JPH0230819B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cutting tool abnormality detection device for detecting abnormalities such as wear and breakage of tips in cutting tools.

[Technical background of the invention and its problems]

Generally, when cutting a workpiece, a cutting tool with a cutting tip attached to the shank is used, but if the tip wears out or breaks, it will no longer be possible to perform the desired cutting and the object will become damaged. Cuttings become defective. For this reason, conventionally,
Since there is no effective way to detect such chip abnormalities, employees are required to perform regular visual inspections, but this may undermine the benefits of unmanned systems, especially in automated systems intended for unmanned systems. Not only is there a problem that a large number of defective products are produced before an abnormality is discovered during inspection.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its object is to provide a tool abnormality detection device that can automatically detect abnormalities such as chip wear and damage.

[Summary of the invention]

The present invention provides a cutting tool in which a cutting tip is attached to the upper surface of the tip of the shank, in which a mounting recess is formed at the tip of the shank and is located below the tip and has an open bottom surface. A piezoelectric transducer is placed in the mounting recess, a presser member for pressing the piezoelectric transducer is installed in the mounting recess, a vibratory electric signal of the piezoelectric transducer based on the vibration of the chip is detected, and the amplitude of the vibratory electric signal is detected. The present invention is characterized in that it includes an abnormality determining means for detecting an abnormality in the chip based on a change in the chip.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a cutting tool, which is a cutting tool made by molding powder of a cemented carbide metal such as tungsten at high temperature and pressure onto the upper surface of the tip of a shank portion 2 formed into a long shape of cast steel or the like. It is configured by attaching chip 3. A mounting recess 2a whose bottom surface is open is formed at the tip of the shank portion 2 of the cutting tool 1, and a piezoelectric transducer 4 made of a resistance wire strain gauge is arranged on the back wall of the mounting recess 2a. Furthermore, a holding member 5 is fitted into the mounting recess 2a so as to press down the piezoelectric transducer 4, and is attached by adhesive or welding, so that the piezoelectric transducer 4 is embedded in the tip of the shank portion 2. has been done. 4a, 4a are lead wires led out from the piezoelectric transducer 4. Reference numeral 6 denotes a support base having a support arm 7, on which the shank portion 2 of the cutting tool 1 is placed and pressed by the tip of a bolt 8 screwed into the support arm 7. As the cutting process progresses, the support stand 6 is moved in the direction of arrow A by a drive motor 9 (see FIG. 3) serving as a drive source. Reference numeral 10 denotes a workpiece to be cut, which is chucked by a chuck (not shown) and rotated in the direction of arrow B by the drive motor 9. Reference numeral 11 denotes a detection amplification circuit, which constitutes a bridge circuit with the piezoelectric conversion element 4 as one side, generates an electric signal, and amplifies the electric signal. It is now being given to 12 people. As will be described later, this calculation/judgment circuit 12 integrates the oscillating electric signal, and when it becomes larger than a certain value, it determines that there is an abnormality and outputs an abnormality detection signal.
The abnormality detection signal is given to the drive circuit 13. The drive circuit 13 is configured to cut off the power to the drive motor 9 when an abnormality detection signal is applied.

Next, the operation of this embodiment will be explained. When the operation switch (not shown) is operated, the drive motor 9
is energized, and as a result, the workpiece 10 is rotated in the direction of arrow B, and the support base 6 is moved in the direction of arrow A, so that the cutting edge 3a of the tip 3 in the cutting tool 1 comes into contact with the workpiece 10. The workpiece 1
0 predetermined cutting is performed. During this cutting, the chip 3 vibrates little by little in the direction of arrow C and in the opposite direction of arrow C due to contact with the workpiece 10, and along with this, the piezoelectric transducer 4 also experiences small changes in resistance. The detection amplification circuit 11 outputs an oscillating electric signal. This oscillating electrical signal is then given to the arithmetic and determining circuit 12, but when the cutting edge 3a of the chip 3 is normal, the amplitude of the oscillating electrical signal is not so large, and the arithmetic and determining circuit 12 does not output an abnormality detection signal. Thereafter, when the predetermined cutting of the workpiece 10 is completed, the support stand 6 is moved backward in the opposite direction of arrow A, and the same operation is repeated thereafter. By repeating this cutting operation, the cutting edge 3 of the chip 3
If the tip a is abnormally worn or the cutting edge 3a is damaged, the contact resistance between the cutting edge 3a and the workpiece 10 becomes abnormally large, and the vibration of the tip 3 in the direction of arrow C and the direction opposite to arrow C becomes significant. As a result, the resistance value change of the piezoelectric transducer 4 also becomes large, and the detection amplifier circuit 11
The amplitude of the vibrating electrical signal output from the oscillator becomes larger than normal. Therefore, since the integral value exceeds a certain value, the calculation/judgment circuit 12 to which this is applied outputs an abnormality detection signal, and the drive circuit 13 cuts off the power to the drive motor 9.

As described above, according to this embodiment, an abnormality such as abnormal wear or damage on the cutting edge 3a of the tip 3 in the cutting tool 1 is detected by the piezoelectric transducer 4 as a change in the amplitude of the vibratory electric signal, and the drive motor 9 is activated. Since the power is cut off, an abnormality in the chip 3 can be automatically detected, and especially in an automatic system, the merits of unmanned operation are not lost, and no defective products are produced. In this case, the piezoelectric transducer 4 is disposed at the tip of the shank portion 2 within the mounting recess 2a formed below the chip 3, so that the piezoelectric transducer 4 Since it is located close to the tip, the vibration of the tip 3 can be detected with high sensitivity, and only the vibration of the tip 3 can be reliably detected without picking up other unnecessary vibrations.

Further, according to this embodiment, the mounting recess 2a is formed at the tip of the shank portion 2 of the cutting tool 1 so that the lower surface thereof is open, and the piezoelectric transducer 4 is disposed within the mounting recess 2a. Since the pressing member 5 is fitted into the recess 2a and attached by gluing or welding to hold down the piezoelectric transducer 4, the mounting structure of the piezoelectric transducer 4 is simple and can be manufactured easily. For example, unlike the case where a strain gauge, which is a piezoelectric transducer, is attached to the cutting tool 1, it is not adversely affected by cutting waste or cutting oil.

In the above embodiment, the power to the drive motor 9 is cut off based on the abnormality detection signal from the calculation/determination circuit 12, but an alarm such as a buzzer may be activated instead.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings; for example, a semiconductor strain gauge, a piezoelectric element, etc. may be used as the piezoelectric transducer, without departing from the scope of the invention. Of course, it can be implemented with appropriate modifications.

〔Effect of the invention〕

As explained above, the present invention disposes a piezoelectric transducer in the mounting recess formed at the tip of the shank portion of the cutting tool and is located below the chip, and presses the piezoelectric transducer with a presser member. Since the determination means detects a change in the amplitude of the vibrating electric signal from the piezoelectric transducer,
It is possible to automatically detect abnormalities such as wear and breakage of the tip of the cutting tool, and it is also possible to detect the vibration of the tip with high sensitivity and reliably.
The mounting structure of the piezoelectric transducer is simple and can be manufactured easily, and the piezoelectric transducer is not adversely affected by cutting waste and cutting oil, which is an excellent effect.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is an overall side view, FIG. 2 is an enlarged side view of the main part partially cut away, and FIG. 3 is a block diagram showing the electrical configuration. be. In the drawing, 1 is a cutting tool, 2 is a shank part, 2a is a mounting recess, 3 is a chip, 3a is a cutting edge, 4 is a piezoelectric transducer, 5 is a holding member, 9 is a drive motor, 11 is a detection amplifier circuit, and 12 is an operation unit. The determination circuit (abnormality determination means) is shown.

Claims (1)

[Claims] 1. A cutting tool in which a cutting tip is attached to the upper surface of the tip of the shank part, a mounting recess formed at the tip of the shank part below the tip and having an open bottom surface; A piezoelectric transducer is arranged, a holding member is mounted in the mounting recess and presses down the piezoelectric transducer, and a vibrating electric signal of the piezoelectric transducing element based on the vibration of the chip is detected, and a change in the vibrating electric signal is used to detect the vibrating electric signal. What is claimed is: 1. An abnormality detection device for a cutting tool, comprising: an abnormality determining means for determining an abnormality in a chip.