JPH0356004A - Conveyor - Google Patents

Abstract

PURPOSE:To maintain conveying time and a stopping position constant by conveying an article to be conveyed by a linear motor unit and a servo motor unit at the time of accelerating, and conveying the article to be conveyed only by the servo motor unit at a time before a predetermined distance for shifting to the conveying intermediate range of the end of an accelerating range. CONSTITUTION:If a pallet P is conveyed between adjacent stations ST1 and ST2, it is conveyed by a linear motor unit 23 and a servo motor unit 31 in an accelerating range at the time of accelerating of the initial of conveying under the control of a station controller 51. It is conveyed only by the unit 31 in a high positioning accuracy at the time of lapse of time before predetermined time for shifting to the conveying intermediate range of the end of the accelerating range. Thus, the conveying time and the stopping position can be always maintained constant.

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 conveyance device, one using a linear motor including a linear motor coil and a reaction member is known. As shown in FIG. 9, for example, a conveyance device using this linear motor includes one of the linear motor coils b, b, . coil b
, b, ...) as a stator and multiple rollers d, d
, . , ... and the reaction member C, the thrust force F generated in the mover (reaction member C) causes the mover (
It is configured to transport the pallet f and items placed thereon via the reaction member C).

In a conveying device using this kind 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 pallet 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 drive of 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 motor is indirectly captured by simply pressing the encoder against the 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 cause a deviation between the set value and the actual value of the speed change point when transitioning from the acceleration region at the beginning of transportation to the intermediate transportation region where constant speed transportation is performed. For this reason, the deceleration start time varies in order to recover the conveyance distance by the shift in the shift point, and the conveyance time and stop position vary.

The present invention has been made in view of the above, and an object of the present invention is to effectively and efficiently use a linear motor and a servo motor in combination to transport the material from an acceleration area to a constant transport time and stop position. This is an attempt to stabilize control when transitioning to the mid-term region.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is such that when a conveyed object is conveyed between adjacent stations of a line having a plurality of stations, from an acceleration region at the initial stage of conveyance. It is assumed that the conveyance device is configured to shift to a medium-term conveyance region in which constant-speed conveyance is performed. 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 acceleration that includes at least a part of the acceleration region, the conveyed object is transported by driving the linear motor unit and the servo motor unit, and is moved to a middle transport region at the end of this acceleration region? and a control means for controlling the operations of the linear motor unit and the servo motor unit so that the object to be transported is transported by only the servo motor unit at a point a predetermined amount before the servo motor unit.

(Function) With the above-described configuration, in the conveyance device of the present invention, when an object to be conveyed is conveyed between adjacent stations, the control of the control means is controlled based on the conveyance state detected by the conveyance state detection means. Below, conveyance is performed by driving the beam near motor unit and servo motor unit in an acceleration region that includes at least a portion of the acceleration at the beginning of conveyance, and a point a predetermined amount before transitioning to the middle conveyance region at the end of this acceleration region. The conveyance is performed by driving only by the servo motor unit. As a result, even if the transport 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 indirect transport speed from the encoder, the servo motor unit with high positioning accuracy allows There is no difference between the set value and the actual measured value of the shift point when moving to the mid-term transport region, and the transport time and stop position can be kept constant.

(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. The adjacent work station ST. ~
The transport is carried out between ST2 (only two of these locations 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 and 11 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.

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 the second plate 15 extends upwardly.
A front and rear cylinder 16 having a piston rod 16a extending forward in the conveying direction (left side in FIG. 1) is arranged on the plate 15, and the front and rear cylinder 16 has a piston rod 16a.
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 stator rows 11 acts on each of the stator rows 11 by the thrust generated by the electromagnetic interaction with each linear motor coil 10 of each of the eight stator rows 11. As a result, the body B on the pallet P is moved to the rear side in the conveying direction along the pallet P with the engagement block 20 engaged with the engagement protrusion member 19. The material is transported sequentially between STz within a certain period of time. Therefore, the linear motor coil 10 and the reaction member 14 constitute a linear motor unit 23.
3, each work station ST+. One is provided for each ST2.

The conveyance device A has each work station ST+
The 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 the two stator rows 11, 11 with the rotating shaft 32a facing upward. a rack member 3 which is provided on the lower surface of the pallet P facing the servo motor 32 and extends in the longitudinal direction (transfer direction) of the pallet P, and has teeth on both sides thereof.
3, a first pinion 34 mounted on the rotating shaft 32a of the servo motor 32, a second pinion 35 that meshes with the first pinion 34 and 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 fourth pinion 37 that meshes with the third pinion 36 and the teeth on the other side of the rack member 33. The pallet P is conveyed by converting the rotational force of the servo motor 32 into linear driving force by a series of pinions 34 to 37 and the rack member 33. In addition, the binions 34 to 37 are connected to the gear box 3 provided on the support stand 38.
Covered by 9.

After the pallet P, which is the object to be transported, is transported to the work station STz on the downstream side, the rod 21 is rotated clockwise in FIG. The engagement state of the engagement block 20 with respect to 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 ST on the upstream side. It is designed to be moved. 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
,,s'r,. , there are adjacent work stations ST1
A speed sensor 41 is provided to detect the conveyance speed of the pallet P between STz and STz. In addition, each of the above stations ST. , s'rz are provided with an encoder 42 that detects the rotation speed of the servo motor 32. moreover,
Each of the work stations ST, s'r; is provided with a deceleration limit switch LS, and the deceleration limit switch LS is an optical switch (not shown) provided on the bottom surface of the pallet P. limit switch LS
An ON signal is output when the pallet P (optical switch) is positioned above the deceleration limit switch LS, and an OFF signal is output when the pallet P (optical switch) is not positioned above the deceleration limit switch LS. The speed sensor 41, encoder 42, and deceleration limit switch LS constitute a transport state detection means 43 that detects the transport state of the pallet P between adjacent work stations S T + to S72.

Furthermore, FIG. 6 shows a block configuration of the control section of the conveyance device A. In the figure, 51 is the adjacent work station ST, ~
Provided across S72, each work station S
A station controller serves as a control means for controlling the operation of the linear motor unit 23 and servo motor unit 31 of TY, ST2, and the station controller 51 receives signals from the speed sensor 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 also controls the encoder 42, 42 (conveying state detection means 43).
a servo motor controller 53 that receives signals, that is, rotation information, from the servo motor controller 53 and performs feedback control of the position information of the pallet P between the work stations ST, , 872;
Upon receiving the position information of the pallet P from the servo motor controller 53, it outputs an ON/OFF command signal to the phase control section 54, . . . (amplifier) provided at the input section of each of the linear motor coils 10. It consists of a sequence controller 55. The sequence controller 55 also receives O from the deceleration limit switch LS.
An N/OFF signal is input. Then, the sequence controller 55 receives the ON signal from the deceleration limit switch LS and the position information of the pallet P from the servo controller 53, and outputs the phase control section 54, . While energizing the linear motor coil 10 to the maximum (reverse phase), receiving the OFF signal from the deceleration limit switch LS and the position information of the pallet P from the servo controller 53,
An OFF command signal is output to the phase control section 54, . . . to control each linear motor coil 10 so as not to excite it. Further, when outputting an ON command signal to the phase control section 54, . . Note that 56 is an amplifier provided at the output section of the servo motor controller 53 (input section of the servo motor 32).

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 S1, the position information of the pallet P from the servo controller 53 is input 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 O, causes the linear motor to 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
L, the operation of the servo motor unit 31 is started. After that, in step S4, the linear motor unit 2
3 and the servo motor unit 31, and measure the velocity V after the linear motor unit 23 and the servo motor unit 31 start accelerating, and measure the elapsed time t from the acceleration transport start time t^.

Then, in step S5, it is determined whether the speed V after the start of acceleration has become equal to the speed v1 at the elapsed time point 1+ (see FIG. 8), which is a predetermined time before the transition to the intermediate conveyance region at the end of the acceleration region. , when the determination is YES, that is, when the speed V1 at the elapsed time t1 is reached, step S
6, the linear motor controller 52 is turned OFF to stop the operation of the linear motor unit 23, and the acceleration is performed only by driving the servo motor unit 31. Note that the driving of the linear motor unit 23 and the driving of the servo motor unit 23 are synchronized until the speed V reaches the speed v1 after the start of acceleration, that is, between the acceleration conveyance start time tA and the elapsed time t1. It has significance as a synchronization period for

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 conveyance start time tB is reached, the acceleration of the servo motor unit 31 is stopped in step S8, and the servo motor unit 31 is is driven to transport the pallet P at a constant speed at the speed VQ at the constant speed transport start time ta. Thereafter, in step S9, the elapsed time t reaches the deceleration conveyance start time tc, that is, the optical switch of the pallet P is positioned above the deceleration limit switch LS of the downstream station ST2, and the deceleration limit switch L
It is determined whether or not an ON signal is emitted from S, and when the front end of the pallet P whose determination is YES is positioned above the downstream limit switch LSz (deceleration conveyance start time 1 (, elapsed), step The linear motor coil 10 is maximally excited to the deceleration side (reverse sheath) in SIO, and the servo motor unit 31 applies braking in step Sll to start deceleration. Thereafter, in step S1
At step 2, the elapsed time t reaches the stop position 10, and the operations of both the linear motor unit 23 and the servo motor unit 31 are stopped. With the above steps, the conveyance of the pallet P between the adjacent work stations 87 and ST2 is completed.

Therefore, in the above embodiment, when the pallet P is transported between adjacent stations /STI to ST2, the beam near motor is Conveyance is performed by driving the unit 23 and the servo motor unit 31, and a predetermined time elapses before the transition to the intermediate conveyance region at the end of this acceleration region. The conveyance is performed by driving only by the servo motor unit 31. by this,
The servo motor unit 31 maintains high positioning accuracy even when the conveyance speed of the pallet P fluctuates due to the drive of the linear motor unit 23, which is essentially an oven lube control system, through operation control based on the indirect conveyance speed from the speed sensor 41. As a result, the pallet P is always transported in a constant transport time without causing a discrepancy between the set value and the actual measurement value at the constant speed transport start time t8, which is the speed change point when transitioning from the acceleration region to the intermediate transport region, Control can be stabilized when transitioning from the acceleration region to the mid-transport region.

Moreover, the control of the linear motor unit 23 is controlled by an O that generates maximum excitation (maximum thrust) in the linear motor coil 10.
A sequence controller 55 that switches between the N state and the OFF state that can be provided by the thrust from the servo motor unit 31.
This eliminates the need for a controller equipped with control equipment 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 (sequence controller 55)
The load placed on the linear motor unit 23 is reduced, and a decrease in reliability and failure of the control system of the linear motor unit 23 can be prevented as much as possible, and the control system of the linear motor unit 23 has a simple configuration. The control system of the linear motor unit 23 can be simplified.

Furthermore, during transportation, the servo motor unit 31 is driven by the beam near motor unit 23 and the servo motor 31 in the acceleration region (up to elapsed time t1) and deceleration region as described above, and in the middle region of transportation, the servo motor unit 31 is driven, and the speed information from the speed sensor 41 is input to the pulse counter 52, so even if the linear motor unit 23 fails, the servo motor unit 31 is always driven during transport. On the other hand, even if the servo motor unit 31 fails, the thrust of the linear motor unit 23 can be used to transport the station to the station to be attacked first, making it possible to transport the station even if one of the units 23 (31) fails. It can be done.

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 conveyed by driving the linear motor unit 23 and the servo motor 31 in the acceleration region until reaching the speed v1. Of course, the pallet on which the body is placed may be transported by driving the linear motor unit and the servo motor unit in at least a portion of the acceleration 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, but can also be applied to the case of transporting other objects to be transported. Of course.

(Effects of the Invention) As described above, according to the conveying device of the present invention, since conveyance is performed by driving only the servo motor unit at a point a predetermined amount before transitioning to the intermediate conveyance region at the end of the acceleration region, it is essentially an oven loop. Even if the conveyance speed fluctuates due to the drive of the linear motor unit that serves as the control system, the servo motor unit with high positioning accuracy allows you to set the speed change point when transitioning from the initial acceleration area to the intermediate conveyance area where constant speed conveyance is performed. The conveyance is carried out so that the conveyance time and stop position are always constant without causing any deviation between the value and the actual measurement value, and it is possible to stabilize the control when transitioning from the acceleration region to the intermediate conveyance region.

[Brief explanation of drawings]

1 to 8 show embodiments of the present invention, in which FIG. 1 is a side view of the conveying device, FIG. 2 is a plan view thereof, and FIG. 3 is a cross section taken along the line ■-■ in FIG. 1. Figure 4 is a front view of the configuration of the servo motor unit when the gear box is cut open, Figure 5 is a sectional view taken along line V-V in Figure 4, and Figure 6 is the block configuration of the control section of the conveyance device. FIG. 7 is a flowchart 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 (object to be transported) ST+. ST2...Work station t1...Elapsed time point (point) 23...Linear motor unit 31...Surho motor unit 43...Transportation state detection means 51...Station controller (control means) and others 2 Name F Figure 9-35-1

Claims (1)

[Claims] (1) In a conveyance device that is configured to transfer an object between adjacent stations of a line having a plurality of stations, the object shifts from an acceleration area at the initial stage of the conveyance to a middle conveyance area where the object is conveyed at a constant speed. are provided with a linear motor unit and a servo motor unit, respectively, and have a conveyance state detection means for detecting the conveyance state of the conveyed object between adjacent stations, and an output of the conveyance state detection means to detect the acceleration mentioned above. During acceleration that includes at least a part of the area, the conveyed object is conveyed by driving the linear motor unit and the servo motor unit, and the object is conveyed by the drive of the linear motor unit and the servo motor unit, and the object is conveyed at a point a predetermined amount before transitioning to the intermediate conveyance area at the end of this acceleration area. 1. A conveyance device comprising a control means for controlling the operation of a linear motor unit and a servo motor unit so that an object to be conveyed is conveyed by driving only by the servo motor unit.