whether or not this movement amount d1.1 satisfies the following equation (3) with respect to a predetermined first tolerance amount 26 (step S3).

d1+1≦26 (3) In the judgment step S3, if the above formula (3) is satisfied, read out the next block. Step S4), find the movement amount d 1.2 from the same root as above. (Step S5), in addition to the previously determined movement ffi d + -t (Step S6),
It is checked whether the added movement amount d satisfies the following equation (4) (step 57).

d≦26 (4) Then, in the judgment step S7, if the above equation (4) is not satisfied, the process returns to step S4 and the above-mentioned operation (
Steps 54 to S7) are repeated to find the maximum n that satisfies equation (4).

On the other hand, in the judgment step S7, the total amount of movement d
If does not satisfy the above equation (4), the previous block is combined into one block (step Sa), that is, the command point C,+ of the maximum n block obtained above. and the command point C8 of the first block, and create a new path TP.
I (see Figure 3).

Note that ε is a tolerance amount that a digitizer or the like has, and is an amount that can be set by an instruction from an operator.

Next, to explain the process of combining minute blocks (secondary combining) 241b, after combining into one block in the step S8, or in the judgment step S3, the movement Mdl+I does not satisfy the above equation (3). If so, the next block is read out and Umeji, which is the best place for firewood, is assumed (step SO). That is, the command point C1+ of the next block
2 and the command point CI of the previous block with a straight line, and connect the command point C1 of the current block between the command point C1+2 and CI.
+10 command point CI + (X + + + + 3' + + + + Z
t++) and the command point CI of the previous block (xl+yI+Z
Substitute l) into the following equation (5).

112+-[(x+*+-Xt)”(Y+++-y+)
' ”(Z+++-2+)2-(^(X+++-Xt)
"[l(y+++-y+)"C(Z+++-Z+)l'
l ”2・・・・・・・・・(5) However, A, B, C, and S are given by the following equation (6), and
It is checked whether this distance 1111 h 2 + satisfies the following equation (7) with respect to a predetermined second tolerance amount ε°. (
Step 512).

1121≦ε° (7) In the judgment step S12, if the equation (7) is not satisfied, the process ends. On the other hand, the judgment step S
In step 12, if the above equation (7) is satisfied, the next block is further read out, a new route is assumed (step 513), and the distances at h 31 and h 3 are calculated in the same way as described above.
2, and these distances at h 31 and h32 are the second
In step 514), it is checked whether the second allowable error amount ε° is exceeded, and if the second allowable error amount ε° is exceeded, the process is terminated. On the other hand, in the judgment step 514, the distance 1111 h 3 + and h32 are the second allowable error amount ε.

If the amount of movement on the new route does not exceed the amount of movement on the previous route, it is checked whether the amount of movement on the new route is monotonically increasing (step 515), and if it is not increasing monotonically, the process proceeds to step S17. The previous block is combined into one block and the process ends.

On the other hand, in the judgment step S15, if the amount of movement of the new path is monotonically increasing, does the amount of movement of the new path exceed the amount of movement TM per unit time determined from the feed rate command data VD on the machining program? If the movement iTM per unit time has not been exceeded (step 516), the process returns to step 513. Then, the above-described operations (steps 513 to 516) are repeated to find the maximum k that satisfies the following equation (8).

11kJ≦ε' (j-1, 2,..., -1)
(8) Note that hkj is obtained by the following equation (9).

bkj-[(x+-j-x+) ” (y+ +j-y
+) ” (ZIIIJ-21)2=(＾(X++j-
Xt)”B(y++”-y+)”C(7,+*J-1+
))2] ”'・・・・・・・・・(9) However, A, B, C, and S are given by the following formula (lO).

...... (lO) On the other hand, in the judgment step 51B, is the movement J1 of the new route equal to the movement f per unit time? If tTM is exceeded, the achievable feed rate is determined by the command value of the machining program, and the synthesis process of the micro blocks is wasted.
Combine the previous block into one block (step 5)
17), that is, connect the command point CI or k of the block with the maximum k obtained above with the command point C1 of the first block, and create a new path TI)2 (see FIG. 4), and end the process.

Note that the second allowable error amount ε° is an allowable error amount of the machining shape, and is an amount that can be set by an instruction from the operator or designation of the machining program.

Then, the above-described process is applied to the command path of the machining program 110, and the speed interpolation unit 242 uses the processed command path.
calculates the amount of movement TM of the tool per unit time, and the axis control unit 150 controls the tool based on the movement iTM per unit time.

In the above explanation, the tolerance amount ε of the digitizer, etc., the moving jaw 'M' per unit time and the allowable error amount ε of the machining shape
The calculation time of the synthesis process is reduced by using both the primary synthesis and the secondary synthesis. In addition, the allowable error amount ε° of the machining shape specified by the operator etc.
By synthesizing micro blocks based on
This is to raise the upper limit of , and increase the tool feed rate to the maximum.

(Effects of the Invention) As described above, according to the method of the present invention, micro blocks are synthesized so that the difference in shape M (difference is within the tolerance amount specified by the operator, etc.) It becomes possible to increase the tool feed rate to the maximum while keeping it within the tolerance amount specified by the operator, etc., and it is possible to perform higher-speed machining, thereby improving machining efficiency.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an outline of an apparatus for realizing the method of the present invention, FIG. 2 is a flowchart explaining an example of the operation of the method of the present invention, and FIGS. 3 and 4 each explain position interpolation by the method of the present invention. FIG. 5 is a block diagram schematically showing the apparatus of the conventional method. +10...Machining program, 120...Program human resources department, 130...Program interpretation department, 150...
Axis control section, 140, 240...Function generation section, 241.
...Position interpolation section, 242...Velocity interpolation section. Applicant's agent Yu Yasugata Three vines 2

Claims (4)

[Claims] (1) When interpolating the position of continuous small blocks commanded by a machining program with a numerical control device that controls a numerically controlled machine tool, the continuous small blocks are synthesized according to a predetermined calculation formula to keep the shape error of the workpiece constant. Keep it within the amount,
A position interpolation method in a numerical control device, characterized in that a path is created that can increase the feed rate of a tool. (2) The method of synthesizing the continuous micro blocks according to a predetermined calculation formula is to sequentially read the command points of the blocks from the machining program, sequentially obtain the movement amount from the command points of the current block and the command point of the previous block, and When the sum of the amounts exceeds a predetermined first tolerance amount, the command point of the previous block and the command point of the first block are connected with a straight line. Position interpolation method in the numerical control device described. (3) The method of synthesizing the continuous small blocks according to a predetermined calculation formula includes sequentially reading command points of the blocks from the machining program, sequentially connecting the command points of the first block and the command points of other blocks with straight lines, and The distances between the command points of blocks located between the straight lines and the straight lines are sequentially determined, and when the distance exceeds a predetermined second tolerance amount, or when the length of the straight lines no longer monotonically increases, or When the length of the straight line exceeds the amount of movement per unit time determined from the machining program, the command point of the previous block and the command point of the first block are connected by a straight line. A position interpolation method in a numerical control device according to item 1. (4) The method of synthesizing the continuous small blocks according to a predetermined calculation formula sequentially reads the command points of block (A) from the machining program, and sequentially calculates the movement distance from the command points of the current block and the command point of the previous block. , when the sum of the movement amounts exceeds a predetermined first tolerance amount, the command point of the previous block and the command point of the first block of the block (A) are connected with a straight line. After the first synthesis process is completed, the command points of block (B) from the machining program are sequentially read out, and the command points of the first block of this block (B) and the command points of the first block of this block (B) are read out sequentially. Sequentially connect the command points of other blocks with straight lines, sequentially find the distances between the command points of the blocks between the straight lines and the straight line,
When the distance exceeds a predetermined second tolerance amount, when the length of the straight line no longer increases monotonically, or when the length of the straight line exceeds the amount of movement per unit time determined from the machining program. Claim 1, wherein when the command point of the previous block and the command point of the first block of the block (B) are connected by a straight line, secondary synthesis is performed. A position interpolation method in a numerical control device described in .