JPS63196355A - Numerically controlled machining system - Google Patents

Abstract

PURPOSE:To automatically detect the existence and position of a base flaw in a workpiece and prevent the occurrence of an inferior product due to said base flaw by providing an ultrasonic probe device on a tool holder to detect a flaw and selecting a workpiece. CONSTITUTION:A reference signal is generated by an exciting part 15 according to an excitation start command from a numerical control part 2a and applied to an ultrasonic probe device 14, by which the signal is converted into a sound wave and radiated within a workpiece 10, and the reflected echo signal groups are gathered and inputted into a wave detecting part 16. In this case, if there is a base flaw on the workpiece 10, the reference signal is reflected even by this base flow and gathered as an echo signal by the ultrasonic probe device 14 and detected by the wave detecting part 16. And, a judging circuit 17 calculates the position of the base flaw form the time difference between the reference signal and the detected signal and, by referring to a workpiece dimension information in the numerical control part 2a, when the base flaw is judged to be rejected, it commands suspension of machining and replace the workpiece. Accordingly, the existence and position of a base flaw in a workpiece 10 can be detected automatically and accurately, preventing the occurrence of an inferior product due to the base flaw.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a numerically controlled machining system that performs machining such as turning and cutting. The present invention relates to a device for inspecting.

[Prior Art] Fig. 5 is a diagram showing the configuration of conventional numerical control. In the figure, (1) is a numerical control device, which includes a numerical control section (2), a display control section (3), and a CRT. (4) and a drive section (5). (6) is a machine tool, which includes a tool holder (8) to which a tool (7) is fixed, a spindle head (9),
It is composed of a chuck (11) that grips the workpiece (10), a tailstock (12), and a drive motor (not shown) that drives the tool hilder (8) in the X-axis direction and the Z-axis direction.

Next, the operation will be explained. The numerical control unit (2) reads the cannibal program from the cannibal program tape (13), analyzes it, and displays the contents of the cannibal program and various messages to the operator via the display control unit (3) on the CRT (
4).

On the other hand, the machine program for driving and controlling the control axes is processed by the same numerical control section (2), and position command information is input to the driving section (5).
The voltage applied to the drive motor is generated based on the position command information input from the machine tool (6), and the drive motor attached to the machine tool (6) is driven to drive the tool holder (
8) to control the position in the X-axis and Z-axis directions. In addition, the spindle head (9) rotates the workpiece (10) gripped by the chuck (11) and tailstock (12) at a predetermined rotation speed based on the spindle rotation speed commanded from the numerical control unit (2). drive

[Problem to be solved by the invention 1 Although the workpiece (lO) is processed into the desired shape by the above control, it is necessary to prevent quality defects in the processed product due to material defects such as internal defects (hereinafter referred to as scratches). In general, the shapes machined by numerical control devices are complex, and
In most cases, it is impossible to detect the presence or absence of scratches in the material of a processed product.

As a method to solve this problem, a method for inspecting steel material scratches (Japanese Patent Laid-Open No. 61-30359) as shown in Fig. 6 is proposed.
No. 2) has been proposed. In the figure, (21) is the object to be inspected, (22) is the cutting tool, (23) is the flaw detection sensor, (24) is the oscillator, (25) is the bridge, (2B
) is an amplifier, (27) is a signal processor, and (28) is a recording display. The high frequency voltage from the oscillator (24) is applied to the flaw detection sensor (23), and since the impedance changes depending on the presence or absence of flaws, it is detected via the bridge (25), and the output of the bridge (25) is sent to the amplifier (26). ), the signal is amplified by a signal processor (27), the signal is processed by a signal processor (27), and the presence or absence of scratches is determined and recorded on a recording display (28). However, this method is based on the eddy current flaw detection method and, in principle, is aimed at specifically detecting ground flaws in the surface layer of the material. Therefore, when a ground flaw exists in the deep part of the material, there is a problem that even if the presence of the ground flaw is detected, the accurate position cannot be detected.

It is an object of the present invention to solve the above-mentioned problems and to provide a numerically controlled machining system that can further utilize inspection results in an expanded manner.

[Means for Solving the Problems] The numerically controlled machining system according to the present invention solves the above problems by using an ultrasonic flaw detection method, and uses an ultrasonic flaw installed as a type of tool in a tool holder. A sonic probe device, an excitation unit that excites the ultrasonic probe device, and an echo signal generated when a reference signal emitted by the ultrasonic probe device is reflected on a ground scratch or the like in a workpiece. A detection unit that detects waves through the probe device, a determination means that automatically determines the presence or absence of ground flaws based on the input workpiece size information and the output signal of the detection unit, and a determination unit that issues an excitation start command to the excitation unit. The apparatus also includes a numerical control section that outputs commands for controlling the movement of the ultrasonic probe device and controlling the attachment and detachment of the workpiece based on the determination output of the determination means.

"Operation" In this invention, after cutting or turning the surface of the workpiece with a normal tool, the ultrasonic probe device installed in the tool holder is controlled in the same way as the tool to contact and move the surface of the workpiece. While performing ultrasonic flaw detection, the presence and location of potential ground flaws is detected three-dimensionally. Then, the workpieces are selected depending on the judgment result of the judgment means.

[Embodiment] FIG. 1 is a diagram showing the configuration of a numerically controlled machining system applied to a lathe as an embodiment of the present invention, and FIG. 2 is a flowchart showing its operation. In Figure 1, (2a
) is a numerical control unit which has a function to output an excitation start command and a function to command workpiece attachment/detachment control to the numerical control unit (2) in Fig. 5, and (14) is an ultrasonic probe device, and an excitation unit (
15). (16) is a detection unit that detects the echo signal collected by the ultrasonic probe device (14), and a determination circuit (17) identifies the presence or absence of ground damage based on the output of the detection unit (16). Make a decision. (3) to (13) are the fifth
Since it is the same as the figure, the explanation will be omitted.

First, in order to set the ultrasonic probe device (14) of the tool holder (8) to a predetermined initial position, the numerical control unit (2a)
For example, i-1 is set, the workpiece (10) is further rotated by the spindle head (9) (Sl), and an excitation start command is given to the excitation section (15) (S2). Next, the tool holder (8)
is moved to a position on the Z axis corresponding to the above setting i-1 (S3).

The excitation unit (15) generates a reference signal (a) as shown in FIG. 3(A) in response to the excitation start command output from the numerical control unit (2a), and the ultrasonic probe device (14) to be applied. The ultrasonic probe device (14) uses this reference signal (a)
is converted into a sound wave and radiated into the workpiece (10), and a group of echo signals reflected within the workpiece are collected and input to the detection section (1B) (S4). The detection section (1B) detects the echo signal group and detects the echo signal (b) reflected at the end of the workpiece. At this time, if there is a ground flaw (el) in the workpiece, the reference signal (a) is The sound is reflected even from this ground flaw (el), becomes an echo signal (cl), is collected by the ultrasonic probe device (14), and is detected by the detection unit (16) (S5). The determination circuit (17) inputs the reference signal (a) detected from the excitation section (15) and the detection signal output from the detection section (16) and calculates the time difference between the reference signal (a) and the detection signal. The position of the point where the echo signal was generated is calculated from the propagation velocity of the sound wave in the workpiece. In addition, the judgment circuit (
17) refers to the workpiece size information in the numerical control unit (2a) to determine whether the echo signal is due to the edge of the workpiece or a ground flaw (S6), and determines that the ground flaw should be eliminated. Then (S7), a machining interruption signal is input to the numerical control unit (2a) to interrupt the machining and to instruct workpiece replacement (S8).

In step (S6), assuming that the workpiece diameter is d11 and the sound propagation speed in the workpiece (lO) is ■, the time difference to between the reference signal (a) and the echo signal at the end of the workpiece is to
-di/v, and the echo signal (cl) detected within this time is determined to be due to ground damage. The location of the ground flaw is then determined based on the time difference between the echo signals. In addition, in step (S7), for example, in the case of boring, the numerical control section (2a) in FIG. 1 stores in advance inspection range information excluding the machining area to be deleted by the machining. Then, by comparing the inspection range information and the position of the ground flaw based on the detection signal from the detection section (1B) in the judgment circuit (17), the ground flaw is detected as shown in FIGS. 4(A) and (B). If (e2) exists in the boring range (d2), the ground flaw is ignored and the process moves to the next flaw detection. In this example, the ground flaw is in the boring range (d2) and is located at a position offset from the center by IC, and the time of the echo signal is the same as when there is no ground flaw indicated by t2 (S6) or that ground flaw. If the flaw detection is not worth replacing (S7), check whether flaw detection has been performed in the entire area (S9), and if it has not been detected in the entire area yet, check the flaw detection on the Z axis of the tool holder (8). In order to move the position, calculate i-i+1 (5IO), step (S
Returning to step 3), the tool holder (8) is moved to the position on the Z axis corresponding to the above i, and the same operation is repeated. In addition,
The X-axis and Z-axis positioning and tracing control at this time are performed based on the inspection program or the previously executed cutting program.

In the above embodiment, a case was described in which the workpiece dimensions were stored in advance, but the determination circuit (17
), input the command position information indicating the tool position stored in the numerical control unit (2a) and the detection signal from the detection unit (16), and then calculate the workpiece dimensions (for example, if it is a lathe) from the position information. (radius x 2 - diameter) may be automatically calculated to determine whether the echo signal is due to the edge of the workpiece or a ground flaw. Furthermore, when it is not necessary to perform flaw detection over the entire workpiece (10), it goes without saying that a desired area may be specified in advance to the numerical control unit (2a) and only that area may be flaw detected.

[Effects of the invention] According to this invention, an ultrasonic probe device is attached to the tool holder to detect flaws and select workpieces, so the existence and location of ground flaws on the workpiece can be automatically and accurately determined. It is possible to detect and prevent product defects due to ground scratches, thereby improving product quality and preventing time loss due to machining of defective workpieces.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the numerical control machining system when this invention is applied to a lathe, Figure 2 is a flowchart showing its operation, and Figures 3 (A) and (B) are diagrams showing the workpiece when flaws are detected. A diagram showing the relationship between echo signals, Figures 4 (A) and (B) are diagrams showing the relationship between the workpiece and echo signals when a workpiece to be bored is detected, and Figure 5 is a configuration diagram showing a conventional numerical control machining system. FIG. 6 is a block diagram of an already disclosed inspection method. In the figure, (1) is a numerical control device, (2a) is a numerical control unit, (14) is an ultrasonic probe device, (15) is an excitation unit, (16) is a detection unit, and (17) is a determination circuit. It is. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) In a numerically controlled machining system that performs machining such as turning and cutting, an ultrasonic probe device attached to a tool holder, an excitation section that excites the ultrasonic probe device, and the ultrasonic probe A detection unit that detects an echo signal generated by the reference signal emitted by the probe device reflecting on a ground flaw or the like in the workpiece through the probe device, and workpiece size information and an output signal of the detection unit. a determination means for automatically determining the presence or absence of ground flaws, and outputting an excitation start command to an excitation unit, and commanding movement control of the ultrasonic probe device and workpiece attachment/detachment control based on a determination output of the determination means. A numerical control machining system characterized by having a numerical control section that performs the following steps. (2) The determination means receives the inspection range information and the detection unit output signal, compares the detection unit output signal and the inspection range information, and determines to ignore the echo signal of the ground flaw removed by processing. A numerically controlled machining system according to claim 1. (3) The determination means inputs the command position information of the numerical control unit and the detection unit output signal, automatically calculates the workpiece dimensions from the command position information, and determines whether the detection unit output signal is a signal due to the workpiece edge or due to ground damage. The numerically controlled machining system according to claim 1, which determines whether the signal is a signal or not.