JPH0443730B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a tool path control method for a numerical control device, and in particular, calculates a tool path using data specifying a curved surface, and controls the tool path obtained by the calculation. The present invention relates to a tool path control method using a numerical control device that immediately moves a tool along a path and then repeats tool path calculation processing and tool movement control processing to process a curved surface.

<Background Art> A three-dimensional free-form surface is generally represented by a plurality of cross-sectional curves on a design drawing, and the shape data between one cross-sectional curve and the next cross-sectional curve is not specified. However, in numerically controlled machining, it is required to process so that the two cross-sectional curves are smoothly connected, even though such an intermediate shape is not provided. In other words, a curved surface between the above two cross-sectional curves is generated from the data of the cross-sectional curve, and an NC tape is created using the data regarding the generated curved surface.
This means that processing must be performed according to instructions from the NC tape. Therefore, a plurality of intermediate cross sections are generated according to a predetermined rule from data specifying several cross sections and cross-sectional curves of a three-dimensional curved body, and a cross-sectional curve (intermediate cross-sectional curve) of the curved surface body based on the intermediate cross sections is generated. A method for generating a curved surface of a three-dimensional curved body using a plurality of generated intermediate cross-sectional curves has been developed and put into practical use. In this method, as shown in FIG.
2a and the cross-sectional curves 21a and 22a obtained when the curved surface is cut by the third and fourth cross sections (not shown), a large number of point sequences (black circles in FIG. 1) on the curved surface are obtained.
Find intermediate cross-sectional curves 13a-1, 13a-2, . The NC tape is input into a numerical control device and the tool is moved along the intermediate cross-sectional curve to process the curved surface. In addition, for the above, create the NC tape offline in advance,
The NC tape is used for numerical control.

By the way, the tool path (position data of the point indicated by the black circle in Fig. 1) is calculated from the data that specifies the most recent curved surface, and the tool is immediately moved from the current position to the newly calculated point using the calculated position data. There is a need for a numerical control device that processes a curved surface by repeatedly calculating the next new point and controlling the tool movement to that point. The problem with such online numerical control is (1) a convex part exists in a predetermined area 30 (see Figure 1) on a curved surface, and the tool is moved over the convex part to move out of the area. (2) or when moving the tool along the convex part to the next point outside the area by cutting feed, and (3) when moving the tool to the next point in area 30 (see Figure 2). This is a case of moving to the next point outside the area while machining the groove (see FIG. 3). This point will be explained below.

Now, assuming that the tool has reached the first boundary point B1 of the region 30 along the intermediate cross-sectional curve 13a-i in FIG. 1, the tool stops rotating at the first boundary point B1. Thereafter, the numerical control device sequentially calculates the tool path (position data of points indicated by white circles) in the region 30 along the intermediate cross-sectional curve 13a-i until the tool path exits the region 30. Once the first point B2 (second boundary point) that exits the region 30 is found, the tool that has been stopped is then rapidly moved or cut along the path shown by the thin line in Figure 2 to the second boundary point B2. The second boundary point B is moved or grooved along the path shown by the thin line in Figure 3.
Move up to 2. By the way, it takes a considerable amount of time to calculate the coordinate values of a point on a curved surface (white circle in Figure 1), so it takes a long time for the tool to stop at the first boundary point until the second boundary point is found and moved. It takes a considerable amount of time. For this reason, the machine remains stationary for a long time while rotating, causing cut marks or gouges on the workpiece, and furthermore, if the workpiece is woodwork, the woodwork may become scorched or burnt.

<Objective of the Invention> The object of the present invention is to provide a method that, when a predetermined region exists on a curved surface, does not leave cut marks on the machined part even when the tool reaches the boundary point of the region, and can also prevent gouging. Furthermore, it is an object of the present invention to provide a tool path control method that does not cause scorching or burning even when the workpiece is woodworking.

Another object of the present invention is to allow the tool to escape to an escape point near the first boundary point when the first boundary point of the area is reached, until a second boundary point for exiting the area is calculated. A tool that stops the tool while rotating, thereby preventing the tool from coming into contact with the workpiece when stopped, preventing cut marks from being formed on the workpiece, and furthermore, preventing gouges and scorching the workpiece. An object of the present invention is to provide a path control method.

Still another object of the present invention is to specify in advance the moving speed at which the tool is moved from the first boundary point to the second boundary point, and to change the area depending on whether the moving speed is rapid traverse or cutting feed. It is an object of the present invention to provide a tool path control method for determining the path through which a tool passes.

Another object of the present invention is to provide a tool path control method that enables groove machining when passing through an area by setting the position of the area passing path below the position of the first boundary point in advance.

Still another object of the present invention is a tool path control method in which a convex portion can be machined when passing through an area by setting the area passing movement speed as the cutting feed in advance and setting the area passing path above the first boundary point. The goal is to provide the following.

<Summary of the Invention> The present invention is a tool path control method in a numerical control device that calculates a tool path using data specifying a curved surface and moves the tool along the tool path. A first step of inputting data including at least data specifying an area on the curved surface and data specifying a path passing through the area, and sequentially calculating a sequence of points on the curved surface using the data specifying the curved surface. a second step in which a straight line connecting the new point and the current position is used as a tool path; a third step in which the tool is moved along the tool path;
a fourth step of determining whether the tool has reached the first boundary point of the region; a fourth step of causing the tool to move away from the boundary point toward the outside of the region and stop when the tool reaches the first boundary point of the region; Step 5: Sequentially calculate a sequence of points on the curved surface using the data specifying the curved surface, monitor whether the calculated points have escaped from the area, and set the points that have escaped from the area as a second boundary point.Sixth step: Calculate the second boundary. a seventh step of moving the tool to the point along the path specified by the area passing path data;
step, followed by an eighth step of moving the tool along the calculated tool path.

<Example> FIG. 4 is a schematic explanatory diagram of the present invention, and FIG.
The area passing path APP is set above the first boundary point B1, and after the tool TL reaches the first boundary point B1, the tool is released to the escape point EP near the first boundary point, and then the tool TL is moved to the escape point EP near the first boundary point B2. is calculated, move the tool rapidly to the area passing path APP, and then move the tool to the second area passing path using simultaneous two-axis control of X and Y.
This is a case where the tool is moved to above the boundary point B2, and then the tool is positioned at the second boundary point B2 by rapid traverse.

In the same figure B, the area passing speed is set to cutting feed in advance, and the area passing path APP is set to the first boundary point B1.
The tool is set above the first boundary point B1.
After TL has arrived, the tool is released to the escape point EP near the first boundary point B1, and after the second boundary point B2 is calculated, the tool is positioned to the first boundary point B1, and then the tool is sent for cutting. Then, the tool is moved along the convex part PR to the region passing path, and then the tool is moved to the second boundary point B2 on the region passing path with cutting feed by simultaneous two-axis control of X and Y, and finally the tool is moved to the second boundary point B2. This is a case of moving along the convex portion PR by cutting feed up to the two boundary point B2.

In the same figure C, the area passing path is set to cutting feed in advance, and the area passing path APP is set to the first boundary point B1.
Set the tool below the first boundary point B1.
After TL arrives, the tool is moved to the escape point EP near the first boundary point B1 and stopped, and after the second boundary point B2 is calculated, the tool is moved to the first boundary point B1.
Then, the tool is lowered by cutting feed to the area passing path APP, and then, by simultaneous two-axis control of X and Y, grooves are processed on the area passing path by cutting feed until below the second boundary point B2. Move and finally the second
This is a case where the tool is moved by cutting feed to the boundary point B2.

FIG. 5 is a block diagram of a numerical control device implementing the present invention, FIG. 6 is a flowchart of the processing of the present invention, and FIG. 7 is an explanatory diagram of data specifying a curved surface and data specifying a region.

In FIG. 5, 101 is a keyboard having keys for inputting various data; 102 is a processor;
103 is a ROM that stores a control program;
4 is RAM, 105 is working memory, 106
107 is a pulse distributor, 107 is a servo circuit, 108 is a motor for each axis, 109 is a display device, 110
is the control panel.

The passage control process of the present invention will be explained below.

(a) First, from the keyboard 101 (a) Three-dimensional curved surface 1
0 (see Figure 7), cross-sectional curve information of the curved surface cut by the cross-section, and other necessary information, (b) the external curve 31 of the region 30 on the three-dimensional curved surface, Projection curve 31 projected onto a plane
Data identifying a, (c) Escape point EP (4th
(see figure), (d) area passing path data such as the Z-direction position (height) Zp of the area passing path, and (e) area passing speed Fp.
These input data are stored in RAM 104. Note that the three-dimensional curved surface 10 is, for example, a cross section 1
1, 12, 21, 22, cross-sectional curves 11a, 12a of the curved surface cut by the cross sections 11, 12, and cross-sectional curves 21a, 22a of the curved surface cut by the cross sections 21, 22.

(b) After the above various data have been input, the operation panel 11
When the start button (not shown) above is pressed, the processor 102 calculates the tool path on the curved surface (calculates the position data of the points indicated by black circles in Figure 1) according to the control program stored in the ROM 103. Execute. The method for calculating position data of points on a curved surface is explained in the Showa era.
See 1957 Patent Publication No. 5109.

(c) When the point positions on the first curved surface are calculated sequentially, the processor 102 determines the contents of the built-in flag register 102a each time. Note that when the flag is 1, it is assumed that the tool has reached the first boundary point B1, and when the flag is 0, the tool has not reached the first boundary point B1 or has already passed the second boundary point. It is assumed that
The initial value of the flag is set to 0.

(d) If the flag is 0 as a result of the determination process in step c, the processor 102 sets the point position as the target position, and uses the point data and the current position data stored in the working memory 105 to create incremental values for each axis. Calculate,
Next, the amount of movement of each axis for T seconds is determined and input to the pulse distributor 106. The pulse distributor executes a pulse distribution calculation based on the input movement amount of each axis to generate a distribution pulse, and inputs the distribution pulse to the servo circuit 107. As a result, the tool moves on the curved surface from the current position toward the point calculated in step b.

Note that the processor 102 calculates the current position in each axis direction.
Xa, Ya, and Za are updated in a well-known manner. That is, the processor 102 calculates the amount of movement of each axis in a predetermined time T seconds from the calculated incremental values of each axis and the cutting speed for cutting the curved surface, and calculates
The pulse distributor 10 calculates the movement amount of each of these axes every T seconds.
At the same time, the following equations Xa±〓X→Xa (1a) Ya±〓Y→Ya (1b) Za±〓Z→Za (1c) are executed, and each axis command current position Xa,
Ya, Za are updated (sign depends on movement direction).

In addition, the actual current position of the machine (current machine position)
As is well known, Xa', Ya', and Za' are monitored by counting up/down pulses generated from a pulse coder provided on each axis according to the direction of rotation. Further, the processor 102 calculates the remaining movement amount Xr, Yr, Zr every 〓T seconds using the following formula.
(The initial values of Xr, Yr, and Zr are the incremental values calculated above) are updated using the following formula: Xr−〓X→Xr (2a) Yr−〓Y→Yr (2b) Zr−〓Z→Zr (2c) ing.

(e) Then, the processor 102 determines the current position of the machine.
It is determined whether Xa', Ya', and Za' have already reached the area specified in step a.

(f) If Xr = Yr = Zr = 0 without the tool reaching the area, that is, if the tool reaches the point calculated in step b without reaching the area, the process returns to step b and the processor executes the next step. The points on the curved surface are calculated and the processes from step c onwards are repeated.

(g) On the other hand, if the tool reaches the area 30 while moving in step e (the reached point is referred to as the first boundary point), the processor 102 moves the tool to the first boundary point B.
1, and the movement amount of each axis 〓X, 〓Y, 〓Z is not outputted to the pulse distributor 106 even after 〓T seconds have passed. Also, the processor
The current position of each axis Xa′, Ya′, Za′ of the boundary point is
It is stored in the working memory as the coordinate values Bx, By, and Bz of the boundary point B1.

(h) Next, the processor 102 sets the flag in the flag register 102a to 1.

(i) Thereafter, the processor uses the data regarding the escape point EP stored in the RAM 104 to cause the tool to escape to the escape point EP. still,
The data regarding the escape point is, for example, the predetermined escape movement amounts 〓x, 〓y, 〓z from the first boundary point in the X, Y, and Z axis directions. Therefore, the processor uses the amount of escape movement to perform the same process as the path control described above to move the tool to the escape point EP. Note that only z may be given, assuming that the escape point EP is a point above the previous point on the curved surface by a predetermined amount z. Through the above processing, if the tool moves to the escape point EP, the process returns to step b and the processor moves to area 3.
The position of the point within 0 (white circle in FIG. 1) is calculated, and then the processing from step c onwards is performed.

(j) Now, since the flag is set to 1 after the tool reaches the second boundary point B1, the process does not proceed to the path control in step d due to the determination in step c.
The following processing is performed.

(k) That is, the processor 102 determines whether the point calculated in step b exists outside the area.

(m) If the point exists inside the area 30, the process returns to step b, and the processor 102 executes the calculation for the next point, and repeats the determination process of step k for the point. Thereafter, the point calculation process and the process of determining whether the point has left the area 30 are repeated until the calculated point leaves the area.

(n) When the point exits the area 30, the position data Bx', By', Bz' of the point is transferred to the second boundary point B2.
It is stored in the working 105 as the position.

(o) After that, the processor 102 determines whether the speed passing through the area is rapid feed or cutting feed.
Determine from the information stored in the RAM 104 (p) If it is fast forwarding, the processor 102
Performing passage control processing using the height direction position (Z-axis direction position) Zp of the area passage passage APP stored in and the Z-axis coordinate value of the escape point,
Move the tool rapidly to the area passing path APP.

(q) After that, the processor positions the tool on the second boundary point B2 in rapid traverse by simultaneous two-axis control, and finally positions the tool on the second boundary point B2 in rapid traverse.

(r) When the tool reaches the second boundary point B2, the processor 102 sets the flag to 0, jumps to step b, calculates the points on the curved surface again, and moves the tool on the curved surface based on the point data. Move and continue curved surface machining.

(s) On the other hand, if the cutting feed is set as the speed for passing through the area as determined in step o, the processor 102 selects the coordinate values of the first boundary point B1 stored in the working memory 105 and the escape point EP. The path control process is performed using the coordinate values to move the tool to the first boundary point.

(t) After that, the processor uses the position Zp of the area passing path APP and the first path stored in the RAM 104.
Using the Z-direction displacement of the boundary point B1, move the tool to the area passing path APP by cutting feed. After reaching the area passing path, the second boundary point X, Y
Simultaneous two-axis control is performed using the coordinate values, and the tool is moved to above or below the second boundary point B2 by cutting feed. Furthermore, if the position Zp of the area passing passage is set above the first boundary point, the tool will move along the convex portion PR (see Fig. 4) by cutting feed, and the position Zp of the area passing passage will be set above the first boundary point. When set below the first boundary point, the tool moves along the area passing path while cutting grooves.

(u) After the tool reaches above or below the second boundary point B2, move the tool to the first boundary point B2. When the tool reaches the second boundary point B2, the process jumps to step r, sets the flag to 0, and returns to step b. Thereafter, points on the curved surface are sequentially determined, and the tool is moved along the curved surface using the points to process the curved surface.

<Effects of the Invention> As explained above, according to the present invention, when a tool reaches an area set on a curved surface, the tool is temporarily released to an escape point near the area, and the tool is rotated at the escape point. Since the tool is configured to stop its movement while it is being moved, the tool does not come into contact with the workpiece when it is stopped, so there is no cutter mark on the workpiece, and there is no possibility of over-cutting. In addition, since the tool does not come into contact with the workpiece when stopped, the workpiece will not be scorched or burned even if the workpiece is made of flammable material such as wood. Furthermore, in the present invention, the speed of passing through the area is rapid feed or cutting feed, and depending on whether the area passage path is above or below the first boundary point. Since the tool path that passes through the area is controlled, if you want to groove a region, just set the cutting feed and set the position of the area passing path below the first boundary point, and the groove will be cut automatically. If you want to move the tool while machining a convex part on the area, set the cutting feed and set the area passage path above the first boundary point to automatically move the convex part. The shaped part is processed.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the curved surface machining method using the offline method, and Figures 2 and 3 show problems with the online method, which calculates the path using data specifying the curved surface and immediately moves the tool using the path data. 4 is a schematic explanatory diagram of the present invention, FIG. 5 is a block diagram of a numerical control device that implements the method of the present invention, FIG. 6 is a flowchart of the process of the present invention, and FIG. 7 is a diagram showing curved surfaces and curved surfaces. FIG. 2 is an explanatory diagram of data specifying boundaries of B1...first boundary point, B2...second boundary point,
EP...Escape point, APP...Area passage,
TL...Tool, 10...Three-dimensional curved surface, 30...Area.

Claims (1)

[Claims] 1. A tool path control method in a numerical control device in which a tool path is calculated using data specifying a curved surface and a tool is moved along the tool path, comprising: data specifying a curved surface, and the curved surface. The first step is to input data that includes at least data that specifies the area above and data that specifies the path passing through the area.The data that specifies the curved surface is used to sequentially calculate a sequence of points on the curved surface, and the calculated new a second step in which the tool path is defined as a straight line connecting the point and the current position; a third step in which the tool is moved along the tool path; and a fourth step in which it is determined whether the tool has reached the first boundary point in the area. Step: When the tool reaches the first boundary point of the region, the tool is moved away from the boundary point toward the outside of the region and stopped.Fifth step: Sequentially calculates a sequence of points on the curved surface using data specifying the curved surface. death,
a sixth step of monitoring whether the calculated point has escaped from the area and setting the point that has escaped as a second boundary point; a seventh step of moving the tool to the second boundary point along the path specified by the area passing path data; A tool path control method in a numerical control device, comprising an eighth step of moving the tool along the calculated tool path. 2. The data of the first step includes the amount of movement of each axis to release the tool from the first boundary point,
2. The tool path control method according to claim 1, wherein in the fifth step, the tool is released to an escape point that is separated from the first boundary point by the amount of movement of each axis. 3. The fifth step is characterized in that when the tool reaches the first boundary point, the tool is caused to escape to an escape point that is a predetermined amount above the point that specifies the previous tool path. tool path control method. 4 Fast-forward to the data of the first step and
Data specifying whether to move the tool to the boundary point or to the second boundary point by cutting feed is included, and in the seventh step, when rapid traverse is specified, the area is moved from the stopping point to the second boundary point by rapid traverse. raising the tool to the passageway and then moving the tool in rapid traverse along the area passageway above the second boundary point;
2. The tool path control method according to claim 1, wherein the tool is then rapidly lowered to the second boundary point. 5 The seventh step is to move the tool from the stopping point to the first boundary point when a cutting feed is commanded, and then to move the tool from the first boundary point if the area passing path exists above the first boundary point. The tool is raised with a cutting feed from the point to the area passing path, then the tool is moved along the area passing path with a cutting feed above the second boundary point, and then the tool is moved with a cutting feed to the second boundary point. A tool path control method according to claim 4, characterized in that: 6 The seventh step is to move the tool from the stopping point to the first boundary point when a cutting feed is commanded, and then to move the tool from the first boundary point if the area passing path exists below the first boundary point. The tool is lowered with cutting feed from the point to the area passing path, then the tool is moved along the area passing path while performing machining with cutting feed until below the second boundary point, and then the tool is moved down to the second boundary with cutting feed. 5. A tool path control method according to claim 4, characterized in that the tool path is moved to a point.