JPH02172656A - Detecting device for abnormality of cutting tool - Google Patents

Abstract

PURPOSE:To simplify structure as well without the danger of the breakdown, etc., of a drill tip by forming the structure transmitting the abnormality signal of a tool by the optical signal of the optical fiber sensor conveying the slippage of one or both parts of the rotary direction and axial direction of a tool fitted shaft. CONSTITUTION:At normal cutting time the rotating member 4 fitted to the main shaft 1 of a machine tool and a tool fitting shaft 8 are integrally rotated by their engagement. At this time, at the intermediate part of an annular member 33, a normal optical signal is transmitted to an optical signal detection circuit by fixing by inserting the optical fibers 39a, 39b and 40a, 40b opposed to the optical fibers 30a, 30b and 35a, 35b of the rotating member 4 fore and aft. Now, in case of the tool fitting shaft 8 being made free in either rotating direction or axial direction or in both directions to the rotating member 4 due to some abnormality, the optical signal becomes abnormal simultaneously. The optical signal detecting circuit having received this abnormal optical signal immediately outputs an abnormality signal, an alarm is transmitted by inputting this signal to the control part of the machine tool and the safety device stopping the main shaft 1 of the machine tool, etc., is actuated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is a tool that can be attached to a tool holder used in a machine tool such as a numerically controlled machine tool equipped with an automatic tool changer (ATC), a so-called machining center, or a turning center. The present invention relates to a tool abnormality detection device for protecting cutting tools.

[Conventional technology]

As a conventional technique, a plunger pressed by a spring is placed between the spindle of a machine tool and a drill chuck, and an engagement recess into which the tip of the plunger engages, as described in Japanese Utility Model Application Publication No. 59-132710. When the resistance applied to the drill fixed to the drill chuck reaches a certain value, the plunger disengages from the engagement recess and separates the spindle and drill chuck, allowing the drill chuck to rotate freely relative to the spindle and increasing the torque. There is one in which a switch is activated to bring the spindle to an emergency stop.

In addition, as in the idea described in Japanese Utility Model Publication No. 54-37513, the difference in rotation between the drive-side rotating body of a machine tool and the tool mounting shaft is converted into axial movement by a screw mechanism, and thereby the differential There is one that uses a transformer to extract changes in torque as an electrical signal.

Furthermore, the invention described in Japanese Patent Publication No. 63-28742,
Pressure air is supplied to one of the three air passages provided in the tool holder, and the pressure cusp inch detects when the valve body, which is moved in the axial direction by the thrust applied to the tool, switches the pressure air passage. There is something I did.

[Problems to be Solved by the Invention] The conventional devices described above have the function of detecting an abnormality in the cutting tool and letting the tool escape, or issuing an alarm and stopping the machine. If the device is equipped with a switch or differential transformer for extracting electrical signals, there is a risk of failure due to vibration or malfunction due to noise generated by other electrical devices.

Also, what switches the air circuit? ! [There is a problem in that a complicated air circuit needs to be constructed, and the rotating parts need to be kept airtight, so it takes a lot of work.

The purpose of this invention is to solve the above problem and provide a device that uses an optical fiber sensor to detect when an abnormality in torque or thrust occurs and the cutting tool is free in the rotational or axial direction. .

[Means to solve the problem]

In order to achieve the above object, the present invention provides a coupling means for freeing the tool mounting shaft relative to the rotating member in either or both of the rotational direction and the axial direction when the resistance applied to the tool mounting shaft exceeds a set value. The rotating member of the cutting tool protection device equipped with
An optical fiber sensor is provided that transmits to the optical fiber the fact that the tool mounting axis has shifted in either the rotational direction, the axial direction, or both relative to the rotating member as a change in the amount of light, and the optical signal sent from the optical fiber is It is equipped with an optical signal detection circuit that performs photoelectric conversion and generates a tool abnormality signal.

[Effect]

This invention has the above-mentioned configuration, and during normal cutting, the rotating member attached to the main shaft of the machine tool and the tool mounting shaft are integrally engaged and rotated.

At this time, a normal optical signal is being sent from the optical fiber sensor to the optical signal detection circuit.

Now, due to some abnormality, the tool mounting shaft becomes free in either the rotational direction, the axial direction, or both relative to the rotating member, and at the same time, the optical signal from the optical fiber sensor becomes abnormal.

The optical signal detection circuit that receives the above-mentioned abnormal optical signal immediately outputs an abnormal signal, which is input to the control section of the machine tool to issue an alarm and perform safety measures such as stopping the main axis of the machine tool. The device works.

〔Example〕

In the first embodiment shown in FIGS. 1 to 9, 1 is a tool holder detachably attached to the main shaft (not shown) of a machine tool such as a machining center, and 4 is a rotating member thereof.

Further, the rotating member 4 has a cylindrical shape, and a tool mounting shaft 8 is fixedly mounted inside the rotating member 4, but this tool mounting shaft is free in both the axial direction and the rotational direction with respect to the rotating member 4.

Reference numeral 11 denotes a rotational coupling means for coupling the member 4 and the tool mounting shaft 8, and this coupling means 11 includes a ball 12 and a plurality of concave spherical recesses 14 formed on the outside of the tool mounting shaft 8 to receive the balls. , a spring 15 that presses the ball 12 against the recess 14, and a spring receiver 16.

The spring receiver 16 is fitted into a radial hole provided in a large diameter portion 2 integrally formed on the outer periphery of the front end of the rotating member 4 so as to be able to move forward and backward.

Further, an outer cylinder 3 for receiving the outer end of the spring receiver 16 is also attached to the outer periphery of the large diameter portion 2.

Reference numeral 17 denotes an axial coupling means which includes a ball 18 and a circumferential groove 1 formed on the entire outer circumference of the sliding member 9 to receive the ball.
9, a spring 20 that presses the ball 18 against the circumferential groove 19, and a spring receiver 21.

The spring receiver 21 is fitted into a radial hole provided in the outer periphery of the intermediate portion of the rotating member 4 and the cylindrical body 22 on the outside thereof so as to be able to move forward and backward.

Further, an outer cylinder 23 for receiving the outer end of the spring receiver 21 is attached to the outer periphery of the cylinder body 22.

Reference numeral 5 denotes a cylindrical support member fitted on the outside of the rotating member 4.

The plurality of radial screw holes provided in the rotating member 4 include
The setscrews 6 are screwed in, and the internal balls 7 are engaged with the circumferential grooves 10 extending over the entire outer circumference of the intermediate portion of the tool mounting shaft 8 to prevent the tool mounting shaft 8 from being removed.

Further, a separate sliding member 9 is arranged at the rear of the tool mounting shaft 8, and a spring 29 is provided between the rear spring receiver 28 in the rotating member 4 and the sliding member 9. A ball 26 at the inner end of a recessed hole 25 with a protruding shaft 27 provided at the rear end of the tool mounting shaft 8
Crimp it.

The support member 5 is a non-rotating member that is detachably fixed to a non-rotating part of a machine tool, and has front and rear ball bearings 31 inside.
．． The rotating member 4 is rotatably attached via 32.

Further, an annular member 33 is provided between both ball hair rings 31 and 32, and this member 33 is fixed to the inner periphery of the member 5.

As shown in FIG. 4, light reflecting surfaces 34 and light non-reflecting surfaces 38 are alternately arranged on the outer periphery of the tool mounting shaft 8 near the rear.

In addition, the front part of the forming part of each surface 34 and 38 is shown in FIG.
As shown in FIG. 7, a light non-reflecting surface 41 is provided over the entire circumference.

Although the shapes of the above surfaces 34, 38, and 41 are changed to be reflective or non-reflective, the reflective surfaces may be white or mirror surfaces, and the non-reflective surfaces may be black or rough.

Two rows of holes are provided radially in the middle of the rotating member 4, front and rear, and two 1 m long optical fibers 30 are installed in each of the front row wells.
A, 30b are inserted and fixed, and a pair of optical fibers 35a, 35b are inserted and fixed into the rear row well holes, respectively, to constitute a thrust optical fiber sensor A and a torque optical fiber sensor B.

In the middle part of the annular member 33, a rotating member 4 is attached in the front and rear directions.
Optical fibers 39a, 39b and 40a, 40 opposite to the optical fibers 30a, 30b and 35a, 35b of
b is inserted and fixed, and optical fibers 39a, 39b and 40a, 40b extending from the annular member 33 are inserted into the front and rear holes provided in the arm 36 that is integrally formed and protrudes from an example of the non-rotating support member 5. Fix it.

The above-mentioned optical fibers 39a and 40a are connected to a light emitting element 42.43 such as a light emitting diode in the optical signal detection circuit shown in FIG. The optical fibers 39b and 40b are connected to a light receiving element 44 such as a phototransistor provided in the optical signal detection circuit.
．． 45.

A driving circuit 48.49 and an oscillation circuit 50.51 are connected to the light emitting elements 42.43 of the optical signal detection circuit, respectively, and an amplifier 52.53 is connected to the light receiving element 44.45, respectively.
and filters 54.55 and judgment circuits 56.57
Connect.

To explain the operation of the above embodiment, the rotating member 4 is fixed to the main shaft of a machine tool, a cutting tool such as a drill is attached to the tip of the tool mounting shaft 8, and the cutting tool is cut into the workpiece by rotation and advancement of the main shaft. .

In normal cutting conditions, the balls 12 and 18 are fitted into the recess 14 and the circumferential groove 19, respectively, as shown in FIGS. 2 and 3, so the rotating member 4 and tool mounting shaft 8 rotate as one unit. are doing.

In addition, in the case of such normal cutting, the optical fibers 30a, 30b, 35 of the rotating member 4 are
The ends of a and 35b face the reflective surface 34 of the tool mounting shaft 8.

On the other hand, from the oscillation circuit 50.51 to the drive circuit 48.49
A signal consisting of a pulse signal or a continuous signal is sent to the light emitting element 42, 43, and a signal as shown in FIG.
, 40a, and the light is transmitted to the optical fibers 39a, 40a.
a, 30a, and 35a to the reflective surface 34,
Each of the lights reflected by the reflecting surface 34 is connected to an optical fiber 30b.
, 35b, the optical fibers 30b, 35b pass through the optical fibers 39b, 40b, reach the light receiving element 44.45, become an electrical signal, are amplified by the amplifier 52.53, pass through the filter 54.55, and then pass through the optical fibers 39b, 40b to the light receiving element 44.45. The waveform becomes as shown in C1(d) and is input to the determination circuits 56 and 57.

In the determination circuits 56 and 57, normal input signal patterns are stored in advance, so if the input signal is normal, no abnormal signal is output from the circuits 56 and 57.

During the above-mentioned cutting process, if the tool mounting shaft 8 stops or rotates late due to large resistance acting on the cutting tool due to clogging with cutting chips, etc., the ball 12 of the coupling means 11 will be forced into the spring 15.
The ball 12 is compressed and retreats, and comes out of the recess 14, leaving the cutter free and protected. However, when the member 4 further rotates with respect to the shaft 8, the ball 12 immediately enters the next recess 14 and returns automatically.

Also, if abnormal thrust is applied to the cutting tool due to clogging of cutting chips or wear of the cutting tool's cutting edge during machining,
The tool shaft 8 moves back against the bar 229, and the ball 18
detaches from the circumferential groove 19 forward and frees the mounting shaft 8.

At the same time, the front ball 12 also leaves the recess 14.

However, since the return force of the spring 2S is always acting on the tool mounting shaft 8, the spring 29
The tool mounting shaft 8 automatically returns.

Furthermore, as described above, if the tool mounting shaft 8 is deviated in the rotational direction with respect to the rotating member 4, the optical fiber 35 as shown in FIG.
Since the light emitted from the tip of the optical fiber a hits the non-reflecting surface 38, it is not reflected, or even if it is reflected, the light does not hit the end of the optical fiber 35b, so the light receiving element 45 does not receive the optical signal.

When the tool mounting shaft 8 stops or its rotation lags behind the rotation of the rotating member 4 as described above, the signal input to the determination circuit 57 is
Since an abnormality occurs as shown in f), an abnormality signal is generated from the same circuit 57 and inputted to the control section of the machining center to stop the main shaft of the machine tool.

In some cases, the abnormality described above is minor and can be restored to normal by retracting the tool, etc. Therefore, when the machine is restarted after some time has elapsed after the machine has been stopped as described above, the machining operation continues as long as the machine has returned to normal operation.

If the condition has not returned to normal, the above-mentioned action is repeated again.

As mentioned above, at the same time as the spindle stops, an alarm such as an audible sound or a pilot lamp is activated to notify the user of an abnormal condition, thereby inspecting this part or replacing the tool or 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 spindle stops, the tool changer will operate and replace the tool with a spare tool holder, which will reduce the amount of time the manning center will be stopped due to an abnormal situation. It can be done in the shortest possible time.

As mentioned above, when the tool mounting shaft 8 is displaced only in the rotational direction with respect to the rotating member 4, a signal is input to the determination circuit 57 and an abnormal signal is issued, but the optical fibers 30a and 30b are always Since the input signal of the determination circuit 56 is opposed to the input signal 56, there is no change in the input signal of the determination circuit 56.

Furthermore, when the tool mounting shaft 8 retreats to the right as shown in FIG. 7 due to an abnormality in thrust, the optical fibers 30a and 30b will be in a state facing the non-reflective surface 41, and an abnormality signal will be issued from the determination circuit 56. However, when the tool mounting shaft 8 and the rotating member 4 are both rotating, the determination circuit 57 does not issue an abnormal signal.

The spring bearing surface on the inner circumference of each of the outer cylinders 3.23 is shaped to form part of a spiral, and the strength of the spring 15.20 is adjusted by rotating the outer cylinder 3.23 relative to the spring bearing 16.21. You should try to get it.

Figures 10 to 12 show the second embodiment,
Portions having the same configuration and function as those in the first embodiment are given the same reference numerals and explanations will be omitted.

In this embodiment, a plurality of notches are formed circumferentially at equal intervals on the outer periphery of the tool attachment shaft 8 near the rear, and a semicircularly curved optical fiber 37 is attached and fixed to each of the notches. Both ends of 37 are exposed on the outer periphery of the tool mounting shaft 8.

Further, two rows of holes in the front and rear are radially provided in the middle part of the rotating member 4, and optical fibers 46a are inserted and fixed in each of the front and rear rows of holes, respectively, to form an optical sensor C. .

Further, optical fibers 47a and 47b are inserted and fixed into the front and rear holes provided in the arm 36 from the annular member 33, respectively.

In this embodiment, the optical fiber 47b is used as the input side of light, and the optical fiber 47a is used as the output side.

In this embodiment as well, during normal operation, the
As shown, both ends of the optical fiber 37 and the optical fiber 46a
, 46b are coincident.

Therefore, optical fibers 46b, 47b and 46a, 47
When a matches as shown in the figure, the light from the optical fiber 47b enters one end of the optical fiber 37 via the optical fiber 46b, exits from the other end, enters the optical fiber 46a, passes through the optical fiber 47a, and enters the thirteenth optical fiber 37. It is input to a circuit similar to the one shown in the figure and generates a signal indicating normal rotation.

In addition, if abnormal torque or thrust is applied to the tool and the tool mounting shaft 8 is displaced in the rotational or axial direction relative to the rotating member 4, both ends of the optical fiber 37 and the optical fiber 46a
, 46b are shifted, the light from the optical fiber 47b no longer reaches the light 46a, and an abnormal signal is generated.

In the case of this embodiment, since the optical sensor C is common to torque and thrust, the abnormal signal is also common, but the first
The number of optical fibers is reduced compared to the embodiment.

〔Effect of the invention〕

As described above, this invention is capable of separating the coupling means when the rotational or axial resistance applied to the tool mounting shaft becomes abnormally large due to clogging of cutting chips or wear of the cutting edge of the drill during cutting. , the tool mounting shaft becomes free in the rotational direction with respect to the rotating member of the tool holder, and also becomes free in the axial direction.

Therefore, even if the tool mounting axis suddenly stops during cutting with fast feed, even if the main spindle continues to feed for a while due to the time lag of the emergency stop device or the inertia of each part, the tool mounting shaft will not reach the tool holder. There is no risk of breakage of the tip of the drill because it moves backwards.

Additionally, if the tool mounting shaft deviates in the rotational or axial direction relative to the rotating member, an optical sensor installed between the rotating member and the tool mounting shaft works to transmit an abnormal signal to the required part as an optical signal. Therefore, there is no need to maintain airtightness as in the air detection method, and the structure is simple, which is advantageous in terms of workmanship.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional side view of the main part showing the first embodiment of the device of the present invention, Fig. 2 is an enlarged cross-sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is an enlarged cross-sectional view taken along the line Enlarged cross section ■Figure 1 and Figure 4 are Figure 1 I
FIG. 5 is a cross-sectional view taken along line V-IV, FIG. 5 is a cross-sectional view taken along line ■-■ in FIG. FIG. 9 is an enlarged cross-sectional view showing each state of the above, FIG. 10 is a longitudinal cross-sectional side view of the main part showing the second embodiment, FIG. 11 is a cross-sectional view taken along line XI-XI in FIG.
Figure 2 is also a cross-sectional view taken along the lines shown in Figure 10 -, Figure 13 is a block diagram showing the detection circuit, and Figure 14 (al or f).
) is a waveform diagram. 1...Tool holder, 4...Rotating member, 8...Tool mounting shaft, 11.17...
...Coupling means, A, B,, C... Optical fiber sensor, D... Optical signal detection circuit. Agent Kamata Figure 1 Figure 2 Figure 3 Figure 6 Figure 8 Figure fs7 Figure 9 Figure 4 Figure 5 Figure 10 Figure 11 Figure 12

Claims (1)

[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 a tool mounting shaft, and when the resistance applied to the tool mounting shaft exceeds a set value, the tool mounting shaft is freed relative to the rotating member in either or both of the rotational direction and the axial direction. In the cutting tool protection device, the rotating member includes an optical fiber sensor that transmits to the optical fiber the fact that the tool mounting shaft has shifted relative to the rotating member in either the rotational direction, the axial direction, or both, as a change in the amount of light. An abnormality detection device for a cutting tool, comprising: an optical signal detection circuit that photoelectrically converts an optical signal sent from the optical fiber and generates an abnormality signal for the tool.