JPH02160407A - Automatic restituting method of cutting tool protection device - Google Patents

Abstract

PURPOSE:To prevent the decrease of work efficiency by releasing the restraint of a cutting tool the moment an abnormal force of torque or thrust is generated, and making the tool to perform an automatic restitution when the force vanishes in a tool holder used for a machining center, etc. CONSTITUTION:A rotary member 4 is fixed to the main shaft of a machine tool, and a cutting tool is attached to a tool mounting shaft 8 to have the cutting tool cut into a work. As balls 12, 18 are usually engaging with a recessed part 14 and a circumferential groove 19, the rotary members 4 and the tool mounting shaft 8 are integrally formed and rotating together. Although the ball 12 of a connecting means 11 compresses a spring 15 and comes off the recessed part 14 releasing the constraint of the tool mounting shaft 8 against the rotary member 4 to protect the tool when a large resistance acts on the tool while cutting work is performed, the ball 12 falls in the next recessed part 14 and automatically restitutes. Also, when an abnormal thrust acts on the cutting tool, the tool mounting shaft 8 retreats resisting a spring 29 and the ball 18 is separated from the circumferential groove 19 to liberate the mounting shaft 8, however, the tool mounting shaft 8 automatically restitutes by the spring 29 when the resistance vanishes.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to tool holders used in machine tools such as numerically controlled machine tools, so-called machining centers or turning centers, etc., equipped with an automatic tool change bag ff (ATC). Regarding an automatic return method for a device that protects an attached cutting tool, in particular, when an abnormal force is applied to the tool, the tool mounting shaft is released from the main shaft in either the rotational direction, the axial direction, or both. By automatically returning to normal condition as soon as the abnormal condition disappears, cutting work can be carried out efficiently.

[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 engaging recess and separates the spindle from the drill chuck, allowing the drill chuck to freely rotate relative to the spindle. There is one that uses a torque switch 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 switch detects when the valve body, which is moved in the axial direction by the thrust applied to the tool, switches the pressure air passage. This is what I did.

[Problem to be solved by the invention]

Conventional devices such as those described above have the ability to detect an abnormality in a cutting tool and release the tool or issue an alarm and stop the machine, but it takes time and effort to return the tool after the abnormal condition disappears. , there was a problem of decreased efficiency.

The purpose of this invention is to solve the above-mentioned problems.The moment an abnormal force such as torque or thrust is generated, the cutting tool is released from its restraint and released, the tool is protected, and then the abnormal force disappears. This provides a method for automatically returning a tool.

[Means to solve the problem]

In order to achieve the above object, the present invention includes 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 mounted, and the tool mounting shaft is integrally engaged with the tool mounting shaft until the resistance in the rotational or axial direction applied to the tool mounting shaft reaches a set value. When the rotational or axial resistance applied to the shaft exceeds a set value, the cutting tool protection device is equipped with a coupling means that frees the tool mounting shaft in the rotational and axial directions with respect to the rotating member. A plurality of recesses are formed in the circumferential direction on a part of the outer periphery, and an engager that engages and disengages from the recesses by spring pressure is provided in the rotating member, and after the engager comes off from the recess due to abnormal torque applied to the tool, This feature is characterized in that the engaging element is returned to the recessed portion again, and the tool mounting shaft and the rotating member are reconnected.

In addition, a circumferential groove is provided around the entire circumference of the member that moves forward and backward together with the tool mounting shaft, and an engager that engages and disengages from the circumferential groove by spring pressure is provided in the rotating member, and the abnormal thrust applied to the tool allows the tool to be mounted. To also provide a method of automatically returning a tool mounting shaft to its original position by an axial restoring spring when the abnormal thrust disappears after the shaft retreats and the engager comes off the circumferential groove.

〔Example〕

In the embodiment shown in FIG. 1, 1 is a tool holder detachably attached to a 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 loosely mounted inside the rotating member 4, but this tool mounting shaft is free in both the axial direction and the rotational direction relative to the rotating member 4.

Reference numeral 11 denotes a rotational coupling means for engaging the member 4 and the tool mounting shaft 8, and this coupling means 11 includes a ball 12, which is an example of an engager, and is formed on the outside of the tool mounting shaft 8 in order to receive the ball. It consists of a plurality of concave spherical recesses 14, a spring 15 that presses the ball 12 against the recesses 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 as an example of a retainer, a circumferential groove 19 formed on the entire outer circumference of the sliding member 9 to receive the ball, and a spring that presses the ball 18 against the circumferential groove 19. 20 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.

Set screws 6 are respectively screwed into a plurality of radial screw holes provided in the rotating member 4 located on the inner circumference of the support member 5, and the ball 7 at the inner end of the set screw It is engaged with the circumferential groove 10 extending around the circumference to prevent the tool mounting shaft 8 from being removed.

Further, the sliding member S is arranged at the rear of the tool mounting shaft 8, and a spring 29 is provided between the rear spring receiving portion 28 in the rotating member 4 and the sliding member 9, and the protruding shaft 27 at the tip thereof Press it onto the ball 26 at the inner end of the recessed hole 25 at the rear end of the tool mounting shaft 8.

Note that the sliding member 9 can also be formed integrally with the tool mounting shaft 8.

The support member 5 is a non-rotating member that is removably fixed to a non-rotating part of the machine tool, and is provided with an air-type detection means. Inside the non-rotating support member 5 are front and rear ball bearings 31.
The rotating member 4 is rotatably attached via 32.

Further, an annular member 33 is provided between both ball bearings 3L 32, and this member 33 is fixed to the inner periphery of the member 5.

Further, the inner circumferential surface of the member 33 is in airtight contact with the outer circumference of the communication hole 34 of the rotating member 4.

A circumferential groove communicating with the communication hole 34 is formed on the inner circumference of the annular member 33 over the entire circumference, and a communication hole 35 in the radial direction communicating with this circumferential groove is provided in the member 33.

A fluid receiving part 36 is integrally provided on one side of the non-rotating support member 5, and a communicating passage 37 communicating with the communicating hole 35 of the annular member 33 is provided in the receiving part 36, and this communicating passage 37 is not shown in the figure. It is detachably connected to an air supply path provided in the machine tool by an omitted connecting means.

Another communication path 39 is provided next to the communication path 37 provided in the fluid receiving portion 36, and the communication path 37 is used for torque detection and the communication path 39 is used for thrust detection.

In addition to the communication hole 35, the annular member 33 is also provided with a communication hole 40 communicating with the communication path 39.

Further, the exhaust hole 38 provided in the tool mounting shaft 8 is formed into an elongated hole shaped in the axial direction for torque detection, and an exhaust hole 41 is separately provided for thrust detection, and the rotating member 4 has a communication hole 42 communicating with the exhaust hole 41. However, a communicating hole 4 is provided on the inner circumference of this member 4.
A circumferential groove 43 extending over the entire circumference leading to the groove 2 is provided.

Although not shown, a compressed air source consisting of a compressor, a receiver tank, etc. is connected to the air supply path of the machine tool, and a pressure sensor is provided in a branch path in the middle of the compressed air source. This pressure sensor is like a pressure switch, and is connected to a control amplifier, from which a control signal for the machining center is transmitted.

The control amplifier is programmed to stop the machine in response to an abnormal signal, but to restart the machine after a certain amount of time has elapsed.

Further, the air supply path is provided with an IT solenoid valve, and a circuit is configured such that this solenoid valve opens under the condition that the tool holder 1 is attached to the main shaft.

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 1S, respectively, as shown in FIGS. 3 and 5, so the rotating member 4 and the tool mounting shaft 8 rotate as one unit. are doing.

In addition, in the case of normal cutting like this, as shown in Figure 1,
The communication hole 34.40 of the rotating member 4 communicates with the exhaust hole 38.41 of the tool mounting shaft 8.

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 cutter is compressed and detached from the recess 14 and rides on the mountain between the adjacent recess 14 as shown in FIG. , but against shaft 8, member 4
When the ball 12 rotates further, 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 mounting shaft 8 retreats against the spring 29, and the ball 18 disengages from the circumferential groove 19 forward as shown in FIG. 6, thereby freeing 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 29 is always acting on the tool mounting shaft 8, the spring 29
There is a function in which the tool mounting shaft 8 automatically returns.

Further, as described above, when the tool mounting shaft 8 is displaced in the rotational direction with respect to the rotating member 4, the exhaust hole 38 and the communication hole 34 are displaced, and the exhaust hole 38 is blocked.

When the exhaust hole 38 is shut off in this way, the air pressure in the air supply path rises rapidly, the pressure sensor senses this, and the signal is input to the control amplifier, which is amplified and input to the control section of the machining center. Stop the main axis of the machine tool.

If the abnormality described above is mild, it may return to normal by retracting the tool. Therefore, when the machine is restarted after a certain period of time has elapsed after the machine has been stopped as described above, the pressurization work will continue as long as the machine has returned to normal.

When the tool mounting shaft 8 is not restored normally, the tool mounting shaft 8 is still stopped or rotates slower than the rotation of the rotating member 4. Therefore, the ball 12 is removed from the recess 14 again.
As before, the restraint on the tool mounting shaft 8 is released and the cutter is released as before.

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 the control amplifier issues an output signal and the spindle stops, the tool changer will activate and replace the tool with a spare tool holder, thereby minimizing the time the machining center will stop due to an abnormal situation. Can be done.

As described above, when the tool mounting shaft 8 is displaced only in the rotational direction with respect to the rotating member 4, there is no change in pressure because the exhaust hole 41 communicates with the communication hole 42 through the circumferential groove 43.

Furthermore, when the tool mounting shaft 8 retreats to the right as shown in Fig. 6 due to an abnormality in thrust, the exhaust hole 41 is blocked and the thrust detector is activated, but since the exhaust hole 38 is elongated, ,
This exhaust hole 38 is not blocked.

Therefore, it is possible to determine whether the torque is abnormal or the thrust is abnormal.
The rotation speed and feed speed can be controlled appropriately according to each 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.

In each of the above embodiments, a pneumatic cutoff method was shown as a means of detecting an abnormality, but the opposite method is used, in other words, the exhaust path is shut off in a normal state, and the exhaust path is opened in an abnormality, and the pressure is reduced by a pressure sensor. The same thing can be done even if the abnormality is detected by detecting.

〔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.

Furthermore, in the case of this invention, the tool mounting shaft has a spring-based restorability, so if the tool mounting shaft retreats and the jammed cutting debris is naturally removed, the tool mounting shaft will return to its original position due to the spring. There is an advantage that the machine returns to normal and the cutting process can be resumed quickly.

In addition, if you have a device that detects an abnormality in the tool mounting axis and stops the machine, it is possible to automatically restart the machine after a certain period of time after the machine stops due to abnormality detection. Since the attached axis has automatically returned, machining can be resumed immediately.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional side view of essential parts showing an embodiment of the device of the present invention, Fig. 2 is a cross-sectional front view taken along the line n--n in Fig. 1, and Fig. 3 is a cross-sectional view of the
Fig. II+-[11 line enlarged cross-sectional view, Fig. 4 is an enlarged cross-sectional view of the same operating state as above, Fig. 5 is an enlarged cross-sectional view taken from Fig. 1 line n-n, Fig. 6 is the tool mounting shaft FIG. 3 is a partially cutaway longitudinal side view showing the retracted state of the vehicle. 1...Tool holder, 4...Rotating member, 8...Tool mounting shaft, 11.17...
...Coupling means, 12.18 ...Ball, 14
・・・・・・Recess, 15.20 ・・・Spring, 1
6.21... Spring holder, 19... Circumferential groove.

Claims (2)

[Claims] (1) The tool mounting shaft is rotatably mounted within a rotating member of a tool holder that is detachably mounted on the main shaft of a machine tool, and the rotational or axial resistance applied to the tool mounting shaft is set within this rotating member. The rotating member and the tool mounting shaft are integrally engaged until reaching In a cutting tool protection device that is provided with a coupling means that allows freedom in the direction, a plurality of recesses are formed in the circumferential direction on a part of the outer periphery of the tool mounting shaft, and an engager that engages and disengages from the recesses by spring pressure is provided in the rotating member. An automatic cutting tool protection device characterized in that the engaging element is disengaged from the recessed part due to abnormal torque applied to the tool, and then the engaging element is returned to the recessed part to reconnect the tool mounting shaft and the rotating member. How to return. (2) A circumferential groove is provided around the entire circumference of the member that moves forward and backward together with the tool mounting shaft, and an engager that engages and disengages from the circumferential groove by spring pressure is provided in the rotating member, so that the abnormal thrust applied to the tool causes the tool to Claim (1) characterized in that, after the attachment shaft retreats and the engagement element comes off from the circumferential groove, when the abnormal thrust disappears, the tool attachment shaft is returned to its original position by an axial restoring spring. Automatic return method for cutting tool protection device.