JP2659127B2 - NC data creation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an NC data creation device for performing milling or the like.

[Background Art] For example, when a box-shaped part having a wall is cut out from a block material, a closed region surrounded by the wall is cut by an end mill or the like. At this time, it is necessary to specify a cutting start point at which cutting by the end mill is started.

Conventional NC data creation equipment does not have a function to select this kind of cutting start point, and when cutting an arbitrary closed area
The operator of the NC data creation device has set the cutting start point. Then, as shown in FIG. 8, the NC data creation apparatus checks whether or not the set cutting start point is within the closed area by regarding the closed area 81 to be cut as a simple convex shape 82. I just did.

"Problem to be Solved by the Invention" However, the closed area to be cut in this type of cutting does not always have a simple convex shape.
For example, in order to cut out a component having a rib or a boss, it is necessary to cut a closed region having a concave shape. In the conventional device, the concave portion of the closed area 81 is used because the checking method is simple.
At 83 and 84, a check was missed, and if the operator specified an incorrect cutting start point, there was a problem that the cutter might bite.

The present invention has been made in view of the above problems,
It is an object of the present invention to provide a device which can automatically search and extract an optimum cutting start point and create NC data only by specifying a closed region to be cut by an operator.

"Means for Solving the Problems" In order to achieve the above object, according to the present invention, in an NC data creating apparatus for cutting an inside of an arbitrary closed region, a constituent point defining a boundary of the closed region is stored. Closed-area storage means, a grid-point generating means for generating at least grid points covering the closed area, and the number of intersections at which each line segment connecting one grid point and each of the constituent points intersects the boundary line of the closed area. Internal and external determining means for determining whether each grid point is an internal grid point inside the closed region or an external grid point outside the closed grid region for each grid point; and NC comprising a perpendicular length calculating means for calculating the total length of the perpendicular for each internal grid point, and a cutting start point selecting means for setting the internal grid point whose perpendicular length is the shortest as a cutting start point, NC A data creation device is provided.

[Operation] In the NC data creating apparatus configured as described above, the optimal cutting start point is extracted from a large number of grid points generated at appropriate grid intervals by the grid point generating means. For this reason, the grid points are first divided into internal grid points inside the closed area and external grid points outside by the inside / outside determination means. Next, a grid point having the shortest perpendicular line length is selected from the internal grid points and set as a cutting start point.

"Example" An example of the present invention will be described with reference to the drawings. First
The figure is a block diagram showing the NC data creation device and the machine tool connected to it.

The machine tool 20 is connected to the numerical control device 10, and the numerical control device 10 is connected to the NC data creating device 30.

The numerical controller 10 includes servo motor drive circuits DUX, DUY,
The DUZ and the sequence controller 11 are connected via an interface (not shown). In the machining center type machine tool 20, the rotation of the servo motors 22, 21, and 23 driven by the servo motor drive circuits DUX, DUY, and DUZ, respectively, causes a workpiece table 25 that supports the workpiece W, and a spindle motor SM. The relative position between the main shaft 26 driven by the main shaft 26 and the main spindle head 24 is three-dimensionally changed. In the tool magazine 27 that holds a plurality of types of tools, the tools in the tool magazine 27 are selectively mounted on the main spindle 26 by a not-shown magazine indexing device and a tool changing device 28, so that the machining of the workpiece W is performed. Done. Also, the sequence controller 11
Is connected to a spindle motor drive circuit 15 that controls the rotation speed of the spindle motor SM.

The NC data creation device 30 is a computer itself in terms of hardware, and includes a microprocessor 31, a clock signal generation circuit 32, a ROM 33, a RAM 34, a hard disk 35, and interfaces 36 and 37.
8 and the CRT display device 39 are connected.

Each means of the NC data creation device 30 is realized as a process in the microprocessor 31.

The processing is described in the flowchart of FIG.
The description will be made with reference to the explanatory diagrams of FIGS.

When the process 100 is started, in step 101, recognition of a cutting area is performed. Recognition of the cutting area is performed by reading data on the workpiece from the hard disk 35 and decoding the data. In step 102, as shown in FIG. 3, a closed area 51 in which the cutting area 50 is offset by the radius of the used tool is defined and stored. The memory of the closed area 51 is
Constituent points P ₁ , P ₂ … defining boundary lines L ₁ , L ₂ … L _n of the closed region 51
P _n , that is, each break point position of the boundary line is stored. Step 102 constitutes a closed area storage means.

Next, in step 103, as shown in FIG.
Assuming a grid 52 with an appropriate grid interval on 1 and a closed area 51
Many grid points G ₁₁ to the cover, G ₁₂ ... to generate a G _ij .... Step 103 constitutes a lattice point generating means.

In steps 104 to 107, for each grid point G _ij , the grid point G _ij is an internal grid point G _ij (in) existing inside the closed area 51 or an external grid point G existing outside the closed area 51.
_{It is} determined sequentially from _ij (out). The internal grid point G _ij (in) turns on its determination flag. The inside / outside determination in this step 104 assumes a line segment connecting the grid point G _ij to be checked and each of the constituent points P ₁ , P ₂ ... _{Pn of the} closed area 51 as shown in FIGS. Then, the number of line segments equal to the number n of the constituent points is
It carried out by checking the number of boundary L _1, L ₂ ... intersection intersecting the L _n. If the number of intersections is even (including 0), the grid point
G _ij is an internal grid point G _ij (in), and if it is odd, it is an external grid point G _ij (out). For example, in the example shown in FIG. 6, the number of intersections is four, and in the example shown in FIG. 7, the number of intersections is five. In this way, the grid points G _ij are _divided into internal grid points G _ij (in) and external grid points G _ij (out), as shown in FIG. Steps 104 to 107 constitute an inside / outside determination means.

In steps 108 and 109, a process of selecting an optimum cutting start point from the internal grid points G _ij (in) is performed. Steps
At 108, as shown in FIG. 5, a perpendicular line is dropped from one internal grid point to each boundary line L ₁ , L ₂ ... L _{n of} the closed region 51 or an extension thereof, and the length l _{1 of} each perpendicular line sums the l ₂ ... l _n calculates the perpendicular line length (perpendicular line length _{= l 1 + l 2 + ...} l n). That is, the sum of the distances from one internal grid point G _ij (in) to each boundary line L ₁ , L ₂ ... L _n is calculated. The perpendicular length calculated for each internal grid point G _ij (in) is compared in step 109, and the internal grid point G _ij (in) having the shortest perpendicular length is selected as the cutting start point. Step 108 constitutes a perpendicular length calculating means, and step 109 constitutes a cutting start point selecting means.

Then, in step 110, NC data for cutting the cutting area 50 is created with the internal grid point G _ij (in) selected in step 109 as a cutting start point, and the process ends.

The NC data created in this way is stored in the numerical controller 10
And the workpiece W is cut along the commanded machining locus.

“Effect of the Invention” The present invention is configured as described above, and thus has an effect that the optimum cutting start point can be automatically searched and extracted. Since the cutting start point is automatically determined and NC data is created, operation errors can be eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an NC data generating apparatus, FIG. 2 is a flowchart showing processing in a processor, and FIGS. 3, 4 and 5 are explanatory diagrams for explaining processing using an example of a closed area. 6 and 7 are explanatory diagrams for explaining the inside / outside determination means, and FIG. 8 is an explanatory diagram showing the operation of the conventional device. 30 …… NC data generator, 31 …… Microprocessor,
33… ROM, 34… RAM, 51… Closed area, 52… Grid, G
_ij ...... grid _{points, L 1, L 2 ... L} n ...... _{boundary, P 1, P 2 ... P} n ...... configuration point.

Claims (1)

(57) [Claims] 1. An apparatus for creating NC data for cutting an arbitrary closed area, comprising: closed area storage means for storing constituent points defining a boundary of the closed area; and a grid point covering at least the closed area. A grid point generating means for generating, and an internal grid which is inside the closed area for each grid point due to the evenness of the number of intersections where each line segment connecting one grid point and each of the constituent points intersects the boundary line of the closed area. Internal / external determining means for determining whether a point or an external grid point is located outside, and a perpendicular length for each internal grid point, which is the sum of the lengths of the perpendiculars drawn from the internal grid points to all the boundaries of the closed area. An NC data creating apparatus comprising: a calculating unit; and a cutting start point selecting unit that sets an internal grid point having the shortest perpendicular line as a cutting start point.