JPH07210228A - Control method for measuring system using nc machine tool - Google Patents

Abstract

PURPOSE:To provide a control method which is applied to the measuring system using a machine tool and can measure the shape and the size of a work with high accuracy. CONSTITUTION:A measuring head attached to the spindle of an NC machine tool is moved toward a work by an NC device after a measuring device is connected to the NC device (S1). A displaced variable produced by a contact between the feeler of the measuring head and the work, i.e., the displaced variable toward each of X, Y and Z axes of an orthogonal coordinates is received from the head and stored (S2). Then a fact that the displaced variable is equal to its target value is detected (S3). Then a skip signal is outputted to the NC device and the movement of the measuring head is stopped by the NC device toward the work (S4). When the movement of the measuring head is completely stopped after detection of the change of the displaced variable, the position data on the head is received from the scale provided on the NC device or an NC machine tool and then stored (S5). Thus the shape and the size of the work are calculated with high accuracy based on the stored data on the displaced variable and the position of the measuring head (S6).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a measuring system using an NC machine tool, and more particularly, a measuring head mounted on the spindle of an NC machine tool capable of detecting displacement is relatively moved by an NC device and brought into contact with a work. Control of a measuring system using an NC machine tool that accurately measures the shape accuracy and dimensions of a workpiece from the position of the measuring head that can detect displacement after the stop and the amount of displacement of the tip of the measuring head that can detect displacement. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, the shape accuracy and size of a work machined by a machine tool are measured by a measuring tool such as a caliper or a micrometer, or placed on a three-dimensional measuring device.
The processing accuracy was inspected. These measuring methods required a long time, and the measuring accuracy with the measuring method using a measuring tool was insufficient. Therefore, in recent years, a measuring system has been adopted in which a measuring head is attached to a spindle of a machine tool to measure the shape accuracy and dimensions of a work after machining.

In such a measuring system, a contact type measuring head is usually used. The contact type includes a touch sensor type and a displacement detection type. The touch sensor type measuring head detects the moment when the measuring head contacts the work. A typical touch sensor type measuring head detects the moment when the measuring head contacts and is pressed by the workpiece, thereby opening a predetermined closed loop electric circuit and stopping current flow. By recording the data of the position of each axis of the Cartesian coordinates at that moment, the shape and size of the work can be measured.

The displacement detection type measuring head usually uses a differential transformer or an optical scale to enable three-dimensional displacement detection. When the measuring head is free of contact with the work, the amount of displacement of the measuring head is zero, and when it contacts the work, the measuring head outputs the amount of displacement corresponding to each axis of the orthogonal coordinates. The shape accuracy and dimensions of the work are calculated from the displacement amount, the data of the position of the measurement head corresponding to each axis of the orthogonal coordinates at the time of output, and the radius of the tip of the measurement head that contacts the work.

[0005]

In the above measuring system, when the data of the position of the measuring head is received from the scale mounted on the NC device or the machine tool, it is necessary to receive the data of the displacement amount of the measuring head at the same time. But
Actually, the data of the position of the measuring head and the data of the amount of displacement of the measuring head cannot be received at the same time, and there is a problem that an error occurs in the measurement accuracy.

Further, the displacement detection type measuring head simultaneously measures the data of the displacement of the feeler of the measuring head and the data of the position of the measuring head at the moment when the tip of the measuring head (hereinafter referred to as "feeler") contacts the workpiece. Since the shape accuracy and dimensions of the workpiece are calculated and calculated, the actual position of the measuring head is NC when the contact of the measuring head with the workpiece is detected.
There is a problem that the measuring head is moved a little before the apparatus stops the measuring head, and as a result, an error occurs in the accuracy of shape and size of the workpiece. Furthermore, the above-mentioned measuring system cannot measure accurately unless the control timing is synchronized with the NC device of the machine tool, and it is difficult to install it not only on a newly manufactured machine tool but also on an existing machine tool. However, there is a problem that the measurement system becomes expensive.

From the above, the present invention moves the measuring head toward the work, detects that the feeler of the measuring head contacts the work, outputs a skip signal to the NC device, and ends the movement of the measuring head. Then, by measuring the data of the displacement of the feeler and the data of the position of the measuring head, the measuring system using the NC machine tool that accurately and highly accurately calculates the shape accuracy and dimensions of the workpiece without the above-mentioned problems It aims at providing the control method of. Here, the skip function means that when an external signal (skip) signal is input during axis movement by the axis movement command of the NC program, execution of this axis movement command is stopped and it is described next to the NC program. The function to execute the command of the block.

[0008]

FIG. 1 is a flowchart showing the basic processing of the control method of the present invention. In order to solve the above-mentioned problems, a control method of a measuring system using an NC machine tool according to the present invention is an NC machine tool in which a measuring head capable of detecting displacement is attached to a spindle of an NC machine tool to measure the shape accuracy and dimensions of a work. A method of controlling a measuring system using a machine is characterized in that a measuring device connected to an NC device executes the following processing (steps S1 to S6). (S1) The measuring head mounted on the spindle is moved toward the work by the NC device controlling the NC machine tool. (S2) Displacement amount generated when the tip portion (feeler) of the measuring head comes into contact with the work, that is, each axis X of orthogonal coordinates,
The amount of displacement in the Y and Z directions is received from the measuring head and stored. (S3) It is detected that the displacement amount has reached the target value. (S4) A skip signal is output to the NC device, and the NC device stops the movement of the measuring head in the direction of the work. (S5) After the movement of the measuring head is completely stopped from the detection of the displacement amount, the position data of the measuring head is received and stored from the position reading scale mounted on the NC device or the NC machine tool. (S6) The shape accuracy and dimensions of the work are obtained from the stored data of the displacement amount of the measuring head and the data of the position of the measuring head.

[0009]

The control method of the measuring system using the NC machine tool according to the present invention detects that the feeler of the measuring head moved toward the workpiece comes into contact with the workpiece to generate the target displacement amount, and skips to the NC device. After outputting the signal, terminating the movement of the measuring head and stopping the measuring head completely, the data of the feeler displacement and the data of the position of the measuring head are measured. Calculate the shape accuracy and dimensions of the workpiece with high accuracy.

[0010]

EXAMPLE FIG. 2 is a schematic configuration diagram of a measuring system according to an example. The figure shows the machine tool generally with the reference numeral 1 with an arrow. Below is the work 4 after machining by the machine tool 1.
The operation of measuring the shape accuracy and dimensions of will be briefly described. The machine tool 1 is numerically controlled by the NC device 2, processes the work 4, and after processing the work 4, brings the measuring head 5 close to the work 4 and starts measuring the shape accuracy and dimensions of the work 4. Such operation of the machine tool is executed by the NC program loaded in the NC device. A feeler 6 is attached to the tip of the measuring head 5, and when the feeler 6 comes into contact with the work 4 and is pushed, the displacement amount of the feeler 6 is transmitted to the measuring device 3 by the displacement detection circuit incorporated in the measuring head 5. It Further, the scale 7 provided in the machine tool 1 outputs the position data by the movement of the measuring head 5 to the measuring device 3 indirectly or directly via the NC device 2. The NC device 2 takes in the data of the position of the measuring head 5 from an encoder (not shown) of a servomotor attached to the machine tool 1 and transmits the data of the position to the measuring device 3. The measuring device 2 measures the shape accuracy and dimensions of the work 4 based on the flowchart shown in FIG.
The operation will be described in detail below.

FIG. 3 is a flowchart showing the processing of the measuring system according to the embodiment. In the figure, the numbers following S indicate step numbers. (S1): It is described that a skip valid flag is set in the first part of a measurement program for measuring the shape accuracy and dimensions of a desired work loaded into the NC device. (S2): The measuring head is attached to the spindle of the machine tool, and NC
Start the execution of the measurement program preloaded on the device,
Start measuring the shape accuracy and dimensions of the workpiece. That is,
The NC device first outputs a movement command to bring the measuring head closer to the work. (S3): The measuring device receives an electric signal output from the measuring head, the electric signal corresponding to the displacement amount of the tip portion (feeler) of the measuring head, determines whether the displacement amount is a target value, and determines the determination value. If the result is YES, the process proceeds to step S4, and if the result is NO, step S3 is repeatedly executed at a constant cycle.

(S4): A skip signal is output from the measuring device to the NC device, and the movement command for bringing the measuring head closer to the work is stopped by the NC device. (S5): The NC device receives the skip signal and transmits dummy data to the measuring device according to an external output command. (S6): Upon receiving the dummy data, the measuring device immediately sends a DC3 command to the NC device. (S7): Upon receiving DC3, the NC device suspends the transmission of dummy data and suspends shifting to the next block. (S8): The measuring device determines whether the displacement amount of the feeler received from the measuring head has reached the target value. If the determination result is YES, the process proceeds to step S9, and if NO, repeats step S8 at regular intervals. Run.

(S9): The measuring device, after detecting that the change amount of the displacement of the feeler has disappeared, displays the displacement amount data and the position data of the measuring head while the operation of the machine tool is stopped. read. The data of the position of this measuring head can be read directly from the scale equipped on the machine tool, or
Alternatively, the data of the position of the triaxial Cartesian coordinate XYZ of the measuring head obtained by reading the output pulse of the encoder coupled to the output shaft of the servomotor attached to the machine tool is read from the NC device. (S10): The measuring device reads the displacement amount data and the position data of the measuring head, and then transmits DC1 to the NC device. (S11): The NC device executes the macro program of the NC device to transmit the remaining predetermined data, the transmission of which has been interrupted in step S7, to the measuring device. This predetermined data includes
For example, there is data of the coordinate values of the Cartesian coordinates XYZ of the NC device. (S12): The measuring device recognizes the end of the transmission of the predetermined data from the NC device to the measuring device by receiving the signal of PCLOS. (S13): The NC device continues the suspended operation.
That is, a movement command for moving the measuring head away from the work is output, and a movement command for directing the measurement head to the next measurement point on the work is output.

[0014]

As described above, according to the control method of the measuring system using the NC machine tool of the present invention, it is detected that the feeler of the measuring head moved toward the work makes contact with the work, A skip signal is output to the NC device, the movement of the measuring head is terminated, and after the movement of the measuring head is completely stopped, the data of the displacement of the feeler and the data of the position of the measuring head are measured. It is possible to accurately and highly accurately calculate and obtain the shape accuracy and dimensions of the workpiece without generating it. According to the present invention, it is possible to perform measurement without synchronizing with the control timing of the NC device of the machine tool, so that it is possible to easily install not only on a newly manufactured machine tool but also on an existing machine tool, and an inexpensive measurement system is provided. Can be provided.

[Brief description of drawings]

FIG. 1 is a flowchart showing a basic process of a control method of the present invention.

FIG. 2 is a schematic configuration diagram of a measurement system according to an embodiment.

FIG. 3 is a flowchart showing processing of the measurement system according to the embodiment.

[Explanation of symbols]

 1 ... Machine tool 2 ... NC device 3 ... Measuring device 4 ... Work piece 5 ... Measuring head 6 ... Feeler 7 ... Scale

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Claims (1)

[Claims] 1. A method for controlling a measuring system using an NC machine tool, wherein a measuring head capable of detecting displacement is mounted on a spindle of an NC machine tool to control the NC machine tool. The measurement head mounted on the spindle is relatively moved by the NC device toward the work, and the displacement amount generated when the tip portion of the measurement head comes into contact with the work is received from the measurement head and stored. The change in the displacement amount is detected, the relative movement of the measuring head in the direction of the workpiece is stopped by the NC device, and the movement of the measuring head is completely stopped after the change in the displacement amount is detected. Receiving and storing data of the position of the measuring head from a position reading scale provided in the device or the NC machine tool, and the stored displacement of the measuring head. A control method for a measuring system using an NC machine tool, characterized in that the shape accuracy and dimensions of the work are obtained from quantity data and position data of the measuring head.