JPS6228374Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a spindle positioning mechanism for an NC lathe.

When performing complex machining such as drilling or milling at a predetermined location on a workpiece, it is necessary to position the workpiece while controlling the rotation angle of the spindle that grips the workpiece using NC. It is considered.

One of the conventional methods is to use one drive source (servo motor), with a drive transmission system prepared to be suitable for general turning processing and a high-precision rotation angle prepared to be suitable for complex processing as in the present application. Control Drive Transmission System Equipped with two drive transmission systems, the so-called C-axis control system, which are selectively used by clutches, etc. to control the drive of the main spindle.During complex machining, the drive transmission system is used for high-precision rotation angle control. There are systems to choose from.

In addition, a turning motor and a rotation angle control servo motor are prepared separately, and a corresponding drive transmission system is prepared for each, and these are used selectively during general turning processing and complex processing. be.

However, although both methods return to origin for the main shaft, they do not return to origin for the C-axis control system, and the meshing teeth of the C-axis spur gear and the main shaft gear change each time they are connected. Therefore, in many cases, highly accurate rotation angle control cannot be expected.

In addition, the C-axis spur gear, which is selectively connected to the main shaft gear, is attached to the rotating shaft with a key or spline so that it can move freely in the axial direction, so a certain amount of clearance is required, and the play caused by this is less accurate. This was one of the reasons for the decline.

This idea was developed in view of the above points, and includes a home return means for each of the spindle and C-axis control system, and the drive transmission system for C-axis control only when the spindle and C-axis control system are at the home. In addition to selecting
The main shaft is characterized in that the C-axis spur gear is integrally coupled to the rotating shaft, and the C-axis spur gear is moved together with the rotating shaft to control the rotation angle of the main shaft with high precision.

This invention will be explained below with reference to embodiments shown in the drawings.

1 is the main shaft with chuck 1a attached to the tip,
It is rotatably supported on the headstock 2 by bearings 6 and 7. Main shaft 1 has pulley 3, gear 4 has key 5
are joined together by. V on pulley 3
A belt 9 is attached so that the rotational force of a spindle motor 12 is transmitted to the main shaft 1. Also,
A belt (timing belt) is attached to one side of pulley 3.
10 and coupled to the pulse coder 11. This pulse coder 11, spindle motor 12, and NC device 29 constitute a main shaft orientation mechanism. A V-groove 4a is bored in the circumferential direction on one side of the gear 4, and the brake shoe 8 operated by the brake cylinder 28 is pressed here, and the main shaft is activated only when the C-axis control drive transmission system is selected. 1 to provide appropriate braking (slightly greater than the cutting resistance). A hollow hydraulic cylinder 13 is provided behind the main shaft 1, and a chuck 1a can be opened and closed to attach and detach a workpiece.

A housing 14 is attached above the headstock 2, and a C-axis control servo motor 15 is attached to the housing 14. Further, a sleeve 16 is attached to the housing 14, and a worm shaft 19 is provided with a worm 19a on the sleeve 16.
is rotatably supported. A gear 18 is fixed to one end of the worm shaft 19 and meshes with the gear 17 of the servo motor 15 so that the rotational force of the servo motor 15 is transmitted to the worm 19a.

Reference numeral 20 denotes a C-axis control rotation shaft, which is supported by the housing 14 via bearings 23 and 24 so as to be rotatable and movable in the axial direction. A helical gear 21 and a C-axis spur gear 22 are integrally attached to the rotating shaft 20, and the helical gear 21 always meshes with the worm 19a, and the C-axis spur gear 22 selectively meshes with the main shaft gear 4. ing. Rotating shaft 20
One end is rotatably connected to a piston rod 26 via a bearing 25. The piston rod 26 constitutes a cylinder-piston mechanism together with a cylinder 14a formed as a part of the housing 14. The rotating shaft 20 is shifted by the amount of movement a according to the stroke of the cylinder. Dog 26a at the rear end of the piston rod 26
By switching the limit switches 31 and 32, the forward and backward ends are detected.

Thus, C between the servo motor 15 and the main shaft 1
A drive transmission system for shaft control is constructed, and this drive transmission system is selectively connected to the main shaft 1 by a cylinder-piston mechanism.

A notch 20a is formed in a part of the rotating shaft 20, and a detector 3 such as a proximity sensor is provided in the housing 14.
0 is set. The notch 20a is the detector 30
In response to this, a home position signal is output from the detector 30 to the NC device 29, and thereafter the servo motor 15 is stopped at this position by the servo lock function, so this constitutes the home position return means of the C-axis control system. Ru.

Next, we will discuss the effect of this idea.

Rotation angle control command (C
When a shaft control command) is executed, the spindle 1 is stopped at the home position by spindle orientation, and at this position, the brake shoe 8 is pressed against the V groove 4a, and the excitation of the spindle motor 12 is released. . This completes the return of the main shaft 1 to its origin. Parallel to the return of the main shaft 1 to the origin, the C-axis return to the origin is also started. That is, the detector 30 determines whether or not the C-axis (rotary axis 20) is at the origin, and if it is not at the origin, the servo motor 15 is driven to return the C-axis to the origin.

When the return of the main shaft 1 and the C-shaft 20 to the origin is thus completed, the cylinder-piston mechanism is operated to move the piston rod 26 forward and shift the C-shaft 20 by a distance a. At this time, the helical gear 21 attached to the C-shaft 20 remains engaged with the worm 19a, and since the rotation direction of the worm 19a is fixed by the servo lock of the servo motor 15, the helical gear 21 is rotated Rotate only the corner. Since this amount of rotation occurs when the C-shaft 20 shifts, the C-shaft spur gear 22 meshes with the spur gear 4 of the main shaft 1 while rotating, causing the main shaft 1 to rotate against the brake resistance. The main shaft torsion angle during shifting can be easily calculated from the shift amount a, the helical angle α° of the helical gear 21, and the bit circle diameter D of the helical gear 21 as a x tan α°/D x π x 360°. , this may be input into the NC device 29 in advance as a correction amount.

When the C-axis connection is completed in this way, the C-axis coordinate system is commanded and a predetermined complex machining is started. As mentioned above, after the C-axis is selected, a brake resistance that is slightly larger than the cutting resistance is acting on the main shaft 1, so when the servo motor 15 rotates in one direction, the play in the gears of the drive system is pressed only in one direction, and vice versa. When it rotates, the tooth surface is pushed in the opposite direction, and the amount of backlash caused by forward and reverse rotation remains almost constant regardless of the cutting resistance, and can be corrected by NC. In this way, highly accurate rotation angle control of the main shaft 1 is possible. Also, C
When the piston rod 26 moves backward in response to the shaft release command, the main shaft spur gear 4 and the C-shaft spur gear 22 are disengaged, and the C-shaft control is released. Then, the brake shoe 8 is lowered to release the main spindle brake, and general cutting becomes possible.

In this invention, as described above, the C-axis control drive transmission system and the main shaft are each returned to their origin, so the C-axis spur gear 22 and the main shaft spur gear 4 always mesh with the same teeth, which further reduces the cutting resistance. By applying a braking force greater than (difference from the indexed position) does not change each time a selection is made. Since the indexing error is constant in this way, it is possible to set the tool offset value,
This error can be eliminated by a so-called C-axis memorized pitch correction function in which the C-axis spur gear 22 and the main shaft spur gear 4 always mesh with the same teeth.

Furthermore, according to this invention, by incorporating a helical gear into the C-axis drive system, C-axis connection can be performed while twisting the shaft, and thereby the C-axis spur gear 22 can be integrally connected to the rotating shaft 20. Summer. This means that when the C-axis is selected, the C-axis spur gear 22 moves together with the rotary shaft 20, so there is no problem of reduced accuracy due to backlash as in the conventional case, and the rotational error corresponding to the helical angle of the helical gear is Since this can be easily processed through correction, there is no problem at all in this respect.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of this invention. Second
FIG. 3 is a sectional view showing a drive transmission section for C-axis control. In the figure, 1...Main shaft, 4...Main shaft gear, 8
... Brake shoe, 12 ... Spindle motor, 15 ... Servo motor, 19 ... Worm shaft, 20 ... Rotating shaft, 20a ... Notch, 21 ...
Helical gear, 22...C-axis spur gear, 30...detector.

Claims (1)

[Scope of utility model registration request] In an NC lathe in which a spindle motor 12 and a positioning servo motor 15 are selectively coupled to the main shaft 1, a spur gear 4 attached to the main shaft 1 is used.
, a worm 19a coupled to the output side of the servo motor 15, a rotating shaft 20 that is parallel to the main shaft 1 and movable in the axial direction, and a cylinder that moves the rotating shaft 20 in the axial direction. a piston mechanism, a helical gear 21 provided on the rotating shaft 20 and constantly meshing with the worm 19a within the movement range of the rotating shaft 20, a C-axis spur gear 22 provided at the tip of the rotating shaft 20, and the main shaft. 1
and an origin return means provided on each of the rotating shafts 20, and the rotating shaft 20 is moved by the cylinder piston mechanism only at the origin of each of the main shaft 1 and the rotating shaft 20, and the C-axis spur gear 22 A main spindle positioning mechanism for an NC lathe, characterized in that the gears mesh with the spur gear 4.