JP2547851B2 - Transfer device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device for transferring an object to be transferred in a production line or the like, and more particularly to one using a linear motor.

(Prior Art) Recently, in a production line of a production factory, it has been desired to quickly and quietly convey an object to be conveyed from the viewpoint of improving production efficiency or improving a working environment. As such a conveying device, one using a linear induction motor including a linear motor coil and a reaction member is known. As shown in FIG. 9, a conveyance device using this linear induction motor has one of linear motor coils b, b, ... And reaction member c (linear motor coil b,
b) are arranged along a roller conveyor e composed of a plurality of rollers d, d, ... As a stator, and the other (reaction member c in the figure) is used as a movable member to attach a member g to a pallet f which is a conveyed object. , And the thrust F generated in the mover (reaction member c) by the electromagnetic action between the linear motor coils b, b, ... And the reaction member c.
Thus, the pallet f and the one placed on the pallet f are conveyed via the mover (reaction member c). In a transfer device using a linear induction motor of this type, a controller is usually provided corresponding to the linear induction motor a of each work station, and when a pallet f is transferred between adjacent stations, each station. The conveyance speed of the pallet f detected by the encoder provided for each is input to the controller, and the linear induction motor a by the controller is input.
It is used for the operation control of.

Further, Japanese Patent Laid-Open No. 55-86307 discloses a direct drive type direct current drive system using gears or the like in order to accurately stop an object to be conveyed at a predetermined position of each station in a conveyance device using a linear induction motor. Equipped with a rotary induction motor, which is a rotary motor, stops the drive of the linear induction motor when the transported object approaches each station and switches to the driving of the rotary induction motor to stop the transported object at each station. It is disclosed to carry to.

(Problems to be Solved by the Invention) By the way, when the thrust-speed characteristics of the linear induction motor and the rotary induction motor are compared, as shown in FIG. A large thrust is generated, and the rotary induction motor generates a large thrust (torque) in a high speed region. From this, as a driving means of the transfer device, a rotary induction motor with high positioning accuracy and a linear induction motor that generates a large thrust at the time of start-up are used in a low speed region such as an acceleration region that requires acceleration in the initial stage of transfer. It is desirable to use them together.

However, if the linear induction motor and the rotary induction motor are used together in the low speed region (acceleration region) as described above, the position control system of the linear induction motor presses the encoder against the conveyed object via the roller to reduce the displacement amount. Since it is an "open loop" that captures indirectly, it is difficult to obtain accuracy and stability as compared with a rotary induction motor control system that directly captures the displacement amount of the transported object. For this reason, the characteristic of the set speed with respect to time of the linear induction motor that generates a large thrust at the time of acceleration (low speed) may be higher than the characteristic of the set speed with respect to time of the rotary induction motor. In this case, a braking phenomenon (internal power generation) by the rotary induction motor occurs, and the control may become unstable because the linear induction motor tries to prevent acceleration.

The present invention has been made in view of the above points, and an object thereof is to set the speed based on the characteristics of a linear induction motor that generates a large thrust at a low speed.
It is intended to prevent the braking phenomenon by the rotary induction motor in the acceleration region by effectively setting the characteristic of the set speed with respect to time of the rotary induction motor. Another object is to prevent a slip between a set speed and an actual speed by a rotary induction motor having a small thrust at a low speed.

(Means for Solving the Problems) In order to achieve the above object, the solution means of the present invention is a linear induction motor unit having a linear motor coil and a reaction member at each station of a line having a plurality of stations as a transfer device. (Linear induction motor) and a rotary induction motor are provided respectively, one of the linear motor coil and the reaction member is mounted on a stator disposed between adjacent stations, and the other is mounted on the linear motor coil and reaction. The rotary induction motor is constituted by moving elements provided on the side of the transported object so as to transport the transported object by the thrust generated by the electromagnetic action between the members, while the rotary induction motor is rotated by the rotational force of the rotary induction motor. Is connected to a gear mechanism that converts a linear motion of the transported object in the transport direction. Then, a conveyance state detection means for detecting a conveyance state of the conveyed object between the adjacent stations, and an output of the conveyance state detection means, and in the acceleration region in the initial stage of conveyance, the linear induction motor unit and the rotary induction motor. So that the object to be transported is driven by
The characteristic of the set speed with respect to time of the rotary induction motor is set to be higher than the characteristic of the set speed with respect to time of the linear induction motor unit such that the difference in the characteristic values gradually increases from the low speed side to the high speed side. And a control means.

(Operation) With the above configuration, in the transporting apparatus of the present invention, when transporting an object to be transported between adjacent stations, based on the transport state detected by the transport state detecting unit, under the control of the control unit. In the acceleration region in the initial stage of conveyance, conveyance is performed by driving the linear induction motor unit and the rotary induction motor.

In that case, the characteristic of the set speed with respect to time of the rotary induction motor is set higher than the characteristic of the set speed with respect to time of the linear induction motor unit so that the difference in the characteristic values gradually increases from the low speed side to the high speed side. Therefore, even if the linear induction motor unit and the rotary induction motor are used together in the acceleration region (low speed region), the thrust of the linear induction motor unit does not exceed the thrust of the rotary induction motor, and at low speed (starting The thrust of the rotary induction motor is effectively assisted by the linear induction motor unit that generates a large thrust at low speed, and a braking phenomenon (internal power generation) by the rotary induction motor occurs in the acceleration region. There is nothing to do.

Moreover, if a linear induction motor unit and a rotary induction motor having different characteristics of set speed with respect to time are used together as described above, the linear induction motor unit with large thrust assists the rotary induction motor with small thrust at startup. As a result, the slip of the rotary induction motor, which is likely to occur due to the difference between the set speed and the actual speed due to the small thrust in the low speed region, is prevented.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIGS. 1 to 3 show a case where a carrier A is applied to a vehicle assembly line as one embodiment of the present invention. The carrier A has a pallet P as a material to be carried, and a body B on the pallet P. Work stations ST _{1 to} S adjacent to each other when placed
Transport between T ₂ (only two of them are shown in the figure) within a fixed time. The pallet P is supported by a roller conveyor 3 composed of a large number of rollers 2, 2, ..., which are rotatably attached to supporting members 1, 1 on both sides of the conveyor line, and is conveyed while sliding on the roller conveyor 3. It is supposed to be done.

Inside the both supporting members 1, 1, for example, two stators composed of a large number of linear motor coils 10, 10, ... (One side) as stators formed by winding an excitation coil around a comb-shaped iron core. Rows 11 and 11 are juxtaposed. Two guide rails 12, 12 extending in the transport direction are arranged on both sides of each stator row 11, and guide a reaction member 14 (other side) described later along each stator row 11. ing.

A first plate 13 is movably engaged with the guide rails 12, 12 on both sides of each of the stator rows 11, and the lower surface of the first plate 13 is made of, for example, iron or aluminum. A reaction member 14 as a mover, which is laminated in a circular shape, is integrally attached. Also,
A second plate 15 extending upward is integrally attached to the upper surface of the first plate 13, and the second plate 15 has a piston rod 16a extending forward (left side in FIG. 1) in the conveying direction. A cylinder 16 is arranged, and a cylinder member 17 is connected to the front end of the piston rod 16a of the front and rear cylinder 16. The cylindrical member 17 is a support shaft for the second plate 15.
An engaging projection member 19 provided on the back surface of the pallet P is supported inside the tubular member 17 so as to be rotatable around 18.
A base end portion of a rod 21 having an engaging block 20 that can be engaged with is fitted and supported on the rod 21, and a coil spring 22 is externally fitted on the rod 21. And each of the above stator rows
The reaction member 14 provided in 11 moves to the rear side in the transport direction along each stator row 11 by the thrust force generated by the electromagnetic action between each stator row 11 and each linear motor coil 10. As a result, the body B on the pallet P is moved within a fixed time between the adjacent work stations ST _{1 and} ST _{2 in} a state where the pallet P is engaged with the engagement projection member 19 by the engagement block 20. It is designed to be transported in sequence. Therefore, the linear motor coil 10 and the reaction member 14 constitute a linear induction motor 23 (linear induction motor unit).
23 is provided for each of the work stations ST ₁ and ST ₂ at a rate of one.

In addition to the linear induction motor 23, the conveyor A has a rotary induction motor 31 in each work station ST ₁ , ST ₂ as its driving means. As shown in detail in FIGS. 4 and 5, the rotary induction motor 31 is arranged so as to be supported by a support 38 between the two stator rows 11 and 11 with the rotary shaft 32a facing upward. Motor main body 32 and the motor main body 32
A rack member 33 which is provided on the lower surface of the pallet P so as to extend in the longitudinal direction (conveying direction) of the pallet P and has tooth portions on both side surfaces, and a first pinion mounted on the rotary shaft 32a of the motor body 32. 34, a second pinion 35 that meshes with the first pinion 34 and the tooth portion on one side surface of the rack member 33.
A third pinion 36 meshing with the first pinion 34 at a position opposite to the second pinion 34, and the third pinion 36.
And a fourth pinion 37 that meshes with the rack member 33 and the tooth portion on the other side surface, and some of these pinions 34 to 37.
A gear mechanism 40 is configured by the rack member 33 and the rack member 33. The gear mechanism 40 converts the rotational force of the motor main body 32 into a driving force in a linear direction to convey the pallet P. The pinions 34 to 37 are covered by a gear box 39 provided on a support base 38.

Here, after transporting the pallet P, which is the transported object, to the work station ST ₂ on the downstream side, the rod 21 is rotated around the support shaft 18 in the clockwise direction in FIG. The engagement state of the engagement block 20 with respect to the engagement projection member 19 is released, and it is retracted obliquely downward, and in this state, the reaction member 14 moving to the downstream work station ST ₂ is moved to the upstream work station ST. It is designed to be moved to ₁ . Further, when the pallet P moves over each roller 2 of the roller conveyor 3 due to the operation of the linear induction motor 23, the vertical fluctuation occurs,
This fluctuation is absorbed by the coil spring 22 fitted onto the rod 21, so that the reaction member 14 does not fluctuate in the vertical direction.

Then, as shown in FIG. 6, each of the stations ST
_1, the ST _2, the speed sensor 41 made of a pulse generator for detecting the transporting speed of the pallet P of between Aitonaru working station ST ₁ ~ST ₂ is provided. Further, each of the stations ST ₁ and ST ₂ is provided with an encoder 42 for detecting the rotation speed of the motor main body 32. The speed sensor 41 and the encoder 42 constitute a carrying state detecting means 43 for detecting the carrying state of the pallet P between the adjacent work stations ST _{1 and} ST ₂ .

Further, FIG. 6 shows a block configuration of a control unit of the carrying device A. In the figure, 51 is the adjacent work stations ST _{1 to} ST ₂
The work stations ST ₁ and ST ₂ are provided so as to be straddled between them.
A station controller as a control means for controlling the operations of the linear induction motor 23 and the rotary induction motor 31 between, the station controller 51 receives the output of the speed sensor 41 and operates the linear induction motor 23 (details Is a linear induction motor controller 52 that controls the excitation of the linear motor coil 10 and a rotary induction motor controller that receives the output of the encoder 42 and controls the operation of the rotary induction motor 31 (specifically, the rotation of the motor body 32). 53 and the outputs of the transport state detecting means 43 (speed sensor 41 and encoder 42), the linear induction motor controller 52 and the rotary induction motor controller 53.
A switching circuit 54 for instructing ON / OFF switching of control, and vehicle control information input from the host computer 55 to the linear induction motor controller 52, the rotary induction motor controller 53, and the switching circuit 54 as a whole control as appropriate. Department
It consists of 56. 57 is a linear induction motor controller
52 and an amplifier provided in each output section of the rotary induction motor controller 53 (the amplifier 57 connected to the linear induction motor controller 52 is specifically a thyristor circuit for performing phase control).

Next, the station controller 51 calculates the current command value (the amount of excitation of the linear motor coil 10) necessary for the thrust of the linear induction motor 23 and the rotary induction motor 31.
The calculation of the current command value (rotational force of the motor main body 32) required for the thrust will be described with reference to FIGS. 7 and 8. FIG. 7 shows the control circuit, and FIG. 8 shows the characteristic of the set speed with respect to time.

In FIG. 7, reference numeral 61 is a speed control unit, and the speed control unit 61 includes a speed command vm ′ and a speed sensor 41.
The difference from the actual transport speed vm detected at is input. 62
Is an OR circuit that receives the pulse signal output from the speed control unit 61 and the pulse signal output from the speed sensor 41, and 63 counts the pulse signal output from the OR circuit 62 and measures the timing to fire. It is a counter that outputs the signal of the angle θ ₀ to the three D / A converters 64a, 64b, 64c. The three D / A converters 64a, 64b, 64c are for obtaining the current command values ia, ib, ic of the three-phase alternating current from the firing angle θo, and the current command values ia, ib, ic are as follows. Calculated from the formula. However, K =
(2/3) ^{1 ] 2} .

ia = K · i · sin θo ib = K · i · sin (θo-2π / 3) ic = K · i · sin (θo + 2π / 3) The current command signals from the above D / A converters 64a to 64c are transistor inverters. Output to circuit 65. In the transistor inverter circuit 65, while performing the excitation control of the linear motor coil 10 based on the current command signal, the actual current value ia ', ib', ic 'and the current command value ia, ib, at that time. Feedback control is performed based on the difference from ic. In FIG. 7, 66 is an F / F provided between the speed sensor 41 and the speed control unit 61.
A V converter, 67 is a V / F converter provided between the speed control unit 61 and the OR circuit 62.

Further, 71 is a comparison circuit, which is a linear induction obtained by differentiating the actual conveyance speed vm from the speed sensor 41 by the F / V converter 66 and then by the differentiating circuit 72. The rising acceleration and falling deceleration dvm / dt (inclination in the acceleration region and deceleration region of FIG. 8) of the motor 23 and the actual transport speed vs from the encoder 42 are converted by the F / V converter 66 and then differentiated. The difference dvs / dt-dvm / dt from the rising acceleration and falling deceleration dvs / dt (inclination in the acceleration region and the deceleration region) of the rotary induction motor 31 obtained by differentiating by the circuit 72 is input. In the comparison circuit 71, the difference dvs / dt-dvm between the acceleration and deceleration of the linear induction motor 23 and the rotary induction motor 31 described above.
/ dt is always constant from the difference dvs / dt-dvm / dt between the linear induction motor 23 and the rotary induction motor 31 between the rising acceleration and falling deceleration gradients Of the linear induction motor
Even if a disturbance element such as friction acts on 23 and the rotary induction motor 31, a constant gradient difference ε = (dvs / dt-dvm
/ dt-a) is compensated.

Reference numeral 73 denotes an integrating circuit that integrates a constant inclination difference ε = (dvs / dt-dvm / dt-a) between the linear induction motor 23 and the rotary induction motor 31 calculated in the comparison circuit 71. The integration circuit 73 calculates the speed variation per minute time (the absolute value variation between the linear induction motor 23 and the rotary induction motor 31) ∫εdt = Δvs, and the speed variation Δvs and the actual value from the encoder 42 are calculated. The difference vs-Δvs from the transport speed vs is output to the amplifier 57 of the rotary induction motor controller 53. Amplifier 57 of the rotary induction motor controller 53
In the motor main body 32 based on the above current command signal.
Rotation control of the encoder 42 at that time
Actual transport speed vs. (rotary induction motor 31 side),
Feedback control is performed based on the difference between the speed variation Δvs obtained by comparing the actual transport speed vm by the speed sensor 41 (on the side of the linear induction motor 23) and the actual transport speed vm by the encoder 42.

Next, the operation of the above-described embodiment will be described. When the pallet P on which the body B is mounted is sequentially fed from the upstream station ST ₁ to the downstream station ST ₂ by the linear induction motor 23, both working stations ST ₁ , Under the control of one station controller 51 corresponding to ST ₂ ,
The body B is mounted by the thrust of the linear induction motor 23 generated in the reaction member 14 by the electromagnetic action between the linear motor coil 10 and the reaction member 14 and the thrust of the rotary induction motor 31 generated by the rotation force of the motor body 32. As shown in FIG. 8, the pallet P to be placed is accelerated and conveyed until it reaches a predetermined speed v ₀ based on the characteristics of the set speed with respect to time of both induction motors 23 and 31 in the acceleration region, and Both induction motors in deceleration area 23,3
Based on the characteristics of the set speed with respect to 1 time, it is decelerated and conveyed from a predetermined speed v ₀ until it stops. When the pallet P reaches a predetermined speed v ₀ , the linear induction motor 23 stops (excitation of the linear motor coil 10 stops).
Then, the pallet P is transported at a constant speed v ₀ in the constant speed region by the thrust of the rotary induction motor 31.

At the time of carrying the acceleration region and the deceleration region of the entire operation region, the station controller 51
According to the control circuit shown in the figure, the current command value required for the thrust of the linear induction motor 23 from the speed sensor 41 is the rising acceleration in the acceleration range, that is, the characteristic (inclination) of the set speed with respect to the time shown in FIG. 8, and the deceleration range. The falling deceleration in FIG. 8, that is, the characteristic of the measured speed with respect to the time shown in FIG.
The current command value required for the thrust of the rotary induction motor 31 from 43 (speed sensor 41 and encoder 42) is the rising acceleration in the acceleration region, that is, the characteristic of the set speed with respect to the time shown in FIG. 8 and the falling in the deceleration region. The deceleration, that is, the characteristic of the set speed with respect to the time shown in FIG. 8, is calculated. And the above station controller
By 51, the difference between the characteristic value of the set speed with respect to time of the rotary induction motor 31 and the characteristic value of the set speed with respect to time of the linear induction motor 23 is increased so as to gradually increase from the low speed side to the high speed side. Will be set.

Then, when the pallet P is conveyed between the adjacent work stations ST _{1 and} ST ₂ , the excitation amount of the linear motor coil 10 is controlled (control during acceleration and deceleration) based on the current command value. And the rotational force of the motor body 32 is controlled, and the pallet P is moved to the work station ST ₁
It is conveyed between ~ST _2.

As described above, the characteristic of the set speed with respect to time of the rotary induction motor 31 is higher than the characteristic of the set speed with respect to time of the linear induction motor 23 such that the difference between the characteristic values gradually increases from the low speed side to the high speed side. Therefore, even if the linear induction motor 23 and the rotary induction motor 31 are used together in the acceleration region (low speed region), the thrust of the linear induction motor 23 (acceleration force due to the rotational force) of the rotary induction motor 31 The thrust of the rotary induction motor 31 at a low speed is effectively assisted by the linear induction motor 23 that generates a large thrust at a low speed without exceeding the thrust (accelerating force due to the amount of excitation). A braking phenomenon (internal power generation) by the rotary induction motor 31 can be reliably prevented.

Moreover, if the linear induction motor 23 and the rotary induction motor 31 having different characteristics of the set speed with respect to time are used together as described above, a linear induction motor having a large thrust at the time of starting is used.
The rotary induction motor 31 having a small thrust is assisted by 23, and since the thrust is small in the low speed region (acceleration region and deceleration region), the rotary induction motor 31 is likely to be generated due to the difference between the set speed and the actual speed. It is possible to reliably prevent the slip.

Moreover, since the characteristics of the set speed with respect to time of the rotary induction motor 31 and the characteristics of the set speed with respect to time of the linear induction motor 23 are set to be higher so as to gradually increase from the low speed side toward the high speed side, The closer the speed to the constant speed range v ₀ , the less the dependency of the rotary induction motor 31 on the linear induction motor 23 becomes, and the rotary induction motor 31 with high positioning accuracy accelerates from the acceleration range to the constant speed range and decelerates from the constant speed range. The positional accuracy of each shift point in the area becomes accurate, and the transport control accuracy in the entire operation area can be improved.

Furthermore, when the rotary induction motor 31 is transported, the linear induction motor 23 and the rotary induction motor 31 drive the transport in the acceleration region and the deceleration region as described above, and the rotary induction motor 31 operates in the constant velocity region in the middle period of the transport. Since the conveyance is performed by driving 31, even if the linear induction motor 23 fails, the rotary induction motor 31 is always driven during the conveyance, so that the conveyance is possible, while the rotation induction motor 31 fails. However, the thrust of the linear induction motor 23 can be used to convey to the first station, and it is possible to convey when one of the induction motors 23 (or 31) fails.

The present invention is not limited to the above embodiment,
It also includes various other modifications. For example, in the above-described embodiment, the pallet P on which the body B is placed is conveyed by driving the linear induction motor 23 and the rotary induction motor 31 in the acceleration region and the deceleration region based on the current command value. Needless to say, the pallet on which the body is placed may be transported by driving the linear induction motor and the rotary induction motor based on the current command value in at least one of the deceleration areas.

Further, in the above-described embodiment, the case where the transfer apparatus A is applied to the vehicle assembly line is shown, but the present invention is not limited to this, and it is needless to say that the present invention can be applied to the case where another object to be transferred is transferred.

(Effects of the Invention) As described above, according to the transport apparatus of the present invention, the characteristic of the set speed with respect to time of the rotary induction motor is changed from the low speed side to the high speed side with respect to the characteristic of the set speed with respect to time of the linear induction motor. Since the difference between the characteristic values is gradually increased as it goes, the thrust of the linear induction motor is effectively assisted in the low speed region without exceeding the thrust of the rotary induction motor, and the rotary induction motor is accelerated in the acceleration region. It is possible to reliably prevent the braking phenomenon due to. Moreover, it is possible to reliably prevent slippage of the rotary induction motor, which is likely to occur by the rotary induction motor having a small thrust in the low speed region.

[Brief description of drawings]

1 to 8 show an embodiment of the present invention. FIG. 1 is a side view of a carrying device, FIG. 2 is a plan view of the same, and FIG. 3 is a cross section taken along line III-III of FIG. Fig. 4 and Fig. 4 are front views of the rotary induction motor with the gear box cut open.
Fig. 4 is a sectional view taken along the line VV in Fig. 4, Fig. 6 is a block configuration diagram of a control unit of the transfer device, Fig. 7 is an electric circuit diagram for calculating a current command value, and Fig. 8 is speed change during pallet transfer. FIG. FIG. 9 is a view corresponding to FIG. 1 showing a conventional example, and FIG. 10 is a characteristic diagram showing thrust-speed characteristics of a linear induction motor and a rotary induction motor. A: Conveyor P: Pallet (object to be conveyed) ST ₁ , ST ₂ …… Work station 10 …… Linear motor coil (stator) 14 …… Reaction member (mover) 23 …… Linear induction motor (linear Induction motor unit) 31 …… Rotary induction motor 40 …… Gear mechanism 43 …… Transport status detection means 51 …… Station controller (control means)

Claims (1)

(57) [Claims] 1. A linear induction motor unit having a linear motor coil and a reaction member, and a rotary induction motor are provided at each station of a line having a plurality of stations, and among the linear motor coil and the reaction member, On the stator placed between the stations where one is next to each other,
On the other hand, each of the other is constituted by a mover provided on the side of the transported object so as to transport the transported object by the thrust generated by the electromagnetic action between the linear motor coil and the reaction member. The motor is connected to a gear mechanism that converts the rotational force of the rotary induction motor into a linear motion in the conveying direction of the conveyed object, and conveys the detected state of the conveyed object between adjacent stations. In order to convey the object to be conveyed by driving the linear induction motor unit and the rotary induction motor in the acceleration region at the initial stage of conveyance, the state detection means receives the output of the conveyance state detection means. Compare the characteristic of the set speed with respect to time to the characteristic of the set speed with respect to time of the linear induction motor unit as the characteristic value changes from the low speed side to the high speed side. There conveying apparatus characterized by comprising a control means for setting the increase to increasing.