JPH0664485B2 - Numerical control device - Google Patents

Description

The present invention relates to a numerical control device, and more particularly to a numerical control device that sets a forbidden area and controls the movement of a movable object.

In a numerically controlled machine tool, the maximum movable range in which tools, tables, etc. (hereinafter referred to as movable objects) can move is determined by the length of balls and screws, etc., and the movable objects runaway due to a program error or some other obstacle. If the movable range (stroke end) is exceeded (overtravel), this is immediately detected, and the movable object is brought to an emergency stop (emergency stop). In order to detect such overtravel, the movable range is usually + X side, -X side, + Y
Limit switches, etc. are provided at the maximum stroke points on both the -side and the -Y side, and a dock is provided on a movable object. When the overtravel occurs, the overtravel is detected by detecting that the dock steps on the limit switch.

However, in a device that limits the stroke end with a limit switch, mounting of the limit switch or dog, the complexity of adjustment work, and coasting due to delay in the operation of the limit switch are not preferable. For this reason, the stroke end position has recently been stored in the memory of the NC device, and it is always judged whether the current position of the movable part has exceeded the stroke end stored in the memory. An output device has been proposed. According to this device (hereinafter referred to as a stored stroke limit device), not only a limit switch and a dog are unnecessary, but also there is an advantage that coasting is small. The stroke end position is set and stored for each axis in two directions of + direction and − direction with a distance from a position unique to the machine (for example, the machine origin). Fig. 1 shows the distance + Lx, -Lx, + Ly, -Ly from the reference position Pr occupied by the machine to the stroke end position in + X direction, -X direction, + Y direction, and -Y direction by the operation called origin return or reference point return. Is stored in the memory and the stroke end is set, and the shaded area is the entry prohibited area of the machine movable portion. In this stored stroke limit method, the machine moving part is returned to the reference point Pr by returning to the origin or by returning to the reference point, and when the return is completed, the contents of the current position registers of the X axis and the Y axis are cleared, and the position of the machine moving part is returned. And the contents of the current position register are matched. After that, the contents of the current position register are updated every time the machine moving unit moves, and it is determined whether the machine moving unit has exceeded the stroke end preset in the memory using the contents of the current position register. .

As described above, the stored stroke limit device is more effective than a device using a dog or a limit switch. By the way, according to the conventional stored stroke limit device, it is always judged whether or not the current position of the movable part of the machine exceeds the stroke end to enter the prohibited area, and if it does, an emergency stop is performed and an alarm is output. It was In other words, the machine does not stop until the movable part of the machine actually enters the prohibited area. For this reason, the work is wasted because it is stopped for the first time after entering the entry-prohibited area due to incorrect machining due to incorrect programming or NC data reading error.
Moreover, it is necessary to determine whether or not the vehicle has always entered the prohibited area, increasing the load on the computer with the built-in NC device.

In view of the above, it is an object of the present invention to provide a numerical controller capable of suppressing waste of work as much as possible and reducing the load on a computer.

Another object of the present invention is to provide a numerical control device for predicting whether or not a movable part of a machine enters a prohibited area by using command NC data before moving in circular interpolation and prohibiting the movement in advance. The purpose is to do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram of an apparatus for determining whether or not the target position enters the prohibited area in the case of a position command or a linear interpolation command.

X-axis current position register 101 and Y-axis current position register 102
Each time the X-axis and Y-axis distributed pulses XP, YP are generated by the pulse distributor 103, their contents are updated one by one in the forward direction or in the reverse direction according to the moving direction, and the current position of the mechanical moving part is always ( Xa, Ya) are remembered. When the incremental position or the linear interpolation data G00 (or G01) XΔX, YΔY; is read from the NC tape 104, the arithmetic units 105, 106 respectively display the current positions Xa, Ya and ΔX, ΔY of the X-axis and the Y-axis. Is used to calculate Xa + ΔX → Xt, Ya + ΔY → Yt (1) to calculate target position coordinates (Xt, Yt).
Next, the stroke end positions + Lx, −Lx, + Ly, −Ly stored in the stroke end storage memory 107 are read out, and the discriminating unit 108 discriminates whether or not the following equation is satisfied.

-Lx <Xt <+ Lx (2) -Ly <Yt <+ Ly (3) If either of the expressions (2) and (3) is not satisfied, it is assumed that the moving part of the machine enters the prohibited area and the alarm AL
M is output, and at the same time, a pulse distribution calculation prohibition signal PDIS is output to the pulse distributor 103 to prohibit movement of the mechanical moving part.

On the other hand, when both the expressions (2) and (3) are satisfied, the distribution start signal PDS is output to the pulse distributor 103 to execute the pulse distribution calculation. If Xp and Yp are generated by the pulse distribution calculation, the contents of the X-axis and Y-axis current position registers 101 and 102 are updated according to the moving direction, and the distributed pulses Xp and Yp are applied to the X-axis and Y-axis servo units 109 and 110. The X-axis motor 111 and the Y-axis motor 112 are rotated to move the movable part of the machine.

FIG. 3 is a block diagram of an apparatus for determining whether or not the machine movable part enters the entry prohibited area when circular interpolation is commanded.

Circular interpolation data G02 (or G03) XΔx YΔy IΔi JΔj; is commanded from the NC tape 201. Incidentally, G02 is a clockwise direction, G03 is a G function command indicating circular interpolation in the counterclockwise direction, Δx, Δy are incremental values from the arc starting point As to the arc ending point Ae, as shown in FIG. j is an incremental value from the arc starting point As to the arc center Ac. Based on this circular interpolation data, the quadrant discrimination and calculation unit 202 determines the quadrant to which the start point As and the end point Ae belong when considering the orthogonal coordinates with the arc center Ac as the origin, as shown in FIG. Now, if the quadrant to which the start point As belongs is the first quadrant, the arc center A when the start point coordinates are (xs, ys)
The coordinates (xc, yc) of c are xc = xs−Δi, yc = ys + Δj (4). Similarly, if the starting point As belongs to the second quadrant, the third quadrant, and the fourth quadrant, the coordinates (xc, yc) of the arc center Ac at that time
Are respectively xc = xs + Δi, yc = ys-Δj ... 2nd quadrant (5) xc = xs + Δi, yc = ys + Δj ... 3rd quadrant (6) xc = xs-Δi, yc = ys + Δj ... 4th quadrant (7) . Therefore, the quadrant discrimination and calculation unit 202, after discriminating the quadrant to which the starting point As belongs, reads a predetermined calculation formula corresponding to the quadrant from the memory 203, calculates the arc center Ac (xc, yc), and outputs it to the calculation unit 204. To do. In addition, the calculation unit 204 determines whether the arc starting point As, the arc ending point Ae belong to the quadrant, G02 / G03, and the arc radius R.
Are input respectively. The arc radius R is Is calculated by the radius calculation unit 205. Now, change points B ₁ and B where the moving direction of at least one axis changes in an arc
The coordinates of ₂ , B ₃ , B ₄ (see FIG. 5) are expressed by the following equations, respectively.

Coordinates of point B ₁ ... xc, yc + R (8) Coordinates of point B ₂ ... xc-R, yc (9) Coordinates of point B ₃ ... xc, yc-R ... (10) Coordinates of point B ₄ ... xc + R , yc (11) Therefore, the calculation unit 204 determines a predetermined change point Bi according to the quadrant to which the arc start point As and the arc end point Ae belong and the clockwise / counterclockwise direction.
The coordinates are calculated according to equations (8) to (11) and stored in the memory 205. For example, the commanded clockwise circular interpolation (G02) is, moreover arc start point As the first quadrant, the arc end point Ae is the change point if that is in the third quadrant B _4, B ₃ and arc end point A
The coordinates of e are stored in the memory 205. The determination unit 206 determines the stroke end position + L from the stroke end storage memory 207.
x, −Lx, + Ly, −Ly are read out, and it is determined whether or not each change point Bi and the arc end point Ae are present in the entry prohibited area. Then, if it exists within one entry prohibition area of the change point Bi or the arc end point Ae, an alarm ALM is output and
A pulse distribution prohibition signal PDIS is output to the circular interpolator 208 to prohibit pulse distribution and prohibit movement of the machine movable part. If all the change points Bi and the arc end points Ae do not exist in the entry prohibited area, the arc interpolator 208 performs the arc interpolation calculation and applies the interpolation pulses XP and YP to the current position register and the servo unit (not shown).

As described above, according to the present invention, when NC data is commanded, not only in the linear interpolation but also in the circular interpolation, it is predicted whether or not the machine movable part enters the entry prohibited area before the movement, and if the entry is made, Since the machine is not moved in advance, the work is not wasted and the computer is not overloaded in the case of computer processing.

[Brief description of drawings]

FIG. 1 is an explanatory view of a stored stroke limit device, FIG. 2 is a block diagram of an embodiment of the present invention in the case of a position command or a linear interpolation command, and FIG. 3 is a block diagram of an embodiment of the present invention in a case of a circular interpolation command. FIG. 4 is an explanatory view of the arc command method, and FIG. 5 is an explanatory view of the position of the change point Bi in the arc. 101 …… X-axis current position register 102 …… Y-axis current position register 103 …… Pulse distributor, 104 …… NC tape 105,106 …… Computing unit 107 …… Stroke end storage memory 108 …… Discrimination unit 201 …… NC tape 202: Quadrant discrimination and calculation unit 203: Memory, 204: Calculation unit 205: Memory, 206: Discrimination unit 207: Stroke end storage memory 208: Pulse distributor

Front Page Continuation (72) Inventor Takao Sasaki 3-5-5 Asahigaoka, Hino-shi, Tokyo Within Fanatsuku Co., Ltd. (56) Reference JP-A-54-44174 (JP, A)

Claims (1)

[Claims] 1. A stroke end storage memory for storing the position data of the movable object invasion prohibited area in a numerical control device comprising means for preventing the movable object from entering an invasion prohibited area other than a quadrangle. Target coordinate position calculation means for calculating the calculated target position coordinates, interpolation calculation means for respectively obtaining a plurality of change points by interpolation calculation between the current position coordinates and the commanded target position coordinates, and the calculated target position coordinate data And comparing the plurality of change points with the position data read from the stroke end storage memory, and the target position coordinate data calculated by the comparison and one of the plurality of change points. And a means for generating a command for prohibiting the pulse distribution operation when the movable object is in the invasion prohibition region.