JP2521530B2 - Composite NC lathe with rotation difference control device and machining method using the same - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite with rotation difference control for controlling one of a spindle and a rotary tool shaft so that the other has a specified rotation difference.
The present invention relates to an NC lathe and a processing method using the same.

2. Description of the Related Art Conventionally, simultaneous turning of a center hole of a workpiece, an outer diameter, and an end surface has been performed by rotating a main shaft at a constant rotation speed according to either one or an intermediate cutting condition. Therefore, it was not possible to obtain proper processing conditions in one or both. Recently, in order to solve this problem, the machining method used in compound NC lathes is that the spindle rotates a certain amount according to the outer diameter cutting condition of the workpiece, and the rotation difference with respect to the rotation speed of the spindle matches the inner diameter cutting condition. A method has been developed in which the rotary tool axis is rotated normally or reversely at the number of revolutions to perform simultaneous cutting.

Conventionally, a general method of tapping the center hole of a workpiece is to cut the spindle by rotating it in the normal or reverse direction at a low speed, stop the spindle at a specified cutting position, and then rotate it in the reverse or forward direction. I was removing the tap.

Problems to be solved by the invention In the simultaneous machining method using the rotation difference between the spindle and the rotary tool axis described in the conventional technique, the set rotational speed of the spindle is constant,
Optimal cutting conditions can be obtained for both straight cutting of outer diameter and center hole, but in the case of end face or outer diameter taper cutting, it is not possible to follow changes in cutting speed during end face and taper cutting. It was almost impossible to cut simultaneously with the center hole. Further, even if simultaneous cutting is performed, satisfactory cutting conditions cannot be obtained, and there is a problem that an appropriate tool life and good machining accuracy cannot be obtained.

Further, in the tapping processing method described last in the conventional technique, since the spindle rotation is slow, the processing is performed in the constant torque range of the drive motor, and the processing is performed in the low horsepower range where the drive motor cannot obtain sufficient performance. Had the problem.

The present invention has been made in view of these problems of the prior art, and an object of the present invention is to rotate an outer diameter taper or a spindle at a constant cutting speed rotation during end face cutting, with a specified rotation difference. Complex with rotation difference control device that rotates the tool axis
It is intended to provide an NC lathe and a machining method using this NC lathe.

Means for Solving the Problems In order to achieve the above object, a compound NC lathe with constant rotation difference control according to the present invention comprises a first drive circuit for driving a spindle and a second drive circuit for driving a rotary tool axis of the rotary tool unit. A first detector for detecting the rotation speed of the main shaft, a second detector for detecting the rotation speed of the rotary tool shaft, and a difference in rotation speed between the first detector and the second detector, A comparison circuit for outputting to the first drive circuit or the second drive circuit a control signal such that the rotational speed difference becomes a designated value externally input, and rotating either the spindle or the rotary tool shaft. On the other hand, the other is rotated with a designated rotation difference.

In addition, the tapping method in the compound NC lathe with rotation difference control is that the spindle that grips the workpiece and the rotary tool shaft that mounts the tap are simultaneously rotated in the same direction via the chuck, and the spindle and the rotary tool shaft rotate. The tapping cycle from tapping to tapping is performed by changing the number difference.

The main spindle is rotated at a constant cutting speed by the first drive circuit so that the cutting speed becomes constant with respect to the outer diameter and the end surface cutting of the workpiece gripped by the chuck, and this rotation speed is input to the comparison circuit by the detector. On the other hand, the rotary tool shaft on which the rotary tool is mounted is rotated by the second drive circuit, and this rotation speed is also input to the comparison circuit by the detector. The designated value of the rotation difference externally input by a program or the like is stored in the comparison circuit, and the second drive circuit is calculated so that the rotation difference between the spindle and the rotary tool shaft is calculated and the rotation difference is always equal to the stored designated value. The control command is sent to and the rotating tool axis is rotating with the specified rotation difference. Then, for example, the outer diameter cutting bite is given synchronous feed in the X-axis direction and the Z-axis direction to start cutting of the outer diameter taper portion from the small end side to the large end side, and at the same time, feed is given to the rotary tool. When the center hole is machined simultaneously, the rotational speed of the spindle decreases continuously with the progress of taper cutting, and the rotational speed of the rotary tool shaft also decreases continuously while maintaining the specified rotational speed difference. Next, when the cutting of the taper portion is completed and the cutting of the outer diameter straight portion is started, the rotation speed of the main spindle becomes constant, and the rotation speed of the rotary tool also becomes constant while maintaining the specified rotation speed difference.

When mounting a tap on the rotating tool shaft and cutting a female thread in the center hole of the workpiece to be gripped by the spindle chuck, specify the rotation difference according to the tap suitability conditions and keep this specified rotation difference. The main shaft and the rotary tool shaft are simultaneously rotated in the same direction, the tap is cut on the positive or negative side of the rotational difference, the positive or negative side of the rotational difference is changed, and the tap is extracted on the negative or positive side.

Example An example will be described with reference to FIG. Known 2
In a composite NC lathe with a tool post, a spindle 1 is supported by a plurality of bearings on a spindle stock installed on the left side of a bed (not shown), and a chuck 2 is fitted to the tip of the spindle.
A workpiece W having a tapered portion at a cutting portion having an outer diameter is gripped by a gripping claw of the chuck.

The bed has two pairs of Z-axis direction slide guide surfaces on the top surface, and on the X-axis direction slide guide surface cut on a carriage (not shown) movably mounted on one slide guide surface. In addition, a tool rest (not shown) is fixedly attached via a middle stand (not shown), and the tool rest is moved and positioned in the X-axis and Z-axis directions by NC control. And Z which is rotatably supported by the tool post
A front turret tool post 3 is fitted to the tip of a horizontal turning shaft in the axial direction, and a bite 5 is detachably attached to a tool attachment station of the turret 3 via a bite holder 4. A tool rest (not shown) is mounted on the other slide guide surface of the bed via a carriage (not shown) and an intermediate stand so that the tool rest can be moved and positioned in the X-axis and Z-axis directions by NC control. At the rotary tool mounting station of the rear turret tool post 6 that can be installed, the rotary tool unit 7
Is detachably mounted, and the rotary tool (drill 9 or tap 13) is detachably fitted to the rotary tool shaft 8 of the rotary tool unit 7. The rotary tool shaft 8 can be rotated normally and reversely by NC control by a motor 10 directly connected to a drive shaft 12 provided in the turret, and the rotation of the rotary tool shaft can be detected by a detector 11. .

The spindle 1 is rotated by a spindle motor 14 via a belt 15, and the rotation of the spindle is detected by a detector 16. With respect to the rotation of the spindle, the constant cutting speed rotation control of the NC device 17 continuously changes the rotation speed according to the position of the cutting edge of the cutting tool 5 in the X-axis direction to maintain the specified cutting speed.

A drive circuit 18 for the spindle motor 14 and a drive circuit 19 for the rotary tool axis drive motor 10 are provided in the NC device 17, and the spindle 1 and rotation input by the detectors 16 and 11 are further provided in the NC device. A comparison circuit 20 is built in which a difference in the number of revolutions of the tool shaft 8 is obtained and a control signal is output to the drive circuit 19 so that the difference in the number of revolutions becomes equal to a preset value which is programmed and stored in advance.

 Next, the first operation of this embodiment will be described.

When the front turret tool post 3 moves in the X-axis and Z-axis directions, the cutting edge of the cutting tool 5 is positioned at the cutting start position, and at the same time, when the rear turret tool post 6 moves in the X-axis and Z-axis directions, the drill 9 is concentric with the spindle. The tip is positioned at the cutting start position, which is slightly to the right of the workpiece tip surface. Then, the main shaft 1 is rotated by the main shaft motor via the belt 15, and the workpiece W gripped by the chuck 2 is rotated. This spindle rotation is controlled by the NC device 17 at a constant cutting speed, and is continuously variable according to the movement of the blade position of the cutting tool 5 in the X-axis direction. The rotation speed of this spindle is determined by the detector 16. It is fed back to the drive circuit 18 and output to the comparison circuit 20. Then, the rotating tool shaft 8 is rotated by the motor 10. The rotation speed of the rotating tool shaft is fed back to the drive circuit 19 by the detector 11 and compared with the comparison circuit.
The control signal is output to the rotary circuit tool drive circuit 19 and is output to the comparison circuit 20 to obtain the difference between the two rotation speeds in the comparison circuit 20 so as to be equal to the designated value which is pre-programmed and stored. Then, the drive circuit 19 drives the motor 10 with a specified rotation difference by the control signal from the comparison circuit 20. Therefore, the rotation of the drill 9 follows the spindle rotational speed that changes depending on the position of the cutting edge of the cutting tool 5 in the X-axis direction, and changes while maintaining a specified rotational difference. The front turret tool post 3 and the rear turret tool post When cutting feed is given to the table 6 and simultaneous cutting is performed, while the outer diameter taper portion is being cut by the cutting tool 5, the spindle rotational speed gradually decreases, and following this, the rotation of the rotary tool axis Also keeps a predetermined rotation difference and gradually decreases. When the cutting of the taper portion is completed and the cutting of the outer diameter straight portion is started, the rotation of the main spindle becomes constant and the rotary tool axis also becomes constant.

Next, the second operation of this embodiment will be described with reference to FIGS. Unlike the first operation described above, a tap 13 is mounted on the rotary tool shaft 8 instead of the drill 9. Rear turret turret 6 turns and taps for right screw 13
Is indexed to the cutting position, and the rear turret tool post 6 is moved in the X-axis and Z-axis directions so that the tap 13 is concentric with the spindle 1 and the tip is positioned at the cutting start position on the right side of the front end face of the workpiece W. Both the main shaft 1 and the rotary tool shaft 8 are rotated clockwise when viewed from the bed rear end side (tailstock side). At this time, as shown in FIG. 3, if the proper rotation speed of the tap 13 is set to 200 rpm, the rotation speed of the both will be +200.
Enter the program into 20. And the number of rotations of the main shaft 1 is 500
If you command rpm, the rotating tool axis will automatically be 700r.pm
Is rotated by. Then tap the rear turret tool post 6 13
The tap is cut by moving to the main spindle side in the Z-axis direction at a feed speed corresponding to 1 pitch. When the tap depth reaches just before the predetermined position, the rotation difference command value is switched to -200, and the rotary tool shaft 8 rapidly changes from 700 rpm to 300 rpm.
The speed is reduced to m. The number of rotations during deceleration is constantly detected by the detector.
11 is input to the comparison circuit 20, and when the rotation difference becomes 0, that is, when the rotary tool shaft reaches 500 rpm, the movement of the rear turret tool post 6 in the Z-axis direction is switched to the anti-spindle side, and the rotary tool continues. The shaft 8 is decelerated to 300 rpm and the tap is pulled out.

Contrary to the above, the rotation of the spindle 1 and the rotary tool 8 is, for example, rotating the rotary tool shaft at 500 rpm, rotating the spindle 1 at 300 rpm to make a tap, and increase the spindle to 700 rpm. It is also possible to speed up tap extraction.

Further, it is possible to simultaneously convert the rotations of both the main shaft and the rotary tool shaft when converting the rotational difference between plus and minus, thereby shortening the tapping cycle.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it has the following effects.

In the lathe of the compound NC with the rotation difference control device according to claim 1, the rotation difference between the spindle and the rotary tool axis is obtained, and either the spindle or the rotary tool axis is set so that this rotation difference becomes a designated value externally input by a program or the like. The rotation of either one is controlled, the spindle is rotated at a constant cutting speed according to the cutting conditions of the outer diameter and the end surface, and the rotating tool shaft is rotated while following the constant cutting speed rotation and maintaining the specified rotation difference. Since the outer diameter of the workpiece and the end surface and the central hole are simultaneously cut, it is possible to keep the outer peripheral cutting including the end surface or the outer diameter tapered portion and the central hole cutting under the optimum machining conditions. Therefore, it is possible to reduce the machining time by ensuring the proper values of machining accuracy and tool life.

Further, in the machining method of claim 2, since the spindle and the rotary tool are simultaneously rotated in the same direction and the rotation difference is changed, the tapping cycle from the tap cutting to the tapping is performed. As described above, the machining in the constant torque region (low output region) of the conventional drive motor becomes the machining in the high horsepower region, and the machining of the maximum capacity of the drive motor becomes possible and the machining time can be shortened.

[Brief description of drawings]

FIG. 1 is a composite with a rotation difference control device including a partial block diagram.
Fig. 2 is an explanatory diagram of the structure of an NC lathe, and Fig. 2 is a composite NC with a rotation difference control device.
Explanatory drawing of the second action of this embodiment showing tapping by a lathe, FIG. 3 is a graph showing changes in the rotational speeds of the spindle and the rotary tool shaft during tapping, and FIG. 4 is tapping of the drive motor. It is a graph figure for an effect explanation of Claim 3 showing a field. 1 ... spindle, 2 ... chuck, 7 ... rotating tool unit, 8 ... rotating tool axis, 11,16 ... detector, W ... workpiece, 18,19 ... driving circuit, 20 ... comparison circuit

Claims (2)

(57) [Claims] 1. A compound NC lathe having a rotary tool unit (7), comprising a first drive circuit (18) for driving a spindle (1),
A second drive circuit (19) for driving the rotary tool shaft (8) of the rotary tool unit, a first detector (16) for detecting the rotation speed of the spindle, and a first detector (16) for detecting the rotation speed of the rotary tool shaft. The second drive (11) and a control signal for calculating a difference in the number of revolutions of the first detector and the second detector and for making the difference in the number of revolutions a designated value externally input, the first drive circuit. Or a comparison circuit (20) for outputting to a second drive circuit, wherein the other is rotated at a specified rotation difference with respect to the rotation of either the main shaft or the rotary tool shaft. Combined NC lathe with. 2. A spindle (1) for gripping a workpiece (W) and a rotary tool spindle (8) for mounting a tap (13) are simultaneously rotated in the same direction through a chuck (2), and the spindle (1) and A tapping method using a compound NC lathe with a rotation difference control device, characterized in that the tapping cycle from tapping to tapping is performed by changing the difference in the number of revolutions with the rotating tool axis.