JPH01244513A - Numerical controller - Google Patents

Abstract

PURPOSE:To improve the measurement precision of a work position and a tool position and to perform the automatic measurement processing free from destruction of a tool or the like by detecting a stop position in a position detecting block executed with the skip signal from a detecting means. CONSTITUTION:A detecting means like a position detecting sensor is arranged in a movement route where the tool is moved, and the skip signal is inputted from the detecting means to an input circuit 8 when a work or the tool is brought into contact with this detecting means. Current limitation of the servo motor of a moving axis is commanded from an output circuit 5. At this time, a program command block is advanced to the next by the skip signal to command abortion of movement. Error data of each shaft stored in a servo control part as an extent of movement which is not executed out of the movement extent command value commanded from the output circuit 5 is subtracted from this movement extent command value to operate the stop position of the axis, which is actually stopped by current limitation, by the operation commanded by the next command block in a CPU 1. Thus, a numerical controller is obtained which improves the measurement precision and is free from destruction of the tool or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a numerical control device that performs automatic measurement processing using a skip function.

(Prior Art) In order to improve machining accuracy with ordinary numerically controlled machine tools, it is important to accurately know the positions of tools and workpieces relative to command programs. Conventionally, a skip function has been used to measure such positions, or an automatic tool length measurement function has been used to measure tool length. The latter commands, for example, G37...;, moves the tool toward a predetermined measurement position, reduces the speed along the way, and moves until a measurement position arrival signal is output from the measuring instrument, and when it reaches the measurement position. , the tool movement is automatically stopped and the tool length is corrected based on the difference between the coordinate values when the measurement position is reached and the commanded coordinate values.

In the former case, for example, G31...; is given, a position display command is given as a subsequent command, and in the middle of this command, a skip signal is input from the outside to cancel the remaining commands, and the next block is started. Execute. In this case, a position detection signal from a limit switch or the like is externally input as a skip signal at just the right timing to forcibly interrupt the movement command block and terminate the operation.

(Problem to be Solved by the Invention) When performing automatic measurement processing with such a conventional numerical control device, noise is generated in the skip signal from the detector when detecting the position of the workpiece or tool using the skip function. If the sensor is included, the detector does not work properly, or the moving speed is too fast, the detection accuracy will decrease due to servo delays and the detected position will become inaccurate. Further, there is a problem that the tool or workpiece may collide with the detector and be damaged.

The present invention was made to solve the above problems, and
The purpose of the present invention is to provide a numerical control device that increases the accuracy of the opening side and eliminates the risk of damage to tools and the like when performing automatic measurements using a skip function.

(Means for Solving the Problems) According to the present invention, the workpiece position or In a numerical control device that detects tool length, there is a detection means installed at a detected position, a command means for commanding a limit on shaft drive torque, and a stop position according to a torque limit command for the axis, which is determined by a movement amount command value and an axis. It is possible to provide a numerical control device characterized in that the stop position is detected by a position detection block executed by a skip signal from the detection means.

(Function) In the numerical control device of the present invention, when there is interference between the detection means and the shaft during automatic measurement processing, excessive torque is limited by limiting the shaft drive l/rook, and the specified movement amount command value is The stopping position can be determined accurately from the error data for each axis.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the numerical control device of the present invention. 1 is a central processing unit (CPU), 2 is a ROM that stores a program that controls the entire numerical control device, 3 is a RAM used for arithmetic processing, etc., and 4 is a nonvolatile memory that stores command programs for machining. remember. 5 is an output circuit connected to a servo motor or the like of a machine tool or the like. The tape reader 6 is for reading an NC tape 7 on which a command program is stored, and the contents of the command are stored in the nonvolatile memory 4.

Note that the command contents may be input directly from the NC tape and processed without providing the nonvolatile memory 4. 8 is an input circuit, and when a predetermined skip signal is input to this input circuit 8, a skip function is executed.

The numerical control device configured as described above is provided with a skip function, for example, by the preparation function code G31, to terminate the execution of the movement command block included in the command program at a predetermined timing and execute the next command block. By driving the axis based on this preparation function code G31, the workpiece position or tool length is automatically detected.

In other words, a detection means such as a sensor for position detection is placed on the movement path of the workpiece or tool, and when the workpiece or tool comes into contact with this detection means, a skip signal is manually inputted from the input circuit 8.

As a result, the output circuit 5 issues a command to limit the current of the servo motor of the moving axis. At this time, the skip signal causes the program command block to advance to the next one and commands to abort the movement. The stop position of the axis that actually stopped due to current restriction is determined from the movement amount command value commanded from the output circuit 8 by calculation commanded in the next command block in the CPU 1. It is calculated by subtracting the error data for each axis stored in the servo control unit as a quantity.

FIG. 2 is a detailed flow diagram of the present invention. The automatic measurement processing program reads the G code in the processing block from RAM3 and indicates that it is a skip function command (
In the case of G31) (step a), the servo control section is commanded to limit the current, and interference with the detector due to tool movement is checked (step b).

Skip processing is performed by manually applying a skip signal detected due to interference (step c). In other words, the movement is terminated by the skip signal. By limiting the current, the tool stops in contact with the detector, and when a movement command is given after that, it is stored as an error amount in the error circuit of the servo control section, and the tool proceeds to the next processing block. , the amount of error is read (
Step e). The difference between the stop command position commanded by this skip processing and the error amount is calculated as the detected position,
displayed (step f). Since this indicates the actual stop position of the tool, accurate position detection is possible. Note that it is necessary to stop the excessive error check function and the in-position check function at the same time as limiting the torque.

As above, this invention has been described in some detail with respect to its most preferred embodiment, but the description of the preferred embodiment does not include variations in detailed parts of the configuration or contrary to the spirit of the invention as described in the claims. It is clear that various modifications or combinations thereof may be made.

(Effects of the Invention) As described above, according to the present invention, it is possible to provide a numerical control device that can improve the measurement accuracy of workpiece positions and tool positions and can perform automatic measurement processing without fear of damage to tools and the like.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operation of the above embodiment. 1...CPU, 4...Nonvolatile memory, 5...Output circuit. Patent applicant: Representative of FANUC Co., Ltd. Patent attorney: Minoru Tsuji Figure 2

Claims (1)

[Claims] In a numerical control device that detects the workpiece position or tool length, the execution of the movement command block is stopped at a predetermined timing and the axis is driven based on the skip function that executes the next command block. The apparatus comprises a detection means installed, a command means for commanding the limitation of the shaft drive torque, and a calculation means for calculating the stop position of the shaft according to the torque limit command from the movement amount command value and the error data for each axis, A numerical control device characterized in that a stop position is detected by a position detection block executed by a skip signal from the detection means.