JPH06134624A - Detecting device for spindle angle of electric discharge machine - Google Patents

Abstract

PURPOSE:To angularly position a spindle at a high accuracy in a device for detecting the indexing angle of the spindle of an electric discharge machine. CONSTITUTION:In a spindle angle detecting device for an electric discharge machine where a rotary motor 16 is connected through an insulating member and an indexing motor 18 is connected through a clutch 19 severally to a main spindle 1 having a conductive ring 11 coming into contact with a feeding brush 12 to supply interpole current, the conductive ring 11 is fixed to the upper end of the main spindle 1 borne by bearings 5, 6 in a spindle housing 2. In addition, a short cylindrical insulating member 23 is adjacently fixed to the upper side of the conductive ring 11, and the scale ring 26 of an angle detecting device 36 composed of the scale ring 26 and a detecting head 27 is fixed to the outer periphery of the insulating member 23. An absolute type device and an incremental type device with an origin detecting function device can be used as the angle detecting device 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the indexing angle of a spindle of an electric discharge machine, and more particularly to a device characterized by the mounting position of the angle detecting device.

[0002]

2. Description of the Related Art For machining a work on an electric discharge machine,
Machining performed while rotating the spindle at a medium number of revolutions using a cylindrical tool, and machining performed by fixing the spindle at a constant angle with a tool asymmetric with respect to the center of the spindle. There is. Since it is technically impossible to perform the rotation and indexing of the spindle in the both machining by the same motor, it is possible to perform accurate rotation angle control at a low speed with a rotation motor that rotates the spindle at a desired speed. It is used in combination with an indexing motor. Usually, the rotary motor is directly connected to the main spindle via an insulator, and the indexing motor is connected to the main spindle via a speed reducer and a clutch.

Conventionally, a speed control motor has been used as a rotary motor, and a servo motor or a pulse motor having a built-in rotary encoder has been used as an indexing motor. Therefore, it is necessary to index the angle of the main shaft with higher accuracy than the resolution of the rotary encoder. A speed reducer is interposed between the indexing motor and the spindle, and the indexing motor is prevented from rotating at an excessive speed and damaged during continuous rotation of the spindle. The motor is separated from the spindle.

FIG. 4 shows an example of a main spindle structure of a conventional electric discharge machine having the above-mentioned structure. The main spindle 1 is a bearing receiver 4 fixed to a main housing 2 through an insulating sleeve 3, and bearings 5 and 6 are provided. A tool holder 7 having a machining electrode attached to the lower end of the main spindle 1 is rotatably supported by an automatic tool changer or the like.

A conductive ring 1 is provided on the upper end of the main spindle 1.
1 is fixed, and a current between electrodes is supplied to the conductive ring 11 from the power feeding brush 12. A connecting shaft 13 is fixed above the conductive ring, a brake 14 for holding the angle of the main spindle is mounted on the connecting shaft, and a rotation for rotating the main spindle 1 via an insulator 15 for noise suppression. The motor 16 is connected. Encoder 17
The indexing motor 18 provided with a clutch 19 and a speed reducer 2
They are connected via 0.

In the conventional structure, when the clutch 19 is disengaged, the correlation between the detected angle of the encoder 17 and the angle of the main spindle 1 disappears. Therefore, the magnet 8 embedded in the outer periphery of the main spindle 1 and the main spindle 1 are separated from each other. Housing 2
Origin detection device 3 using lead sensor 9 fixed to
7 is provided. Since this origin detection sensor does not have high detection accuracy, a mechanical lock mechanism 40 which is more mechanical is usually provided. When indexing the spindle 1 to the machining position or tool change position, the clutch 19
After connecting, the spindle spindle 1 is temporarily returned to the phase origin detected by the origin detection device 37, and the mechanical lock mechanism 40 positions it again, and then the spindle spindle 1 is indexed with this position as the origin.

[0007]

In the conventional apparatus, when the main spindle 1 is indexed, the rotation of the indexing motor 18 is transmitted to the main spindle 1 via the speed reducer 20 and the clutch 19, but feedback is required. The output pulse of the encoder 17 used as a signal only detects the rotation angle of the indexing motor 18, and it has not been confirmed whether the indexing angle of the spindle spindle 1 has been accurately indexed as instructed. As a practical problem, backlash included in the speed reducer 20, slipping of the clutch 19, or torsional deformation of a member interposed between the encoder 17 and the spindle spindle 1 affects the indexing accuracy of the spindle spindle 1, and the spindle spindle 1 The positioning accuracy of No. 1 is reduced by an error caused by the speed reducer 20 and the clutch 19.

When the clutch 19 is disengaged, the correlation between the angle detected by the encoder 17 and the angle of the spindle spindle 1 disappears. Therefore, the origin phase of the spindle must be detected each time the clutch 19 is disengaged. , Encoder 17
Even if an absolute encoder or an encoder having a home position detection function is used, the detected value becomes completely meaningless.

As described above, in the conventional structure, even if the indexing motor 18 is accurately positioned using the high-precision encoder 17, the indexing motor 18 and the spindle spindle 1
There is a problem that the positioning accuracy of the main spindle 1 cannot be increased due to various errors that occur between and. Moreover, the origin position detection of the spindle spindle 1 must be repeated every time the clutch 19 is disengaged for tool replacement, and it is meaningless to use an absolute type or encoder with an origin detection function as the encoder 17. 1
The origin detection device 37 and the mechanical lock mechanism 40 for positioning the origin are essential. An object of the present invention is to solve such a problem, and an object thereof is to provide a technical means for angularly positioning the main spindle of the electric discharge machine with higher accuracy.

[0010]

SUMMARY OF THE INVENTION A spindle angle detecting device for an electric discharge machine according to the present invention is a power supply brush 1 for supplying a machining gap current.
Spindle spindle 1 with conductive ring 11 contacting 2
In a spindle angle detecting device of an electric discharge machine in which a rotary motor 16 is connected to the shaft via an insulator and an indexing motor 18 is connected via a clutch 19, the spindle housing 2 is axially supported by bearings 5 and 6. The conductive ring 11 is fixed to the upper end of the main spindle 1 and the cylindrical cylindrical insulator 23 is fixed to the upper side of the conductive ring 11 and the angle detection device 36 including the scale ring 26 and the detection head 27 is fixed. The scale ring 26 of the insulator 23
It is characterized in that it is fixed to the outer periphery of.
As the angle detecting device 36, an absolute type or an incremental type with an origin detecting function can be used.

[0011]

In the electric discharge machine, it is the tool that requires accurate angular positioning. Therefore, in order to prevent the intervention of various errors, it is most preferable to detect the angular position of the tool spindle mounting side end of the spindle spindle 1. However, in the electric discharge machine, a large machining current flows from the spindle spindle 1 to the tool holder 7. Therefore, when the angle detection device is provided on the spindle spindle 1, the electrical system of the angle detection device malfunctions due to noise when the machining current fluctuates. Will be caused. In particular, it is completely impossible to use an angle detection device using a magnetic scale.

In the present invention, an insulating ring 23 is provided adjacent to the opposite side of the conductive ring 11 for supplying a machining current to the main spindle 1 from the main spindle, and a scale ring 26 for detecting the main spindle angle is provided on the insulating ring. As a result, the angle of the spindle 1 is detected at the position closest to the tool holder 7 without being affected by the machining current. The insulator 23 cuts off a current that gives noise to the electrical system of the angle detection device 36, and connects the main spindle 1 to the rotary motor 16 and the indexing motor 18 via the insulator 23, so that the motor 16 , 18 is also prevented.

Further, in the apparatus of the present invention, the angle detecting device 3
Since 6 directly detects the angle of the main spindle 1,
The relative relationship between the detection value of the angle detection device 36 and the angle of the spindle spindle 1 is not lost unless the spindle spindle 1 rotates at a speed at which the detection signal of the angle detection device 36 cannot be read. . Therefore, for example, it is not necessary to return the spindle to the home position after changing the tool.
Also, if an absolute type or an incremental type with origin detection function is used as the angle detection device 36,
There is no need to install a spindle origin detection device or mechanical lock mechanism.

[0014]

1 and 2 are views showing a spindle head portion of an electric discharge machine equipped with an angle detecting device of the present invention, FIG. 1 is a schematic view, and FIG. 2 is a more specific cross-sectional view. is there. The spindle spindle 1 to which the tool holder 7 is fixed is pivotally supported by bearings 5 and 6 on a bearing receiver 4 mounted on the spindle housing 2 via an insulating sleeve 3 as in the conventional device of FIG. A conductive ring 11 made of a good conductor such as copper is fixed to the conductive ring 11 with a bolt 21, and the insulating ring 2 made of ceramics is fixed to the upper end of the conductive ring with a bolt 22.
3 is fixed.

An insulating holder 24 is provided in the main shaft housing 2 so as to surround the conductive ring 11, and the feeding brush 12 is attached to the insulating holder so as to be slidable in the radial direction and toward the conductive ring 11 by a spring (not shown). It is energized and worn. Further, a cylindrical scale ring 26 provided with a magnetic slit is fixed to the outer periphery of the insulating ring 23,
A detection head 27 for detecting the slit is fixedly provided on the spindle housing side.

A nut material 28 in the axial direction is embedded in the upper surface of the insulating ring 23, and a connecting flange 31 is fixed by a bolt 29 screwed onto the nut material 28. A thin flexible connecting disc 34 is fixed to the upper surface of the connecting flange 31 with a bolt 32, and the bolt 3 is attached to the connecting disc 34.
The connecting shaft 13 is fixed at 5. A brake 14 and a rotary motor 16 are directly connected above the connecting shaft 13, and an indexing motor 18 is further connected via a clutch 19 and a speed reducer 20.

The main body of the scale ring 26 is made of ceramic in order to insulate it from the discharge pulse given from the power feeding brush 12, and a magnetic slit showing the angular position is formed on the outer peripheral surface thereof. Further, since the angle detection device 36 uses magnetism as a detection principle, the use of a material having magnetism near the device causes a functional failure. Therefore, the detection head 27 is fixed by the insulating bracket 38. As the scale ring 26, an incremental type that does not have the same origin detection function as the conventional apparatus is used, and the spindle spindle has the same origin detection apparatus 37 as the conventional apparatus.
Although the mechanical lock mechanism 40 and the mechanical lock mechanism 40 can be provided (the same structure as in FIG. 4), the scale ring 26 can be an absolute type or an incremental type with an origin slit at one point on the circumference. The detection device 37 and the mechanical lock mechanism 40 can be omitted.

When the tool holder 7 mounted on the spindle spindle 1 is positioned from one angular position to another angular position in the spindle having the above-mentioned structure, a signal corresponding to the angle to be moved with the clutch 19 engaged is given. It is sent from the control device to the indexing motor 18, and the rotation of the indexing motor 18 is transmitted to the main spindle 1 via the reduction gear 20. At this time, the detection head 27 reads the amount of angular movement of the scale ring 26 as a pulse signal corresponding thereto, and a signal corresponding to the angle to be moved and the pulse signal read by the detection head 27 are subjected to arithmetic processing, and closed loop control is performed. Angular positioning of the spindle 1 is performed.

Whether or not the spindle spindle 1 is accurately moved to the commanded angular position depends on the amount of angular movement of the scale ring 26 which is substantially integrated with the spindle spindle 1 and is detected by the detection head 2.
Since it is confirmed by reading at 7, the speed reducer 20
It can be accurately confirmed without being affected by the backlash inherent in the vehicle and the slip of the clutch 19. Therefore, if the angle detecting device 36 detects the moving angle of the main spindle 1 with high accuracy, there is an advantage that the high angle transmission accuracy of the speed reducer or the clutch alone, which is conventionally required, is not necessarily required.

Further, in the apparatus of the present invention, since the scale ring 26 is substantially integrated with the main spindle 1, the relative angular relationship between the scale ring 26 and the main spindle 1 changes even if the clutch 16 is disengaged when the tool is changed. There is no danger, and even if an incremental type scale ring 26 is used, the clutch 1
There is no need to return the spindle spindle 1 to the origin after connecting and disconnecting 9. If indexing is required again after the main spindle 1 has been continuously rotated, the origin only needs to be indexed once. Further, by using the absolute type scale ring, the indexing angle can be read without returning the spindle 1 to the origin one by one.

As a structure for accurately setting the origin position of the main spindle 1, there is a structure using a mechanical lock mechanism. FIG. 3 schematically shows an example of a mechanical lock mechanism. A positioning pin 42 is erected in the spindle spindle 1 in the radial direction, a mechanical lock body 41 is incorporated in the spindle housing 2, and the mechanical lock body 41 has a mechanical lock body 41. Positioning pin 4 extends in the radial direction of the spindle 1
A grooved key 43 for fixing 2 is built in. The grooved key 43 slides on the mechanical lock body 41 without backlash, and is moved forward and backward by an actuator (not shown). The tip of the positioning pin 42 may be tapered, but it is effective to make it spherical when higher positioning accuracy is desired.

The grooved key 43 is used as the mechanical lock body 4
In order to make the slide in the No. 1 without any play, as shown in FIG. 3 (B), the mechanical lock body 41 is divided and a hard ball 44 is inserted between the mechanical lock body 41 and the grooved key 43 to divide the mechanical lock body 41. Key 43 with groove on Mecha Lock Body 41
Is adjusted so that the grooved key 43 can be slid smoothly without rattling, and as shown in FIG. 6C, the grooved key 43 is formed into a wedge-shaped groove. It is possible to adopt a structure in which the grooved key 43 is slidably inserted by inserting a wedge piece 46 utilizing the force of the leaf spring 45 between the body main body and the grooved key 43 as a key.

When setting the origin position of the spindle spindle 1, first the origin detector 37 is used to set the origin spindle 1.
Is roughly positioned at the origin position, the grooved key 43 is advanced and fitted into the positioning pin 42 to fix the spindle spindle 1, and in this state, the origin of the angle setting device 36 is reset.

In the electric discharge machine, the main spindle 1
Due to the property of applying a discharge pulse to the main spindle 1, the electrical equipment incorporated in the spindle 1 needs to be insulated as a measure against noise.
The use of ceramics, which is an insulator, for the body of 6 is very effective in this respect as well.

In the above embodiments, a magnetic device is used as the angle detecting device, but an optical rotary encoder can also be used. Considering the influence of the angular positioning accuracy due to the twist of the main shaft constituent member, the angle detection device must be provided at a position as close to the main spindle 1 as possible, and a hollow rotary encoder is suitable for that purpose. However, regarding the atmosphere near the angle detecting device, in the case of an optical rotary encoder, in order to avoid erroneous detection due to oil smoke or dust, it is necessary to take protective measures such as sealing the angle detecting device. On the other hand, in the case of the magnetic type, it is not necessary to take special measures against oily smoke and dust, so that there is an advantage that the angle detection device can be configured more compactly. The present invention is also effective for a spindle spindle provided with only an indexing mechanism.

[0026]

According to the present invention, since the angle of the main spindle can be confirmed by an angle detecting device which is substantially integrated with the main spindle, highly accurate angular positioning of the tool holder enables rigidity of the entire system constituting the main spindle and reduction of the speed reducer. It can be realized with high accuracy without being affected by backlash or slippage of the clutch. In addition, it is not necessary to reset the origin of the spindle when attaching or detaching the tool holder.By using the incremental angle detector or absolute type angle detector with the origin detection function, the origin detector and mechanical lock mechanism can be separated. Therefore, there is an effect that the angle of the spindle can be indexed more quickly because it is not necessary to use it for.

[Brief description of drawings]

FIG. 1 is a side view schematically showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a more detailed embodiment of a spindle housing portion.

FIG. 3 is an explanatory diagram showing an example of a mechanical lock mechanism.

FIG. 4 is a side view schematically showing a conventional structure.

[Explanation of symbols]

 1 Spindle spindle 2 Spindle housing 5 Bearing 6 Bearing 11 Conductive ring 12 Power supply brush 16 Rotary motor 18 Indexing motor 19 Clutch 23 Insulation ring 26 Scale ring 27 Detection head 36 Angle detection device 40 Mechanical lock mechanism

Claims (2)

[Claims] 1. A rotary motor (16) is connected via an insulator to a main spindle (1) having a conductive ring (11) in contact with a power supply brush (12) for supplying a current between poles, and a clutch ( In the spindle angle detection device of the electric discharge machine to which the indexing motor (18) is connected via (19), the spindle housing
A conductive ring (11) is fixed to the upper end of the main spindle (1), which is supported by bearings (5) and (6) in (2), and is adjacent to the upper side of this conductive ring (11) in a short cylindrical shape. The insulator (23) is fixed, and the scale ring (26) of the angle detection device (36) including the scale ring (26) and the detection head (27) is fixed to the outer periphery of the insulator (23). A spindle angle detection device for an electric discharge machine, characterized in that 2. The spindle angle detecting device for an electric discharge machine according to claim 1, wherein the angle detecting device (36) is an absolute angle detecting device or an incremental angle detecting device with an origin detecting function.