JPH0665454B2 - Tool mounting adapter with load detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tool mounting adapter with a load detector that includes a detector that detects a cutting load applied to a cutting tool.

[Prior Art] With the recent commercialization of production systems such as FMC and FMS, machine tools such as machining centers and NC lathes have come to be operated unattended, and cutting conditions for monitoring abnormalities during workpiece machining. In-process measurement is strongly desired, and measurement of cutting force and cutting force, which have a great relation to tool abnormalities, is a major issue.

Conventionally, for the measurement of cutting force and cutting resistance, strain measurement performed by incorporating a strain gauge or a crystal oscillator into a jig or the like, and measurement of a load current of a spindle motor have been attempted.

[Problems to be Solved by the Invention] However, in strain measurement, since the detector is expensive and the rigidity of the detector itself is low, it is easily damaged when an excessive force is applied. In both strain measurement and motor load current measurement, when measuring a small cutting force or cutting resistance such as a small diameter drill or tap, the detection sensitivity is low, so it is affected by noise etc. It is difficult to measure the cutting force and cutting resistance, which has been a major factor in preventing unmanned operation of machine tools.

The present invention has been made in view of the above-mentioned conventional problems, and a novel load detection capable of directly and accurately measuring a load applied to a cutting tool without changing the structure of a machine tool or a cutting tool. An object is to provide a tool attachment adapter with a tool.

[Means for Solving the Problems] In order to achieve this object, according to the present invention, a shaft 11 having a tool holder 1 attached to one end and a tool 8 attached to the other end, and a load detector 18 are sandwiched. And the spacer rings 14 and 15 that are rotatable with respect to the shaft portion 11, and the rotation that prohibits the rotation of the spacer rings 14 and 15 when the shaft portion 11 is locked by the spacer rings 14 and 15 and rotates. Locking member 20
And thrust bearings 12, 13 each of which is rotatably attached together with the shaft portion 11 and the other one rotatably holds the spacer rings 14, 15 together, and the load detector 18 further includes , Electrode layers 22a, 2 on both sides of the piezoelectric material layer 21.
The shaft portion 11 is formed at the center of the circular film sheet forming 2b.
Is formed in an annular shape by forming a through hole for penetrating.

According to the present invention, the load detector 18 is divided into four in the circumferential direction of the shaft portion 11 so that the respective division detection portions 18a to 18d are arranged with the shaft portion 11 as a center and the division detection orthogonal to the shaft portion 11 is performed. Part 18a
It is characterized in that the load in the XY directions is detected by each detection signal of ~ 18d.

[Operation] In such a tool attachment adapter with a load detector of the present invention, since a film sheet-shaped piezoelectric sensor is used as a detector, the thickness is as thin as about 0.2 mm and is lightweight. By incorporating a detector in the adapter, the cutting load applied to the cutting tool can be directly detected.

In addition, the film sheet type piezoelectric sensor can detect thrust load in a wide range from 1 Kgf to 1000 Kgf by switching the external circuit, and has a high disassembling capacity of about 100 gf, and even a small diameter drill or tap can be added to the tool The cutting load can be detected accurately.

Further, since the film sheet piezoelectric sensor has a small film thickness, the deformation amount (compressive strain) is very small even when subjected to a cutting load, and does not affect the processing accuracy.

Furthermore, since the piezoelectric constant (charge generation amount per unit force) that determines the sensitivity of the piezoelectric sensor is constant regardless of the size of the area that receives the load, increasing the area reduces the load per unit area. And high rigidity can be obtained.

Further, in the present invention, since the tool holder 1 is attached to one end of the shaft portion 11 and the tool 8 is attached to the other end, the machine tool on the tool holder 1 side and the tool 8 are attached. The load applied to the tool 8 can be directly and accurately measured without changing the structure.

[Embodiment] FIG. 1 is an explanatory view showing an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a tool holder having a taper shaft portion 2 formed on a spindle mounting side and a flange 4 having a flange groove 3 formed on a tip side thereof. A tool mounting hole 5 shown by a broken line is formed. The tool holder 1 has a size and shape according to, for example, the MAS standard, and can be attached and detached as a standard product to the spindle of all machine tools.

Following the tool holder 1 is an adapter 6 provided with a detector for detecting the cutting load. The adapter 6 has a mounting shaft 7 that is mounted on the tool mounting hole 5 of the tool holder 1 at the top.
, And a chuck 9 for attaching a drill 8 as a cutting tool is fixed to the lower part. The adapter 6 may be formed integrally with the chuck 9, but in order to use the adapter 6 as a standard product for all cutting tools, a tool attachment member such as the chuck 9 is detachably provided on the adapter 6. Is desirable. Of course, the chuck 9 is not provided for the adapter 6, and the drill 8 is directly used.
It is also possible to attach a cutting tool such as.

The adapter 6 mounted with the mounting shaft 7 in the tool mounting hole 5 of the tool holder 1 has a flange 10 and a shaft portion 11 having a smaller diameter than the flange 10. The flange 10, the shaft portion 11, and the flange 4 of the tool holder 1 To form the bearing part.

A pair of thrust bearings 12, 13 are assembled in the axial direction in the bearing portion formed by mounting the adapter 6 on the tool holder 1, that is, the shaft portion 11 between the flange 4 of the tool holder 1 and the flange 10 of the adapter 6. A detector 18 using a film sheet type piezoelectric sensor is mounted in a sandwiched state between the thrust bearings 12 and 13 with spacer rings 14 and 15 and a washer ring 16 interposed.

Further, a rotation locking member 20 is mounted on the outer circumference of the spacer rings 14 and 15 for sandwiching and fixing the detector 18 via the washer ring 16 between the thrust bearings 12 and 13.
However, the rotation locking member 20 is connected so as to be displaceable in the axial direction, although it restricts the movement of the spacer rings 14 and 15 in the rotation direction.

FIG. 2 is an enlarged explanatory view of the mounting structure of the detector 18 in the adapter 6 of FIG.

As is apparent from FIG. 2, when the adapter 6 is attached to the tool holder 1, the shaft portion 11 formed between the flanges 4 and 10 is formed.
A spacer ring 1 between the thrust bearings 12,13
4 and 15 are incorporated, and the detector 18 is incorporated between the spacer rings 14 and 15 with the washer ring 16 interposed therebetween. 16 washer ring between spacer rings 14 and 15
On both sides of the detector 18 sandwiched by the O-rings 19a,
19b is provided to seal the detector 18.

In such a built-in structure of the detector 18 with respect to the adapter 6, even if the tool holder 1 and the adapter 6 are rotated by the spindle of the machine tool, the spacer rings 14 and 15 sandwiching the detector 18 are shown in FIG. Rotation locking member 2 as shown
The rotation is stopped by 0, and the detector 18 does not rotate.

On the other hand, the cutting load at the time of cutting by the drill 8 attached to the tip of the adapter 6 is applied in the axial direction of the adapter 6, and this cutting load is applied to the flange 10 of the adapter 6 and the tool holder 1.
The thrust bearings 12 and 13, the spacer rings 14 and 15 and the washer ring 16 between the thrust bearings 12 and 13, and the detector 18 which is sandwiched therebetween.

FIG. 3 is a sectional view showing the detector 18 incorporated in the adapter 6 shown in FIGS. 1 and 2, and FIG.

In FIG. 3, the detector 18 has a piezoelectric material layer 21 in the center, electrode layers 22a and 22b are formed on both sides of the piezoelectric material layer 21, and insulating sheets 23a and 23b are provided outside the electrode layers 22a and 22b. It is fixed by an adhesive or the like, and lead wires 24a, 24b are drawn out from the electrode layers 22a, 22b, respectively.

The detector 18 having such a structure constitutes a film sheet type piezoelectric sensor (piezoelectric film) by the piezoelectric material layer 21 and the electrode layers 22a and 22b formed on both sides, and when a load is applied from both sides, A signal charge is generated according to the load.

The thickness of the film sheet piezoelectric sensor composed of the piezoelectric material layer 21 and the electrode layers 22a and 22b is about 0.2 mm, and the piezoelectric constant (amount of electric charge generated per unit force) that determines the detection sensitivity is It is constant regardless of size. Therefore, by increasing the area of the piezoelectric sensor, the load applied per unit area can be reduced, and the rigidity of the piezoelectric sensor can be increased without lowering the sensitivity. Further, a piezoelectric sensor having a thickness of about 0.2 mm has a very small amount of deformation due to force even if the Young's modulus is small, and as shown in FIG. 1, the flange 4 of the tool holder 1 and the flange 10 of the adapter 6 are Even if it is sandwiched between the thrust bearings 12 and 13, there is no problem with the influence of the deformation strain of the piezoelectric sensor on the processing accuracy.

Further, the load detection signal is taken out from the detector 18 using the piezoelectric sensor by using a charge amplification circuit (charge amplifier). As is well known, the charge detection circuit is connected with a piezoelectric sensor as an input capacitance, and therefore outputs a signal voltage according to the amount of generated charge according to the load on the piezoelectric sensor. Further, since the detector 18 receives a predetermined initial load in the state of being incorporated in the adapter 6 as shown in FIG. 1, the feedback capacitor provided in the charge detection circuit is discharged prior to load detection during cutting. By resetting, the load is detected after the zero point adjustment.

According to the detector 18 using such a piezoelectric sensor, the load can be detected over a wide range from 1 Kgf to 1000 Kgf by switching the capacitance of the feedback capacitor provided in the charge amplification circuit (charge amplifier). Yes, and 100gf
A high degree of resolution can be obtained.

Next, the operation of the above embodiment will be described.

When the tool holder device of the present invention shown in FIG. 1 is mounted on a spindle of a machine tool and cutting of a workpiece is started by a drill 8 mounted on a chuck 9 via an adapter 6, the spindle head or the work table moves at a constant speed. Processing is sent.

At this time, a cutting load in the axial direction is applied to the drill 8 according to the cutting resistance, and the cutting load of the drill 8 is between the flange 10 of the adapter 6 and the flange 4 of the tool holder 1 and the thrust bearings 12, 13 and the spacer ring. 14, 15 and the cutting load in the axial direction from the charge amplification circuit (charge amplifier) that acts on the detector 18 sandwiched via the washer ring 16 and inputs and connects the lead wires 24a and 24b of the detector 18. A signal voltage corresponding to is obtained.

For this reason, when the cutting resistance increases due to the wear of the blade of the drill 8 or the drill 8 is broken, a detection signal of an abnormal cutting load is obtained. Corresponding measures can be taken.
Furthermore, since the detection output of the cutting load by the detector 18 has sufficient resolution, a reference pattern of a predetermined cutting load is determined according to the processing progress state, and feedback is provided so that the actual cutting load follows this reference pattern. Control can also be performed.

FIG. 5 is an explanatory view showing another embodiment of the detector mounted on the adapter 6 of FIG. 1, and in this embodiment,
The detector sandwiched between the spacer rings 14 and 15 via the washer ring 16 is divided into four around the shaft circumference, and the detector 18a,
It is characterized by being 18b, 18c, 18d.

If the X and Y coordinates orthogonal to the axial direction are set as shown in the figure, the detectors 18a and 18b are arranged in the Y axis direction with respect to the center, and the detectors 18c and 18d are arranged in the X axis direction with respect to the center. To be done.

By dividing the detector into the detectors 18a to 18d in this manner, not only the load in the axial direction, that is, the Z-axis direction, but also the loads in the Y-axis direction and the X-axis direction can be detected.

That is, the load in the Z-axis direction can be detected by obtaining the sum or average of the detection signals of the detectors 18a to 18d, and the detectors 18a and 1
The load in the axial direction can be detected by taking the difference between the detection signals of 8b, and X by taking the difference between the detection signals of detectors 18c and 18d.
Axial load can be detected.

As described above, according to the present invention, since the film sheet piezoelectric sensor is used as the detector for detecting the cutting load (thrust load) applied to the tool, the piezoelectric sensor is extremely thin. Moreover, since it is lightweight, it is possible to directly detect the cutting load applied to the cutting tool by incorporating a detector in the adapter.

In addition, the film sheet type piezoelectric sensor can detect loads in a wide range from 1 Kgf to 1000 Kgf by adding an external circuit and has a high resolution of 100 gf, so it is not only heavy cutting but also a small diameter drill or tap. However, the cutting load applied to the tool can be accurately detected.

Further, since the film sheet type piezoelectric sensor has a small film thickness, the amount of deformation (compressive strain) is very small even when subjected to a cutting load, and even if the tool holder device for mounting the tool on the spindle is provided with the piezoelectric sensor. It does not affect the processing accuracy.

Furthermore, since the piezoelectric constant (the amount of electric charge generated per unit force) that determines the sensitivity of the piezoelectric sensor is constant regardless of the size of the area that receives the load, increasing the sensor area reduces the load per terminal area. High rigidity can be obtained against cutting load.

Further, in the present invention, since the tool holder 1 is attached to one end of the shaft portion 11 and the tool 8 is attached to the other end, the machine tool on the tool holder 1 side and the tool 8 are attached. The load applied to the tool 8 can be directly and accurately measured without changing the structure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing an embodiment of the present invention; FIG. 2 is an enlarged explanatory view showing a detector mounting portion of FIG. 1 taken out; FIG. 4 is a plan view in which the detector of FIG. 3 is partially broken; FIG. 5 is an explanatory view showing another embodiment of the detector used in the present invention. is there. 1: Tool holder 2: Tapered shaft part 3: Flange groove 4, 10: Flange 5: Mounting hole 6: Adapter 7: Mounting shaft 8: Drill 9: Chuck 11: Shaft part 12, 13: Thrust bearing 14, 15: Spacer Link 16: Washer ring 18: Detector (Film sheet piezoelectric sensor) 19a, 19b: O-ring 20: Rotation locking member 21: Piezoelectric material layer 22a, 22b: Electrode layer 23a, 23b: Insulation sheet 24a, 24b: Lead

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kihachiro Toho 150 Nikamicho, Takaoka-shi, Toyama Prefecture Central Research Institute, Toyama Prefectural Industrial Technology Center (72) Inventor Masahiro Kakuzaki 25-4 Tomodawari, Iino, Toyama, Toyama Prefecture Toyama Prefectural Industrial Technology Center, Toyama Research Institute (56) Reference JP-A 1-222851 (JP, A) JP-A-49-86067 (JP, A) JP-A-60-34295 (JP, A) Actual development Sho-58- 136208 (JP, U)

Claims (2)

[Claims] 1. A shaft ring 11 having a tool holder 1 attached to one end thereof and a tool 8 attached to the other end thereof, and a spacer ring 14 sandwiching a load detector 18 and rotatable with respect to the shaft portion 11. 15 and a rotation locking member 20 that is locked to the spacer rings 14 and 15 to prevent the rotation of the spacer rings 14 and 15 when the shaft 11 rotates, and one of them is rotatable together with the shaft 11. And thrust bearings 12 and 13 each of which is rotatably sandwiched between the spacer rings 14 and 15, and the load detector 18 further includes electrode layers on both sides of the piezoelectric material layer 21.
An adapter for mounting a tool with a load detector, which is formed in an annular shape by forming a through hole through which the shaft portion 11 penetrates in the center of a circular film sheet on which 22a and 22b are formed. 2. The load detector 18 is divided into four in the circumferential direction of the shaft portion 11, and the respective division detection portions 18a to 18d are arranged with the shaft portion 11 as the center, and the division detection orthogonal to the shaft portion 11 is performed. Part 18a-1
A tool mounting adapter with a load detector, which detects the load in the XY directions by each 8d detection signal.