JPH01222809A - Machine tool - Google Patents

Abstract

PURPOSE:To carry out the machining of the corner portion of a workpiece with a rapid movement in a machine tool for carrying out the machining of a metal mold, etc. by least displacing the bit of a tool in the mutually close condition of the bit of the tool and the rotating axis of an arm. CONSTITUTION:A tool 2 of an end mill, etc. is removably installed on the spindle 1a of a spindle head 1 and a motor for rotating the tool 2 at a high speed is installed inside the spindle head 1. The spindle head 1 is installed on the end portion of an arm 4 which is linked to a vertically extending rotary shaft cylinder 3 and the arm 4 is perpendicularly supported to the rotary shaft cylinder 3. The rotary shaft cylinder 3 is housed in the body case 6 of a moving body which is driven for advancing in parallel to the three-axis direction of x-axis, y-axis, and z-axis with respect to a workpiece while being driven together with the arm 4 to be rotated around a C-axis, or the axis thereof. The rotation center of a machining device is offset from the rotary axis of the arm 4 so that the bit of the tool 2 can be brought close to the rotating axis of the arm 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a machine tool in which a processing device to which a tool is attached is rotationally driven around two axes.

[Conventional technology]

Generally, when machining the shape of a mold using a machine tool, if the orientation of the tool is fixed in one direction, interference may occur when machining deep workpieces, or a continuous machined surface cannot be obtained. Therefore, there is an inconvenience that a large number of man-hours are required for manual finishing. Therefore, there have been conventionally provided processing devices that are capable of not only moving a processing device that supports a tool in parallel, but also rotating it around one or more axes.

As an example, the structure of a conventional five-axis movable machine tool will be described with reference to FIG. In the same figure, 101 is a spindle head, and this spindle head 101 is a main spindle 1.
A tool 102 is removably attached to the tip of the tool 01a, and the base is attached to a support shaft 104 so as to be rotatable about a horizontal axis 103. This support shaft 104 is driven to rotate around a vertical axis, and is also driven to translate integrally with the spindle head 101 relative to the workpiece. Therefore, the spindle head 101 in this machine tool moves in translation with respect to the workpiece, and
It is possible to turn around two axes, a horizontal axis 103 and a support axis 104, so that it can be oriented in a suitable direction with respect to the workpiece.

[Problem to be solved by the invention]

In the above machine tool, the spindle head 1 is
01, the tip position of the tool 102 is aligned with the support shaft 1.
04, so if the support shaft 104 is rotated in this state, the tip of the tool 102 will be largely displaced in the horizontal direction (see the two-dot chain line in the figure). In other words, in order to rotate the support shaft 104 while keeping the tip position of the tool 102 constant, the support shaft 104 itself must be largely revolved on a horizontal plane as the support shaft 104 rotates.

Therefore, for example, a workpiece 10 as shown in FIG.
5, in order to turn the corner while keeping the tool 102 in contact with the workpiece 105, the support shaft 104 must be turned far outside the outer shape of the workpiece 105. (See the arrow in the same figure)
Such a turn increases machining errors and impedes improvement in feed speed around corners. In addition, the movement of the support shaft 104 etc. becomes complicated, so in a numerically controlled machine tool that automatically controls these drives, the drive control program becomes complicated.
There are problems that lead to increased costs.

In view of these circumstances, an object of the present invention is to provide a machine tool that can speed up machining and improve accuracy by making it possible to smoothly move around the corners of a machining device without waste. shall be.

[Means to solve the problem]

The present invention provides a machine tool equipped with a processing device to which a tool is attached, including an arm supported on a support shaft in a state substantially orthogonal to the support shaft and configured to be able to rotate around the support shaft. , the processing device is attached to this arm so as to be rotatable around an axis in a direction that substantially coincides with the tangential direction of the rotation, and the cutting edge of the tool in the processing device can be brought close to the rotation axis of the arm. The center of rotation of the processing device is offset from the pivot axis of the arm.

[For production]

In the above configuration, when the rotation axis of the arm and the cutting edge of the tool are close to each other, the cutting edge of the tool will hardly be displaced even if the arm is rotated, so it is possible to smoothly machine a part of the corner of the workpiece in this condition. can be done.

〔Example〕

1 and 2 show the main parts of a machine tool in an embodiment of the present invention. In these figures,
1 is a spindle head (processing device); this spindle head 1
A tool 2 such as an end mill is detachably attached to the main shaft 1a of the main shaft 1a, and a motor (not shown) for driving the tool 2 to rotate at high speed is housed within the main shaft head 1.

The spindle head 1 is a rotating shaft cylinder (support shaft) extending in the vertical direction.
3, and the arm 4 is supported in a state perpendicular to the rotating shaft cylinder 3, that is, in a horizontal state. The rotary shaft cylinder 3 is housed in a main body case 6 of a movable body (see Fig. 3 below) that is driven in translation in the three axes directions of the χ, q, and χ axes with respect to the workpiece. It is designed to be driven to rotate together with the arm 4 around the C axis (vertical axis) which is the central axis.

Then, around the axis in the direction that matches the tangential direction of this turning (
That is, the spindle head 1 is attached to the arm 4 so as to be rotatable about a horizontal axis. The center axis of this rotation is offset from the rotation axis of the arm 4,
With the spindle head 1 tilted as shown in Figure 1, the tool 2
The cutting edge of the arm 4 is set so that it is located approximately on the pivot axis of the arm 4. In the following description, the rotation center axis of the spindle head 1 is referred to as the A axis for convenience, but it goes without saying that the direction of the rotation center axis of the spindle head 1 changes as the arm 4 turns.

3 to 11 show the internal structure of the moving body T. As shown in the figure, the main spindle head 1 is connected to an eight-axis rotation drive mechanism 5 provided in an arm 4, and a rotary shaft cylinder 3 is rotatably supported in a main body case 6. It is connected to the shaft turning section 1IIIll structure 7.

First, the structure of the six-wheel turning drive mechanism 5 will be explained based on FIGS. 3 to 7. The bases of pivot shafts 8a and 8b, which are rotatably supported by the casing of the arm 4, are fixed to both sides of the spindle head 1, and a pinion gear 9 is fixed to the tip of one pivot shaft 8a. A brake 22 is connected to the other pivot shaft 8b.

On the other hand, inside the arm 4 is a six-wheel drive servo motor 10.
A ball screw 11, a nut 12, and two racks 13 that mesh with the pinion gear 9 are provided. A pulley 14 is fixed to the drive shaft 10a of the servo motor 10, and a toothed belt 16 is stretched between the pulley 14 and a pulley 15 fixed to the ball screw 11. Appropriate tension is applied to this toothed belt 16 by a tension roller 18.

The ball screw 11 is rotatably supported on the arm 4 side via a bearing 15, and the nut 12 is screwed into the threaded portion of the ball screw 11. One end of a rack mounting bar 17 extending in the longitudinal direction of the arm 4 (in the axial direction of the ball screw 11) is fixed to this nut 12.
The pair of racks 13 described above are fixed to the other end of the rack 7 in parallel. On the other hand, a rail 19 is provided on the upper surface of the inner wall of the arm 4.
is fixed, and the rack mounting bar 17 is supported on this rail 19 via two slide bearings 20, so that the rack mounting bar 17 can freely slide along the rail 19.

Note that the reason why two racks 13 are provided is to prevent backlash.

In such a structure, when the servo motor 10 is rotationally driven, its rotation is transmitted to the ball screw 11 via the toothed belt 16, and as the ball screw 11 rotates, the nut 12, the rack mounting bar 17, And the rack 13 slides together along the rail 19.

As a result, the pinion gear 9 that meshes with the rack 13 rotates, and the spindle head 1 is rotationally driven relative to the arm 4 about the pivot shafts 8a and 8b to which the pinion gear 9 is fixed. Note that the pivot shaft 8a
An encoder (rotation detector) 21 is connected to the end of the spindle head 1, and the encoder 21 detects the rotational state of the spindle head 1, that is, the turning state about the A-axis.

Next, the structure of the C-wheel turning prevention mechanism 7 will be explained based on FIG. 3 and FIGS. 8 to 11. A rotating shaft 3a is connected to the upper part of the rotating shaft cylinder 3, and this rotating shaft 3a is supported by the main body case 6 via a slip ring 34, and the lower part of the rotating shaft cylinder 3 is also connected via a bearing 35. and is supported by the main body case 6.

Two worm wheels 23a and 23b are fixed to the outer peripheral surface of the intermediate portion of the rotary shaft cylinder 3, and two worm gears 248, 24b meshing with the worm wheels 248 and 23b are provided on the main body case 6 side. These worm gears 2
4a and 24b are horizontal shafts 25a rotatably supported by the main body case 6;

25b, respectively.

Inside this main body case 6 is a C-axis drive servo motor 26.
and a drive shaft 27 are provided. Servo motor 26
A pulley 28 is fixed to the drive shaft 26a, and this pulley 28 and a pulley 29 fixed to the drive shaft 27 are connected to each other.
A toothed belt 30 is hung between the two. Drive shaft 27
is rotatably supported by the main body case 6, and has helical gears 318 and 31b fixed at two locations on both ends thereof, and these helical gears 31a and 31b are
helical gears 32a fixed to a and 25b, respectively;
It meshes with 32b. In addition, the worm wheel 23a
, 23b, and two worm gears 24a, 24b are provided in order to prevent backlash.

In such a structure, when the servo motor 26 is driven, the rotation of the drive shaft 26a is transmitted to the drive shaft 27 via the toothed belt 30.
The rotation of worm gears 24a, 2 through helical gears 31a, 32a and helical gears 31b, 32b.
4b are respectively transmitted to fixed horizontal shafts 25a and 25b.

As a result, the rotary shaft cylinder 3 is rotationally driven together with the worm wheels 23a and 23b, and the arm 4 is rotated about the C-axis. Note that an encoder 3 is installed on this rotating shaft cylinder 3.
3 are connected so that the rotational state of the rotating shaft cylinder 3 can be detected.

On the other hand, the six-wheel drive servo motor 10 and the C-axis drive servo motor 26 are
It is connected to a control circuit (not shown). This control circuit uses the numerical value υ311 inputted from a floppy disk, etc.
A control signal is output to each servo motor 26 based on one program and the detection signals output from the encoders 22 and 33. This allows rotational drive around the A-axis (i.e., pivot axes 8a, 8b) and rotational drive around the C-axis (i.e., rotating shaft cylinder 3)! lll1 and the spindle head 1 and tool 2 are oriented in the appropriate direction.

According to such a machine tool, with the spindle head 1 tilted inward as shown in FIG.
C-axis), thereby making it possible to reduce the displacement of the cutting edge of the tool 2 to almost zero as the arm 4 turns. Therefore, when machining a part of the chevron-shaped corner of the workpiece B as shown in FIG.
By moving the tool 2 so that it substantially follows the outer shape of the workpiece B, it is possible to perform smooth continuous machining of a part of the corner while the tool 2 is brought into contact with the workpiece B.

Therefore, it is not necessary to turn the rotary shaft cylinder 3 to the outside of the workpiece B by a large amount as in the conventional case, so that machining at a part of the corner can be performed at high speed and with high accuracy. In addition, since the translational movement control of the rotary shaft cylinder 3 becomes simple,
It is possible to reduce costs due to program creation.

Also, when machining a part of the valley-shaped corner of the workpiece B as shown in FIG. 13, by moving the rotating shaft 13 along the outer diameter of the workpiece B as in FIG. , Smooth continuous machining can be performed while avoiding interference with the workpiece B, and furthermore, as described above, costs can be reduced by creating a program.

Although this embodiment shows a machine tool in which the rotary shaft cylinder 3, which is the support shaft of the arm 4, extends in the C-axis (vertical axis) direction, in the present invention, the rotary shaft cylinder 3, which is the support shaft of the arm 4, extends in the C-axis (vertical axis) direction.
The direction may be set as appropriate regardless of the direction.

(Effects of the Invention) As described above, the present invention has a processing device attached to an arm that can rotate around a support shaft so as to be rotatable around an axis in a direction that substantially coincides with the tangential direction of this rotation, and The center of rotation of the processing device is offset from the rotation axis of the arm so that the cutting edge of the tool in the device can approach the rotation axis of the arm, and the cutting edge of the tool and the rotation axis of the arm are brought close to each other. As a result, the displacement of the tool tip due to arm rotation can be reduced to approximately 0, so in this state a part of the corner of the workpiece can be machined with quick movements without wasting any waste, and this allows continuous machining. This has the effect of increasing precision.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the main parts of a machine tool according to an embodiment of the present invention, Fig. 2 is a perspective view showing the main parts of the machine tool, and Fig. 3 is a sectional view showing the movable body of the machine tool. , FIG. 4 is a partial cross-sectional front view showing the main parts of the moving body, and FIG. 5 is the V of FIG. 7.
-Va sectional view, FIG. 6 is a sectional view taken along the line Vl-Vl in FIG. 7,
FIG. 7 is a cross-sectional side view showing the A-axis turning drive mechanism in the moving body, FIG. 8 is a cross-sectional plan view showing the C-axis turning drive mechanism in the moving body, and FIG. 9 is a cross-sectional front view showing the same mechanism.
Fig. 10 is a side view showing the same mechanism, Fig. 11 is a sectional side view showing the same mechanism, Fig. 12 is a plan view showing the movement of the spindle head etc. when machining a part of the chevron corner with the same machine tool, 1
Figure 3 is a plan view showing the movement of the spindle head etc. when machining a part of a valley corner using the same machine tool, Figure 14 is a front view showing the main parts of a conventional machine tool, and Figure 15 is a diagram using the same machine tool. FIG. 3 is a plan view showing the movement of the spindle head and the like during machining. 1... Spindle head, 2... Tool, 3... Rotating shaft cylinder (arm support shaft), 4... Arm. Patent applicant Agent: Shin Nippon Koki Co., Ltd.
Patent Attorney Etsushi Kotani Patent Attorney Chief 1) Masamukai Patent Attorney Yasuo Itaya Figure 1 Figure 2 Figure 11 Figure 12 Figure 13 Figure 14 m Figure 15

Claims (1)

[Claims] 1. A machine tool equipped with a processing device to which a tool is attached is provided with an arm supported on a support shaft in a state substantially orthogonal to the support shaft and configured to be able to rotate around the support shaft, and The processing device is attached to the arm so as to be rotatable around an axis in a direction that substantially coincides with the tangential direction of the rotation, and the processing device is arranged so that the cutting edge of the tool in the processing device can approach the rotation axis of the arm. A machine tool characterized in that the rotation center of the arm is offset from the rotation axis of the arm.