JP4870413B2 - Rotary table indexing device for machine tools - Google Patents

Description

The present invention relates to an indexing device for a rotary table used in a machine tool (for example, a machining center), and in particular, a stator for a motor fixed to a main body frame, and coaxially provided facing the stator. A rotor for a motor fixed to a shaft rotatably supported by a main body frame, a rotary table fixed to the shaft, and an angular position of the indexed rotary table held by a clamp member The present invention relates to a so-called motor direct drive type rotary table indexing device including a clamping device.

As an indexing device for a rotary table of a motor direct drive system, there is one described in Patent Document 1. A rotary indexing device described in Patent Literature 1 is fixed to a motor stator fixed to a casing (main body frame), a motor rotor provided on a shaft rotatably supported by the casing, and the shaft. Including an indexing table (rotating table). That is, a motor is built in the casing, and the indexing table is directly rotated by the motor shaft.

In addition, the indexing device described in Patent Document 1 is provided with a clamp device for holding the stop position (= angle position) of the indexed table. The clamp device includes a friction disk fixed to the indexing table, and a clamp piston (clamp member) disposed so as to sandwich the friction disk. According to this clamping device, by pressing the clamp piston toward the friction disk by hydraulic pressure, the friction disk is clamped (held) and locked, the indexing table is prevented from rotating, and its stop position is maintained. It becomes a state.

Another motor direct drive type rotary table indexing device is described in Patent Document 2. In the indexing device described in Patent Document 2, the clamp device has a clamp ring (clamp member) in which a clamp surface is formed on the inner periphery. The table (rotary table) has a pressure receiving surface formed on the outer periphery thereof, and the diameter of the portion forming the pressure receiving surface is set so as to have a margin for the inner peripheral surface of the clamp ring. Then, by supplying the pressure oil to the pressure receiving surface, the clamp ring is bent in the unclamping direction with respect to the table, so that the table can be rotated (indexed).

In the case of the indexing device described in Patent Document 1, for example, when the power supply to the machine tool is cut off due to the occurrence of a power failure or the like, there is a problem that the holding force by the clamping device is lost. That is, when a power failure occurs, the power supply to the machine tool is cut off, and accordingly, the power supply to the motor built in the indexing device is also cut off, so that the motor shaft can be freely rotated. In addition, since the pump that supplies pressure oil for pressing the clamp piston against the friction disk also stops operating, the force for pressing the clamp piston against the friction disk is lost, and the clamping device enters an unclamped state. .

In this state, since the rotary table can rotate freely, the rotary table is inadvertently rotated due to the gravity acting on the work on the rotary table. Depending on the rotation table and the tilt angle of the work, The problem arises that the battery collides with the base and breaks. In addition, due to inadvertent rotation of the workpiece, the workpiece collides with a tool located in the vicinity of the workpiece, causing damage to the tool. The problem of affecting

In the indexing device described in Patent Document 2, pressure oil is supplied at the time of indexing the rotary table to bend the clamp ring in the unclamping direction. In other words, the clamp ring is stopped by stopping the supply of pressure oil. However, the mechanical structure generates a holding force. Therefore, even when a power failure occurs as described above, the rotary table is not in a state where it can freely rotate, and the problem with the rotary indexing device described in Patent Document 1 does not occur. .

However, in the indexing device described in Patent Document 2, the clamp ring is bent to be in an unclamped state by supplying pressure oil between the clamp surface of the clamp ring and the pressure receiving surface of the rotary table. Even during clamping, hydraulic oil remains between the clamping surface and the pressure-receiving surface, and the frictional force is reduced due to the influence of the hydraulic oil, and the required holding force may not be stably obtained. Further, when foreign matter is mixed into the supplied pressure oil and adheres to the clamp surface or the pressure receiving surface, this also becomes a factor that the required holding force cannot be obtained. If the required holding force cannot be stably obtained in this way, the angular position of the rotary table is displaced during workpiece machining, which hinders workpiece machining accuracy.

Furthermore, in order to stably obtain the required holding force without being affected by the presence of the pressure oil as described above, the holding force by the clamp ring is made very large (that is, the clamp ring It is necessary to increase the interference fit between the clamping surface and the pressure-receiving surface of the rotary table. However, in this case, in order to bend the clamp ring that generates such a large holding force so as to be in an unclamped state, it is necessary to increase the pressure of the supplied pressure oil. As a result, the load on the pump for supplying the pressure oil increases, and the members (O-ring, oil seal, etc.) inside the indexing device are damaged.
JP-A-4-289042 JP-A-10-29125

Accordingly, an object of the present invention is to provide an indexing device for a rotary table for a machine tool, even if power supply to the device for operating the clamping member of the clamping device is cut off due to a power failure or the like. An object of the present invention is to provide an indexing device for a rotary table that can reliably hold the stop position of the table and can stably hold the stop position of the rotary table during workpiece machining.

Based on the above-described problems, the present invention is a clamp device that holds the stop position of the indexed rotary table by the clamp member, and generates a holding force by the clamp member by supplying power to the device that drives the clamp member. In the above-described rotary table indexing device having a clamping device, the holding device is different from the first holding device as the clamping device and drives the clamp member of the first holding device. And a second holding device that applies a holding force to the shaft that supports the rotary table when power supply to the device is stopped.

The above-mentioned “device for driving the clamp member” means, for example, a fluid pressure-operated brake that generates a holding force when the clamp device supplies a compressed fluid (pressure oil) as in the prior art described above. In the case of a (holding device), a device for supplying a compressed fluid (oil, air, etc.) for operating a clamp member (clamp piston, etc.) (for example, a pump, a compressor, etc.) or a supply of compressed fluid should be controlled. An electromagnetic valve provided on the compressed fluid supply line corresponds to this. Further, when the clamp device is an excitation actuated electromagnetic brake (holding device), this corresponds to an electromagnetic coil that is energized (excited) to operate the clamp member. In general, the device for supplying the compressed fluid, the electromagnetic valve, or the electromagnetic coil are all supplied with operating power from the machine tool side, so that the machine tool itself drives the clamp member. It can be said that it corresponds to.

In addition, “when power supply is stopped” to the above-described device may be considered to be the occurrence of a power failure described in the above-described conventional technology. In this case, power supply to the machine tool itself is stopped, and accordingly, power supply to the device that drives the clamp member is stopped. Also, not only when such a power failure occurs, for example, when there is a mistake in the NC control program for a machine tool, and an abnormality is found in the relationship between the operation of the machine tool and the operation of the indexing device, When an abnormality is found in the operation of the device for driving the member or the indexing device, the operator may manually stop the machine tool and the indexing device by operating the emergency stop button. This includes the case where power supply to the device that drives the clamp member is actively stopped.

According to the above-described rotary table indexing device for a machine tool according to the present invention, a clamp device that holds the stop position of the rotary table during workpiece processing in the event of a power failure or the like (hereinafter, distinguished from the second holding device). In order to maintain the stop position of the rotary table even when power supply to the device that drives the clamp member (hereinafter also referred to as “first holding device”) is stopped (hereinafter simply referred to as “power supply stop”). Because the holding device (second holding device) is provided, the rotary table does not rotate carelessly, and the workpiece, tool, or the like is not damaged.

In addition, in the present invention, the first holding device is not provided with a function of generating a holding force when power feeding is stopped as in the prior art, but the second holding device is separated from the first holding device. Since the holding device is provided, the first holding device can adopt a device that can stably generate the holding force required at the time of workpiece machining without considering the countermeasures at the time of stopping power supply. High machining of workpieces can be guaranteed.

Specifically, in the conventional rotary table indexing device, there is no technical idea that two types of clamping devices (holding devices) are provided at the same time, and only the holding position of the rotary table is held by one clamping device. Not. Therefore, conventionally, in order to cope with the power supply stop, it has only been considered that this one clamping device is configured to generate a holding force even when the power supply is stopped. However, when one clamping device is configured to generate a holding force when power supply is stopped while generating a holding force when machining a workpiece, a compressed fluid or the like as in the technique described in Patent Document 2 described above. Therefore, it is necessary to adopt a configuration in which the clamping member is displaced by moving the clamping member to bring the clamping device into an unclamped state, and conversely, this becomes a factor that hinders a stable holding force during workpiece processing. . On the other hand, in the present invention, as a countermeasure against power supply stop, a second holding device that generates a holding force only when power supply is stopped is provided separately from the first holding device that holds the stop position of the rotary table during workpiece processing. Therefore, the rotation position of the rotary table can be stably maintained with the required holding force when the workpiece is processed, and the rotary table is also stopped when the power supply to the device that drives the clamp member of the first holding device is stopped. The stop position is maintained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 and 2 show an embodiment of a rotary table indexing device according to the present invention. As shown in FIG. 1, the indexing device 1 of the present invention is processed by a main body frame 11 and a machine tool. The rotary table 12 to which the workpiece to be mounted is attached, and the spindle 13 as a shaft supported rotatably with respect to the main body frame 11 are included.

The main body frame 11 has legs 11a that can be fixed with bolts or the like at predetermined positions such as a table of a machine tool. The main body frame 11 supports the spindle 13 rotatably by a bearing (for example, a roller bearing) 62. The rotary table 12 is fixed to one end of the spindle 13 by a plurality of bolts 61 screwed on the circumference at equal pitch intervals.

The indexing device 1 is a motor direct drive system as described above, and is provided in the main body frame 11 coaxially with the motor stator 21 fixed to the main body frame 11 so as to face the stator 21. And a motor rotor 22. The rotor 22 is fitted and fixed to the spindle 13 via a sleeve 14 fixed to the spindle 13 by a plurality of bolts 64. The stator 21 and the rotor 22 constitute a motor 20 that directly drives the rotary table 12 and indexes the rotation.

The indexing device 1 also includes a rotational position detection device 40 such as an encoder that detects the rotational angle of the spindle 13. The rotational position detecting device 40 is a known device and includes a rotating portion 41 that is fixed to the spindle 13 and rotates together with the spindle 13, and a fixed portion 42 that is fixed to the disk 16. The disk 16 is assembled to the main body frame 11 by bolts 65 at a plurality of locations, and cannot rotate with respect to the frame. Accordingly, the fixed portion 42 is also fixed to the main body frame 11 so as not to rotate. In this rotational position detecting device 40, when the spindle 13 rotates, the rotating portion 41 rotates accordingly. Therefore, the fixed portion 42 electrically detects the amount of rotation and outputs a pulse signal corresponding to the amount of rotation. It is sent to a controller of a machine tool (not shown). Then, the machine tool grasps the rotation angle of the rotated spindle 13 based on the pulse signal output from the rotational position detection device 40.

Further, the indexing device 1 is supplied with a compressed fluid (for example, air, oil, etc.) as a clamping device that is a first holding device for holding the stop position of the rotary table 12 during workpiece processing. Is provided with a clamping device 30 for generating a holding force. The clamp device 30 includes a clamp ring 31 whose inner peripheral surface is a clamp surface 32. A groove 33 communicating with the compressed fluid supply passage 15 formed in the main body frame 11 is formed on the outer peripheral surface of the clamp ring 31 over the outer periphery, and this groove 33 serves as a pressurizing chamber. When the compressed fluid to be supplied is compressed air, the compressed air is supplied to the pressurizing chamber 33 via the electromagnetic on-off valve V by the compressor C which is a device for driving the clamp member as shown in the figure. Further, when the compressed fluid to be supplied is pressure oil, a pump is used instead of the illustrated compressor C, and the pump pumps up the hydraulic oil from the oil tank, and the pump compresses it and sends it as pressure oil. The pressure is supplied to the pressurizing chamber 33 through the on-off valve V.

In the clamp device 30, when the compressed fluid is supplied from the supply path 15 to the pressurizing chamber 33, the clamp ring 31 receives the pressure action of the compressed fluid and is deformed in a direction in which the inner diameter is reduced. As a result, the clamp surface 32 of the clamp ring 31 presses the pressure receiving surface 12a of the rotary table 12 facing the clamp surface 32, and the rotary table 12 is held by the frictional force between the clamp surface 32 and the pressing surface 12a. 12 and the spindle 13 are unable to rotate. Further, when the rotary table is indexed, the pressure by the pressurized fluid applied to the pressurizing chamber 33 is released, so that the clamp ring 31 returns to the original state, and the contact between the clamp surface 32 and the pressure receiving surface 12a is separated. The frictional force between the two is lost, and the rotary table 12 and the spindle 13 become rotatable.

In this way, the illustrated clamping device 30 generates a holding force when supplied with a compressed fluid, and generates a holding force with a mechanical configuration and releases the holding force as in the prior art. Therefore, since the compressed fluid is not supplied, the required holding force can be stably obtained. In addition, the pressure of the compressed fluid to be supplied is sufficient as the pressure corresponding to the required holding force, and no higher pressure is required. Therefore, the load of the apparatus for supplying the compressed fluid increases. Therefore, the members (O-ring, oil seal, etc.) inside the indexing device are not damaged.

The clamp device 30 shown in the figure is a fluid pressure-operated brake that generates a holding force by supplying a compressed fluid. In other words, the clamp device 30 can supply a compressed fluid, that is, to a device that drives a clamp member. It is a device that can generate a holding force in a state where power can be supplied. As a clamping device capable of generating a holding force in a state where power is supplied to the device for driving such a clamp member, an excitation actuation type electromagnetic brake is used instead of the fluid pressure actuation brake. It can also be adopted.

In the rotary table indexing device 1 for a machine tool as described above, the present invention includes a clamp device 50 as a second holding device, in addition to the clamp device 30 described above. The illustrated example employs a non-excitation operation type electromagnetic brake as the clamp device 50.

Although this non-excited operation type electromagnetic brake itself is known, to be described just in case, the clamp device 50 includes a field core 51 that houses an electromagnetic coil 52 therein, and screw members ( (Not shown) or the like. The magnetic armature 53 is loosely fitted to the spindle 13 so as to be movable in the axial direction of the spindle 13. The cylindrical disk 54 is formed with a polygonal hole 54a and is fitted to the outer peripheral surface of the hub 55. The cylindrical disk 54 is movable in the axial direction of the spindle 13 with respect to the hub 55, and The relative rotation is impossible.

The hub 55 is engaged with a key 13 a provided on the spindle 13 to prevent relative rotation with respect to the spindle 13, and is fixed to the other end of the spindle 13 by a stop ring 56. The side plate 57 and the armature 53 on the disc are attached to the field core 51 so as to be movable in the axial direction by means of attachment screws 66 at a plurality of locations. A collar 59 longer than the sum of the thickness dimensions of the armature 53 and the disk 54 is provided on the outer periphery of the mounting screw 66, thereby forming a magnetic gap a. The armature 53 is pressed toward the disk 54 by compression springs 51 b built in a plurality of holes 51 a formed in the field core 51, whereby a magnetic gap a is formed between the field core 51 and the armature 53. The

The electromagnetic coil 52 is always energized (excited) during the operation of the indexing device 1, and the armature 53 is attracted to the field core 51 against the spring force of the compression spring 51b. And a slight gap is formed between the disk 54 and the side plate 57, and the frictional force between them is almost zero. For this reason, the holding force with respect to the spindle 13 by this clamp apparatus 50 does not generate | occur | produce.

On the other hand, when the power supply to the machine tool is stopped due to the occurrence of a power failure or the like, the operation of the compressor C that drives the clamp ring 31 of the clamp device 30 is also stopped, and the holding force of the rotary table 12 by the clamp device 30 is lost. Is called. However, since the energization to the electromagnetic coil 52 is stopped along with the power supply stop, the electromagnetic coil 52 is brought into a non-excited state, and the armature 53 is pressed against the side plate 57 via the disk 54 by the spring force of the compression spring 51b. It is done. As a result, the disk 54 is clamped between the armature 53 and the side plate 57, and the holding force is increased by the frictional force between the armature 53 and the disk 54 and the frictional force between the disk 54 and the side plate 57. The spindle 13 is prevented from rotating, and the rotary table 12 is also prevented from rotating along with this.

As described above, in the illustrated example, even if the power supply to the device that drives the clamp member of the clamp device 30 is stopped, the clamp device 50 generates a holding force along with the spindle 13 and the rotation. The table 12 is prevented from rotating. Thereby, even if the power supply to the device that drives the clamp member of the clamp device 30 is stopped, the rotary table 12 does not rotate carelessly, and the workpiece, tool, or the like is not damaged.

Incidentally, in the clamp device 50 as the second holding device, the armature 53 and the side plate 57 correspond to a second clamp member, and the electromagnetic coil 52 corresponds to a device that drives the second clamp member. That is, the second holding device of the present invention generates a holding force by driving the clamp member when power supply to the device that drives the clamp member is stopped.

The second holding device is not limited to the non-excitation operation type electromagnetic brake having the configuration specifically described in the above embodiment, but may be of another configuration. For example, even when a non-excitation operation type electromagnetic brake is employed, it is also possible to employ a known non-excitation operation type electromagnetic brake having a configuration different from the above.

Further, as the second holding device, instead of the non-excitation operation type electromagnetic brake, the holding force is generated by a mechanical configuration as in the above-described conventional technique, and the holding force is generated by the pressure action of the compressed fluid. It is also possible to employ a clamping device of a releasing type. That is, as described above, the clamping device that releases the holding force by the pressure action of the compressed fluid cannot stably obtain the holding force required when processing the workpiece. The holding force required to hold the stop position of the table may be smaller than the holding force required at the time of machining the workpiece. Therefore, the second holding referred to in the present invention that generates the holding force only when power feeding is stopped. It can be used sufficiently as a device. As this type of clamping device, in addition to the one using the deformation of the clamping member as in the prior art described above, a member that is biased in the clamping direction by a spring or the like is compressed fluid as in the above electromagnetic brake. It is conceivable to displace in the unclamping direction by the action of pressure.

Further, in the present invention, power supply to the device that drives the clamp member of the first holding device and the device that drives the second clamp member of the second holding device inevitably stops, such as when a power failure occurs. The second clamp is not limited to the case, and when the power supply to the device that drives the clamp member of the first holding device is stopped for some reason (for example, when it is stopped by the manual operation of the operator), This includes a power supply circuit that supplies power to the device that drives the second clamp member so that the power supply to the device that drives the member is cut off.

Further, the present invention is not limited to any of the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

The side sectional view showing one embodiment of the present invention. The perspective view which shows an example of the indexing apparatus by which this invention is employ | adopted.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Indexing device 11 Main body frame 12 Rotary table 13 Spindle as shaft 15 Compressed fluid supply path 20 Motor 21 Stator 22 Rotor 30 Clamp device 31 Clamp ring 32 Clamp surface 33 Pressurizing chamber 40 Rotation position detector 50 Second holding device Clamping device 51 Field core 52 Electromagnetic coil 53 Armature 54 Disc 55 Hub 56 Stop ring 57 Side plate 59 Color

Claims (3)

A motor stator that is fixed to a main body frame and a rotor that is coaxially provided opposite to the stator and is fixed to a shaft that is rotatably supported by the main body frame. A clamping table that holds the rotary table fixed to the shaft and the indexed stop position of the rotary table by a clamping member, and is fed by the clamping member by supplying power to the device that drives the clamping member. In a rotary table indexing device for a machine tool including a clamping device that generates a holding force,
A second holding device that is different from the first holding device that is the clamping device and that generates a holding force when power supply to the device that drives the clamping member of the clamping device is stopped. ,
A rotary table indexing device for machine tools. The second holding device includes a second clamp member for holding the stop position of the rotary table, and generates a holding force when power supply to the device that drives the second clamp member is stopped. ,
The rotary table indexing device for machine tools according to claim 1. The second holding device is a non-excitation operation type electromagnetic brake.
The rotary table indexing device for machine tools according to claim 2.

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