JPH0445799Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This idea is related to the spindle positioning mechanism of an NC lathe.

[Conventional technology]

When performing complex machining such as drilling or milling at a predetermined location on a workpiece using an NC lathe, it is necessary to position the workpiece while controlling the rotation angle of the spindle that grips the workpiece using an NC device. Such control has conventionally been carried out, for example, in the
This is done by the method shown in Publication No. 7858.
In other words, there is a spindle drive system that is rotationally driven by a spindle motor and is suitable for general turning machining, and a drive transmission system for spindle rotation control that is driven by a servo motor and is suitable for complex machining, that is, the so-called C-axis control. When switching from general turning to complex machining, the main spindle drive system is disconnected, the C-axis control system is connected, and the main spindle is rotated by the C-axis control system. is positioned at a predetermined rotation angle.

[Problem that the invention attempts to solve]

In that case, spur gears are used in the final connection between the main shaft and the C-axis drive transmission system, but with this structure, these spur gears cannot (a) achieve a large reduction ratio, and (b) The amount of backlash between spur gears is determined by the machining accuracy of the gears and gear box and is difficult to correct. (c) There is a large amount of bump in the tangential direction of the main shaft. There were various problems such as lack of rigidity when cutting force was applied.

[Means to solve the problem]

This invention was made to solve the above-mentioned problems, and therefore, according to this invention, a rotationally driven main shaft, a main shaft braking device for regulating the rotation of the main shaft, and a servo motor for positioning the main shaft are provided. an NC comprising: a drive transmission system that selectively transmits the driving force of the servo motor to the main shaft; and a return-to-origin means provided on each of the main shaft and the drive transmission system.
In the main spindle positioning mechanism of a lathe, the final connecting part between the main shaft and the drive transmission system is comprised of a gear transmission mechanism with a large reduction ratio formed by intersecting gear shafts, and the drive transmission system is arranged in a direction parallel to the axial direction of the main shaft. The gearbox is movably supported by the gearbox, and the gearbox is moved between the gearbox and the main shaft as means for adjusting the backlash of the gear transmission mechanism when the main shaft and the drive transmission system are connected. The present invention is characterized in that an adjustment screw is provided for regulating the amount, and that the main shaft braking device is activated after the main shaft is positioned at a predetermined rotation angle by driving the servo motor.

【Example】

In the figure, 1 is a main shaft with a chuck 2 attached to its tip, and bearings 4 and 5 are mounted on the headstock 3.
It is rotatably supported by. Two gears 7 and 8 having different numbers of teeth are each integrally connected to the main shaft 1 so that the rotation speed thereof can be varied. The gears 7 and 8 selectively mesh with gears 11 and 12 attached to an intermediate transmission shaft 10 movable in a direction parallel to the main shaft 1 by a piston (not shown), respectively, and the gear 11 is a spindle for rotationally driving the main shaft 1. It is designed to mesh with a gear 16 attached to a rotating shaft 15 of a motor 14. The main shaft 1 also includes a pulley 17 attached to the rear end, a pulley 18 attached to the headstock 3,
The encoder 20 is connected to the encoder 20 by a belt 19 stretched between both pulleys 17 and 18. An NC device (not shown), a spindle motor 14, and an encoder 20 constitute a spindle orientation mechanism. A brake disk plate 24 is coupled to the rear end of the main shaft 1 and is actuated by a piston 23 that moves forward and backward as a result of switching of oil pressure by a solenoid valve 22 . The brake disc plate 24 is pressed against the headstock 3 to apply braking to the spindle 1 only when a C-axis control drive transmission system, which will be described later, is selected. Furthermore, a hollow hydraulic cylinder 2 is installed behind the main shaft 1.
5 is provided, and chuck 2 is provided depending on the operating mode.
The opening/closing drive and thus the attachment/detachment of workpieces are performed. A gearbox 27 is placed above the headstock 3. A part of the gearbox 27 is formed as a cylinder part 28, and together with a piston 29 protruding from a part of the headstock 3, it constitutes a cylinder-piston mechanism. It is adapted to shift in the axial direction by an amount of movement corresponding to the stroke of the cylinder portion 28 using a dovetail groove (not shown) as a guide. A C-axis drive transmission system is provided within the gearbox 27 and selectively connected to the main shaft 1 using a servo motor 31 for controlling the C-axis attached thereto as a drive source. When this C-axis drive transmission system is connected to the main shaft 1, the gears of this connection part are arranged so that the gear axes intersect and a large reduction ratio can be obtained so that the error of the C-axis drive transmission system is reduced on the main shaft 1. For example, a combination of a hypoid gear and a hypoid pinion. That is, the drive transmission system includes a gear 32 at the tip of a motor shaft of a servo motor 31, and a hypoid pinion 3 for C-axis control rotatably supported by a gear box 27.
4, and a spur gear train 35 disposed between them.
Further, a hypoid gear 9 that meshes with a hypoid pinion 34 is attached to the main shaft 1, and by switching the solenoid valve 30, the gear box 27 is moved backward, that is, shifted to the left in the figure, and the hypoid pinion 34 is engaged with the hypoid gear. 9, the rotational force of the servo motor 31 is transmitted to the main shaft 1. Further, as a means for adjusting the backlash of the hypoid gear 9 and the hypoid pinion 34, for example, an adjusting screw 38 is provided on the gear box 27 so as to be movable forward and backward, facing a stopper 37 provided on the headstock 3, and the screw 38 can be adjusted. By doing so, the movement of the gear box 27 with respect to the main shaft 1 is restricted, and the meshing between the hypoid gear 9 and the hypoid pinion 34 is eventually prevented.
The delay time is adjusted so that the backlash can be easily set to an appropriate value. The operation of the NC lathe configured in this way is as follows. That is, the gear box 27 is moved forward, that is, shifted to the right in the figure by switching the solenoid valve 30, and the hypoid gear 9 and the hypoid pinion 34 are disengaged, and then the main shaft 1 is moved by the NC device.
When a rotation angle control command, that is, a C-axis control command, is issued, the spindle 1 is stopped at the home position by spindle orientation, and at this position, the brake disc plate 24 is pressed against the headstock 3 by switching the solenoid valve 22. At the same time, the excitation of the spindle motor 14 is released. This completes the return of the main shaft 1 to its origin. On the other hand, parallel to the return of the main shaft 1 to the origin, the C-axis return to the origin is also started. That is, a detector (not shown) determines whether or not the hypoid pinion 34 is at the home position, and if it is not at the home position, the servo motor 3
1 to return the hypoid pinion 34 to its origin. Thereafter, the cylinder piston mechanism is actuated by switching the solenoid valve 30 to move the gear box 27 backward, shifting the hypoid pinion 34 by the aforementioned stroke and engaging it with the hypoid gear 9. Next, when the servo motor 31 is rotated according to a command from the NC device, the hypoid gear 9, that is, the main shaft 1, is rotated by a predetermined angle by the hypoid pinion 34 against the braking resistance by the brake disc plate 24, and the predetermined main shaft positioning is completed. do. In this state, the desired complex machining is started, but in that case, when tangential force acts on the spindle 1 due to cutting etc., the hydraulic pressure is increased to forcefully press the brake disc plate 24 against the headstock 3. Make sure to clamp the main shaft 1. After completion of the complex machining, when the solenoid valve 30 is switched by the C-axis control release command and the gear box 27 moves forward, the hypoid gear 9 and the hypoid pinion 34 are disengaged. Next, when the piston 23 is moved back by switching the electromagnetic valve 22 and the main shaft brake is released, a state becomes available for general cutting. In the above embodiment, a combination of the hypoid gear 9 and the hypoid pinion 34 is described as a gear with a large reduction ratio, but the combination is not limited to this as long as it is a gear other than a spur gear, and a worm and a wheel etc. A combination is also possible. Also, the screw for adjusting the backlash is attached to the gear box 27 above.
Instead, it may be provided on the headstock 3 side.

[Effect of the idea]

As is clear from the above, according to this invention, the final connecting part between the main shaft and the drive transmission system that transmits the driving force of the main shaft positioning servo motor is a gear transmission with a large reduction ratio where the gear shafts intersect. Since it is composed of a mechanism, the meshing of the same parts is smooth, the driving force of the servo motor is effectively transmitted to the main shaft, and the reduction ratio in the same part is large, so it can be used in the drive transmission system. The influence of the accuracy of other gears on the meshing accuracy of the same part is also reduced. In other words, the error of the C-axis drive transmission system is reduced on the main shaft, and the relationship between the main shaft and the drive transmission system by the gear transmission mechanism is reduced. Together with the work of the adjustment screw, which is a means of adjusting the backlash during connection, and the spindle braking device, it is possible to achieve highly accurate and stable spindle positioning, and it also provides rigidity when a large cutting force is applied in the tangential direction of the spindle. Therefore, processing quality and work efficiency in complex processing can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the spindle positioning mechanism of an NC lathe according to this invention, and FIG. 2 is an enlarged view of portion A in FIG. 1. 1... Main shaft, 7, 8, 11, 12, 16... Gear, 9... Hypoid gear, 14... Spindle motor, 17, 18... Pulley, 19... Belt, 20... Encoder, 22, 30... ... Solenoid valve, 23, 29 ... Piston, 24 ... Brake disk plate, 27 ... Gearbox, 28 ... Cylinder part, 31 ... Servo motor, 34 ... Hypoid pinion, 35 ... Spur gear train, 37 ... ...stopper, 38...adjustment screw.

Claims (1)

[Claims for Utility Model Registration] (1) A rotationally driven main shaft, a main shaft braking device for regulating the rotation of the main shaft, a servo motor for positioning the main shaft, and a driving force of the servo motor selectively applied to the main shaft. In a main spindle positioning mechanism for an NC lathe, which includes a drive transmission system for transmitting data, and origin return means provided on each of the main shaft and the drive transmission system, the final connecting portion between the main shaft and the drive transmission system is a gear shaft. comprising a gear transmission mechanism with a large reduction ratio in which the main shaft and the drive transmission system intersect, a gear box supporting the drive transmission system so as to be movable in a direction parallel to the axial direction of the main shaft; As a means for adjusting the backlash of the gear transmission mechanism when the gear transmission mechanism is connected, an adjustment screw is provided between the gearbox and the main shaft to regulate the amount of movement of the gearbox, and the main shaft is adjusted by driving the servo motor. After being positioned at the specified rotation angle,
A main spindle positioning mechanism for an NC lathe, characterized in that the main spindle braking device is activated. (2) The spindle positioning mechanism for an NC lathe according to claim 1, wherein the gear transmission mechanism is a hypoid gear.