KR20130140735A - Machining apparatus - Google Patents

Abstract

The insulated electrode member 17e is disposed close to the pressure receiving portion 16a of the rotor shaft 16 to form a capacitor C between the pressure receiving portion 16a and the electrode member 17e. When a current is supplied from the inverter power supply 20 to the stator 19b, an axial voltage is induced in the rotor shaft 16, and this axial voltage is also induced in the electrode member 17e via the capacitor C, The detection device 29 which detects the storage voltage is connected to the electrode member 17e. When the spindle 29 descends, and the tip of the drill 5 contacts the workpiece in the grounded state, the detection device 29 cannot detect the axial voltage detected so far. Output to 30). When the detection signal is input, the NC device 30 determines that the drill 5 is in contact with the workpiece, and processes the drill 5 to drill a hole from the position to a predetermined depth.

Description

MACHINING APPARATUS

TECHNICAL FIELD This invention relates to the processing apparatus which processes a to-be-processed object, such as a printed circuit board, for example. Specifically, It is related with the sensor structure which detects the contact of a tool and a to-be-processed object.

Generally, the printed circuit board perforator which rotates a rotor shaft by a motor and drills a hole in a printed circuit board (workpiece) by the drill provided in the front-end | tip of this rotor shaft is known. Such a printed board perforator drills a plurality of through holes (through holes) or blind holes (holes with a bottom) to the printed board for connecting between circuits formed in different layers. In recent years, the printed board has become thinner. At the same time, as the multilayering progresses, more processing precision is required.

In more detail, since the said printed board perforator processes a hole by the predetermined depth from the position which the tip of the drill reached in the surface of a printed board, in order to improve the processing precision, the tip of a drill must be exactly It is important to detect that the surface has been reached. Therefore, it is conventionally designed to connect a comparator to a press foot while placing a printed board on an insulated state on a work table and detecting a predetermined voltage within an axial voltage induced in the rotor shaft (patent) See Document 1).

When the printed circuit board punching machine of the said patent document 1 punches a hole in a printed circuit board, first, it supplies an alternating voltage from an inverter power supply to a stator coil, rotates a rotor shaft, and rotates a holder in the state which the said rotor shaft is rotating. Lower When the holder begins to descend, the bush of the press foot first contacts the surface of the printed board. Thereafter, when the air cylinder contracts, only the spindle descends while the press foot is in contact with the printed board, and the tip of the drill reaches the surface of the printed board. When the drill contacts the printed board, the axial voltage is output to the comparator through the copper foil on the surface of the printed board and the bush of the press foot. Then, the NC device receives a detection signal indicating that a predetermined voltage is detected from the comparator, so that the printed circuit board punching machine detects that the drill has reached the surface of the printed board.

Japanese Patent Publication No. 4184575

In this way, by using the axial voltage induced in the rotor shaft based on the supply of the alternating current voltage to the stator coil, it is possible to detect that the drill and the printed circuit board are exactly in contact with each other. In general, however, the workpiece is placed on the processing table in a fixed state by a metal reference pin, clamp, or the like, and thus, the workpiece is in a frame-earthed state. Since the axial voltage applied to the rotor shaft is detected through the bush of the foot, it is necessary to insulate the printed board from the machining table, and the above-described metallic pins and the like cannot be used, and an insulating material (for example, ceramic) It was necessary to write a pin consisting of. In addition, the bush of the press foot to which the comparator was connected was formed of a conductive material, and the holder holding the bush had to be formed of an insulating material.

Therefore, an object of the present invention is to provide a processing apparatus that can accurately detect the contact between the workpiece surface and the tip of the drill without using an insulated voltage without insulating the workpiece from the machining table.

According to the present invention, a tool for processing a workpiece is attached to a tip, and a rotor shaft rotatably supported in an insulated state, a rotor provided on the rotor shaft, and a motor are formed together with the rotor. And a work table for supplying an alternating voltage to a coil for generating a rotating magnetic field installed in these stators or rotors, and a work table for placing the workpiece in an earthed state. A processing apparatus for processing a workpiece by rotating the rotor shaft by

An electrode member disposed close to the rotor shaft in an insulated state and forming a capacitor between the rotor shaft;

A detection device connected to the electrode member and configured to detect a voltage induced in the rotor shaft by supplying an AC voltage to the coil;

When the voltage detected by the detection device is no longer detected, provided with a control unit for determining that the tip of the tool is in contact with the workpiece

.

Accordingly, a capacitor is formed between the rotor shaft and the electrode member disposed close to the rotor shaft in an insulated state, and a voltage induced in the rotating rotor shaft during machining by connecting a detection device to the electrode member. The (axial voltage) can be detected without passing through the workpiece. Thereby, the workpiece can be easily fixed to the machining table by a metal pin or the like, and the contact between the tool and the workpiece can be detected with high accuracy based on the fact that the axial voltage is not detected by the detection device. .

In addition, specifically, the rotor shaft is rotatably supported by an air bearing,

It is preferable to form the electrode member by insulating the upper end portion of the air bearing with an insulating member.

Accordingly, by supporting the rotor shaft by the air bearing, the rotor shaft can be rotated at high rotation with little frictional loss, and can be supported in an insulated state without contact with the air bearing. In addition, by insulating the upper end of the air bearing with an insulating member to form an electrode member, the axial voltage can be detected without changing the basic structure of the processing apparatus, and the parts can be shared.

1 is a front view of a processing apparatus according to an embodiment of the present invention.
It is a schematic diagram which shows the workpiece fixation method of the machining table which concerns on embodiment of this invention.
It is a schematic diagram which shows the touch sensor structure of the processing apparatus which concerns on embodiment of this invention.

[Schematic Configuration of Processing Device]

EMBODIMENT OF THE INVENTION Hereinafter, embodiment which concerns on this invention is described. As shown in FIG. 1, the printed circuit board perforator 1 as a processing apparatus which processes a to-be-processed object has the processing table 3 which mounts the printed board 2 as a to-be-processed object, and the drill 5 (tool) at the front-end | tip. And a spindle 6 to hold the spindle 6 and a tip of the spindle 6 to contact the printed board 2 prior to the drill 5 to press the printed board 2 to the machining table 3. It has a press foot 7. The printed circuit board 2 is formed by alternately stacking an insulating layer and an electric circuit, and is attached to a copper foil 2a for forming a circuit pattern on the surface thereof, and as shown in FIG. 2, two reference pins. It is fixed to the processing table by (9a, 9b). Specifically, on the surface of the processing table 3, a rectangular groove 10 and a groove 11 having one side formed in a V shape are formed, and one reference pin 9a is formed as a rectangular groove ( 10 is inserted into and fixed by the clamp plate 12 (the state of the dashed-dotted line in FIG. 2), the movement of the printed board 2 in the Y-axis direction is regulated. In addition, the other reference pin 9b is inserted into the V-shaped groove 11 on one side thereof, and the reference pin 9b is fixed to the V-shaped portion 11a by the clamp plate 13 to thereby print. Movement of the substrate 2 in the X-axis direction is regulated.

On the other hand, as shown in FIG. 1, the spindle 6 disposed so as to face the machining table 3 has a cylindrical main body 15 and a drill 5 for processing the printed board 2 at its tip. ) Is provided with a rotor shaft (16) to which it is attached, an air bearing (17) rotatably supporting the rotor shaft (16), and a motor (19) for rotating the rotor shaft (16). The air bearing 17 supports the rotor shaft 16 in the radial direction by the radial air bearing 17a in the up-down direction by the thrust air bearing 17b. The radial air bearing 17a is composed of a plurality of ejection openings that eject compressed air from the body portion 17c of the air bearing toward the rotor shaft 16 in the radial direction, and the thrust air bearing 17b Compression from top and bottom to the hydraulic pressure section 16a by the gap 17d of the air bearing main body section 17c into which the ring-shaped hydraulic pressure section 16a provided in the upper end of the rotor shaft 16 is inserted. It is comprised by the some blowing port which blows out air.

The motor 19 includes a rotor 19a (a rotor) in which a copper material is formed in a short-circuit ring shape at the center of the rotor shaft 16, and the spindle body 15 It consists of the stator 19b (stator) provided in the position which opposes the rotor 19a, and when an alternating voltage is supplied from the inverter power supply 20 to the coil 19c of the stator 19b, it will change a magnetic field (rotating magnetic field). Is generated to rotate the rotor 19a (rotor shaft 16). For reference, the inverter power supply 20 converts the commercial AC voltage input from the three-phase power supply 21 into an AC voltage with a high frequency.

The main body 15 of the spindle 6 is fixed to the saddle 23 which is movable in the vertical direction (Z-axis direction) with respect to the cross slide 22, and the cross slide 22 is a working table ( It is supported by the cross rail (not shown) provided in the bed 25 so that it may cross 3) so that a movement to a left-right direction (Y-axis direction) is possible. In addition, the processing table 3 is provided on the bed 25 so as to be movable in a direction orthogonal to the cross slide 22 (the X-axis direction), and the printed circuit board puncher 1 includes the spindle 6. Is moved in the Y-axis direction by the cross slide 22, and the machining position is positioned by moving the machining table 3 in the X-axis direction. When the machining position is positioned, the spindle is lowered by the saddle 23 to drill a hole in the printed board. For reference, when the saddle 23 is lowered in the Z-axis direction, the bush 7a of the press foot 7 comes into contact with the printed board 2 before the drill 5, and the press foot 7 is a pair. It is supported by the air cylinder 26, and this air cylinder 26 is comprised by the spindle 6 so that relative movement is possible.

[Configuration of Touch Sensor]

Next, a sensor structure 31 (hereinafter referred to as a touch sensor) for detecting that the drill 5 has reached the surface of the printed board 2 will be described based on FIGS. 1 and 3. As for the main-body part 17c of the air bearing 17 by which the said injection ports 17a and 17b are drilled, the upper end part 17e is the main body part 15 of the spindle 6 and the air bearing by the insulating member 27. It is fixed in the insulated state with respect to the lower part 17f of (17). The upper end portion 17e forms a gap between the lower portion 17f of the air bearing which is the main body portion 17c of the air bearing 17 on the lower side thereof, and the hydraulic pressure portion 16a of the rotor shaft 16. The gap portion 17d is formed, and an electrode member having a high earth resistance is formed, and the capacitor C is formed between the water pressure portion 16a of the rotor shaft 16.

The rotor shaft 16 is rotatably supported by the air bearing 17 in a floating state from the surroundings. That is, although the rotor shaft 16 is electrically supported in the insulated state with respect to the circumference (the main body part 15 of the spindle, the air bearing 17), the inverter power supply (the power source) (the coil 19c of the stator 19b) is supported. When a three-phase AC voltage is supplied from 20, a so-called zero-phase voltage is generated, and this zero-phase voltage causes the coil 19c and the frame (for example, the lower portion of the air bearing 17) of the motor 19 to flow. (17f)) and an induced voltage (V ₀ ; hereinafter referred to as an axial voltage) are induced to the rotor 19a through the stray capacitance between the rotor 19a (a few V). When the axial voltage V ₀ is induced, a voltage is also induced to the electrode member 17e which forms a capacitor between the rotor shaft 16, and the axial voltage V0 is applied to the electrode member 17e. The detection apparatus 29 which detects the is connected.

By the way, the reference pins 9a and 9b fixing the printed board 2 are made of metal such as iron, and the processing table 3 is made of metal such as steel, and the printed board 2 has its surface. The copper foil 2a of is grounded to the case ground (earth) via the reference pins 9a and 9b. Therefore, when the tip of the drill 5 contacts the surface of the printed board 2, the potential of the rotor shaft 16 becomes zero, so that no voltage is induced in the electrode member. The detection device 29 is connected to an NC device 30 (control unit) that controls a printed board perforator, detects an axial voltage V ₀ , and simultaneously drills 5 to the surface of the printed board 2. When the axial voltage V ₀ that has been reached and detected is not detected, it is configured to output a detection signal to the NC device 30. The NC device 30 judges that the tip of the drill 5 has reached the surface of the printed board 2 based on the detection signal from the detection device 29, and determines the spindle position at that time. Let it be a reference position (zero point position).

The touch sensor 31 is comprised by these rotor shaft 16, the electrode member 17e, the detection apparatus 29, and the NC apparatus 30, and is between the rotor shaft 16 and the electrode member 17e. By forming the capacitor C at, the axial voltage V ₀ induced in the rotating rotor shaft 16 can be detected without passing through another member (for example, a printed circuit board). Since the contact between the tip of the drill 5 and the surface of the printed board 2 is detected in accordance with the change of V ₀ ), the position of the tip of the drill 5 can be known accurately.

In addition, the movement range of the spindle 6 in the up-down direction (Z-axis direction) is regulated, and the NC device 30 has a predetermined time, for example, the spindle (after starting to lower the spindle 6). It is determined that the drill 5 is broken when the detection signal is not input from the detection device 29 even if 6) elapses from the upper end position to the surface of the printed board 2.

Next, the effect | action of the printed circuit board punching apparatus 1 which concerns on embodiment of this invention is demonstrated. When the worker drills the printed circuit board 2, the operator first places the printed board 2 on the work table 3 and prints the reference pins 9a and 9b made of a conductive material such as iron. The substrate 2 is fixed to the machining table 3.

When the printed circuit board 2 is placed on the processing table 3, the inverter power supply 20 is operated to supply an alternating voltage to the coil 19c of the stator 19b, and to rotate the rotor shaft 16. When an alternating voltage is supplied to the coil 19c of the stator 19b, the axial voltage V ₀ is induced to the rotor shaft 16, and this axial voltage V ₀ is detected by the capacitor C through the detection device ( 29).

Then, the NC device 30 moves the machining table 3 and the cross slide 22 to position the machining position when the preparation is ready. When the drill 5 is positioned above the machining position, the saddle 23 is moved. Lower it. When the saddle 23 descends, both the press foot 7 and the spindle 6 start to descend, and first, the press foot 7 presses the printed board 2 onto the machining table 3.

If the saddle 23 is further lowered from this state, the air cylinder 26 is contracted, and only the spindle is lowered from the state in which the press foot 7 is in contact with the printed board 2, so that the tip of the drill 5 is lowered. The surface of the printed board 2 is reached. When the tip of the drill 5 is in contact with the surface of the printed board 2, the potential of the rotor shaft 16 becomes 0, and the detection device 29 also cannot detect the axial voltage V ₀ . When the axial voltage V ₀ can not be detected, the detection device 29 outputs a detection signal to the NC device 30, and when this detection signal is input, the NC device 30 is connected to the drill 5. It is judged that the front end has reached the surface of the printed circuit board 2, and the position of the spindle 6 at that time is made into the reference position of a process. Then, the spindle 6 is lowered by the desired distance programmed in advance from this reference position to drill a hole in the printed board 2.

As described above, according to the present embodiment, the electrode member 17e insulated from the periphery is disposed close to the rotor shaft 16 to form the capacitor C, whereby the axial voltage induced in the rotating rotor shaft 16 ( V ₀ ) can be detected without passing through other members. In particular, the rotor shaft 16 is formed by the air bearing 17, and a part of the air bearing 17 (in the present embodiment, the upper end constituting the thrust air bearing 17b) is used as the electrode member 17e. As the clearance 17d with the rotor shaft 16 is made smaller, the performance of the air bearing and the detection performance of the axial voltage V ₀ are also improved.

In addition, since there is no need to change the basic structure of the processing apparatus, the parts can be shared with other processing apparatuses, the structure is simple, and there is no need to prepare a special voltage source for detecting the drill. In addition, since it is not necessary to insulate the printed board 2, the pin of the metal can fix the printed board 2 to the processing table 3, and the insulation of the printed board 2 is insufficient. There is no fear that the machining precision will decrease.

Note that, in this embodiment, the detection device 29, can not be detected, and detecting the shaft voltage (V ₀₎ which is finally had to output a detection signal to the NC unit 30, the shaft voltage (V ₀ ) Is detected, the detection signal is output to the NC device 30. When the detection signal is no longer output, the NC device 30 may determine that the drill 5 is in contact with the printed board 2. That is, if it detects that the detection apparatus was unable to detect the axial voltage V ₀ , the output method of the detection signal may be performed. In addition, the detection apparatus 29 may detect the predetermined voltage of the axial voltage V ₀ through a filter.

In addition, if the electrode member 17e is arrange | positioned close to a rotor shaft, it may be provided anywhere and does not necessarily need to be integral with the air bearing 17. As shown in FIG. In addition, the electrode member 17e may not be attached to the spindle via an insulating member such as ceramic, as in the present embodiment, but may be insulated by coating the whole with an insulating member. In addition, the rotor shaft 16 may be rotatably supported in an insulated state by a ceramic bearing or the like.

In addition, the printed circuit board 2 may be fixed to the processing table 3 not only by metal pins but also by metal clamps and the like. In addition, although the punching machine of the printed circuit board 2 was demonstrated in this embodiment, what kind of thing may be sufficient as it is a processing apparatus which processes the to-be-processed workpiece at least, and the tool which processes a to-be-processed workpiece is not limited to a drill. Instead, other tools such as end mills may be used.

For reference, in the present embodiment, an induction motor for supplying and driving a three-phase inverter output to a coil for generating a rotating magnetic field installed in the stator has shown an example of an axial voltage induced in the rotor shaft with a zero-phase voltage. The same applies to a magnet synchronous motor using a permanent magnet or an electromagnet, and an alternating voltage (direction of current flowing through a coil) using a brush or the like in an armature coil installed in the rotor. The present invention is effective because the axial voltage is induced in the rotor shaft through the stray capacitance between the armature coil and the rotor shaft even in a direct current motor or the like which supplies and drives the same).

Industrial availability

This invention relates to the processing apparatus which processes a to-be-processed object by rotating a tool with a motor, For example, it can be used for the processing apparatus which processes using a tool, such as a drill and an end mill, on a printed board.

1: processing device (printed substrate punching machine)
2: workpiece (printed substrate)
3: machining table
5: tool (drill)
16: rotor shaft
17: air bearing
17e: electrode member
19: Motor
19a: rotor
19b: Stator
19c: coil
20 power supply (inverter power supply)
27: insulation member
29: detection device
30 control part (NC device)
C: Capacitor
V ₀ : Voltage (axis voltage)

Claims (2)

A rotor shaft which is attached to a tip for machining a workpiece and is rotatably supported insulated;
A motor having a rotor and a stator installed in the rotor shaft, the motor rotating the rotor shaft;
A power supply for supplying an alternating voltage to a coil for generating a rotating magnetic field installed in these stators or rotors;
A processing table for placing the workpiece in an earthed state;
An electrode member disposed close to the rotor shaft in an insulated state and forming a capacitor between the rotor shaft;
A detection device connected to the electrode member and configured to detect a voltage induced in the rotor shaft by supplying an AC voltage to the coil;
And a control unit for determining that the tip of the tool is in contact with the workpiece when the voltage detected by the detection device is no longer detected. The method of claim 1,
Rotatably supporting the rotor shaft by an air bearing,
The processing apparatus in which the said electrode member was insulated from the upper end part of the said air bearing by the insulating member, and was formed.

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