JP3736039B2 - Processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a precision part hole machining apparatus.
[0002]
[Prior art]
There are various types of drilling targets that account for the largest proportion of machining, such as drill holes, reamer holes, tapped holes, boring holes, and stepped holes.
[0003]
Among them, hole finishing with a boring tool is most commonly performed, and since it does not depend on the processing accuracy of the pilot hole, it has a feature that a deep hole can be processed with high accuracy. FIG. 5 shows a conventional boring head, where 100 is a tool shank portion, 101 is a cutting tool provided with a tip 106 at the tip, 102 is a cutting tool holder, 103 is an adjusting screw, 104 is an adjusting ring, and 105 is vernier. It is. Adjustment of the tool diameter (R in the figure) is performed by rotating the adjusting screw 104 provided with a gear to move the adjusting screw 103 in the radial direction. After processing is completed, the inner diameter of the workpiece is measured by a touch sensor installed outside. If the bore diameter does not satisfy a predetermined specification due to wear of the insert 106 or the like, the adjustment screw 103 is adjusted again, and the tool diameter is set so as to satisfy the specification.
[0004]
However, there is a limit in terms of machining accuracy in adjusting the tool diameter via a gear that is basically accompanied by backlash. Therefore, when the adjustment process is automated, the processing accuracy obtained is limited to 3 to 4 μm at most.
[0005]
[Problems to be solved by the invention]
The present invention is based on a boring process that has limited machining accuracy despite the need for skilled operations such as tool setting, tool wear correction, tool management, etc., in high-precision drilling in conventional machining centers. The new processing equipment which improves from the above is provided.
[0006]
[Means for Solving the Problems]
The present invention is a processing method for processing a workpiece in which a tool provided on a main shaft supported by an active control type bearing has a hollow portion, the center of the main shaft being in the hollow portion, and the main shaft is The inner peripheral surface of the workpiece is processed by making one revolution with respect to the workpiece during one rotation .
[0007]
According to the present invention, it is possible to realize high-accuracy drilling that sequentially corrects the wear amount of the cutting tool, non-circular machining of an arbitrary shape, taper drilling with a minute inclination angle, and the like.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention, there is provided a rotating-side main shaft supported by an active control type bearing, a fixed-side holder that accommodates the main shaft, a motor that rotationally drives the main shaft, In a boring machining apparatus for boring a workpiece by mounting a spindle composed of a boring head having a cutting tool mounted on the workpiece side and mounting the spindle, the locus of the cutting tool tip coincides with a predetermined inner surface machining shape. In addition, the center position of the main shaft is controlled in synchronization with the rotation of the main shaft, and a high accuracy for automatically correcting the wear amount of the tool, for example, without requiring a skilled worker. Can be drilled.
[0009]
The present invention will be described below with reference to FIGS. 1 ( a ) and 1 ( b ) which are principle diagrams.
Figure 1 (a) (b) in 1 byte, 2 bytes holder, 3 denotes a workpiece as a workpiece. The tool holder 2 is supported by an active control type magnetic bearing as will be described later with reference to FIG.
[0010]
FIG. 1 ( a ) shows a state where the cutting tool 1 is not yet worn. At this stage, the center of the bit holder 2, that is, the shaft 10 of the magnetic bearing spindle shown in FIG. 2 (center 4 shown in FIG. 1) is installed at the center position 5 of the boring hole. That is, as in the conventional boring process, the cutting tool 1 rotates around the center position 5 of the boring hole as the axis.
[0011]
1 (b) shows a case where byte 1 is worn by a dimension △ r. This amount of wear: Δr is known in advance by, for example, an external measuring means, and the center 4 of the spindle shaft 10 is decentered by Δr with respect to the center 5 of the initially set bore hole. Swing motion in the state. This swivel motion is made by the microactuator function of the magnetic bearing. That is, like the movement of the moon with respect to the earth, the bite holder 2 revolves once during one rotation. The rotation angle, rotation speed, and turning motion of the tool holder 2 are perfectly synchronized, and the tip position of the tool is always in contact with the machining surface.
[0012]
An embodiment of the present invention will be described below with reference to FIG.
FIG. 2 shows a magnetic bearing spindle fitted with a boring head. The basic structure of the mechanism of this magnetic bearing spindle is known. 10 is the spindle of the spindle, 11 is the rotor of the motor, 12 is the stator of the motor, 13 is the rotor of the radial magnetic bearing on the front side, 14 is the stator, 15 is the rotor of the radial magnetic bearing on the rear side, 16 is the stator, 17 is A rotor of the thrust magnetic bearing, 18 and 19 are stators, and 20 is a fixed-side sleeve for housing the magnetic bearing and the motor. 21a and 21b are front side X-axis displacement sensors for detecting the radial position of the main shaft 10, and 22c (not shown) and 22d (broken lines) are Y-axis displacement sensors for detecting the axial position of the main shaft 10. It is. The X-axis displacement sensors 21a and 21b and the Y-axis displacement sensors 22c and 22d are provided orthogonally. The Y-axis sensor 22d arranged on the back side of the drawing is indicated by a broken line. Reference numerals 24a and 24b denote rear-side X-axis displacement sensors for detecting the radial position of the main shaft 10, and reference numerals 24c (not shown) and 24d (broken lines) denote Y-axis displacement sensors. On the front side described above, the axis O ₁ 25 of the main shaft 10 (see FIG. 1) is obtained by the rotor 13 of the magnetic bearing, the stator 14 of the magnetic bearing, the X-axis displacement sensors 21a and 21b, and the Y-axis displacement sensors 22c and 22d. And a magnetic bearing actuator 50 for generating a regular turning motion on the axis O ₁ 25 around the center O ₂ 26 of the borehole (corresponding to 5 in FIG. 1). Is configured. The same applies to the components of the rear side magnetic bearing actuator 51. Reference numeral 27 denotes an encoder rotor for detecting the rotation angle and rotation speed of the main shaft 10, and 28 denotes a stator, which is provided between the upper end portion of the main shaft 10 and the fixed member 29. The rotor 11 of the motor, the stator 12, the rotor 27 of the encoder, and the stator 28 constitute a rotary actuator 52 that regularly rotates the main shaft 10 based on rotational position information obtained by the encoder. 60 is a boring head mounted on the spindle 10 of the magnetic bearing spindle, 30 is a cutting tool, and a tip 31 is mounted on the tip. Reference numeral 32 denotes a workpiece which is a workpiece.
[0013]
FIG. 3 shows a block diagram of the turning motion control unit 53 that drives the front-side magnetic bearing actuator 50. In this turning motion control unit 53, each axis of the magnetic bearing is driven in synchronization with the rotational motion. In the figure, a structural model of a magnetic bearing is described, and the stator 14 is composed of X-axis stators 14a and 14b and Y-axis stators 14c and 14d. In order to give the main shaft 10 a turning motion having a radius of Δr, a sine wave having a phase difference of 90 ° is given to the drive circuit of the X-axis stator and the Y-axis stator. The method for controlling and driving the magnetic bearing actuator 51 on the rear side is the same. In the example applied to the mass production site, the turning radius: Δr was obtained by sampling a boring hole diameter after processing to obtain a correction value of the hole diameter from the difference between the design value and the actual measurement value.
[0014]
FIG. 4 is a block diagram of the entire control circuit of this embodiment. The rotation signal generator 54 outputs a frequency (pulse train) for determining the rotation speed and the rotation position. One of the outputs is input to the rotary motion control unit 55. The rotary motion control unit 55 generates a signal for driving and controlling the rotary actuator 52.
[0015]
On the other hand, the turning motion control unit 53 sends the pulse train obtained from the rotation signal generator 54 to the X-axis and Y-axis signal processing units 58 and 59 of the magnetic bearing actuator 50 shown in FIG. As indicated by a chain line in FIG. 4, the phase between the rotational motion and the turning motion can be accurately controlled by feeding back the output from the encoders 27 and 28 to the turning motion control unit 53.
[0016]
【The invention's effect】
According to the present invention, as described in the embodiment, it is possible to realize high-accuracy boring hole processing that can automatically and automatically correct the wear of the cutting tool tip. By applying the present invention to a mass production site, it is possible to automate high-precision machining on the order of submicron in boring hole machining where accuracy of several microns was the limit even for a conventional veteran operator.
[0017]
Also, since the turning radius of the spindle can be set arbitrarily, it can be applied to taper hole machining with a gentle inclination angle, elliptical machining used for automobile engine cylinders, etc., or non-circular machining of any shape, and its effect Is enormous.
[Brief description of the drawings]
FIG. 1A is a diagram illustrating the principle of the present invention when there is no correction of the wear amount of a cutting tool. FIG. 1B is a diagram illustrating the principle of the present invention when correcting tool wear. FIG. 3 is a front cross-sectional view of a spindle equipped with a boring head of the machining apparatus in FIG. 3. FIG. 4 is a block diagram of a turning motion control unit for driving the spindle shown in FIG. Overall block diagram [Fig. 5] Front sectional view of a boring head in a conventional processing machine [Explanation of symbols]
10 Spindle 11 Holder 11, 12 Motor 30 Boring head 31 Work 25 Center position of spindle

Claims (2)

  A processing method for processing a workpiece in which a tool provided on a main shaft supported by an active control type bearing has a hollow portion, the center of the main shaft being in the hollow portion, and while the main shaft rotates once. A processing method characterized in that the inner peripheral surface of the workpiece is processed by making one revolution with respect to the workpiece.   The machining method according to claim 1, wherein the revolution radius of the cutting tool is corrected by Δr while detecting the wear amount Δr of the cutting tool.

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