JPH0591692A - Indexing device - Google Patents

Abstract

PURPOSE:To retard positional shift of turn table due to disturbance torque by setting the lead angle and frictional coefficient of a spiral groove made in a cam according to power transmission efficiency from a cam follower to the cam. CONSTITUTION:Holding torque of a turn table is increased even if the holding torque at the rotational position of a drive shaft 30 is constant by setting the transmission efficiency eta' at a low value. The transmission efficiency eta' is set based on the lead angle beta, frictional resistance mu and pressure angle z< of worm. On the other hand, strength of shaft is designed such that the force to be applied on the shaft of roller 51 will be within the range of elastic deformation. In other words, rotation of the turn table is retarded by taking advantage of the speed reduction ratio and the transmission efficient eta' between the drive shaft 30 and the cam follower 50. According to the invention, positional shift of turn table can be retarded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an index device which is incorporated in an automation line or the like and positions the rotary position of a turntable.

[0002]

2. Description of the Related Art Conventionally, such an index device has a structure shown in FIG. 5, for example. This device transmits the rotational power of the motor 1 to the turntable 4 through a speed reducer composed of two spur gears 2 and 3 to rotate the turntable 4. Then, the motor control unit 5
The turntable 4 is positioned by controlling the rotational position of the tool, and the component 6 is placed at the processing position.
Since power is transmitted by spur gears in this index device, the index device is configured to easily rotate when an external force is applied to either the motor side or the turntable side. Therefore, even if the turntable 4 is positioned with great care, the position will be easily displaced when an external force is applied. This becomes a particular problem in a production line or the like in which a press machine is arranged near the index device.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and it is
It is an object of the present invention to realize an index device in which a bull is less likely to be displaced due to a disturbance torque.

[0004]

The present invention is an index device having the following configuration. (1) In an indexing device that performs a positioning operation, a drive shaft connected to a direct drive motor is formed in a worm shape, and a spiral groove is formed on the peripheral surface. The cam fixed to the shaft, the cam follower that is engaged with the cam and rotates with the rotation of the cam, the turntable connected to the cam follower, and the absolute of the direct drive motor. A rotation sensor that detects the rotation position and a command value is calculated based on the table value of the cam curve table stored in the memory, and the command value is calculated based on this command value and the detection value of the rotation sensor. The direct drive motor is feedback-controlled to position the turntable, and a motor control unit is provided. The lead angle and friction coefficient of the spiral groove formed in the cam are provided. The value of the cam Index and wherein the from Orowa those set according to the power transmission efficiency to the cam. (2) The index device according to (1), wherein the drive shaft has connecting portions at both ends. (3) The rotation sensor includes a 1X resolver that detects a rotation position with a resolution of 1 / n rotation (n is an integer) and an nX resolver that detects a rotation position within the detected 1 / n rotation, and is a direct drive. The motor is connected to one end of the drive shaft, and one resolver is direct
The index device according to (2), which is connected to the drive motor, and the other resolver is connected to the other end side of the drive shaft. (4) The direct drive motor and the drive shaft are connected by a joint (1)
The described index device. (5) The origin sensor for detecting the origin of the rotational position of the turntable is provided on the turntable, and the rotation sensor is an increment type. Index device. (6) The index device according to (1), wherein the drive shaft is an output shaft.

[0005]

According to the present invention, the disturbance torque applied to the turntable is reduced by the transmission efficiency from the cam follower to the cam and the reduction ratio from the drive shaft to the cam follower. As a result, the disturbance torque transmitted to the output shaft of the motor is reduced, and the turntable is less likely to be displaced due to the disturbance torque. The transmission efficiency from the cam follower to the cam is set by the lead angle and friction coefficient of the worm cam. Also, connect a direct drive motor to either end of the drive shaft. Connection is made by joints. The rotation sensor will be an absolute type. Also, set the origin sensor on the turntable. In this case, the rotation sensor is of increment type.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Figure 1
FIG. 3 is a sectional view of the configuration of an embodiment of the present invention. In FIG. 1, 10 is an actuator, which is a combination of a direct drive motor (hereinafter referred to as DD motor) 11 and a rotation sensor such as a magnetic resolver 12.
Although this actuator is schematically shown in FIG. 1, its basic structure is similar to that of the actuator described in the specification of Japanese Patent Application No. 1-85614. That is, the actuator 10 is an outer rotor type, and the inner stator is a DD motor 11 having a hollow structure.
And the magnetic resolver 12 are attached to each other. The magnetic resolver 12 is composed of a 1X resolver and an nX resolver. The 1X resolver detects the rotational position of the DD motor 11 with a resolution of 1 / n rotation (n is an integer). The nX resolver detects the rotational position within the detected 1 / n rotation. D with these resolvers
Detect the absolute rotation position of D motor. The rotation sensor 11 is not limited to the magnetic resolver and may be an optical encoder. The rotor 13 of the actuator 10 is the connecting member 1
It is connected via 4 and 15 to the output shaft of the DD motor, ie the input shaft 16 of the indexing device. The input shaft 16 penetrates the hollow portion of the actuator. The stator 17 of the actuator 10 is fixed to the main body 21 of the transfer device via a fixing member 20.

Reference numeral 30 is a drive shaft connected to the input shaft 16 by a joint 31. The drive shaft 30 has bearings 32, 33.
It is rotatably supported by the main body 21. Drive shaft 3
Stepped portions are formed at both ends of 0, and can be connected to the actuator from either end portion. In the figure, the actuator is connected to the left end. A cover 22 is covered on the end side which is not connected. 40
Is a worm-shaped cam, and a spiral groove 41 is formed on the peripheral surface. 50 is a turn
It is a rotatable cam follower connected to a bull. 51
Are rollers arranged at a constant pitch along the outer periphery of the cam follower 50. The roller 51 is arranged with the radial direction as the central axis. The roller 51 is inserted in the groove 41 of the cam 40. The engagement state of the roller 51 and the cam 40 is shown in FIG. With this engagement, when the drive shaft 30 makes one rotation, the cam follower 50 is rotated by one pitch of the roller 51. As a result, the reduction ratio from the drive shaft 30 to the cam follower 51 becomes 1/8. Returning to FIG. 1, reference numeral 60 denotes a motor control unit, which obtains a command value from the table value of the cam curve table stored in the memory, and based on this command value and the detected value of the magnetic resolver 12. Feedback control of the DD motor 11 is performed to position the rotation position of the turntable.

FIG. 3 is an external view of the index device of FIG. In FIG. 3, 70 is a turntable.

Here, the power transmission by the cam 40 will be specifically described. "University Course Mechanical Element Design Kuranishi,
Sotogi, Kageyama, Sugimura Ohmsha ", page 52-5
An explanation will be given based on the description of "9.7 Worm Gear" on page 6. In the apparatus of FIG. 1, the cam 40 is mechanically equivalent to a worm, and the cam follower 50 is a worm wheel that meshes with the worm. A worm gear consisting of a worm and a worm wheel is usually used to rotate the worm gear around the worm. However, sometimes the worm is used as a spindle to rotate the worm. The transmission efficiency η'of the worm gear when used in this way is as follows. η ′ = tan (β−φ) / tanβ (1) β: worm advance angle, φ: friction angle, tanφ = μ / c
os α μ: Coefficient of friction of the contact surface between the worm and the worm wheel α: Pressure angle of the cross section of the teeth of the worm wheel at a right angle Here, when torque is applied to the turntable, drive The torque transmitted to the shaft 30 is (torque applied to the turntable) x (transmission efficiency η ').
X (reduction ratio from the drive shaft 30 to the cam follower 50). This means that the torque transmitted to the drive shaft 30 is small even if a large torque is applied to the turntable. From this, (Turntable holding torque) x (Transmission efficiency η ') x
(Reduction ratio from drive shaft 30 to cam follower 50) = (holding torque of drive shaft 30) In the present invention, paying attention to this point, by making the transmission efficiency η ′ a small value, the holding torque of the turntable becomes large even if the holding torque at the rotational position of the drive shaft 30 is constant. I have to. The transmission efficiency η'is set by the values of the worm advance angle β, the friction coefficient μ and the pressure angle α. As a condition for satisfying the expression (1), the strength of the shaft is designed so that the force applied to the shaft of the roller 51 is within the elastic deformation range. As described above, the reduction ratio of the drive shaft 30 to the cam follower 50 and the transmission efficiency η'are used to make the turntable hard to rotate. by this,
Prevents misalignment of the turntable.

On the other hand, the transmission efficiency η when the worm wheel is rotated about the worm as the spindle is given by η = tan β / tan (β + φ) (2), so that the transmission efficiency η'is reduced. However, the transmission efficiency η is not impaired. As a result, the power transmission efficiency from the DD motor to the turntable does not deteriorate.

Next, the structure of the motor controller 60 will be described. FIG. 4 is a diagram showing a specific configuration example of the motor control unit 60. In the figure, U is an electronic index unit that controls the feedback of the motor, and C is an upper controller that controls the electronic index unit U. L is the target
This is the load required to rotate the table. The magnetic resolver 12 comprises the 1X resolver 121 and the nX resolver 122 as described above. In the electronic index unit U, 612 is an encoder interface unit (hereinafter, the interface is I / F) connected to the magnetic resolver 12.
613 is an absolute position detector for detecting the absolute position from the detection signal taken out through the encoder I / F unit 612. Reference numeral 614 designates the DD motor 11 as a feedback signal using the detection signal of the absolute position detector 613 as a feedback signal.
The position control unit 615 for dubbing control, the position control unit 61
The signal from 4 is the speed command signal, and the encoder I / F unit 61
Signal from 2 is used as feedback signal for DD motor 1
1 is a speed control unit for feedback controlling the rotation speed of 1. Reference numeral 616 is a torque limiter that limits the output torque of the DD motor 11, and reference numeral 617 is a current detector that detects the current flowing through the coil of the DD motor 11. In this example, D
Since the D motor 11 is a three-phase motor, when the exciting currents of the coils of the two phases are detected by the two current detectors, the exciting currents of the coils of the other phases can also be detected. 618 is a DD monitor that uses the detection current of the current detector 617 as a feedback signal.
This is a current control unit for feedback controlling the exciting current of the coil of the switch 11. A cam curve table storage unit 619 stores the cam curve table and the number of divisions. Here, the cam curve is, for example, the time on the horizontal axis and the displacement, speed, and acceleration generated by the rotation of the cam on the vertical axis. The cam curve table storage unit 619 stores a plurality of types of cam curves. An event management unit 620 is provided between the upper controller C and the position control unit 614.
It starts, stops, receives and generates synchronization signals. Here, the synchronization signal is generated to drive the motor control unit 60 and the other power source in synchronism with each other when there is another power source in addition to the motor control unit 60. It is a signal. 621 is A
It is a power supply unit to which C100V or AC200V is input and which supplies power to each unit of the electronic index unit U. Reference numeral 622 is a clamp that holds the rotational position of the motor when it is stopped in response to an on / off signal from the event management unit 620. In the upper controller C, 630 is a
Di / Do line (D
An activation signal is given to the event management unit 620 via the ATA in / DATA out line) 631 and a synchronization signal is received from the event management unit 620. 632 is a teaching box using a personal computer, for example, RS2
The cam curve table is written in the cam curve table storage unit 619 via the 32C communication line 633, and an activation signal is given to the event management unit 620.

The operation of such a motor control unit 60 will be described. (1) Preparation Operation When the operation pattern of the load L is determined, the cam curve table and the division number are stored in the cam curve table storage unit 619 by the teaching box 632. In a special case, when the motor is positioned at a certain rotational position and it is necessary to output a synchronizing signal to the outside, this is designated by the teaching box 632. In addition, if the load operation is switched to multiple types during use,
Set the table for all required cam curves. These cam curves are managed in the electronic index unit by cam number.

(2) Operation during use When the motor start command is received from the sequencer 630 or the teaching box 632, the event management section 620.
Moves the table value of the cam curve specified at that time to the position control unit 614, and the position control unit 614 sets the transferred table value to the command value and sets the DD motor 11 to the positioning file. Dodge control. When the motor is positioned at the predetermined position, the event management unit 620 detects it by the detection signal from the absolute position detector 613, and outputs it to the host controller C if requested. Generally, the above operation is repeated. When it is desired to switch the cam curve, the clamp attached to the DD motor 11 which gives a switching instruction through the sequencer 630 or the teaching box 632 while the motor is stopped is a motor. Holds rotational position when stopped.

In the embodiment, the actuator 10 is 1
Although the case where the X resolver and the nX resolver are built in has been described, the right end of the drive shaft 30 is not used as shown in FIG. 1, so one of the 1X resolver and the nX resolver may be attached to this portion. Also, turntable 70
An origin sensor that detects the origin of the turn position of the turntable may be installed above. In this case, the magnetic resolver 12
Should be of the incremental type. Also, the drive shaft 30
Since the right end of is not used, the drive shaft 30 may be the output shaft of the index device.

[0015]

According to the present invention, the following effects can be obtained. When disturbance torque is applied to the turntable 70,
The torque transmitted to the drive shaft 30 is (transmission efficiency η ′) ×
(Reduction ratio from the drive shaft 30 to the cam follower 50). That is, even if the disturbance torque is applied to the turntable, the torque is reduced during transmission to the output shaft of the DD motor. As a result, the output torque of the DD motor is less likely to rotate due to the disturbance torque, and the position displacement of the turntable is less likely to occur. In the present invention, the holding force of the turntable can be arbitrarily set by selecting the lead angle and friction coefficient of the worm gear including the cam 40 and the cam follower 50. Cam curve table written in the cam curve table memory
Since the rotation of the motor is controlled using the bull value as a command value, the design and manufacture of a cam such as a device using a cam mechanism becomes unnecessary. That is, in the present invention, since the computerized cam is used instead of the cam as the machine, the cam curve can be easily changed. This can shorten the development period of the device. Since an electronic cam is used, it is possible to easily connect a host controller such as a sequencer or a teaching box to give a signal. Since both sides of the drive shaft 30 are connectable, the actuator can be attached from either side of the drive shaft 30. As a result, the shape of the index device can be flexibly changed according to the layout of the production line. A magnetic resolver may be connected to the end of the drive shaft that is not used. Since the drive shaft and the output shaft of the motor are connected by a joint, the motor can be easily changed according to the load applied to the drive shaft. If the origin sensor is installed on the turntable, the magnetic resolver may be of the incremental type.

[Brief description of drawings]

FIG. 1 is a configuration cross-sectional view of an embodiment of the present invention.

FIG. 2 is a configuration diagram of main parts of the apparatus of FIG.

FIG. 3 is an external view of the index device of FIG.

4 is a main part configuration diagram of the apparatus of FIG. 1. FIG.

FIG. 5 is a diagram showing a configuration example of a conventional index device.

[Explanation of symbols]

 11 DD motor 12 Magnetic resolver 30 Drive shaft 31 Junit 40 Cam 41 Groove 50 Cam follower 60 Motor control unit 619 Cam curve table Storage unit 70 Turn table

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hisao Takagi 3030 Kamiyori, Atsugi-shi, Kanagawa Okubo Dental Industry Co., Ltd. (72) Inventor Yasuhiko Muramatsu 3176, Motooshima, Matsukawa-cho, Shimoina-gun, Nagano Prefecture In-house (72) Yutaka Ono 3176 25, Motooshima, Matsukawa-cho, Shimoina-gun, Nagano Yokogawa Precision Co., Ltd. (72) Inventor Koichi Sato 3176, Motooshima, Matsukawa-cho, Shimoina-gun, Nagano 25 Yokogawa Precision Co., Ltd.

Claims (6)

[Claims] 1. An indexing device for positioning operation, comprising: a drive shaft connected to a direct drive motor; and a worm-shaped drive shaft, wherein a spiral groove is formed on a peripheral surface of the drive shaft. A cam fixed to the drive shaft, a cam follower engaged with the cam and rotating with the rotation of the cam, a turntable connected to the cam follower, and the direct drive motor. Of the cam curve table stored in the memory and the rotation sensor that detects the absolute rotational position of the command value is calculated based on this command value and the value detected by the rotation sensor. And a motor control unit that controls the direct drive motor for feedback and positions the turntable, and a lead angle of a spiral groove formed in the cam. Value of friction coefficient , Index and wherein the from the cam follower is obtained is set according to the power transmission efficiency to the cam. 2. The index device according to claim 1, wherein the drive shaft has connecting portions at both ends. 3. The rotation sensor comprises a 1X resolver for detecting a rotation position with a resolution of 1 / n rotation (n is an integer) and an nX resolver for detecting a rotation position within the detected 1 / n rotation. .The drive motor is connected to one end of the drive shaft, one resolver is connected to the direct drive motor, and the other resolver is connected to the other end of the drive shaft The index device according to claim 2. 4. The index device according to claim 1, wherein the direct drive motor and the drive shaft are connected by a joint. 5. An origin sensor for detecting the origin of the rotational position of the turntable is provided on the turntable, and the rotation sensor is of an increment type. The described index device. 6. The index device according to claim 1, wherein the drive shaft is an output shaft.