JPS5973265A - Tool holder type detector - Google Patents

Abstract

PURPOSE:In an NC machine tool, to detect a cutting force easily without influence of disturbance by arranging means for detecting displacement occurred in the structure of detecting section and a radio transmitter for transmitting the detected electrical signal in a tool holder. CONSTITUTION:The central shaft 4 of a tool holder 1 for mounting a rotary tool such as drill or end mill of small diameter is arranged at the inside of a shaft tube section 3 coupled with a shank section 2 of tool holder while the central shaft 4 and shaft tube section 3 are coupled through a supporting structure 5 of thin board flexible with component of force applied onto the central shaft 4 in detecting direction and a substantially parallel thin board detecting structure. Displacement produced in the detecting section is converted into an electrical signal by means of a converter comprising a strain gauge and transmitted by means of a radio transmitter 20 assembled in the tool holder 1 then received by a receiver 35 of a chip 37 through transmit/receive antennas 34, 36 arranged in proximity. Consequently even small variation of force of small diameter rotary tool can be detected correctly and easily without influence of disturbance.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to machine tools, especially machine tools, using rotating tools and rotating contacts (hereinafter referred to as rotating J-tools) such as small-diameter drills, taps, and mills. In order to adaptively control NC machine tools, it is necessary to accurately grasp the state of force generated during machining, the state of the tool, the method of the workpiece, the state of the shape, the state of tool approach, etc. It can be used in certain technical fields.

Taking machining using a conventional machining machine as an example, the diameter is 20 m.
Since there is a relatively large number of drilling operations of less than 1.5 ft (m) in diameter (typically pilot holes for screws), and the number of holes drilled at one time is generally large, it is important to predict breakage of rotating tools. be. However, the fluctuations in the cutting force are extremely small compared to the inertial force of the rotating system, so even if an attempt was made to detect the cutting force by measuring the current flowing through the spindle motor, sufficient detection would be impossible.

As a solution to this drawback, the present inventor's presentation of the 1μ sum 1, 1
, 978-990. This involves attaching a cutting dynamometer based on the principle described below directly to the main shaft, thereby simultaneously detecting the cutting force in the thrust and torque directions, and extracting the detected signal to the outside via wireless. result,
It is disclosed that it is possible to predict breakage of small diameter rotary tools. This cutting power cutting method prevents a decrease in the rigidity of the main shaft, which is a problem when installing a cutting dynamometer on the rotating side, and also improves the detection sensitivity. In addition, a thin plate-like detection section structure is adopted. The structure of the detection part has the advantage that when one part is fixed and a load is applied from -L to the other part, the deformation is performed in such a way that the center of gravity moves in parallel, so that the decrease in rigidity is small. Four lane gauges are attached to the substantially parallel thin plate portions of the detection structure, and among these,
The two strain gauges receive compressive strain proportional to the force, and the two pond plates receive tensile strain. These four strain gauges form a bridge and the magnitude of the force at that moment is detected by obtaining a heavy air signal via an amplifier.

Purpose of the Invention The above-described spindle mounting system still has concerns that it may not be able to function satisfactorily due to problems such as contact between the tool holder and the spindle and problems caused by the use of oil. Therefore, the present invention has been made with the aim of eliminating such inconveniences.

Structure of the Invention The structure of the present invention which achieves this object is that the central axis of the tool holder, which allows rotary tools to be reloaded, is disposed inside a shaft cylinder portion connected to the shank portion of the tool boulder. Between the central axis and the shaft cylinder part, there is a thin plate-like support structure that can bend in the direction of the saw to be detected out of the force applied to the central axis, and a thin plate-like detection part that is substantially parallel to the saw. Connected through the structure and covered. Furthermore, the displacement caused in the detection part structure is electrically transmitted.
A means for converting the electrical signal into the tool holder and a focal beam transmitting device for transmitting the electrical signal are mounted inside the tool holder, and a wireless receiving device is disposed outside.

The present invention will now be described in detail with reference to the accompanying drawings showing preferred embodiments of the present invention.

The operator's holder 1, which is located at J3 in FIG.
7 The link part 2 is the shaft cylinder part 3 connected with the J bolt 7.
and a central axis 4 disposed inside the cylindrical part 3, and the cylindrical part 3 and the central axis 4 form a support structure 5 in the form of a thin plate that can be bent in the direction of the force to be detected, which will be described in detail later. .5 and the inner end surface of the shaft cylinder part 3 and the lower end surface of the central shaft 4 (J pole [
-8, and connected to a plate-shaped detection part side 6 forming a substantially parallel and thin plate-shaped detection part structure 16. The tip 9 of the central shaft 4 is the drill bit 1! Ivy or colette? It has a shape suitable for pulling the chuck 42 for mounting a tool such as a chuck. Incidentally, the member designated by the reference numeral 10 provided in the sink 1/ink portion 2 is for being held by the claws of the automatic tool changer.

The force to be detected is I.lux or slus 1~ applied to the tool, or both. When it is desired to detect 1 Herc, the thin plate-like support structure 5 has shoulder parts 1 formed above and below the central axis 4.
1.11 Two annular bodies 12 that can be engaged and locked
As shown in Fig. 3, two elongated through holes 13°13 were bored in each annular body from the arbitrary diametrical direction J3 and from the direction perpendicular to this on the left side facing each other at a narrow interval. After forming four thin plate structure parts 14 along the axial direction in a radial manner, the parts of the annular body 12 above the horizontal grooves 15 are separated by dividing the far apart through holes 13, 13 with the horizontal grooves 15. and the portion of the annular body 12 below the horizontal groove 15 are the four radial thin plate structural portions 14 (referred to as a structure connected by a pu). . The lower part of the annular body 12 is welded to the shaft cylinder part 3.In this way, one end of the 11i-shaped thin plate structure part 14, which is close to the center ttll14, is fixed to the central shaft 4, and the end which is far from the central shaft 4 is fixed to the central shaft 4. By fixing the other end to the shaft cylinder part 3,
Torque acting on the tools is transmitted to the shaft cylinder portion 3 via the thin plate-like support structure 5 radially extending from the central shaft 4.
Displacement due to torsion will occur between the shaft and the outer shaft cylinder portion 3.

On the other hand, regarding the attachment of the plate-shaped detection member 6 to the mounting bolt 8'' C-shaft cylindrical portion 3 and central shaft 4 (not mentioned above), the detection structure 16 for detecting torque is shown in FIG. As shown, two elongated vertical through holes 17.1 are provided in the detection member 6.
7, substantially parallel 1 is formed between both end surfaces of the detection member 6 and the inner surfaces of both ends of the vertical through hole 17.
It can be obtained by forming one i9 plate-shaped part. Although the illustrated 8ij m through hole 17 has a shape in which two small 1L holes are connected by a linear groove, it may be formed by a square hole or by partially overlapping a large number of small round holes. Since elastic deformation due to torsion occurs in the detection part structure 16 at a torque of 1~1, a means 18 for converting the displacement into an electrical signal, specifically a strain gauge, is pasted at 16 locations on the structure. Measured using a bridge circuit according to the method.

When it is desired to detect the thrust 1-, the thin plate-shaped support structure 5 is constructed with a through hole 13 vertically opposed to the annular body 12, as shown in FIG.
', 13' are drilled to form four horizontally oriented thin plate structure parts 1
4′ are formed in a radial manner, through-holes 13′ are formed which face each other vertically,
13' are divided by vertical grooves 15', and the upper ends of the two opposing parts thus divided into four parts are welded to the center shaft 4, then the lower ends of the remaining two opposing parts P1 are attached to the shaft cylinder part. 3
Weld with. In this way, the thin plate-shaped support structure 5 has a different orientation of the thin plate surface depending on whether torque detection or thrust detection is performed.

The same thing is the substantially parallel and thin plate-like detection part + MT.
The same can be said about i16. For thrust detection, the 8th
As shown in the figure, two elongated horizontal through holes 1 are provided in the detection member 6.
By drilling 7' and 17' as well as two other elongated horizontal through holes 17' and 17' that intersect with these,
Forming a substantially parallel thin plate-like portion between the upper and lower surfaces of the detection member 6 and the inner surfaces of both ends of the four horizontal through holes 17';
The thrust 1- causes elastic deformation in the axial direction.

It is best to measure the displacement in the same way as for torque.

A thin plate-shaped support structure 5 that is easily deformed to the above-mentioned torque or thrust 1 and difficult to be deformed by force or torque in other directions.
However, the substantially parallel and thin plate-like detection section structure 1G for detecting the value can also be used as one of the above two parts. In addition, in order to detect torque and thrust simultaneously and separately, it is possible to overlap
It is also possible to have an integral structure.

A wireless transmitting device 20 for transmitting the electrical signal obtained by the converting means 18 is mounted inside the tool holder 1. As shown in FIG. 5, two batteries 21 are used as a power source, taking into account the balance against centrifugal force and ease of installation and removal, and are fixed at symmetrical locations on the outer periphery of the shaft cylinder portion 3. The fixed connection is attached using the mounting bolt 22 (= J-kuru protective cover 23
cover to isolate it from the outside. Attach pilots 1 to 2/l to the shaft cylinder part 3 so that you can confirm from the outside that the transmitting electric circuit is on.
, and the battery 21 (connect as shown in Figure 6. In the figure,
Two limits connected via resistor R [~switch 2
5 is a cover to prevent wasteful consumption of the battery 21, and as shown in FIGS. 1 and 5, it is constantly repelled outward by a spring 26 and its head 27 is attached to a tool holder. An operating rod 28 that can be protruded and retracted from the shank portion 2 is provided, and the head 27 of the operating rod 28 is connected to the machine tool side 1 system joint 3.
In other words, the limit switch 25 is turned on when the tool holder 1 is mounted on the machine tool, and turned off when the tool boulder 1 is removed. In the illustrated example, one operating rod 28 is divided into two parts, the front part 28a and the shaft part 28b, and the through holes 30 and 31 are provided in the bushing 29 that guides the shaft part 281) and the shaft part 28b, respectively. This is because, during assembly and disassembly, by inserting bottles (not shown) into both through holes 30 and 31, the length can be set in a shortened state. A wireless transmitter 33 electrically connected to the limit switch 25 is installed inside the switch section 2. (1) The transmitting antenna 34 is placed around the outer periphery of the sink portion 2 of the sink 17, and is hardened with a filling material to avoid damage during use. The receiving antenna 3G of the receiving device 35 that receives radio signals is also placed in the groove of ]737 and then hardened with a filler.

When transmitting wirelessly a signal emitted from the rotating shaft of a rotating machine, in order to receive as strong a signal as possible without distortion, the transmitting antenna should be placed on the rotating shaft side, and the machine body supporting the rotating shaft should be placed near the rotating shaft. The receiving antenna must be placed so as to surround the entire circumference of the area. However, in the space around the main shaft, various equipment such as a cutting board, a processing device for chips and cutting fluids, etc. are installed, so the space around the main shaft is
The space to place the ``737'' is limited to a narrow space. In the case of the fan-shaped top 37 in FIG. 2, its central angle is only about 30°. If the receiving antenna 36 can be disposed only in a very small portion around the main axis for such reasons, the impedance Za of the receiving antenna and the input impedance zb of the receiver 38 will be greatly different. ! -For example, the receiving antenna has a coil C with one turn, the wire diameter of the coil is r @ 0.5 x 10 m, the total length of the ml coil is 100 x 10-5 m, and the frequency of belief is f.
Assuming that Qx is 10'' Hertz and the magnetic impermeability μ is 1, the impedance Za of the receiving antenna is approximately 0.3Ω, whereas the input impedance Zb of the receiver is as high as 75Ω.

Although it is necessary for good reception (this must be Za → 7b), if there is a large difference as described in item 1, the signal will be attenuated and even become unreceivable. As a solution to this case, as shown in the electrical wiring diagram of FIG. 6, the impedance seen from the antenna side is Za between the receiving antenna 36 and the three coaxial cables that transmit signals to the receiver 38, Insert a bridge consisting of coil 1- and capacitor C that matches the impedance zb seen from the coaxial cable side. Such a bridge is piece 37
It is preferable to form a sealed cavity 40 in the early part of the body (see FIG. 1), and store it within that cavity 40.

The specific value of =1il L and capacitor C is ω=2π'
As, ω'1c=1 and L/C=Za −Zll, which is the solution of the simultaneous equation +−=, J”'E'M−Otsu]−/2πd and C=
1/2 πr, J? ``It can be determined from T71.'' Applying the above example to this paralysis formula and calculating the value of C, L = 0.01 x 10 Henrys and C = 400 x 10 Farads. The result of actually providing a circuit with such impedance conversion is that the distance from the transmitting antenna 34 to 1m1tll is
Even if the receiving antenna 36 is placed at a low angle, the receiver 3
8's output did not drop. It has also been confirmed that if it is obtained by the above formula or if the value of C does not exceed 5ff, it is fine.

The parts where the shank part 2 and the shaft cylinder part 3 overlap, the parts where the protective cover 23 fits into the shaft cylinder part 3, and the parts where the operating rod 28 slides are sealed with, for example, O-rings to prevent internal and external connections within the main body. Ensures isolation from the outside world and prevents oil splashes and chips from entering. If it is covered, it is possible to fill the inside with nitrogen gas, etc. .

Effects of the Invention With the present invention, no matter what kind of rotating tools are attached to the chuck 42, the tool will be placed in close proximity to the chuck 42.
3, detect the force you want to know, extract it by wireless transmission and reception, and have the advantage of being able to accurately and easily capture small force changes in any small-diameter rotary tools without being affected by disturbances. Therefore, the following uses are possible. It is already known that when tipping occurs at the cutting edge of a tool, a downward spike appears as a decrease in torque, and immediately before the drill breaks, a sharp spike in the cutting resistance value TR occurs, which is caused by the torque, It doesn't matter what kind of thrust it is, and the same thing can happen with taps and end mills. By using the tool holder type detection device of the present invention, it is possible to detect minute changes in cutting resistance, so it is possible to detect abnormalities such as chipping, wear, or breakage in the tool, and facilitate tool damage monitoring and tool replacement.

Can be used for self-diagnosis of machine tools, etc.

In addition, in various types of machining using machine tools, it is necessary to detect contact between a workpiece and a tool, and to accurately measure the inside diameter of a hole in a workpiece. By allowing the rotary tool to also function as a contact, there is no need to stop rotating the tool and replace the tool and touch sensor each time. Furthermore, you can optionally feed the tool in rapid traverse while the tool does not touch the workpiece, and switch to cutting feed the moment the tool touches the workpiece, or embed a thermocouple to compensate for the temperature. It is possible to implement

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of one embodiment of the present invention, FIG. 2 is a plan view of a part thereof, and FIG. 3 is a part of the thin plate-shaped support structure shown in FIG. 1 for easy understanding. FIG. 4 and FIG. 5 are perspective views taken along lines IV-IV and V-v in FIG. 1 and viewed in the direction of the arrows. FIG. 7 is a perspective view of a support structure showing another embodiment different from that of FIG. 3, and FIG. 8 is a sectional view showing a detection structure combined with the support structure of FIG. 7. 1...Tool holder, 2...Silent part, 3...
Axial cylinder part, 4... Central shaft, 5... Thin plate-like support structure,
16...Substantially parallel and thin plate-like detection part structure, 1
8... Means for converting the displacement generated in the detection unit structure into an electrical signal, 20... Radio transmitting device, 35... Radio receiving device. Patent Applicant: Yotabe Hatamura, Attorney, Yuki Omata, Shigeru Yudo, Estimate
Yunosuke Araki375

Claims (1)

[Claims] 1. Tool holder (1
) of the central axis (4) of the tool holder.
It is placed inside the shaft cylinder part (3) connected to the central shaft (4).
A thin plate-shaped support structure (5) that can be bent in the direction of the force that is desired to be detected out of the forces acting on the rotary tools, and a thin plate-shaped support structure (5) that is substantially parallel to the shaft cylinder part (3). A means (18) for converting the displacement generated in the detecting section IMi (1G) into an electrical signal and a wire transmission (tU) for transmitting the electrical signal are connected via the detecting section structure 16) of A tool holder type detection device characterized in that a limb (20) is self-mounted in the tool holder (1) and a wireless receiving device (35) is disposed outside. 2. The wireless transmission (Fi device) (20) is provided with an operating rod (28) which is always resiliently repelled outward and whose head (27) can be retracted and retracted from the tool holder shank portion (2) (J). The head (27) of the operating rod (28) and the T-shaped machine main body side engaging part (32) cooperate to connect the wireless transmitter (2).
0) A holder-type detection device according to item 1 which turns on and off the electric circuit of t'1. 3. The receiving device (35) includes a receiving antenna (36) originating from a part of the space around the rotating shaft of the machine tool 2, and a coaxial device that sends signals from the receiving antenna (3G) to the receiver <38>. The tool holder type detection device according to claim 1, wherein a circuit with impedance conversion, which is a bridge circuit of a capacitor and a coil, is interposed between the cables (39).