JPH0590386A - Conveyor - Google Patents

Abstract

PURPOSE:To reduce the vibration and impact to be applied to a material to be conveyed and to allow a stepout to scarcely occur in a motor by coupling moving elements by using two linear motors, performing a conveying operation by the motor for driving based on a cam curve and controlling to feed back the motor for generating a conveying power. CONSTITUTION:When an article is picked up by a conveyor, conveyed to a target position and positioned, a direct drive motor is driven by motor controllers 2, 3 for controlling to feed back based on a cam curve, and a drive shaft 4 is rotatably and linearly moved. The shaft 4 is then secured to the stator 51 of a first linear motor 5. Further, the moving element 52 of the motor 5 is coupled to the moving element 61 of a second linear motor 6, and conveyed by the motion of the stator 62 of the motor 6 becoming movable. Thus, a vibration and an impact to be applied to a material to be conveyed are reduced, and even if the weight of the material to be conveyed is increased, the motor is scarcely stepped out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a transfer device used for transferring semiconductor wafers.

[0002]

2. Description of the Related Art A semiconductor wafer transfer apparatus is an apparatus for transferring a wafer in a semiconductor process step. Conventionally, as such a semiconductor wafer transfer device, there has been, for example, a combination of a stepping motor for performing open loop control and a link mechanism. However, recently, in addition to 6-inch size wafers, 8-inch size wafers have been widely used. 8
The inch wafer has a thickness equal to that of the 6 inch wafer, and has a large area of the substrate surface. Therefore, 8
Inch wafers are more fragile than 6-inch wafers. For this reason, when an 8-inch wafer is transferred by a transfer device using a conventional stepping motor and a link mechanism, the wafer is destroyed due to vibrations generated during transfer or shocks given to the wafer when the transfer is stopped. It may happen. Also, with the open loop control that positions the transfer position by applying a pulse to the stepping motor, if an 8-inch wafer is transferred, an excessive load is applied to the motor, causing step out. is there. Since many of the ICs formed on the wafer are custom-made or highly integrated and are becoming expensive, when the wafer is broken, the damage caused by it is also large.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the vibration and impact applied to a conveyed product are small, and even when the weight of the conveyed product is increased, The purpose of the present invention is to realize a transfer device that is less likely to lose step-out on a computer.

[0004]

SUMMARY OF THE INVENTION According to the present invention, in a carrying device for picking up an object, carrying it to a target position and positioning it, a direct drive motor is driven to cause a drive shaft to perform a rotational motion and a rectilinear motion. A command value is calculated based on the table value of the cam curve table stored in the axis drive unit and the storage unit, and the direct drive motor is fed back based on the calculated command value. A motor control unit for controlling, a first linear motor having a stator fixed to the drive shaft, a mover connected to the mover of the first linear motor, and the stator is movable. A second linear motor, and a linear motor control unit for controlling the first and second linear motors, and the conveying operation is performed by the movement of the stator of the second linear motor. A transport device characterized by performing .

[0005]

According to the present invention as described above, the stator of the second linear motor is moved up and down and rotated by the drive shaft driven based on the cam curve. Further, this stator is moved laterally by the first and second linear motors. The transport operation is performed by such movement of the stator.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Figure 1
FIG. 1 is a configuration diagram of an embodiment of the present invention. In FIG. 1, 1
Is a shaft drive unit for causing the output shaft 13 to perform rotational movement and rectilinear movement by actuators 11 and 12 using a direct drive motor (hereinafter, referred to as DD motor). Reference numerals 2 and 3 are motor control units for controlling the feedback of the DD motor using the cam curve. Reference numeral 4 is a drive shaft connected to the output shaft 13, and reference numeral 41 is a support member into which the drive shaft 4 is inserted and which supports the drive shaft 4 so as not to incline.
Reference numerals 5 and 6 are linear motors. The stator 51 of the linear motor 5 is fixed to the drive shaft 4. Linear motor 6
The mover 61 is connected to the mover 52 of the linear motor 5, and the stator 62 is movable on the mover 61. A hand or the like for grasping a conveyed object is attached to the movable stator 62. Reference numeral 42 denotes a guide member, which is engaged with the stator 51 at the guide groove 43,
Guide the movement of 1. The structure of the engaging portion is shown in FIG.
As shown in FIG. 2, the engaging member 5 fixed to the stator 51
3 is inserted in the guide groove 43. And the stator 5
When 1 moves in the direction orthogonal to the paper surface, the engagement member 53 moves along the guide groove 43 and guides the movement of the stator 51. These linear motors 5 and 6 are pulse motors. Reference numerals 7 and 8 are linear motor control units for feedback controlling the linear motors 5 and 6. In such a carrying device, the stator 62 performs a lifting operation and a rotating operation by a drive shaft driven based on a cam curve. Further, the stator 62 is moved laterally by the linear motors 5 and 6. A robot hand is attached to the stator 62 performing such an operation, and the movement of the robot hand and the stator picks up and conveys the wafer to position it at the processing position.

Now, the structure of the shaft drive unit 1 will be described. FIG. 3 is a diagram showing a specific configuration example of the shaft drive unit 1. In FIG. 3, the actuator 11 is basically the same in structure as the actuator described in the specification of Japanese Patent Application No. 1-35079. That is, the actuator 11 comprises a motor section 111, a sensor section 112 using a magnetic resolver, and a bearing 113 common to these, a rotor 114 on the outer side, and a stator 11 on the inner side.
It is 5. The rotor 114 is a motor unit 111 and the rotor of the sensor unit 112 are connected to each other, and the stator 115 is a stator of the motor unit 111 and the sensor unit 112.
It is a combination of data. The actuator 12 also has the same structure as the actuator 11. 13-1
Reference numerals 6 and 161 denote casings that support the actuators 11 and 12 and integrate the two actuators.
The two integrated actuators are arranged with their central axes aligned. Reference numeral 17 is a connecting member connected to the rotor 114 of the actuator 11. Reference numeral 18 denotes a linear bearing, which supports a rotary shaft 19 housed in the hollow portion of the actuator 11. The rotary shaft 19 is connected to the connecting member 17 in the rotating direction by the linear bearing 18 and is supported so as to be movable in the axial direction. The linear bearing 18 is a ball spline nut, and includes a spline shaft 181 and a spline nut 182. FIG. 4 is a radial cross-sectional view of the ball spline nut. The upper end of the rotary shaft 19 is a spline shaft 181, and a ball 183 is housed in a recess formed between the spline shaft 181 and the spline nut 182. The ball 183 is a shaft of the spline shaft 181. Are arranged in the direction. The ball 183 causes the spline shaft 181 to rotate together with the spline nut 182 and is movable in the axial direction. The spline nut 182 is fixed to the connecting member 17.

Returning to FIG. 3, 130 is the actuator 1.
2 is a connecting member connected to the rotor 124, 131 is a nut member that is internally threaded and is connected to the connecting member 130, and 132 is a straight shaft that is externally threaded and is screwed into the nut member 131. Is. The linear shaft 132 is housed in the hollow portion of the actuator 12. Reference numeral 140 denotes a connecting mechanism that connects the rotating shaft 19 and the rectilinear shaft 132. In the connecting mechanism 140, 141 is a cylindrical member having one end opened, and is fixed to the lower end of the rotary shaft 19. 142
Is a ball bearing housed in the cylindrical member 141. Straight axis 1
32 is rotatably supported by the cylindrical member 141 by a ball bearing 142. With the connecting mechanism having such a configuration, the rectilinear movement of the rectilinear shaft 132 is transmitted to the rotary shaft 19, but the rotational movement of the rotary shaft 19 is not transmitted to the rectilinear shaft 132.

When the actuator 11 is rotated in the shaft driving section having such a structure, the rotary motion is generated by the connecting member 1.
7, transmitted to the rotary shaft 19 via the linear bearing 18, and the output shaft 13 performs rotary motion. Even if the rotary shaft 19 rotates, the connecting mechanism 140 does not transmit the rotary motion to the linear shaft 132. As a result, the rectilinear shaft 132 does not move in the axial direction due to the rotation of the rotary shaft 19. On the other hand, when the actuator 12 rotates, the rotation motion is the nut member 1.
The linear movement is converted by the screw mechanism composed of 31 and the linear movement shaft 132, and the linear movement shaft 132 performs the linear movement. This linear movement is transmitted to the rotary shaft 19 via the connecting mechanism 140. Since the rotary shaft 19 is held by the linear bearing 18 so as to be movable in the axial direction, the rotary shaft 19 makes a linear motion by the transmitted power in the linear direction. As a result, the output shaft 13 moves straight. Such rotary motion and linear motion are separately driven actuators 11 and 12
Independently.

FIG. 5 is a diagram showing the movement of the shaft drive unit.
When the actuator 11 rotates, the output shaft 13 rotates as shown in FIG. 5 (a). When the actuator 12 rotates, the output shaft 13 moves straight as shown in FIG. 5 (b). When both actuators 11 and 12 rotate, the output shaft 13 moves in a straight direction while rotating, as shown in FIG. 5 (c).

Next, the structure of the motor controller 2 will be described.
FIG. 6 is a diagram showing a specific configuration example of the motor control unit 2. In FIG. 6, reference numeral 210 is a keyboard 220 for inputting the moving distance (stroke) and moving time of the motor drive object and the data of the type of cam curve table described later.
Receives the input of the keyboard 210 and responds to this input.
A data input unit 230 for outputting a command is a non-volatile memory in which the NC command from the data input unit 220 is stored. An interpreter 240 sequentially fetches NC commands from the memory 230 and executes them. A cam curve memory 250 is provided with a plurality of types of cam curve tables 2501 to 250n. Here, the cam curve table is a table in which the rotational displacement of the motor and the data in which the time is made dimensionless correspond to each other. A cam curve command unit 260 selects one of the cam curve tables 250 1 to 250 n from the data of the kind of cam curve given from the interpreter 240, and selects the selected cam curve table. With reference to this command, a command value that satisfies the stroke and travel time given by the interpreter 240 is calculated. A positioning servo driver 270 controls the DD motor 111 based on the command value calculated by the cam curve command unit 260 so that the motor rotational position matches the command value. Here, DD mode
The data 111 is a DD motor in the actuator 11.

The operation of the motor control unit thus constructed will be described. Data input section 220 by means of keyboard 210
The NC command is written in the memory 230 via. The interpreter 240 sequentially fetches NC commands from the memory 230 and executes them. When issuing a motor operation command,
The interpreter 240 instructs the cam curve command unit 250 to read stroke, movement time, and cam curve table types.
The timer 41 is used to sample every time τ. As shown in FIG. 7, the cam curve is a graph showing the relationship between the rotational displacement of the motor and the time-dimensionalized data at each constant time ΔT. As shown in FIG. 8, the cam curve table includes data in which the data of the cam curve is associated with each time ΔT, the reciprocal 1 / ΔT of the pitch of the table, and the dimensionless maximum velocity Vm. , The dimensionless maximum acceleration Am is stored.

The cam curve command unit 260 is activated by the timer 41 every τ seconds. The operation of the cam curve command unit 260 will be described with reference to the time chart of FIG. In FIG. 9, first, the process A
The moving real time Rt is updated by 1, and then the process A2
The time updated by is converted into the dimensionless time T. next,
In the process A3, the dimensionless time T to the index in the cam curve table (corresponding dimensionless time in the table) ΔT
Find n. In step A4, the dimensionless displacement S is obtained by the interpolation calculation given by the following equation using the data of the cam curve table.

## EQU00001 ## S (.DELTA.Tn): value of S at time .DELTA.Tn S (.DELTA.Tn + 1): value of S at time .DELTA.Tn + 1 Then, the dimensionless displacement S is converted to the actual displacement s in process A5. Then, in process A6, the actual displacement s is sent to the driver as a command signal. Next, when T ≧ 1 in the process A7, the process of the cam curve command unit 260 is ended, and when it is not the case, the process from A1 is repeated again. The interpreter 240
Means may be provided to check the maximum speed of the motor. That is, it is possible to provide a means for taking an error when the maximum speed V 0 becomes V 0 ≦ (h / tn) · Vm. Mor
The motor control unit 3 also has the same configuration as the motor control unit 2.

The linear motor control units 7 and 8 position the linear motors 5 and 6 by feedback control. This control unit has, for example, the configuration described in the application specification of Japanese Patent Application No. 2-248216 by the present applicant.

[0015]

According to the present invention, the following effects can be obtained. Since the carrying operation is performed by the motor driven based on the cam curve, the carrying operation is smooth. As a result, it is possible to reduce the vibration applied to the transported object during the transportation and the impact applied to the transported object when the transportation is stopped, and it is also possible to transport the fragile 8-inch wafer. Since the motor that generates the transportation power is feedback controlled, even if the weight of the transported object increases, the motor will not be overloaded. This prevents out-of-step of the motor and ensures stable operation. From this,
It can easily handle the transfer of 8-inch wafers. Since the two linear motors connecting the moving elements are used, the stator 62 changes from the state shown in FIG.
It is possible to move to the state shown in. As a result, the moving range of the stator can be widened without increasing the width of the device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

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

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

FIG. 4 is a radial cross-sectional view of the ball spline nut shown in FIG.

5 is an operation explanatory view of the apparatus of FIG.

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

FIG. 7 is an operation explanatory diagram of the apparatus of FIG.

FIG. 8 is an operation explanatory diagram of the apparatus in FIG.

9 is an explanatory view of the operation of the apparatus of FIG.

FIG. 10 is a diagram showing a position taken by the stator shown in FIG.

11 is a diagram showing a position taken by the stator shown in FIG.

[Explanation of symbols]

 1 Axis drive unit 2,3 Motor control unit 4 Drive shaft 5,6 Linear motor 51,62 Stator 52,61 Mover 7,8 Linear motor control unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeru Mizunuma 133, Bodhi, Hadano-shi, Kanagawa 16 Global Machinery Co., Ltd. (72) Inventor, Yasuhiko Muramatsu 3176 25, Motooshima, Matsukawa-cho, Shimoina-gun, Nagano Yokogawa Within Precision Co., Ltd. (72) Inventor Hideo Manzai 3176-2 Motooshima, Matsukawa-cho, Shimoina-gun, Nagano 25 Yokogawa Precision Co., Ltd.

Claims (1)

[Claims] 1. A transport device for picking up an object, carrying it to a target position and positioning it, a shaft drive part for driving a direct drive motor to rotate and drive a drive shaft, and a storage part. A motor control unit that calculates a command value based on the stored cam curve table table value and performs feedback control of the direct drive motor based on the calculated command value. A first linear motor having a stator fixed to the drive shaft, and a slider connected to the slider of the first linear motor,
The stator has a movable second linear motor, and a linear motor for controlling the first and second linear motors.
And a controller for controlling the movement of the stator of the second linear motor.