JPS60263646A - Tool holder associated with ae breakdown detector - Google Patents

Abstract

PURPOSE:To reduce damping of signal considerably thus to improve the reliability of abnormality detection by arranging an acoustic emission (AE) sensor in the proximity of the tool through a thin flat bearing. CONSTITUTION:AE sensor 6 is secured to an oiless flat bearing 3 sliding through oil film against the outercircumference of a tool holder 11 adjoining to the tool 5 grasping section 13 and supporting the spindle 2 rotatably. Since AE signal is taken out through AE sensor from an oiless flat bearing sliding through oil film against the outercircumference of tool holder adjoining to the tool grasping section, the distance L between the tool 5 and the sensor 6 can be shortened while since the metal joints are reduced, damping of signal can be reduced considerably.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an improvement of a tool holder that is used for machining with a machine tool and that is rotated by nine spindles and holds a tool at the tip of the n-shaft, and particularly for drilling in machining centers and the like. The present invention also relates to a tool holder with a built-in AE sensor that can notify a machine controller of the abnormality when a tool breakage abnormality occurs during machining such as tapping.

(Prior art) Acoustic emission lt lower AE! : call)
The tool abnormality detection method using
It is known that the attenuation of the AE wave becomes large in the case of (see figure). Figure 3 shows the relationship in which the AE signal level detected by the sensor decreases as the distance between the signal generator, such as a tool, and the sensor, that is, the propagation distance, increases; When metals are connected between the signal generator and the sensor, a relationship is shown in which the more metals are connected, the more the AE signal level detected by the sensor is attenuated. For this reason, various studies have been made to install the sensor as close to the processing point as possible without intervening a large amount of metal. It would be best if the AE sensor could be mounted directly on the tool, but in reality the tool rotates and is replaced, so anything that rotates cannot be removed or replaced. It is also not possible to reattach the AE sensor every time it is used.

Next, it is desirable to attach it to the tool holder body, but since this rotates co-synchronously with the tool, it is not possible to attach a sensor. Therefore, 1.Currently, the AE sensor is attached to the housing of the spindle, or to the table or jig of the machine. However, since the spindle housing contains a bearing, it is difficult for AE waves to propagate, and it takes a lot of time to find an appropriate detection position or make detection adjustments, and it is still difficult to detect abnormalities in small diameter tools. The downside is that I can't do it, but I didn't have 2'L. Furthermore, when attempting to attach the sensor to a table or jig, the table moves, particularly rotation in the case of a rotary table, making it difficult to attach the sensor.

(Problem to be Solved by the Invention 9) The purpose of the present invention is to provide an AE system that eliminates the above-mentioned drawbacks of conventional products, has a high signal level, and can reliably and reliably detect abnormalities in tools with extremely small diameters. 1) A tool holder with a tool breakage detector may be installed.

(Means for Solving the Problems) Therefore, the present invention provides a tool holder that is rotated by a main shaft and that grips a tool at its tip. With a tool breakage detector using AEK, including an Oiles type flat bearing fixed to a main shaft housing that is in sliding contact with the main shaft through a rotatable support and rotatably supports the main shaft, and an AE sensor fixed to the Oiles type flat bearing. It is a tool holder.

(Function) In the present invention, since the AE sensor extracts the AE multiplied signal from the Oiles type flat bearing that slides into contact with the outer periphery of the tool holder adjacent to the gripping part of the tool via an oil film, the third The distance l between the two explained in the figure can be shortened, and the fourth
The number of metal connections explained in the diagram is small, and there is no rolling bearing involved, so the AE multiplied signal can be transmitted very easily.
And signal attenuation was significantly reduced.

(Example) Next, an example of the present invention will be described with reference to the drawings.
As shown in Figure 1, the tool holder (1) is attached to the main shaft (2).
The main shaft...Using CLQ is fixed to and rotated.
It is rotatably supported. The gripping portion σ3 of the tool holder (1) grips and holds a tool (5), which is a drill, via a collet (4). The tool holder outer periphery (1υ) adjacent to the gripping portion α4 is in sliding contact with the inner periphery α2 of the Oiles type bearing (3) via an oil film.
3) is fixedly supported within the sensor housing α, which is connected and fixed via the arm 0 fixed to the main shaft housing (IG) and the connector (8).AE sensor (6)
u, is fixed to the outer periphery of the Oiles type plain bearing (3). (7) 00 is the sensor lead wire, (9) ll'' is the wiring terminal. If the tool (5) is damaged,
As shown in the figure, the KAE sensor (6) detects the tool breakage AE double signal, and outputs the signal via the preamplifier CD attached to the fixed part of the machine via the lead wire (71 (lfffl), terminal (9), and connector (c). The signal is amplified, and the signal processing section (to) performs processing to confirm tool damage, and the machine controller (c) is notified that the tool is abnormal.In response to this signal, the machine stops or goes into emergency return mode. I'm like n.

In the example, a collet (
4) was used, but a large-diameter tool may be directly gripped by the gripping portion without using a collet. In addition, in the case of a tool holder that is tightened from above the outer circumference αυ of the tool holder (1) using a needle roller, etc., avoid this part and avoid tightening the tip near the tool (5) or the main shaft (2) side through the member. It is desirable that there is no such thing.

(Effects of the Invention) According to the present invention, the AE sensor (6) is mounted very close to the tool that is the AE signal generator via a relatively thin-walled Oiles type plain bearing (3) and is connected to a small number of metal connections. Since the AE multiplied signal is detected through the
And signal attenuation was significantly reduced. For this reason, it has become extremely easy to detect tool abnormalities with extremely small diameters, and the reliability of abnormality detection has increased.

Furthermore, even if the dimensions of the workpiece to be machined become very small, the signal is detected by the AE sensor from the tool holder via the Oiles type plain bearing, so the distance E in Fig. 3 is extremely short.
This is intended to solve the problem that conventionally occurs when a large workpiece is attached to the edge of the table at a distance of 2 from the workpiece. Furthermore, even if the table or workpiece rotates or the workpiece is moved to the next station, such as a pallet-moving transfer machine, the table or workpiece may slide into contact with the tool holder regardless of the table or workpiece. Since the bearing and the AE sensor can be attached, detection can now be performed without being affected by such influences. Also, the AE sensor has already been added to the tool holder, and the installation time is 17xs.
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[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a tool holder with an AE-based tool breakage detector according to an embodiment of the present invention, FIG. 2 is a block diagram showing the signal processing electric circuit of the AE sensor of FIG. 1, and FIGS. FIG. 4 is a graph showing the relationship between the detected AE signal level and the intervening metal and distance between the signal generator and the AE sensor. ■...Tool holder 2...Main shaft 3...Oiles type plain bearing 5...Tool 6...AE sensor 11
...Outer periphery 13...Gripping part 16...Main shaft housing agent Patent attorney Jun Kawauchi Futami 1 figure connecting five Maro J books (→ Ji 4 gardens)

Claims (1)

[Claims] In a tool holder that is rotated by a main shaft and that grips a tool at its tip, a gripping portion α3 that grips the tool (5)
an Oiles type flat bearing (3) which is fixed to a spindle housing αQ that is in sliding contact with the outer circumference ◇υ of the tool holder (1) adjacent to the tool holder (1) via an oil film and rotatably supports the spindle (2);
A tool holder with an AE tool breakage detector, characterized in that it includes the Oiles type flat bearing (3) and an AE sensor (6) fixed to the K.