JPH01289646A - Abnormal tool forecasting device - Google Patents

Abstract

PURPOSE:To prevent a small diameter drill from breakage by mounting rotatably a tool mounting shaft in a rotary member of a tool holder to couple both members with each other with a magnetic coupling means within a predetermined resistance set value and release the magnetic coupling when said value is exceeded. CONSTITUTION:Ring-like drive side magnet cases 16, 17 are back and forth at intervals secured fixedly to a large diameter bore of a rotary member of a tool holder. A ring-like driven side magnet case 18 is secured fixedly to a tool mounting shaft inserted rotatably in a rotary member and disposed in an interval between the cases 16, 17 through gaps t, t'. The cases 16, 17, 18 are provided circumferentially with a plurality of holes 19, 20, 21 respectively. Permanent magnets 24, 25, 26 are embedded in every other holes and disposed such that the opposed magnetic poles are same. Thus, when fixed or more resistance is applied to the tool mounting shaft the rotation of the magnetic case 18 is delayed to disturb the balance and stopped with a communicating hole of air being closed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is an automatic tool changer! Numerical control machine tools with F (A, TC), so-called machining centers, or
The present invention relates to a device for predicting an abnormality in a tool attached to a tool holder used in a machine tool such as a turning center, and is particularly capable of predicting an abnormality in a small diameter cutting tool.

[Conventional technology]

As a conventional technique, there is an engagement in which a plunger pressed by a spring is engaged between the spindle of a machine tool and a drill chuck, and the tip of this plunger is engaged, as described in Japanese Utility Model Application Publication No. 32710. A recess is provided so that when the resistance applied to the drill fixed to the drill chuck reaches a certain value, the plunger disengages from the engaging recess and separates the spindle and drill chuck, allowing the drill chuck to rotate freely relative to the spindle. There is also a cam clutch type in which a torque switch works to bring the spindle to an emergency stop.

(Problems to be Solved by the Invention) In the case of the above-mentioned prior art, the plunger must be disengaged from the engagement recess when the tool malfunctions, but due to frictional resistance, there is a limit to the minimum value of the operating torque. When used with a small diameter drill (0.2 to 0.71 m), it is impossible to install a tool abnormality prediction device on a small diameter drill because the drill will break before the engaging part separates. It had been.

It is an object of the present invention to solve the problems of the prior art as described above and to provide a device that can detect tool abnormalities without causing breakage of the drill even in the case of a small diameter drill. .

[Means to solve the problem]

In order to achieve the above object, the present invention provides a rotating member of a tool holder that is detachably attached to the main shaft of a machine tool.
The tool mounting shaft is rotatably installed, and inside this rotating member,
The rotating member and the tool mounting shaft are connected together by magnetic force until the resistance applied to the tool mounting shaft reaches a set value, and when the resistance applied to the tool mounting shaft exceeds the set value, they are separated and the tool is connected to the rotating member. A magnetic force coupling means for freeing the mounting shaft is provided, and a detection means is provided for detecting separation of the magnetic force coupling means and emitting an abnormal signal to stop the rotation of the main shaft.

In addition, the magnetic coupling means is formed by front and rear ring-shaped drive-side magnet cases that rotate together with the rotating member, and a driven-side magnet case that is located between the re-drive side magnet cases and rotates together with the tool mounting shaft. It has a structure in which a plurality of opposing permanent magnets are provided on the case at regular intervals, and a permanent magnet on the driven side magnet case is sometimes movably attached.

[Effect]

Since this invention has the above configuration, a tool boulder with a small diameter tool such as a small diameter drill attached to the lower end of the tool mounting shaft is attached to the main shaft of a machine tool, and machining such as drilling a hole in a desired workpiece is performed by rotation of this main shaft. When machining is being performed normally, the rotating member and the tool mounting shaft are coupled by the magnetic coupling means and rotate as a unit.

However, if for some reason an abnormally large resistance acts on the tool mounting shaft, that is, if the binding force due to magnetic force is overcome,
The rotation of the tool mounting shaft lags behind the rotation of the rotating member.

As described above, when the rotation of the tool mounting shaft lags behind the rotation of the rotating member, the magnetic force coupling means separates, and at the same time the detection means operates to stop the rotation of the main shaft.

Further, when the permanent magnet attached to the driven side magnet case of the magnetic coupling means is movable, the self-excited vibration of the cutting edge during cutting is transmitted to the movable permanent magnet, causing the magnet to vibrate. When the magnet vibrates, the driven side magnet case also vibrates due to this vibration, and this is transmitted back to the cutting tool, resulting in vibration cutting.

(Embodiment) In the embodiment shown in Fig. 1, 1 is a non-rotating part of a machine tool body such as a machining center, 2 is a main shaft driven by an appropriate drive means, 3 is a tool holder, and a rotating member 4
and a non-rotating support member 5 that supports this rotating member via a ball bearing.

A tapered shank 6 that fits into the tapered hole of the main shaft 2 is provided at the upper part of the rotating member 4. The lower part of this taper shank is AT
The holding portion 7 has a circumferential groove into which the claw of the manipulator C fits, and is integrated with the rotating member 4.

Further, the rotating member 4 has a cylindrical shape, and a holding cylinder 9 is provided inside the rotating member 4.
is fixed, and a tool mounting shaft 8 is rotatably mounted in this holding cylinder S, and a cutting tool 1) such as a small diameter drill is mounted on a collet chuck 10 at the tip thereof.

A is a magnetic coupling means for coupling or separating the rotating member 4 and the tool mounting shaft 8.

The coupling means A is provided in the large diameter portion 15 at the rear of the holding cylinder 9, and is located between the front and rear ring-shaped drive-side magnet cases 16.17 and both cases 16.17, as shown in FIG. It consists of a ring-shaped driven side magnet case 18.

As shown in FIGS. 3 and 5, the drive-side magnet case 16, 17 is attached to the holding cylinder 9 by engaging the set screw 13 screwed into the screw hole of the large diameter portion 15 into the axial groove 12 on the outer periphery. The magnet case 18 is fixed to the rear end of the tool mounting shaft 8.

Further, in each magnet case 16, 17, 18, a plurality of holes 19, 20, 21 (six in the figure) are engaged in the circumferential direction with the same bifuner.

In each of the above holes 19, 20, 21 there is a permanent magnet 2
4.25.26 are embedded, and the magnetic poles S and N of each permanent magnet 24.25.26 are oriented so that opposite sides thereof have the same polarity.

Each of the above permanent magnets 24, 25, 26 has a magnet case 16.1.
Although the permanent magnet 26 is fixed by being press-fitted into each hole 19, 20, 21 of 7.18, the permanent magnet 26 may be movably attached to the hole 21 with a slight M gap.

The large diameter portion 15 is provided with a plurality of communication holes 28, and the outer periphery of the magnet case 18 is also provided with a notch 2S that connects to the communication hole 28.

Further, on the inner periphery of the rotating member 4, there are provided a circumferential groove 30 extending all the way to the communicating hole 28, and a plurality of communicating holes 31 communicating the circumferential groove 30 with the outer periphery of the rotating member 4.

A circumferential groove 32 communicating with the communication hole 31 is provided on the inner periphery of the non-rotating support member 5 located outside the rotating member 4, and this circumferential groove 32 is opened to the atmosphere through an exhaust hole 33.

Reference numeral 35 denotes an annular member fixed to the inner periphery of the non-rotating support member 5, and the inner periphery of this member 35 is in airtight contact with the outer periphery of the communication hole 36 of the rotating member 4.

A circumferential groove communicating with the communicating hole 36 is formed all around the inner circumference of the annular member 35, and a communicating hole 37 in the radial direction communicating with this circumferential groove is provided in the member 35.

A fluid receiving part 38 is integrally provided on one side of the non-rotating support member 5, and a vertical hole 40 having a predetermined depth is provided from the retaining part 39 at the upper end of this receiving part 38. The annular member 35 is connected to the m hole 37.

The lower surface of the non-rotating portion 1 is provided with an engaging recess into which the engaging portion 39 is fitted, and when the engaging portion 39 is fitted into the engaging recess, a vertical hole 40 passes through the air supply path 46 provided in the non-rotating portion 1. so that

A cap 41 is screwed into the rear part of the large diameter portion 15 to adjust the screwing depth, and a thrust adjuster screw 42 is screwed into the front part of the screw hole at the center of the cap 41. By bringing the steel pole 43 into contact with the rear end of the tool mounting shaft 8 at its tip, the magnet case 16 shown in FIG.
While adjusting the gaps t and tl between 17 and 18 equally, the steel pole 43 receives the thrust acting on the cutting tool 1).

The magnet case 17 has a cylindrical wall 22 integrally formed at the rear part of its outer periphery, and the rear end can be pushed by the front end of the cap 41.

With this structure, the case 17 can be moved forward and backward by loosening the regular screw 13 that fixes the magnet case 17, and the large diameter portion 15
The magnet case 16, 17, shown in FIG.
After adjusting the coupling torque by adjusting the gaps [, t' between 18 and 18, the magnet case 17 is fixed to the large diameter portion 15 by tightening the set screw 13.

Further, a circumferential groove and a communication hole are provided in the rear part of the large diameter portion 15, the cap 41, and the thrust adjustment screw 42, and the communication hole 36 is provided with a circumferential groove and a communication hole.
is always connected to the space 45 at the rear of the magnetic coupling means A, and the center hole of the rear magnet case 17 to the magnetic coupling means is set to have a large diameter. The center hole passes through a notch 29 in the outer periphery of the case 18 through a gap t' between the magnet cases 17 and 18.

Further, in the magnetic force coupling means A, the intermediate magnet case 18 is held at a neutral position between the front and rear magnet cases 16 and 17 by the repulsive magnetic force of the opposing permanent magnets,
At this time, the notch 29 and the communication hole 28 are completely damaged.

Although not shown, the air supply path 46 of the non-rotating part
is connected to a compressed air source consisting of a compressor, receiver tank, etc., and a pressure sensor is installed in a branch path along the way. This pressure sensor is like a pressure switch, and is connected to a control amplifier, from which the control 1) ft signal of the machining center is transmitted.

Further, a solenoid valve is provided in the supply path, and a circuit is configured such that the solenoid valve opens under the condition that the tool holder 3 is attached to the main shaft 2.

Next, to explain the operation of the above embodiment, the cylinder link 6 of the tool holder 3 is fitted into the main shaft 2 using a tool changer or the like, and when the main shaft 2 starts rotating, the cutting tool 1) attached to the tool mounting shaft 8 Machining of the workpiece begins, but while the machining is being performed normally, the magnet case 1 is closed as shown in Figure 2.
8 is balanced at the neutral position, that is, when the magnetic force coupling means A is coupled, the magnet cases 16 and 17
．． 18 rotate together, and cutting is performed using the cutting tool 1).

While cutting is being performed without any problems, the notch 29 and the communication hole 28 are aligned as shown in FIGS. 1 and 4, so compressed air from the compressed air source is supplied! 48-Vertical hole 4〇Series of through holes 37Series of through holes 36-Space 45-Notch 29Series of through holes 2
8 - Exhaust hole 33 - and is discharged to the outside air, so the air pressure in the supply path 46 is maintained at a normal value and the pressure sensor does not work.

During such cutting work, if the resistance applied to the tool mounting shaft 8 increases and exceeds a certain value due to drill wear, poor drill selection, chip clogging, etc., the balance of the magnetic coupling means A will be lost and the magnet will Since the rotation of the case 18 lags behind the rotation of the magnet cases 16 and 17, the notch 29 in FIG.
and 1) the m hole 28 is shifted and communication with the exhaust hole 33 is cut off.

When the exhaust hole 33 is shut off in this way, the air pressure in the air supply path 46 rises rapidly, the pressure sensor senses this, and the signal is sent to the control amplifier, which is amplified and sent to the control section of the machining center. The main shaft 2 is stopped manually.

As soon as the main spindle 2 stops, an alarm such as a sound or a biloft lamp is activated to notify the user of the abnormal condition, thereby allowing inspection of this part or replacement of the tool holder.

In addition, in the case of unmanned operation late at night, if an output signal is issued from the control amplifier and the main spindle stops, the automatic tool changer will interrupt the process and replace it with a spare tool or torque, so that the machining center will stop due to an abnormal situation. You can minimize the time.

FIG. 6 shows a second embodiment, in which, as in FIG. 1,
Eliminate thrust adjuster 42 and steel pole 43 +hL
, the front surface of the cap 41 presses against the cylindrical portion at the rear of the magnet case 17, but other structures and functions are the same as those shown in FIG.

Further, in the third embodiment shown in FIGS. 7 and 8, a communication hole 50 is provided that crosses the central magnet case 18 of the magnetic force coupling means A and the tool mounting shaft 8, and the notch 29 shown in FIG. 4 is eliminated. A communication hole 51 is provided in the rear large diameter portion 15 of the holding cylinder 9, and the iI communication hole 0 is communicated with the communication hole 36 through the communication hole 51.

In the case of this embodiment as well, if a certain amount of resistance is applied to the cutting tool 1) and the balance of the case 18 to the magnet coupling means is lost, 28 is shifted and the exhaust hole 33 is blocked.

The above embodiment has been described in which the exhaust hole 33 is closed when an abnormality occurs, but conversely, the exhaust hole 33 may be opened when an abnormality occurs to detect a decrease in air pressure in the air supply path 46. .

〔Effect of the invention〕

As described above, when the resistance applied to the tool mounting shaft becomes abnormally large during cutting, the coupling means separates, and the tool mounting shaft becomes free with respect to the rotating member of the tool holder, resulting in breakage of the cutting tool. However, in particular, in this invention, the rotating member on the main shaft side of the machine tool and the cutting tool mounting shaft are connected by magnetic coupling means, so the frictional resistance like the conventional rotary clutch 2 is reduced. There aren't many. Therefore, the torque during operation can be reduced, making it ideal for preventing breakage in small-diameter drills. In addition, it is smaller and lighter than cam clutch 2, can rotate at high speed, and is non-contact, so it does not change over time due to wear and is durable.

In addition, when a permanent magnet is movably attached to the driven side magnet case that constitutes the magnetic coupling means, the permanent magnet vibrates due to the automatic vibration of the cutting tool's blade edge during cutting, and this vibration is reversely transmitted to the cutting tool. The effect of vibration cutting can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical side view showing an example of the device of the present invention, FIG. 2 is an enlarged expanded cross-sectional view of an embodiment of the magnetic coupling means section cut along the circumferential direction, and FIGS. 3 to 5 are respectively 1
Figures 6 and 7 are longitudinal cross-sectional views of main parts showing other embodiments; Figure 8 is an enlarged cross-sectional view taken along lines III-III, IV-IV, and ■-V; It is a cross-sectional view taken along the −■ line. 1...Non-rotating part, 2...Main shaft,
3...Tool holder, 4...Rotating member, 8...Tool mounting shaft, 1)...
・Cutting tool, 16.17.18... Magnet case, 19.20.21... Hole, 24.25.26... Permanent magnet, 28...
...Communication hole, 29...Notch, 33...
...Exhaust hole, 46...Air supply path, A
...Magnetic coupling means.

Claims (4)

[Claims] (1) The tool mounting shaft is rotatably mounted within the rotating member of the tool holder, which is detachably mounted on the main shaft of the machine tool, and the rotating member remains in the rotating member until the resistance applied to the tool mounting shaft reaches a set value. and the tool mounting shaft are coupled together by magnetic force, and when the resistance applied to the tool mounting shaft exceeds a set value, the tool is separated and the tool mounting shaft is freed from the rotating member. Tool abnormality prediction device. (2) The tool abnormality prediction device according to claim (1), further comprising a detection means for detecting separation of the magnetic force coupling means and generating an abnormality signal such as stopping rotation of the spindle. (3) The magnetic coupling means is composed of front and rear ring-shaped drive-side magnet cases that rotate together with the rotating member, and a driven-side magnet case that is located between the two drive-side magnet cases and rotates together with the tool mounting shaft. 2. The tool abnormality prediction device according to claim 1, wherein each magnet case is provided with a plurality of reciprocally repelling permanent magnets at regular intervals. (4) The tool abnormality prediction device according to claim (3), wherein the permanent magnet of the magnet case on the driven side of the magnetic force coupling means is movably attached.