JPS6121764B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tool holder equipped with an ultrasonic vibration transmitting device suitable for use in a tool breakage prevention device that utilizes arcuate emission.

In recent years, with the advancement of production technology, the demand for labor-saving and unmanned cutting processes has rapidly increased.In such automatic machining, it is necessary to detect abnormal conditions such as damage or breakage of cutting tools in-process. This is an important issue.

One effective method for in-process detection of abnormal conditions such as damage or breakage of cutting tools is to detect acoustic emissions that naturally occur as a result of tool damage or breakage.
There is a known detection method that detects AE) and uses the detection signal to issue an alarm and interrupt subsequent work. The level of AE signal generated by wave damage or breakage of the tool is sufficiently large, so the above detection method using AE is effective for in-process detection of tool damage or breakage, but it cannot be detected after the tool has been waved or broken. Since it cannot be detected, it cannot be used to predict breakage. Research has also been conducted on in-process detection methods that utilize AE, which occurs as a precursor to tool breakage, but the AE signal is small and detection is extremely difficult, and even if detection is possible, the spindle may be damaged. Since it takes a certain amount of time to stop, there is a high possibility that it cannot be used to prevent tool breakage.

On the other hand, rotary cutting tools such as drills, taps, and end mills are more likely to break due to chip clogging or welding of the cutting edge rather than local damage or breakage.
Moreover, since broken tools are embedded in the workpiece and removing them requires a lot of effort and processing time is often long, it is possible to not only detect breakage in-process, but also to predict breakage and prevent breakage. equipment is needed. As a means of preventing breakage of such rotary cutting tools during cutting, it is well known that, for example, a tri-limiter is used to prevent the tap from breaking. In such a case, the same condition as when testing the durability of the tri-limiter occurs, leading to the destruction of the tri-limiter, which has the drawback that it cannot be applied to unmanned processing.

Furthermore, a method of predicting breakage of a drill using changes in the load current of the electric motor that rotates the tool has also been put into practical use. This method uses a medium diameter drill (φ10 ~
20) is effective to some extent in preventing breakage, but in the case of small-diameter drills of φ9 or less that easily break, there is a drawback that it cannot be used to prevent breakage because the change in load current is small in general-purpose machine tools.

Furthermore, a method is known in which cutting resistance or its component force ratio is detected using a strain gauge attached to the tool holder, spindle, etc., and drill breakage is predicted based on changes in these forces, but this method also has problems with small-diameter drills. In some cases, the load applied to the tool is small, so the change in strain is small and difficult to detect.

In this way, there is no effective way to prevent breakage, especially for small-diameter rotary cutting tools, so the current situation is to avoid using small-diameter tools that are prone to breakage as much as possible during automatic machining using machining centers, etc. .

In view of these circumstances, a patent application was filed in 1983 for a tool breakage prevention device using acoustic emission that can effectively prevent breakage even for small diameter tools.
-Proposed in No. 069354.

The above-mentioned tool breakage prevention device includes a tool holder or spindle that generates an elastic wave of a certain level or more in response to an overload applied to a tool during cutting, which may cause the tool to break. A detector is installed in the head and receives the elastic waves generated by the means externally, discriminates it from noise, and generates an output, and issues an alarm based on the output signal from the detector,
The device is configured to perform a protective operation for the tool, and the means for generating the elastic wave includes:
A tri-limiter that generates a relatively large level of elastic waves when activated is considered to be preferable because it is simple and also serves as a protective action for the tool, and an implementation in which the tri-limiter is incorporated in the rear end of the tool holder has been shown.

However, when using the elastic vibrations generated during the operation of the trich limiter as the detection signal as described above,
For small-diameter drills and taps, for example, drill diameters of φ9 or less and taps of M8 or less, for which methods to prevent tool breakage are most sought after, the cutting torque is small, so elastic vibrations that occur when the tri-limiter operates are also avoided. In an environment with a small size and therefore a large amount of noise, it becomes difficult to distinguish between the detection signal and the noise, making it difficult to employ the above-mentioned tool breakage prevention device.

The present invention has been made with the aim of solving such problems, and is equipped with an ultrasonic vibration transmitting mechanism that generates elastic vibrations of high frequencies including ultrasonic range in conjunction with the operation of the trick limiter. It is intended to provide a tool holder.

In order to achieve the above object, the present invention includes a cylindrical main body that is rotated in conjunction with a main shaft of a machine, a spindle that is rotatably fitted into the main body, and a cylindrical main body that is rotatably fitted into the main body, and a a tool gripping portion; a transmission member rotatably mounted on the rear end of the main body and interlockingly connected to the rear end of the spindle; and a trigger limiter interposed between the transmission member and the detection signal. a torque limiter interposed between the transmission member and the main body, a spring member is provided on one of the rotating parts of the transmission member and the main body, and a spring member is provided on the other side to flip up the spring member. A member is provided, and when the trilimiter is activated, the spring member and the flip-up member intermittently collide with each other to generate ultrasonic vibrations.

Therefore, if the tool holder of the present invention is used,
Even if the set torque of the limiter is small,
When the tri-limiter is activated, the ultrasonic transmitting mechanism that is linked to it generates elastic vibrations with high frequencies that include the ultrasonic range. It also has the advantage of being able to be used effectively even in noisy environments.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Fig. 1 shows an example in which the present invention is applied to a drill holder, in which 1 is a holder main body, which has a cylindrical shape and has a lock nut 3 screwed into a threaded portion 2 carved on the outer periphery of the front half. . Reference numeral 4 denotes a spindle for holding the drill D, which is formed into a bottomed cylindrical shaft having a bottom 5 at the rear end, and is rotatable with the front end protruding from the main body 1 via a ball bearing 6 and a thrust bearing 7. A locking ring 8 fitted to the rear end is locked to a retaining ring 9 fitted inside the main body 1 to prevent it from coming off in the axial direction. A square hole 10 is bored in the bottom 5 of the spindle 4, and the front end opening is formed into a tapered hole 11, and a collet 12 fitted into the tapered hole 11 is formed.
The drill D is inserted into the spindle 4, and the collet 12 is tightened with a tightening nut 14 rotatably attached to the front end of the spindle 4 via a ball bearing 13 to hold the drill D fixed. At this time, the rear end of the drill D comes into contact with the adjustment screw 15, and the length of the drill D protruding from the main body 1 is regulated.

Reference numeral 16 denotes a transmission member for transmitting the rotational force of the main body 1 to the spindle 4, and as shown in FIG. Disc 17 to be fitted
and a square shaft 1 protruding from the central part of one side of the disk 17.
8 and a screw shaft 19 protruding from the center on the other side, the disk 17 is provided with an annular groove 21, and several pins 22 are inserted into the annular groove 21 at appropriate intervals in the circumferential direction. are arranged parallel to the axis. The spherical body 20 is fitted into through holes 23 having four bottom openings with slightly smaller diameters, which are bored at 90 degrees out of phase in the peripheral wall of the rear end opening of the main body 1.
is engaged with the annular groove 21 of the disc 17 and the transmission member 16
is configured to be rotatably and removably attached to the main body 1, and when attached to the main body 1, the square shaft 18 is slidably inserted into the square hole 10 of the spindle 4 and engaged with the spindle 4. It's becoming like that. A shallow annular groove 24 is provided on the outer periphery of the rear end of the main body 1 so as to surround the four through holes 23, and a band-shaped leaf spring 25 is loosely wound around the annular groove 24. The leaf spring 25 functions as a pressing spring to prevent the sphere 20 fitted into the through hole 23 from falling out, and at the same time, one end thereof is formed tapered and bent to pass through the through hole 26 bored at the rear end of the main body 1. The tip portion 25a is connected to the pin 2 provided on the transmission member 16.
2, the plate spring 25 forms an ultrasonic vibration transmitting mechanism in which the pin 22 intermittently springs up the tip portion 25a when the tri-limiter is activated to be described later, and the plate spring 25 generates elastic vibrations with high frequencies including the ultrasonic range. are doing.

The trilimiter 27 is assembled to the screw shaft 19 of the transmission member 16, and includes a bottomed cylindrical retainer 28 as a main body, and a 120°
Balls 31 accommodated in three holes 30 bored at different phases, and a large number of disc springs 3 arranged on the screw shaft 19 in alternating directions and stacked one on top of the other.
2, a lid 33 screwed onto the shaft 19, and the lid 33
and three concave portions 35 extending in an arc shape and recessed in the side surface of the disc 17 of the transmission member 16 with a phase difference of 120 degrees in correspondence with the ball 31, The set torque can be adjusted by adjusting the amount. The retainer 28, as best shown in FIG.
three ball receiving holes 30 are provided concentrically with respect to the holes 36 and are spaced apart from each other by 120 degrees. A pair of transmission notches 38 provided in
(See FIG. 2) is integrally provided with a protrusion 37 that engages.

The tool holder of the present invention having the above structure is inserted into the side lock holder 40 as shown by the imaginary line in FIG.
It is used by being detachably connected to the main shaft 41 of a machine tool via the main shaft 41, and moves with the rotation of the main shaft 41 to form the holder 40, main body 1, tri-limiter 27, and transmission member 1.
6 and spindle 4, a drill D4 is rotated. 42 is a spindle head, 43 is a bearing, and 44 is a workpiece, which is set on a table 45 and fixed to a vise 46.

Reference numeral 51 denotes a tool breakage prevention detector, which is composed of a detection section 52, a high-pass filter 53, an amplifier 54, an average value detector 55, and an amplitude discriminator 58. It is attached. In the figure, 57 is an alarm signal generator, and 58 is a machine tool controller.

Clogging of chips and wear of the cutting edge during cutting tools,
If an overload exceeding the set torque of the tri-limiter 27 is applied to the drill D due to welding or the like, and there is a risk that the drill D will break, the tri-limiter 27 will operate and a slip will occur between the main body 1 and the transmission member 16. Due to this slip, the ball 31 of the trilimiter 27 and the recess 35 repeatedly engage and disengage, generating elastic vibrations, and the main body 1 and the transmission member 16 rotate relative to each other, causing the ultrasonic vibration transmitting mechanism The pin 22 is the tip portion 25 of the leaf spring 25.
a is intermittently bounced to generate high frequency elastic vibrations including ultrasonic waves.

The level of elastic vibration generated by the operation of the trilimiter 27 increases or decreases depending on the magnitude of the set torque. If the drill D has a small diameter, the set torque is small, so the level of the generated elastic vibration also becomes small. On the other hand, the elastic vibration generated by the transmitting mechanism consisting of the pin 22 and the leaf spring 25 is not affected by the set torque of the torque limiter 27, and the main shaft 4
The rotation speed is usually 500r.p.
m or more, high-frequency elastic vibrations, including those in the ultrasonic range, are always generated.

The elastic vibration generated by the ultrasonic vibration transmission mechanism passes through the side lock holder 40 and the bearing 43, is transmitted to the spindle head 42, and is detected by the detector 52.
The frequency is in the ultrasonic range of 300KHz or higher, and is higher than the frequency of noise and vibration generated by the drill D itself, tool holder, bearings, and other external environments during cutting operations with the drill D, so these noises are used to set the threshold to 300KHz. High pass filter 5 set to
3, amplified by the amplifier 54, and detected by the detector 5.
5 performs average value detection. Furthermore, the amplitude discriminator 56
When a signal exceeding this is detected, the alarm signal generator 57 issues an alarm, the controller 58 issues a step bag command, and according to this command, the spindle head retreats and the drill D
This is to prevent the drill D from breaking. Further, the controller 58 is configured to determine that the tool life has expired and issue a tool exchange signal when the stepback command occurs more than a certain number of times within a unit time.

7 to 9 show examples in which the present invention is implemented in a tap holder. The drill holder is basically the same as the drill holder of the above embodiment, but the spindle 4 is fitted to the main body so as to be rotatable and slidable in the axial direction, and the tap T is opened by the action of a spring 60.
The difference is that there is a built-in floating mechanism for correcting errors between the feed by self-propelling action and the feed by the main shaft 41. Further, a leaf spring 25 constituting the ultrasonic vibration transmission mechanism is disposed in a groove 61 extending in the axial direction on the outer peripheral surface of the main body 1, and its base end is fixed to the main body 1 with a screw 62. The tapered tip portion 25a is bent to pass through the through hole 26, engages with the pin 22, and generates high frequency elastic vibrations including the ultrasonic range when the trilimiter is operated. In this case, it is necessary to provide a pressing spring 63 separately from the leaf spring 25 to prevent the ball 20 that locks the transmission member 16 to the rear end of the main body 1 from falling off.

As detailed above, the tool holder of the present invention has
This is because the ultrasonic vibration transmitting mechanism, which consists of a spring member that interlocks with the trigger limiter when it is activated, and a flip-up member that flips up the spring member, is configured to generate high-frequency elastic vibrations that include the ultrasonic range. When used in a tool breakage prevention device using AE, the ultrasonic vibration generated by the transmitting mechanism is used as a detection signal that can be clearly distinguished from noise and vibration generated by the tool itself, holder, bearing, and other external environments during cutting operations. It becomes easier to
There is an advantage that the tool breakage prevention device can be used even in a noisy environment. In particular, the tool holder described above is effective for small diameter tools. In addition, the configuration of the ultrasonic vibration transmitter is simple and easy to manufacture.
It can be provided at low cost.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a longitudinal sectional front view of the tool holder of the present invention, FIG. 2 is a plan view of the same essential parts, and FIG. 3 is a sectional view taken along line 3-3 in FIG. 1. ,
Fig. 4 is a perspective view of the transmission member, Fig. 5 is a perspective view of the retainer of the tri-limiter, Fig. 6 is a schematic illustration of a tool breakage prevention device using the same tool holder, and Fig. 7 is a longitudinal section of another embodiment. 8 is a front view of the same essential parts, and FIG. 9 is a sectional view taken along line 9-9 in FIG. 7. 1...Main body, 4...Spindle, 16...Transmission member, 27...Trick limiter, 22...Pin,
25... Leaf spring, 25a... Tip portion of leaf spring 25, D... Drill, T... Tap.

Claims (1)

[Scope of Claims] 1. A cylindrical body that is rotated in conjunction with a machine main shaft, a spindle that is rotatably fitted into the body, and a tool grip provided on a protrusion at the front end of the spindle. , a transmission member rotatably attached to the rear end of the main body and operatively connected to the rear end of the spindle, and a torque limiter interposed between the transmission member and the main body, A spring member is provided on one of the rotating parts of the transmission member and the main body, and a flip-up member that flips up the spring member is provided on the other, and when the torque limiter is activated, the spring member and the flip-up member are intermittently activated. A tool holder with an ultrasonic vibration transmitter configured to generate ultrasonic vibrations upon collision. 2. The spring member is a band-shaped leaf spring that is loosely fitted into an annular groove or an axially extending groove formed on the outer periphery of the main body, and the flip-up member is a pin provided on the transmission member, and The tool holder with an ultrasonic vibration transmitting device according to claim 1, wherein one end is bent and engaged with the pin. 3. A floating mechanism that can be driven in the axial direction is provided between the main body and the spindle, and the transmission member is interlocked and engaged with the rear end of the spindle so as to be relatively displaceable in the axial direction. A holder with a tool equipped with an ultrasonic vibration transmitting device according to claim 1 or 2, characterized in that: