JPH0356003A - Conveyor - Google Patents

Abstract

PURPOSE:To enhance a stopping position accuracy by decelerating to convey an article to be conveyed by a linear motor unit and a servo motor unit at the time of decelerating, and decelerating to convey the article to be conveyed by decelerating only b the servo motor unit at a point before a predetermined distance for stopping the article to be conveyed at the end of the decelerating range. CONSTITUTION:If a pallet P for placing a body B is conveyed between adjacent stations ST1 and ST2, it is effectively decelerated to be conveyed by a linear motor unit 23 and a servo motor unit 31 in a decelerating range of a start point at the decelerating conveying starting time as a speed shifting point for shifting from the constant speed conveying of the intermediate of the conveying range to the decelerating range under the control of a station controller 51. The decelerating conveying is conducted only by the unit 31 in high positioning accuracy of a decelerating point before a predetermined distance form stopping at the end of the decelerating range.

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. For example, as shown in FIG. 9, a conveyance device using this linear motor includes one of the linear motor coils b, b, ... and reaction member C (in the figure, the linear motor coil coil b
, b, ...) as a stator and multiple rollers d, d
, . , ... and the reaction member C, the thrust force F generated on the mover (reaction member C) causes the pallet f and the pallet placed on it to be moved through the mover (reaction member C). It is designed to transport things.

In a conveying device using this type of linear motor, a controller is usually provided for each working station linear motor a, and when a pallet f is transported between adjacent stations, a controller is provided for each station. The palette f detected by the encoder
The transport speed is input to the controller, and the controller controls the operation of the linear motor a.

Furthermore, Japanese Patent Application Laid-Open No. 55-86307 discloses that a conveyance device using a linear motor is equipped with a DC servo motor as an auxiliary drive device in order to accurately stop the conveyed object at a predetermined position at each station. , it is disclosed that when an object to be transported approaches each station, driving of the linear motor is stopped and driving is switched to the servo motor to transport the object to the stop position of each station.

(Problem to be Solved by the Invention) By the way, when conveying objects between adjacent stations as described above, the linear motion can be indirectly captured by simply pressing an encoder against a pallet via a roller or the like. Since the operation is controlled based on the conveyance speed of the pallet, slipping occurs between the pallet and the rollers, resulting in an essentially open-roof control system, which causes fluctuations in the conveyance speed when the pallet is conveyed. This may result in a discrepancy between the set value and the actual value of the shift point when shifting from constant-speed conveyance to decelerated conveyance. Therefore, the deceleration start time varies by the amount of shift in the shift point, and the accuracy of the stop position decreases.

The present invention has been made in view of these points, and its purpose is to effectively and efficiently use a linear motor and a servo motor in combination, and to change the speed change point when transitioning from constant speed conveyance to deceleration conveyance. In addition to accurate control, the final positioning and stopping control is performed only by a servo motor unit with high positioning accuracy, thereby increasing the accuracy of the stopping position.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention provides a constant speed in the middle of the conveying region when conveying an object between adjacent stations of a line having a plurality of stations. It is assumed that the conveyance device is configured to shift from conveyance to deceleration conveyance at the end of the conveyance region. Each of the stations is provided with a linear motor unit and a servo motor unit, and also includes a conveyance state detection means for detecting the conveyance state of the conveyed object between adjacent stations, and receives the output of the conveyance state detection means. , during deceleration that includes at least part of the deceleration region, the conveyed object is decelerated and conveyed by the drive of the linear motor unit and the servo motor unit, and at the end of this deceleration region, the conveyed object is conveyed by a predetermined amount before it stops. The apparatus is configured to include a control means for controlling the operations of the linear motor unit and the servo motor unit so that the conveyed object is decelerated and conveyed by decelerating only by the servo motor unit at the point.

(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. , effective deceleration conveyance is performed by the beam near motor unit and the servo motor unit in a deceleration region that includes at least a part of the deceleration starting from the speed change point where the transition from constant speed conveyance to deceleration conveyance occurs, and at the end of this deceleration region. At a point a predetermined amount before the conveyed object stops, deceleration conveyance is performed using only the servo motor unit with high positioning accuracy. Therefore, even if the conveyance speed fluctuates due to the drive of the linear motor unit, which is essentially an open-loop control system due to operation control based on the conveyance speed indirectly from the encoder, it can be kept constant by driving the servo motor unit with high positioning accuracy. There is no difference between the set value and the actual value of the shift point when the speed transfer is shifted to the deceleration transfer and the deceleration is started. By this, after accurately controlling the shift point where the transition from constant speed conveyance to deceleration conveyance occurs,
As described above, in the deceleration region, the linear motor unit and the servo motor unit are appropriately used in combination to perform deceleration conveyance, thereby effectively increasing the accuracy of the stop position.

(Example) Embodiments of the present invention will be described below 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 ST1~
The transport is carried out between STz (only two of which are shown in FIG. 6) 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 the support members 1, 1, there are two stator rows each consisting of a large number of linear motor coils 10, 10, . 11.11 are installed 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.

In addition, guide rails 12.1 on both sides of each stator row 11 are provided.
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 a piston rod 16a extending forward in the conveying direction (left side in FIG. 1) is attached to the second plate 15. Front and rear cylinders 16 with
are arranged, and the piston rod 16 of the front and rear cylinders 16
a. A cylindrical member 17 is connected to the tip. The cylinder member 1
7 is rotatably supported by the second plate 15 about a support shaft 18, and inside the cylinder member 17 is a retainer that can engage with a retaining protrusion member 19 provided on the back surface of the pallet P. A proximal end portion of a rod 2l having a mating block 20 at its tip is fitted and supported, and a coil spring 22 is externally fitted onto the rod 21. The reaction member 14 provided in each stator row 11 is moved along each stator row 11 by the thrust 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 to the rear side in the conveyance direction, and the body B on the pallet P is moved to the adjacent work stations ST, . It is designed to transport the material sequentially between ST2 within a certain period of time. Therefore, the linear motor coil 10 and the reaction member 14 constitute a linear motor unit 23, and one linear motor unit 23 is provided for each work station ST1, ST2.

The conveying device A has a drive means for each work station ST. ,ST2
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 pinion 34 , and 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, Binion 34~
37 is covered by three gear boxes 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 respect to one mating projection member is released and retracted diagonally downward, and in this state, the reaction member 14, which is moving to the downstream work station ST2, is moved to the upstream work station ST, It is designed to be moved to . 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 14 so as not to fluctuate in the vertical direction.

As shown in FIG. 6, each station ST
,, ST2 includes adjacent work stations STI to ST.
A speed sensor 4 detects the conveyance speed of the pallet P between the two
1 is provided. In addition, each station above
+ r S T 2 is provided with an encoder 42 that detects the number of rotations of the servo motor 32. The speed sensor 41 and encoder 42 constitute a transport state detection means 43 that detects the transport state of the pallet P between adjacent work stations ST, -ST2.

Furthermore, FIG. 6 shows a block configuration of the control section of the conveyance device A. In the figure, 51 is an adjacent work station STI~
ST. Each work station S
The station controller 51 serves as a control means for controlling the operation of the linear motor unit 23 and servo motor unit 31 of the TI and ST2, and the station controller 51 receives signals from the speed sensors 41, 41 (conveying state detecting means 43). That is, the pulse counter 52 receives speed information, controls the operation of the servo motor unit 31 (more specifically, the rotation of the servo motor 32), and controls the encoder 42. 42 (Transportation state detection means 4
3) A servo motor controller 5 that receives signals, that is, rotation information, from the servo motor controller 5 and performs feedback control of position information of the pallet P between each work station STI and ST2.
3, and a phase control section 54, .
and a sequence controller 55 that outputs an ON/OFF command signal to the controller. The sequence controller 55 is connected to the servo controller 53.
Upon receiving the position information of the pallet P from the phase controller 54,
. . to output an ON command signal to maximum excite each linear motor coil 10, while receiving the position information of the pallet P from the servo controller 53, the phase control section 54, .
... is controlled so that each linear motor coil 10 is not excited by outputting an OFF command signal. In addition, 56 is the output part of the servo motor controller 53 (servo motor 32
This is an amplifier installed in the human power department of the company.

Next, the conveyance control of the pallet P based on the operation control of the linear motor unit 23 and the servo motor unit 31 by the station controller 51 will be explained using FIGS. 7 and 8. FIG. 7 shows a control flow, and FIG. 8 shows changes in conveyance speed.

In FIG. 7, first, in step S+, the position information of the pallet P from the servo controller 53 is inputted to the sequence controller 55, and in step S2, the ON command signal from the sequence controller 55 which has received the position information of the pallet P causes the linear motor to be activated. The coil 10 (linear motor unit 23) is fully excited to the acceleration side (positive phase), and the linear motor unit 23 is excited in step S3.
Control of the servo controller 53 is turned on in synchronization with the operation of
At L, the operation of the servo motor unit 31 is started. After that, in step S4, the linear motor unit 23
and starts accelerating the servo motor unit 31, and measures the speed V after the linear motor unit 23 and the servo motor unit 31 start accelerating,
The elapsed time t from the acceleration transport start time tA is measured.

Then, in step SS, it is determined whether the speed V after the start of acceleration has become equal to the speed v1 at the acceleration point L+ (see FIG. 8) at a predetermined time before transition to the middle stage of the conveyance region at the end of the acceleration region, and the determination is made. When is YES, that is, when the speed v1 at the acceleration point t1 has been reached, in step S6, the control of the linear motor controller 52 is turned off to stop the operation of the linear motor unit 23, and acceleration is performed only by driving the servo motor unit 31. It should be noted that, until the speed V reaches the speed v1 after the start of acceleration, that is, between the accelerated conveyance start time tA and the acceleration point t1, the driving of the linear motor unit 23 and the servo motor ? It has significance as a synchronization period for synchronizing the drive of the data unit 23.

Subsequently, in step S7, the speed V at constant speed conveyance start time tB is
When the determination is YES, that is, when the speed VQ at the constant speed transport start time tB is reached, the pallet P is continuously transported at a constant speed only by driving the servo motor unit 31 in step S8. It is transported at a constant speed at the speed VO at the start time tB. After that, step S9
It is determined whether the elapsed time t is smaller than the deceleration conveyance start time tc, and when the determination is No and the deceleration conveyance start time tc has passed, the servo motor unit 31 applies braking to start deceleration in step SIO. At the same time, in response to the ON command signal from the sequence controller 55 that received the position information of the pallet P in step Sl1, the linear motor coil 10 is fully excited to the deceleration side (reverse phase), and the linear motor unit 23 applies braking to decelerate. Start.

After that, in step Su, the speed V after the start of deceleration is set to a deceleration point tz a predetermined time before the stop position t at the end of the deceleration region.
It is determined whether the speed is equal to the speed v2 of (point), and if the determination is YES, that is, the deceleration point t2
When the speed v2 of the pallet P is reached, the sequence controller 55 receives the position information of the pallet P in step S+3.
The braking of the linear motor unit 23 is stopped so that the linear motor coil 10 is not excited by the OFF command signal from the controller.

After that, in step S14, the elapsed time t is changed to the stop position tO.
, and the operation of the servo motor unit 31 is stopped. As a result of the above, adjacent work stations ST, ~ST
The conveyance of the pallet P between the two stations by the station controller 51 is completed.

Therefore, in the above embodiment, adjacent stations ST. When transporting the pallet P on which the body B is placed between ST2 and ST2, under the control of the station controller 51, the starting point is the deceleration transport start time tc, which is the speed change point at which the constant speed transport in the middle of the transport region shifts to the deceleration region. Effective deceleration conveyance is performed by the beam near motor unit 23 and servo motor unit 31 in the deceleration region, and the deceleration point t2 is a predetermined amount before stopping at the end of this deceleration region.
Decelerated conveyance is performed only by the servo motor unit 31 with high positioning accuracy. For this reason, the speed sensor 41
Even if the conveyance speed fluctuates due to the drive of the linear motor unit 23, which is essentially an open loop control system due to the operation control based on the indirect conveyance speed from There is no difference between the set value and the actual measured value of the deceleration conveyance start time tc when the constant speed conveyance shifts to the deceleration region and deceleration is started. As a result, after accurately controlling the deceleration conveyance start point 1 (the transition from the middle stage of the conveyance region to the deceleration region), deceleration conveyance is performed using the linear motor unit 23 and the servo motor unit 31 as appropriate in the deceleration region as described above. Therefore, it is possible to effectively improve the accuracy of the stop position.

Moreover, the linear motor coil 10 is controlled only by ON/OFF command signals from the sequence controller 55,
In the low speed region (acceleration region and deceleration region), the linear motor unit 23 is controlled by the driving force of the linear motor unit 23 and the driving force of the servo motor unit 31 that supplements the driving force of the linear motor unit 23. Control requires only switching between an ON state in which maximum excitation (maximum thrust) is generated in the linear motor coil 10 and an OFF state in which the thrust generated by the servo motor unit 31 is sufficient. This eliminates the need for complex control equipment or a near motor controller, which were necessary to control the excitation of the linear motor coil based on the conveyance speed from the speed sensor, and the control system of the linear motor unit 23 ( The burden placed on the sequence controller 55) is reduced, making it possible to prevent a decrease in reliability and failure of the control system of the linear motor unit 23 as much as possible, and to simplify the control system of the linear motor unit 23. As a result, the control system of the linear motor unit 23 can be simplified.

Furthermore, as described above, conveyance is performed by driving the linear motor unit 23 and servo motor 31 in the acceleration region and deceleration region, and conveyance is performed by driving the servo motor unit 31 in the middle of the transport region. Even if the unit 23 breaks down, the servo motor unit 31 is always driven during transport, so transport is possible; however, even if the servo motor unit 31 breaks down, the thrust of the linear motor unit 23 will take you to the first station. 23 (31) is in failure.

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 the linear motor unit 23 and the servo motor 31 between the deceleration transport start point 1 (and the deceleration point t2) in the deceleration area, but the deceleration Of course, the pallet on which the rebody is placed may be transported by the linear motor unit and the servo motor in at least a part of the deceleration area that includes at least a part of the deceleration area. Further, the pallet on which the body is placed may be transported by driving the near motor unit and the servo motor unit from a point a predetermined amount before the transition from the middle stage of the transport region to the deceleration region.

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 can of course be applied to the case of transporting other objects to be transported. It is.

(Effects of the Invention) As described above, according to the conveyance device of the present invention, the effects of the linear motor unit and the servo motor unit are achieved in the deceleration region starting from the speed change point where the constant speed conveyance in the middle of the conveyance region shifts to the deceleration region. Since the servo motor unit with high positioning accuracy performs decelerated conveyance only at a point a predetermined amount before the end of the deceleration region where it stops, the shift point where the transition from the middle of the conveyance region to the deceleration region changes is the conveyance speed. It is possible to accurately hold down the position without causing a deviation between the set value and the measured value due to fluctuations in the position, and to perform the final positioning stop control with high precision, thereby effectively improving the accuracy of the stop position.

[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 configuration of the servo motor unit when the gear box is cut open, FIG. 5 is a sectional view taken along line V-V in FIG. 7 and 7 are flowcharts showing the control flow, and FIG. 8 is a characteristic diagram showing changes in conveyance speed. FIG. 9 is a diagram corresponding to FIG. 1 showing a conventional example. A...Transport device P...Pallet (transferred object) ST1, ST2...Working station t2...Deceleration point (point) 23...Linear motor unit 31...Servo motor unit 43...・Transportation state detection means 51...Station controller (control means) Fig. 8-25-

Claims (1)

[Claims] (1) In a conveying device that shifts from constant speed conveyance in the middle of the conveyance area to decelerated conveyance at the end of the conveyance area when conveying an object between adjacent stations of a line having a plurality of stations, each of the above-mentioned Each station is provided with a linear motor unit and a servo motor unit, and includes a conveying state detecting means for detecting the conveying state of objects to be conveyed between adjacent stations, and receiving the output of the conveying state detecting means, During deceleration that includes at least a portion of the deceleration region, the conveyed object is decelerated and conveyed by the drive of the linear motor unit and the servo motor unit, and at the end of this deceleration region, the conveyed object reaches a point a predetermined amount before it stops. and control means for controlling the operations of a linear motor unit and a servo motor unit so that the object to be transported is decelerated and transported by deceleration by only the servo motor unit.