JP2002346990A - Work machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work machining method in which the maintenance and examination are easy, and the accuracy of the hole depth is excellent even when conductive chips are adhered to the vicinity of a tip of a tool. SOLUTION: A printed circuit board 31 is fixed to a table 30 so that a copper foil 31c faces a drill 14, and an insulating layer 31i faces the table 30. An insulating plate 50 is placed on the upper side of the copper foil 31c. Chips 60 adhered to the vicinity of the tip of the drill 14 are removed by the insulating plate 50 during the machining. Thus, the tip of the drill 14 is brought into contact with the copper foil 31c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work processing method for processing a work by holding a tool on a rotatable rotor shaft having a high ground resistance.

[0002]

2. Description of the Related Art FIG. 4 is a front view of a processing section in a conventional printed circuit board drilling machine. The cross slide 1 is movably supported in the left and right (Y) directions in the figure by moving means (not shown). A pair of linear guide devices 2 is fixed to the cross slide 1. The saddle 3 is supported by the linear guide device 2 and is movable in the vertical (Z) direction in the figure by moving means (not shown). A holder 4 is fixed to the center of the saddle 3, and a spindle 5 is fixed to the holder 4.

The rotor shaft 6 has an air radial bearing 7a.
7c rotatably supported by the spindle 5 and positioned axially by an air thrust bearing 8 and supported. On the rotor shaft 6, a rotor (rotor) 9 in which a copper material is formed in an end ring shape is disposed. A coil (stator) 10 is disposed at a position of the spindle 5 facing the rotor 9. The coil 10 is connected to an inverter power supply 11. The inverter power supply 11 converts a commercial AC voltage input from the three-phase power supply 12 into a high-frequency AC voltage. A drill 14 is held at the tip of the rotor shaft 6.

[0004] A pressure foot 20 is fitted to the tip of the spindle 5. The pressure foot 20 is supported by a pair of air cylinders 21. Air cylinder 21
Are supported by the holder 4. One end of the measurement terminal 22a of the digital scale 22 supported by the saddle 3 is fixed to the pressure foot 20, and measures the relative position between the pressure foot 20 and the holder 4. Digital scale 22
Are connected to the NC device 23. Pressure foot 2
A bush 24 is fixed to the leading end of the “0”.

[0005] A printed circuit board 31 is fixed to the table 30. The table 30 is movable in a direction perpendicular to the paper surface (X direction).

Then, a blind hole having a depth H from the surface of the printed circuit board 31 (hereinafter, referred to as a "blind hole") is processed in the following procedure. That is, prior to machining, the air cylinder 21 is operated, and the piston rod 2
The distance A from the lower end of the bush 24 to the tip of the drill 14 is obtained in a state where 1a protrudes most. When the inverter power supply 11 is operated and a current flows through the coil 10, a rotating torque is generated in the rotor 9 by the magnetic field generated in the coil 10, and the rotor shaft 6 rotates.

When the saddle 3, ie, the holder 4, is lowered in this state, first, the lower end of the bush 24 comes into contact with the printed board 31, and the printed board 31 is pressed against the table 30. Then, the pressure foot 20 stops descending while pressing the printed board 31, and thereafter rises relatively to the holder 4 against the air pressure. NC device 2
3 is the Z-axis coordinate Z when the measurement terminal 22a starts moving.
0 is read, and the holder 4 is lowered from the coordinate Z0 by A + H. As a result, it was possible to perform processing with excellent accuracy.

[0008]

On a single printed circuit board, not only blind holes but also through holes are machined. In the case of the above-mentioned conventional technology, the scale part is worn by sliding because the measuring terminal moves up and down even when processing a through-hole in which it is not necessary to precisely control the depth of the hole. Therefore, it is necessary to frequently check the accuracy of the digital scale and to periodically replace parts to prevent a decrease in measurement accuracy.

In addition, since the height of the tip of the drill is measured via the pressure foot, there is a limit to the accuracy of the depth of the hole.

The applicant of the present application has filed Japanese Patent Application No. 2000-16.
No. 3681, in a work processing method for processing a work by holding a tool on a rotatable rotor shaft having a high ground resistance, the work is insulated from the ground, and an axial voltage generated on the rotor shaft is passed through the work. A method for machining a workpiece, characterized by detecting the tip position of a tool by measuring, is proposed. According to this processing method, maintenance and inspection are easy, and the depth of the hole can be precisely processed. However, when conductive small pieces (hereinafter, referred to as "chips") adhere to the vicinity of the tip of the tool,
In some cases, the end of the swarf was mistaken as a tool tip, and the depth of the hole was reduced.

An object of the present invention is to solve the above-mentioned problems in the prior art, to facilitate maintenance and inspection, and to have excellent hole depth accuracy even when conductive chips are attached near the tip of a tool. An object of the present invention is to provide a work processing method.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a method of processing a workpiece by holding a tool on a rotatable rotor shaft having a high ground resistance. In addition, a non-conductive member is arranged on a side of the work facing the tool, and a tip voltage of the tool is detected by measuring an axial voltage generated on the rotor shaft through the work. It is characterized by the following.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

FIG. 1 is a front view of a machined part in a printed circuit board drilling machine according to the present invention, and the same components or components having the same functions as those in FIG.

The printed circuit board 31 is fixed to the table 30 so that the copper foil 31c faces the drill 14, and is insulated from the table 30 by an insulating layer 31i. An insulating plate 50 is mounted on the upper surface of the copper foil 31c. The copper foil 31c is connected via a cable 42 to an input terminal 43a of a filter (here, a bandpass filter) 43. The output terminal 43b of the filter 43 is connected to the input terminal 44a of the comparator 44, and the ground terminal 43e is connected to the ground. The output terminal 44b of the comparator 44 is connected to the NC device 2
3 is connected. Holder 4, pressure foot 20
And the table 30 are grounded.

Next, the shaft voltage will be described.

The rotor shaft 6 has an air radial bearing 7a.
7d and the air thrust bearing 8 and do not contact the spindle 5. That is, the rotor shaft 6 and the spindle 5 are substantially insulated electrically. When a switch (not shown) of the three-phase power supply 12 or the inverter power supply 11 is turned on, an axial voltage V0 is generated on the rotor shaft 6 via the coil 10.

FIG. 2 is an explanatory diagram of the shaft voltage.

When the frequency of the three-phase power supply 12 is 50 Hz,
The shaft voltage V0 generated on the rotor shaft 6 has a waveform shown in FIG. This waveform is the frequency Vs of the three-phase power supply 12 shown in FIG.
A voltage Vi1 of 1 kHz (not shown), which is a control frequency of the inverter power supply 11, and 3k, which is three times the control frequency of the inverter power supply 11 shown in FIG.
It is substantially equal to a waveform obtained by superimposing a waveform of the voltage Vi2 of Hz.

Next, a procedure for processing a blind hole having a depth H from the surface of the printed circuit board 31 will be described.

Prior to machining, the air cylinder 21 is operated to make the piston rod 21a protrude most. Then, the inverter power supply 11 is operated to supply a current to the coil 10, and the holder 4 (that is, the drill 14) is lowered while the rotor shaft 6 is rotated.

Then, first, the lower end of the bush 24 comes into contact with the insulating plate 50, and the printed board 31 is interposed via the insulating plate 50.
Is pressed against the table 30, and the descent is stopped in that state. When the holder 4 further descends and the tip of the drill 14 penetrates the insulating plate 50 and comes into contact with the copper foil 31c, the shaft voltage V0 generated in the rotor shaft 6 is input to the filter 43. The filter 43 outputs the voltage Vi1 of the shaft voltage V0.
(Or Vi2) is output to the comparator 44. Comparator 44
Outputs a detection signal to the NC device 23 when the sine wave voltage Vi1 (or Vi2) exceeds a predetermined voltage. N
When the C device 23 receives the detection signal from the comparator 44,
The Z-axis coordinate Z1 at that time is read, and the holder 4 is moved to the coordinate Z.
After lowering by H from 1, the holder 4 (that is, the drill 14) is raised. Then move to the next processing position,
Repeat the above steps.

When drilling is performed on the printed circuit board, the cuttings 60 of the copper foil 31c cut off during the processing may adhere to the tip of the drill 14 coming out of the insulating plate 50 in some cases.

FIG. 3 shows a processing state in the case where chips are attached to the tip of the drill.

As shown in FIG. 3A, when the chips 60 are attached near the tip of the drill 14, first, the lower end of the chips 60 is attached to the insulating plate 50 as shown in FIG. Abut Since the drill 14 is rotating at a high speed, most of the chips 60 are removed from the drill 1 at the moment the lower end contacts the insulating plate 50.
4 is detached from the lower end. The chips 60 that have not separated from the lower end of the drill 14 move to the rear of the drill 14 (upward in the figure) by the drill 14 cutting the insulating plate 50. As a result, as shown in FIG.
4 directly contacts the copper foil 31c.

As described above, even if the chips 60 are attached near the tip of the drill 14, the chips 60 do not intervene between the tip of the drill 14 and the copper foil 31c. The position of the tip can be reliably measured.

[0027]

As described above, according to the present invention,
Since the chips attached to the tip of the drill can be reliably removed, it is possible to perform processing with excellent depth accuracy.

Further, since a special process for removing chips is not required, the processing efficiency is not reduced.

[Brief description of the drawings]

FIG. 1 is a front view of a processing unit in a printed board drilling machine according to the present invention.

FIG. 2 is an explanatory diagram of a shaft voltage.

FIG. 3 is a diagram showing a processing state when chips are attached.

FIG. 4 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 14 drill 30 table 31 printed circuit board 31c copper foil 31i insulating layer 50 insulating plate 60 cutting chips

Continued on the front page (72) Inventor Yukihiro Yamada 2100 Kamimaizumi, Ebina-shi, Kanagawa F-term in Hitachi Via Mechanics Co., Ltd. (reference) 3C029 AA21 3C036 AA01 LL08 3C060 AA11 BA05 BG13

Claims (1)

[Claims] 1. A method of processing a workpiece by processing a workpiece by holding a tool on a rotatable rotor shaft having a high ground resistance, wherein the workpiece is insulated from the ground, and a non-contact is provided on a side of the workpiece facing the tool. A method of processing a work, comprising: arranging a conductive member and measuring an axial voltage generated on the rotor shaft through the work to detect a tip end position of the tool.