JPS6133202B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a motion range limiting device that limits the movement range of a tool or workpiece controlled by a numerical control device and prevents the tool or workpiece, or even the machine tool itself, from being damaged due to interference. ,
The purpose of this is to make it possible to change the movable range depending on the area where the tool or workpiece is located, so that the operating area of the tool or workpiece controlled by the numerical control device is surrounded by a rectangle or rectangular parallelepiped. The object of the present invention is to make it possible to limit the operating range even when the shape is such that it does not exist. The numerical control device for one-way transport distributes servo motor pulses for each axis based on numerical control commands given by paper tape, manual feed commands, etc., and thereby moves the tool or workpiece in a specified direction. Although the system is designed to accurately move a fixed amount, if an incorrect numerical control command is programmed or the manual feeder is operated incorrectly, the tool or workpiece may move to an unexpected area and the tool may not be able to machine the tool. It may interfere with objects or jigs and damage tools or workpieces. For this reason, general numerical control devices detect that the tool or workpiece has moved beyond a predetermined operating range and stop the movement of the tool or workpiece. , it was detected that the tool or workpiece exceeded the operating range when the amount of movement of the tool or workpiece in each axis direction exceeded the maximum movement amount set for each axis. The operating area in which the workpiece can move is a rectangular area when there are two control axes, and a rectangular parallelepiped area when there are three control axes. For this reason, the operating area of the tool or workpiece cannot be surrounded by a rectangle or rectangular parallelepiped, as in machines that numerically control the workpiece by moving the tool or workpiece across two areas located on either side of an obstacle. In machine tools, it is not possible to process a workpiece with a restriction on the operating area, and it has not been possible to set a restriction on the operating area. The present invention has been made in view of such conventional drawbacks, and includes coordinate values indicating the boundaries of each region for each of the regions divided into a plurality of regions along one of the two axes, and the coordinate values allowed in each region. A limit value table is created in which the limit values of the movement range in the other axis direction are written in correspondence with each other, and the coordinate values along a specific axis of the tool are sequentially compared with the coordinate values for each area stored in the limit value table. By doing this, it is determined which of the multiple regions the tool is located in, and then the limit value in this determined region is read from the limit value table, and the tool is restricted along the other axis. This feature is characterized in that it is determined whether or not the tool is moving beyond a value, and the movement of the tool is restricted based on this. Embodiments of the present invention will be described below based on the drawings. In FIG. 1, 1 is a servo motor attached to a machine tool (not shown), and in this embodiment, two servo motors 1X and 1Y are used to move the tool relative to the workpiece in the X-axis and Y-axis directions. It is provided. These servo motors 1X, 1Y are connected to a central processing unit 4 via drive circuits 2X, 2Y and an interface 3. 5 is a tape reader that reads the numerical control commands programmed on the paper tape 6; 7 is a data input device for manually inputting numerical control commands and setting limit values for the amount of movement; and 8 is for manually moving the tool. These are connected to the central processing unit 4 via an interface 9. Reference numeral 10 denotes a storage device composed of a core memory and the like, and a tape reader 5 is included in this storage device 10.
It stores a numerical control program that distributes pulses to each axis according to numerical control commands given by the controller, and a monitor program that limits the operating range to stop pulse distribution when it detects that the tool has exceeded the operating range. has been done. Moreover, in this storage device 10,
Data areas are also provided, including an area for temporarily storing read numerical control data, an area for forming a current position counter for storing the current position of the tool, and an area for forming a limit value table for storing limit values for the amount of tool movement. There is. Reference numeral 11 denotes an interrupt signal generating circuit that generates an interrupt signal IRS1 to the central processing unit 4 at fixed time intervals, for example, every 5 mS.When the interrupt signal IRS1 is given from the interrupt signal generating circuit 11, the central processing unit 4 Device 4
executes the numerical control data reading routine NCBR,
Following this, the routine MONT of the monitor program for limiting the operating area is executed. Further, 12 is an interrupt signal sent from the central processing unit 4 to the central processing unit 4 at a preset period.
This is a preset counter that sends out the IRS2, and the preset counter 12 is preset with cycle data calculated from the speed command value of the numerical control data. When an interrupt occurs, the pulse distribution routine PGEN is executed. FIG. 2 shows the numerical control data reading routine NCBR, which is first executed when the numerical control device starts operating. First, in step 10, a pulse distribution completion flag DEN is set and tested to see if it is in the state of 1, thereby determining whether pulse distribution is in progress or pulse distribution has been completed. If pulse distribution is not completed, the subsequent program is skipped and the monitor routine is started.
Jump to MONT, and if pulse distribution is completed, proceed to step 11 to read numerical control data. At step 12, the tool movement axis and movement direction are determined from the read numerical control data and stored in the movement axis register MAR. In this embodiment, only one axis is controlled at the same time, so
"1" is written in only one bit of a plurality of bits constituting the movement axis register depending on the movement axis and movement direction. That is, if the movement command specified by the numerical control data is in the + direction of the X-axis, "1" is written to the 1st bit of the movement axis register MAR, and if the movement command is in the - direction of the X-axis,
In the case of the Y-axis + direction and the Y-axis - direction, "1" is written to the 2nd, 3rd, and 4th bits of the movement axis register MAR, respectively. At step 13, the movement amount commanded by the numerical control data is preset in the movement amount counter. Then, at step 14, the pulse distribution period T is calculated from the speed command of the numerical control data and stored in the data area. Thereafter, in step 15, the distribution completion flag DEN is reset, and in step 16, the preset counter 12 is set to zero, and the process jumps to the monitor routine MONT. When the preset counter 12 is set to zero, the preset counter 12 immediately counts up and provides the central processing unit 4 with an interrupt signal IRS2. Since the interrupt from the preset counter 12 is set to have a higher priority than the interrupt from the interrupt signal generation circuit 11, the interrupt from the central processing unit 4
jumps to the pulse distribution routine PGEN in response to an interrupt request from the preset counter 12. FIG. 3 is a flowchart showing this pulse distribution routine PGEN. In step 20, the pulse oscillation period T stored in the data area is read out and set in the preset counter 12. As a result, the preset counter 12 outputs the interrupt signal IRS2 again after a time corresponding to the oscillation period T has elapsed, and the central processing unit 4 is interrupted. Therefore, the pulse distribution routine PGEN is repeatedly executed at time intervals corresponding to the period T set in the preset counter 12. At the second step of the pulse distribution routine PGEN, step 21, the movement axis register
It is determined whether MAR is in an all-zero state, and if all is zero, the process returns to the base routine without performing pulse distribution. This is because when the tool moves beyond the operating range, the movement axis register MAR is cleared in the monitor routine MONT, which will be described later, thereby stopping pulse distribution. On the other hand, if the movement axis register MAR is not all zero, the process moves to step 22 and the movement direction is determined. Then, in step 23, a + pulse or - pulse is sent to the relevant axis, and in step 24, the current position counter of the relevant axis is added or subtracted. Thereafter, in step 25, the movement amount counter is subtracted, and in step 26, it is detected whether the count value of the movement amount counter has become zero. If the movement amount counter becomes zero, the pulse distribution completion flag DEN is set in step 27, and the process returns to the base routine. By repeating such pulse distribution routine PGEN, the tool is accurately moved by a predetermined amount in the X-axis or Y-axis direction. In addition, the count value of the current position counter is also increased or decreased accordingly, and the data representing the current position of the tool is constantly corrected. FIG. 4 shows a monitor routine MONT having a function of limiting the operating range of the tool.The operation of this monitor routine will be explained below. Step 30
is a program that selects the limit value of the movement amount according to the area where the tool is located from the limit value table in the data area. In this example, the X-axis is set as the reference axis, and the X-axis coordinate value of the tool is The corresponding limit value of the amount of movement in the Y-axis direction is searched from the limit value table. Then, in the following step 31, the Y of the tool is
The current position in the axial direction is compared with the searched limit value, and if the current position in the Y-axis direction exceeds the limit value, the current moving direction is stored in step 32.
At step 33, the bit corresponding to the current direction of movement in the movement axis register MAR is reset to zero. As a result, the movement axis register MAR becomes all zeros, and pulse distribution is stopped. Further, in the subsequent step 34, an error message is displayed externally, and the process returns to the base routine. Note that after this, a movement command in the opposite direction to the current movement direction is given by manual operation or the like, and when the tool is moved toward the operating area, pulse distribution is restarted. This is because it is determined in step 31 that the tool is out of the operating range, and bits other than the current direction of movement are not cleared even after the routines of steps 32 and 33 are passed. Therefore, the tool can be easily returned to the working area. Next, detailed operations will be explained using a specific example. Now, as shown in FIG. 6, the grindstone G is moved in the X-axis and Y-axis directions by numerical control to process the workpiece W held between the main spindle 50 and the tailstock 51. In a numerically controlled grinding machine that corrects the grinding wheel using a rotary dresser 52 provided behind the main shaft 50, when the operating range of the grinding wheel G is limited to the range above the boundary line indicated by the two-dot chain line. Considering this, the movable area of the tool is expressed as shown in Table 1, assuming that point P in the figure is the absolute origin.

[Table] When setting an operable area in this way, in this embodiment, the area number, the maximum value of the X-axis coordinate value, and the maximum value of the Y-axis coordinate value of that area are input using the data input device 7. do. As a result, data as shown in Table 2 is written in the limit value table of the data area.

[Table] When selecting a limit value corresponding to the X-axis coordinate value from such a limit value table, a selection routine LVAS as shown in FIG. 5 is used. First, step 40, together with steps 41, 42, and 43, constitutes a determination means, in which the count value of the read counter is set to 1, and step 41
Then, the X-axis coordinate value of the address specified by the read counter is read out. At first, the count value of the read counter is 1.
Therefore, 500 is read out as the X-axis coordinate value.
At step 42, the current coordinate value of the tool in the X-axis direction is compared with the X-axis coordinate value read from the limit value table. If the current coordinate value is larger than the X-axis coordinate value read from the limit value table, the read counter is incremented in step 43 and the X-axis coordinate value of the next address is read out. Thereafter, similar operations are repeated, and when it is determined that the current coordinate value is smaller than the X-axis coordinate value read from the limit value table, step 44, which constitutes the limit value reading means, is executed.
The data at the Y-axis coordinate value of the address specified by the read counter is set as the read limit value.
Therefore, when the X-axis coordinate value changes, the amount of movement in the Y-axis direction is changed in a stepwise manner, and the movable range is optimally limited. As a result, the 6th
As shown in the figure, even when the tool is moved over two areas located on both sides of the spindle 50 to perform numerical control, the operating area can be limited. As described above, in the operating area limiting device of the present invention, by sequentially comparing the coordinate values along a specific axis of the tool and the coordinate values for each area stored in the limit value table, Determine in which region the tool is located, then read the limit value in this determined region from the limit value table, and check whether the tool is moving beyond the limit value along the other axis. Since the movement of the tool is restricted based on this, the movement of the tool is
The limit value of the amount of movement in other axial directions can be changed stepwise according to the axial position. Therefore, even when controlling a numerically controlled tool machine where the operating area of the tool or workpiece cannot be surrounded by a rectangle or rectangular parallelepiped, it is possible to perform control to limit the operating area and prevent the tool or workpiece from interfering. This has the advantage of preventing damage caused by twisting. In addition, in the present invention, in order to perform region determination, at most, the same number of comparisons as the number of regions along one axis is performed, and one comparison is performed to determine whether the determined region exceeds the limit value. It is possible to determine whether the tool is within the allowable operating range, and it is possible to determine whether the tool is out of the operating range by comparing the number of regions plus one at most when considered as a whole. Therefore, when the determination process is performed by a computer, the amount of time required for the determination is lower than the method in which the area is determined for each axis and logical operations are performed on the determination results for each axis to determine whether or not it is outside the operating area. This has the advantage that processing time can be significantly shortened and determination processing can be performed without significantly affecting other processing such as pulse distribution. Furthermore, when the number of divisions of the operating region along one axis increases, the content of the limit value table may be additionally modified accordingly, and there is an advantage that the increase in the number of divisions can be easily accommodated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a numerical control device incorporating an operating area limiting device according to the present invention;
Fig. 2 is a flowchart showing the numerical control data reading routine, Fig. 3 is a flowchart showing the pulse distribution routine, Fig. 4 is a flowchart showing the monitor routine, and Fig. 5 is a flowchart showing the limit value selection routine. FIG. 6 is a diagram showing the setting state of the operating range in the numerically controlled grinding machine. 1X, 1Y... Servo motor, 2X, 2Y...
Drive circuit, 4...Central processing unit, 5...Tape reader, 7...Data input device, 8...Manual pulse generator, 10...Storage device, 11...Interrupt signal generation circuit, 12... Preset counter, 30
. . . Step for selecting a limit value, 31 . . . Step for comparing the current position with the limit value, 33 . . . Step for stopping pulse distribution.

Claims (1)

[Claims] 1. In a numerical control device that distributes pulses to the servo motors of each axis according to movement commands given to numerical control data to move a tool in two axial directions relative to a workpiece, the servo motors of each axis The current position of the tool is stored by counting the distributed pulses, and coordinate values indicating the boundaries of each region and each region are calculated for each of the regions divided into a plurality of regions along one of the two axes. means for storing a limit value table written in association with a limit value of the movement range in the other axial direction allowed in the axial direction; determining means for sequentially reading and comparing with the current position of the tool along the one axis to determine in which region the tool is located; and a restriction for reading a limit value corresponding to the determined region from the limit value table. a value reading means; a determining means for determining whether the amount of movement of the tool in the other axis direction exceeds the limit value read by the limit value reading means; 1. An operating area limiting device for a numerical control device, comprising: stopping means for stopping distribution of pulses in the axial direction.