JPH0356002A - Conveyor - Google Patents

Abstract

PURPOSE:To prevent a servo motor unit from slopping by so setting the difference of characteristic values of the set speed of the unit to the time of the unit from those of the set speed to the time of a linear motor unit to a larger value as to gradually increase from a low speed side toward a high speed side. CONSTITUTION:The characteristic of a set speed to a time of a servo motor unit 31 is so set to a larger value as to increase the difference of the characteris tic value from the characteristic of the set speed to the time of a linear motor unit 23 from a low speed toward a high speed. Accordingly, even if the units 23, 31 are simultaneously employed in an accelerating range, the thrust of the unit 23 does not exceed that of the unit 31, and the thrust of the unit 31 at the time of a low speed is effectively assisted by the unit 23 for generating a large thrust at the of the low speed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a conveying device for conveying objects in a production line or the like, and particularly to one using a linear motor.

(Prior Art) Recently, in production lines of production factories, it has been desired to transport objects quickly and quietly in order to improve production efficiency and improve the working environment. - As such a conveying device, one using a linear motor consisting of a linear motor coil and a reaction member is known. As shown in FIG. 9, the conveyance device using this linear motor consists of one of the linear motor coils b, b, ... and the reaction member C (in the figure, the linear motor coil is b,b
,...) as a stator and multiple rollers d, d,...
The linear motor coils b, b, . The thrust force F generated in the mover (reaction member C) by the electromagnetic action between ... and the reaction member C causes the pallet f and the objects placed thereon to be moved through the mover (reaction member C). configured to be transported. In a conveying device using this type of linear motor,
Normally, a controller is provided for each linear motor a at each work station, and when a pallet f is transported between adjacent stations, the transport speed of the pallet f detected by an encoder provided at each station is sent to the controller. The signal is input and used to control the operation of the linear motor a by the controller.

In addition, Japanese Patent Application Laid-open No. 55-86307 discloses that in a conveyance device using a linear motor, a direct drive type direct current type using gears etc. is used to accurately stop the conveyed object at a predetermined position at each station. It is disclosed that the apparatus is equipped with a servo motor, and when an object to be conveyed approaches each station, the drive of the linear motor is stopped and the drive is switched to the drive of the servo motor to convey the object to the stopping position of each station. ing.

(Problem to be Solved by the Invention) By the way, when comparing the thrust-speed characteristics of the above-mentioned linear motor and a servo motor, which is a rotary motor, the first
As shown in Figure 0, the linear motor generates a large thrust in a low speed range such as during startup, and the servo motor generates a large thrust (torque) in a high speed range. For this reason, the drive means for the conveyance device should be a servomotor with high positioning accuracy and a servomotor with high It is desirable to use it in conjunction with a near motor that generates thrust.

However, if a linear motor and a servo motor are used together in the low speed region (acceleration region and deceleration region) as described above, the position control system of the linear motor will press the encoder against the conveyed object via the roller and capture the displacement amount. Because it is an "oven loop," it is difficult to obtain accuracy and stability compared to a servo motor control system. For this reason, especially when a large thrust is generated during acceleration (at low speed), the characteristics of the set speed relative to the time of the near motor may be higher than the characteristics of the set speed relative to the time of the servo motor, and this causes A braking phenomenon (internal power generation) by the servo motor occurs in the servo motor, which attempts to prevent the linear motor from accelerating, which may result in unstable control.

The present invention has been made in view of the above points, and its purpose is to generate a large thrust at low speeds or to generate a characteristic of the set speed with respect to time of the servo motor based on the characteristic of the set speed with respect to the time of near motor rotation. By effectively setting , the braking phenomenon caused by the servo motor is prevented in the acceleration region. Also,
Another purpose is to improve the deceleration performance of the servo motor by generating a large thrust in the deceleration region and effectively utilizing the near motor.

A further object is to prevent slipping between the set speed and the actual speed due to the servo motor having a small thrust at low speeds.

(Means for Solving the Problem) In order to achieve the above object, the solving means of the present invention includes providing a linear motor unit and a servo motor unit at each station of a line having a plurality of stations as a conveying device, and A conveyance state detection means for detecting the conveyance state of the conveyed object between adjacent stations; In order to convey the conveyed object by driving the linear motor unit and the servo motor unit, the characteristics of the set speed with respect to time of the servo motor unit are changed from the low speed side to the characteristics of the set speed with respect to time of the linear motor unit. The configuration includes a control means for setting the characteristic value to a higher value so that the difference in the characteristic value gradually increases as the speed increases.

(Function) With the above-described configuration, in the conveyance device of the present invention, when conveying an object between adjacent stations, the conveyance state is detected by the conveyance state detection means, and the conveyance device is operated under the control of the control means. The transport is performed by driving the beam near motor unit and the servo motor unit in at least one of an acceleration region at the beginning of transport and a deceleration region at the end of transport.

In that case, the characteristic of the set speed versus time of the servo motor unit is set higher than the characteristic of the set speed versus time of the linear motor unit so that the difference in characteristic value gradually increases from the low speed side to the high speed side. Therefore, even if the linear motor unit and servo motor unit are used together in the acceleration region (low speed region), the thrust of the linear motor unit will not exceed the thrust of the servo motor unit, and the servo motor unit will The thrust generated by the servo motor unit generates a large thrust force at low speeds and is effectively assisted by the near motor unit, and the braking phenomenon (internal power generation) caused by the servo motor unit does not occur in the acceleration region. On the other hand, if a linear motor unit and a servo motor unit are used together in the deceleration region (low speed region), the thrust (deceleration force) of the servo motor unit will be effectively assisted by the thrust of the linear motor unit, resulting in deceleration. It is possible to utilize the raking phenomenon by the servo motor unit in the area.

Furthermore, if you use a linear motor unit and a servo motor unit that have different set speed characteristics with respect to time as described above, the near motor unit with a large thrust will assist the servo motor unit with a small thrust at the time of startup, resulting in a low speed. This prevents the servo motor unit from slipping, which is likely to occur due to the difference between the set speed and the actual speed since the thrust force is small in this region.

(Example) Hereinafter, embodiments of the present invention will be described based on the drawings.

FIGS. 1 to 3 show a case in which a conveyance device A is applied to a vehicle assembly line as an embodiment of the present invention. Adjacent work stations S T
+ to ST2 (only two of these locations are shown in the figure) within a certain period of time. The pallet P is supported by a roller conveyor 3 consisting of a large number of rollers 2, 2, . It is designed to be transported while

Inside both of the supporting members 1.1, a large number of linear motor coils 10, 10. Two stator rows 11.11 consisting of... are arranged in parallel. Each stator row 11 above
Two guide rails 12 extending in the transport direction are provided on both sides of the
．． 12 are arranged to guide a reaction member 14, which will be described later, along each of the stator rows 11.

Also, the idle rails 12.1 on both sides of each stator row 11 are
2, a first plate 13 is movably engaged with and arranged on the lower surface of the first plate 13, and a reaction member 14 as a movable element made of, for example, laminated iron and aluminum in a plate shape is disposed on the lower surface of the first plate 13. It is integrally installed. Further, a second plate 15 extending upward is integrally attached to the upper surface of the first plate 13, and the second plate 15 extends upwardly.
A front and rear cylinder 16 having a piston rod 16a extending forward in the conveyance direction (left side in FIG. 1) is disposed on the plate 15, and a piston rod 16g of the front and rear cylinder 16 is disposed on the plate 15.
A cylindrical member 17 is connected to the tip. The cylindrical member 17 is supported by the second plate 15 so as to be rotatable around a support shaft 18, and has an engagement projection member 19 provided on the back surface of the pallet P inside the cylindrical member 17. The proximal end of a rod 21 having an engaging block 20 at its tip is fitted and supported, and a coil spring 22 is attached to the rod 21.
is fitted externally. The reaction member 14 provided in each of the fixed rows 11 moves along each stator row 11 by the thrust generated by the electromagnetic interaction with each linear motor coil 10 of each stator row 11. As a result, the body B on the pallet P is moved to the rear side in the conveyance direction, and the body B on the pallet P is moved to the adjacent work station STI~ with the retaining block 20 of the pallet P engaged with one of the retaining protrusions. The materials are transported sequentially between STZs within a certain period of time. Therefore, the linear motor coil 10 and the reaction member 14 constitute a linear motor unit 23.
is at each work station ST+. One is provided for each ST2.

The conveyance device A has each work station ST+, ST2 as its driving means, apart from the linear motor unit 23.
is equipped with a servo motor unit 31. As shown in detail in FIGS. 4 and 5, the servo motor unit 31 is supported by a support stand 38 between two stator rows 11, 11 with the rotating shaft 32a facing upward. a servo motor 32; a rack member 33 provided on the lower surface of the pallet P facing the servo motor 32 and extending in the longitudinal direction (conveying direction) thereof, and having teeth on both sides;
The first motor mounted on the rotating shaft 32a of the servo motor 32
a second pinion 35 that meshes with the first pinion 34 and the teeth on one side of the rack member 33;
a third pinion 36 that meshes with the first pinion 34 at a position opposite to the second pinion 34; and a third pinion 36 that meshes with the third pinion 36 and the teeth on the other side of the rack member 33. The rotational force of the servo motor 32 is converted into linear driving force by a series of pinions 34 to 37 and the rack member 33 to drive the pallet P.
is configured to convey. In addition, pinion 34~
37 is covered by a gear box 39 provided on a support stand 38.

After the pallet P, which is the object to be transported, is transported to the work station ST2 on the downstream side, the rod 21 is rotated clockwise in FIG. The engagement state of the engagement block 20 with the mating protrusion member 19 is released and retracted diagonally downward, and in this state, the reaction member 14, which is moving to the work station ST2 on the downstream side, is moved to the work station STI on the upstream side. It is designed to let you do so. Also,
Vertical fluctuations occur when the pallet P moves over each roller 2 of the roller conveyor 3 due to the operation of the linear motor 23, but this fluctuation is absorbed by the coil spring 22 fitted onto the rod 21, and the reaction member 141; Vertical fluctuations are prevented from occurring.

As shown in FIG. 6, each station ST
,, sT2 has adjacent work stations STI to ST.
A speed sensor 41 consisting of a pulse generator or the like is provided to detect the conveyance speed of the pallet P between Z. Further, each of the stations ST, ST2 is provided with an encoder 42 for detecting the rotation speed of the servo motor 32. Then, the speed sensor 41 and the encoder 42 control the speed of the adjacent work stations ST, -ST.
A transport state detection means 43 is configured to detect the transport state of the pallet P between the two pallets.

Furthermore, FIG. 6 shows the block configuration of the control section of the conveyance device A. In the figure, 51 is an adjacent work station ST. ~
Provided across ST2, each work station S
A station controller serves as a control means for controlling the operation of the linear motor unit 23 and the servo motor unit 31 between T,, ST2, and the station controller 51 receives the output of the speed sensor 41 and controls the operation of the linear motor unit 23. The near motor controller 52 controls the operation (in detail, the excitation of the near motor coil 10), and receives the output of the encoder 42, and operates the servo motor unit 31 (in detail, the servo motor 3
The servo motor controller 53 controls the rotation of the linear motor controller 52 and the servo motor controller 53, and receives the output from the steam conveyance state detection means 43 (speed sensor 41 and encoder 42). a switching circuit 54 that commands
It is comprised of an overall control section 56 that outputs vehicle type information and the like manually input from a host computer 55 to the linear motor controller 52, servo motor controller 53, and switching circuit 54 as appropriate.

In addition, 57 is an amplifier provided at each output section of the linear motor controller 52 and the servo motor controller 53 (the amplifier 5 connected to the linear motor controller 52).
Specifically, 7 is a thyristor circuit that performs phase control.

Next, the station controller 51 calculates the current command value necessary for the thrust of the linear motor unit 23 (the amount of excitation to the linear motor coil 10) and the current command value necessary for the thrust of the servo motor unit 31 (the amount of excitation of the servo motor 32). The calculation of rotational force) will be explained using FIGS. 7 and 8.

FIG. 7 shows the control circuit, and FIG. 8 shows the characteristics of the set speed with respect to time.

In FIG. 7, 61 is a speed control unit, and the difference between the speed command V1 and the actual conveyance speed V1 detected by the speed sensor 41 is input to the speed control unit 61. 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; 63 counts the pulse signal output from the OR circuit 62, and calculates the timing by counting the pulse signal output from the OR circuit 62; The signal of arc angle θ0 is sent to three D/A converters 6 4 a * 6
This is a counter that outputs to 4b and 64c. The above three D/A converters 6 4 a r 6 4 b, 6
4 c is the three-phase AC current command value ia from the firing angle θ0,
ib, ic, and the current command value iB, ib
, ic are obtained from the following formula. However, K- (2
/3) 1l2.

iamK*i*sinθO ibs++Kei*sLn(θ0-2π/3)ie-K
*iesin(θ0+2π/3) Each of the above D/A converters 6
A current command signal is outputted to the transistor inverter circuit 65 from 4a to 64c. In the transistor inverter circuit 65, the excitation control of the linear motor coil 10 is performed based on the current command signal, and the actual current values iB', ib',
ic and the above current command values iB, ib. Feedback control is performed based on the difference with IC.

In FIG. 7, 66 is an F/V converter interposed between the speed sensor 41 and the speed control unit 61, and 67 is an F/V converter interposed between the speed control unit 61 and the OR circuit 62. V
/F converter.

Further, 71 is a comparison circuit, and the comparison circuit 71 includes:
The actual conveying speed V from the speed sensor 41 is converted by the F/V converter 66 and then differentiated by the differentiating circuit 72 to obtain the rising acceleration and falling deceleration dvm/dt (8th the actual conveyance speed V9 from the encoder 42 is converted by the F/V converter 66 and then differentiated by the differentiating circuit 72. The difference dvs/dt - dvs/dt from the falling deceleration dvs/dt (the slope in the acceleration region and the deceleration region) is input.

In this comparison circuit 71, both the units 23.3
Difference in acceleration and deceleration of 1 dvs /d t-dv
The variation dvs/dt is adjusted so that s/dt is always constant.
- Further, from dvm/dt, a constantly necessary slight variation a per unit time between the slope of the rising acceleration and falling deceleration of the servo motor unit 23 and the linear motor unit 31 is subtracted, and Even if a disturbance element such as friction acts on the unit 31, a constant slope difference e- (dvs/dt
-dv+e/dt-a) is compensated.

73 is a constant slope difference ε-(dvs/dt-dvm/dt-a) between the servo motor unit 23 and the linear motor unit 31 calculated in the comparison circuit 71.
), the integrating circuit 73 calculates the speed variation (absolute value difference between both units 23.31) fsdt-Δv3 per minute time, and calculates the speed variation Δvs and the encoder. 42 and the actual conveyance speed vs -ΔVS is output to the amplifier 57 of the servo motor controller 53. The amplifier 57 of the servo motor controller 53 controls the rotation of the servo motor 32 based on the current command signal, and
At that time, the encoder 42 (servo motor unit 31
side) and the actual conveyance speed vs. the speed sensor 41
Feedback control is performed based on the difference between the speed variation ΔVS, which is a comparison between the actual conveyance speed V (on the linear motor unit 23 side) and the actual conveyance speed vm determined by the encoder 42.

Next, the operation of the above embodiment will be explained. When the linear motor 23 sequentially transports the pallet P on which the body B is placed from the upstream station ST, to the downstream station ST2, both work stations ST, , S72
Under the control of one station controller 51 corresponding therebetween, the reaction member 141 is
;The servo motor unit 3 is generated by the thrust of the linear motor unit 23 and the rotational force of the servo motor 32.
Due to the thrust of 1, the pallet P on which the body B is placed,
As shown in FIG. 8, both units 23 in the acceleration region
．． The unit 23 is accelerated and conveyed until it reaches a predetermined speed vO based on the characteristics of the set speed with respect to time of both units 23.
It is decelerated and conveyed from 0 until it stops. Furthermore, when the pallet P reaches a predetermined speed VQ, the linear motor unit 23 stops (the excitation of the linear motor coil 10 stops).
The pallet P is moved by the thrust of the servo motor unit 31.
is transported at a constant speed in the constant speed region at a speed VQ.

During transportation in the acceleration region and deceleration region among all operating regions, the station controller 51 controls the seventh
According to the control circuit shown in the figure, the current command value required for the thrust of the linear motor unit 23 from the speed sensor 41 is determined based on the rising acceleration in the acceleration region, that is, the characteristic (slope) of the set speed with respect to time shown in FIG. 8, and the deceleration region. It is calculated so that the falling deceleration at , that is, the characteristic of the set speed with respect to time shown in FIG. Calculate the required current command value so that it has the characteristics of the rising acceleration in the acceleration region, that is, the set speed with respect to time shown in Figure 8, and the falling deceleration in the deceleration region, that is, the characteristics of the set speed with respect to time shown in Figure 8. be done. Then, the station controller 51 determines that the difference between the characteristic value of the set speed with respect to time of the servo motor unit 31 and the characteristic value of the set speed with respect to time of the linear motor unit 23 increases from the low speed side to the high speed side. It will be set high so that it increases gradually.

When the pallet P is transported between adjacent work stations ST+ to ST2, the amount of excitation of the linear motor coil 10 is controlled (
(control during acceleration and deceleration), the rotational force of the servo motor 32 is controlled, and the pallet P is transported between work stations ST+ to ST2.

In this way, the characteristic of the set speed with respect to time of the servo motor unit 31 is higher than the characteristic of the set speed with respect to time of the linear motor unit 23 so that the difference in characteristic value gradually increases from the low speed side to the high speed side. Therefore, even if the linear motor unit 23 and servo motor unit 31 are used together in the acceleration region (low speed region),
The thrust of the linear motor unit 23 (acceleration force due to rotational force) does not exceed the thrust of the servo motor unit 31 (acceleration force due to the amount of excitation), and the thrust of the servo motor unit 31 at low speeds generates a large thrust at low speeds. The servo motor unit 31 is effectively assisted by the servo motor unit 23 in the acceleration region.
It is possible to reliably prevent the braking phenomenon (internal power generation) caused by On the other hand, if the linear motor unit 23 and the servo motor unit 31 are used together in the deceleration region (low speed region), the thrust (deceleration force) of the servo motor unit 31 is effectively reduced by the thrust (deceleration force) of the linear motor unit 23. As a result, deceleration performance during deceleration can be improved by utilizing the braking phenomenon by the servo motor unit 31 in the deceleration region.

In addition, if the linear motor unit 23 and the servo motor unit 31, which have different set speed characteristics with respect to time, are used together as described above, the servo motor 3, which has a large thrust at startup, and the near motor unit 23, which has a small thrust, can be used together.
1 is assisted, and the slip of the servo motor unit 31 that 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 (acceleration region and deceleration region) can be reliably prevented. .

Moreover, the characteristics of the set speed with respect to time of the servo motor unit 31 and the characteristics of the set speed with respect to time of the linear motor unit 23 are set to be high so that they gradually increase from the low speed side to the high speed side. The closer the speed region is to the speed VQ, the lower the dependence of the servo motor unit 31 on the linear motor unit 23, and the higher the positioning accuracy of the servo motor unit 31 from the acceleration region to the constant speed region and from the constant speed region to the deceleration region. The positional accuracy of the shift point becomes accurate, and the accuracy of conveyance control in the entire operating range can be improved.

Furthermore, during transportation, the servo motor unit 31 is driven by the near motor unit 23 and the servo motor 31 in the acceleration region and deceleration region as described above, and in the constant speed region in the middle of transportation, the servo motor unit 31 is driven. Even if the linear motor unit 23 fails, the servo motor unit 31 is always driven during transportation, so transportation is possible. The thrust of unit 23 can be carried to the station to attack first, and either unit 23 (3
1) Transportation in the event of a failure can be made possible.

It should be noted that the present invention is not limited to the above embodiments, but includes various other modifications.

For example, in the above embodiment, the pallet P on which the body B is placed is transported by driving the linear motor unit 23 and the servo motor 31 based on the current command value in the acceleration range and the deceleration range. Of course, the pallet on which the body is placed may be transported by driving the near motor unit and the servo motor based on the current command value in at least one of the regions.

Further, in the above embodiment, the case where the transport device A is applied to a vehicle assembly line is shown, but the present invention is not limited to this, and it goes without saying that it can be applied to the case of transporting other objects to be transported.

(Effects of the Invention) As described above, according to the conveying device of the present invention, the characteristic of the set speed with respect to time of the servo motor unit 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 motor unit. Therefore, in the low speed range, the thrust of the linear motor unit is effectively assisted without exceeding the thrust of the servo motor unit, and in the acceleration range, the braking by the servo motor unit is reduced. While this phenomenon can be reliably prevented, the deceleration performance during deceleration can be improved by utilizing the braking phenomenon by the servo motor unit in the deceleration region. In addition, it is possible to reliably prevent the servo motor unit from slipping, which is likely to occur with a servo motor unit having a small thrust in a low speed region.

[Brief explanation of drawings]

1 to 8 show embodiments of the present invention. FIG. 1 is a side view of the conveying device, FIG. 2 is a plan view of the same, and FIG. 3 is a cross section taken along line 1 and 2 in FIG. 4 is a front view of the gear box of the servo motor unit cut open, FIG. 5 is a cross-sectional view taken along the line v-V in FIG. 4, and FIG. 6 is a block diagram of the control unit of the conveyance device. FIG. 7 is an electric circuit diagram for calculating the current command value, and FIG. 8 is a characteristic diagram showing speed changes during pallet conveyance. FIG. 9 is a diagram corresponding to FIG. 1 showing a conventional example, and FIG. 10 is a characteristic diagram showing thruster speed characteristics of a near motor and a servo motor. A...Transportation device, P...Pallet (object to be transported) STI, ST2...Work station 23...Linear motor unit 31...Servo motor unit 43...Transportation state detection means 51...・Station controller/ (control means) F Fig. 1, construction

Claims (1)

[Claims] (1) A transport state detection means for detecting the transport state of the transported object between adjacent stations, in which each station of a line having a plurality of stations is provided with a linear motor unit and a servo motor unit; In response to the output of the transport state detection means, the servo is configured to transport the transported object by driving the linear motor unit and the servo motor unit in at least one of an acceleration region at the beginning of transport and a deceleration region at the end of transport. control means for setting the characteristic of the set speed with respect to time of the motor unit to be higher than the characteristic of the set speed with respect to time of the linear motor unit so that the difference in the characteristic value gradually increases from the low speed side to the high speed side; A conveying device characterized by comprising: