JPH0356006A - Conveyor - Google Patents

Abstract

PURPOSE:To improve a conveying control accuracy by conveying an article to be conveyed by a linear motor unit and a servo motor unit in an initial conveying range and an end range, and so controlling the linear motor unit and the servo motor unit as to convey it by the servo motor unit in a conveying intermediate 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 to become an initial conveying range and a decelerating range of a conveying end under the control of a station controller 51, and conveyed by the unit 31 in a constant speed range of a conveying intermediate range. That is, the unit 31 is always driven at the time of conveying, conveying is conducted by the unit 23 only in a low speed range, and substantially an open loop as a whole control is supplemented by the unit 31 having high positioning accuracy.

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, . . . A plurality of rollers d, with motor coils b, b, ...) as a stator,
The linear motor coils b, . The mover (
The pallet f and the objects placed thereon are transported via the mover (reaction member C) by the thrust force F generated in 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 servo motor to transport the object to the stopping position of each station.

(Problem to be Solved by the Invention) By the way, when comparing the thruster speed characteristics of the above-mentioned linear motor and a servo motor, which is a rotary motor, the first
As shown in Figure 1, the linear motor generates a large thrust in a low speed range such as during startup, and the servo motor generates a large thrust in a high speed range a predetermined time after starting. For this reason, as shown in FIG. 10, the driving means of the conveying device should be designed to maintain near-movement in low-speed areas such as an acceleration area that requires acceleration at the beginning of the conveyance and a deceleration area that requires deceleration at the end of the conveyance. , it is desirable to use a servo motor in a high speed region where the speed reaches a predetermined speed (high speed) after acceleration.

However, the operation of the linear motor is controlled based on the conveyance speed of the pallet, which is indirectly detected by simply pressing an encoder against the pallet via a roller or the like, so slippage may occur between the pallet and the rollers. Due to the virtually open roof control system, the conveyance speed during pallet conveyance may fluctuate as shown by the imaginary line in Figure 10. Discrepancies occur in the high speed range (constant speed range) of the servo motor, and the shift points from the high speed range of the servo motor to the low speed range (deceleration range) of the linear motor, resulting in variations in the overall control accuracy of conveyance. become.

The present invention has been made in view of the above points, and its purpose is to effectively and efficiently use a linear motor and a servo motor in combination to improve conveyance control accuracy and speed in all operating ranges. The purpose of the present invention is to provide a conveying device that can obtain the desired results. Another object of the present invention is to enable transportation of either the linear motor or the servo motor when the motor is out of service.

(Means for Solving the Problems) 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; and at least part of each of an acceleration region at the beginning of the conveyance and a deceleration region at the end of the conveyance, in response to the output of the conveyance state detection means. In the initial conveyance area and the final conveyance area, the conveyed object is conveyed by the drive of the linear motor unit and the servo motor, and in the intermediate conveyance area, which includes at least part of the constant speed area in the intermediate conveyance period, the servo motor unit The control means controls the operation of the linear motor unit and the servo motor unit so that the conveyed object is conveyed by the drive of the linear motor unit and the servo motor unit.

(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 conveyance is performed by driving the beam near motor unit and the servo motor unit in the initial conveyance area and the final conveyance area, which include at least part of each of the acceleration area at the initial stage of conveyance and the deceleration area at the final stage of conveyance, and the constant speed area during the middle conveyance period. In the middle stage region of transport, which includes at least a portion of , transport is performed by driving the servo motor unit. In other words, since the servo motor unit is constantly driven during conveyance, conveyance by the linear motor unit is performed only in low speed areas (initial conveyance area and final conveyance area), and the linear motor unit essentially becomes an oven lube. is compensated for by a servo motor unit with high positioning accuracy, and there is no deviation in each shift point from the acceleration area (low speed area) to the constant speed area (high speed area) and from the constant speed area to the deceleration area (low speed area). . This improves the stability of conveyance and the accuracy of the stop position, and improves the conveyance control system over the entire operating range.

In addition, as mentioned above, in the initial transport region and final transport region, transport is performed in the low speed region by the sum of the thrust of the beam near motor unit and the servo motor unit, so the acceleration force and deceleration force in this low speed region are effectively used. It will be elevated.

Furthermore, as described above, transport is performed by driving the beam near motor unit and servo motor in the initial transport region and final transport region, and transport is performed by driving the servo motor unit in the middle transport region. Even if the unit fails, that is, the linear motor unit fails, the servo motor unit is always driven during transportation, so transportation is possible.However, even if the servo motor unit fails, the station will go first due to the thrust of the linear motor unit. It can be transported up to

(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 ST, ~
The transport is carried out between ST2 (only two of which are shown in the figure) within a certain period of time. The pallet P is a roller conveyor 3 consisting of a large number of rollers 2, 2, . . . rotatably attached to support members 1, 1 on both sides of the conveyor line.
It is supported by and conveyed while sliding on the roller conveyor 3.

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, the guide rail 12.1 on the south side of each stator row 11
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 l6 having a piston rod 16a extending forward in the conveyance direction (left side in FIG. 1) is arranged on the plate 15, and the piston rod 16a of the front and rear cylinder 16
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 inside the cylindrical member 17 there is a member that engages with one retaining protrusion provided on the back surface of the pallet P. The proximal end of a rod 21 having a matable engagement 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 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, with the engagement block 20 of the pallet P being engaged with the engagement protrusion member 19. It is designed to transport the parts sequentially 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, as its driving means, separate from the linear motor unit 23, each work station ST+. ST
2 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 rack member 33 which is provided on the lower surface of the pallet P facing the servo motor 32 and extends in the longitudinal direction (conveying direction) thereof and has teeth on both side surfaces; A first pinion 34 mounted on the rotating shaft 32a, and a second pinion 3 that meshes with the first pinion 34 and teeth on one side of the rack member 33.
5 and the first pinion 34 at a position opposite to the second pinion 34.
A third pinion 36 meshes with the pinion 34, and a fourth pinion 37 meshes with the third pinion 36 and the teeth on the other side of the rack member 33. The pinions 34 to 37 and the rack member 33 are configured to convert the driving force into linear driving force to convey the pallet P. Furthermore, Binion 34
37 are 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 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 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
I, ST2 has an adjacent work station S T +
A speed sensor 41 is provided to detect the conveyance speed of the pallet P between ST2 and ST2. Further, each of the stations ST, ST2 is provided with an encoder 42 for detecting the rotation speed of the servo motor 32. The speed sensor 41 and the encoder 42 constitute a transport state detection means 43 that detects the transport state of the pallet P between adjacent work stations STI to S72.

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~
Provided across the STZ, each work station S
T,,ST2 is a station controller as a control means for controlling the operation of the linear motor unit 23 and the servo motor unit 31, and the station controller 51 is a station controller that controls the operation of the linear motor unit 23 (
Specifically, the near motor controller 52 controls the excitation of the near motor coil 10), and the operation of the servo motor unit 31 (specifically, the rotation of the servo motor 32), and the signals from the encoders 42, 42, that is, rotation information. Based on the conveyance status from the conveyance status detection means 43, each work station ST+ . A servo motor controller 53 performs feedback control of the position information of the pallet P between S72, and receives the output from the servo motor controller 53 and controls the linear motor controller 52 and the servo motor based on the vehicle type information etc. input from the host computer 54. It consists of an overall control section 55 that instructs the controller 53 (servo motor 32) to switch on and off the control, and also provides acceleration/deceleration command values to the linear motor controller 52 based on the signals from the speed sensors 41, 41, that is, speed information. . In addition, 5
Reference numeral 6 denotes an amplifier provided at each output section of the linear motor controller 52 and the servo motor controller 53 (the amplifier 56 connected to the linear motor controller 52 is specifically a thyristor circuit or the like that performs phase control).

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, vehicle type information is received, and in step S2, a speed control pattern is selected in accordance with the vehicle type (and in turn, the pallet weight jl including the weight of objects such as body B). After that, in step S3, the linear motor unit 2 is controlled according to the selected speed control pattern.
At the same time, in step S4, the control of the servo motor controller 53 is turned ON in synchronization with the operation of the linear motor unit 23, and the operation of the servo motor unit 31 is started. Then, in step S5, acceleration of the linear motor unit 23 and the servo motor unit 31 is started, and the elapsed time t from the acceleration transport start time tA of the linear motor unit 23 and the servo motor unit 31 is measured.

Then, in step S6, it is determined whether or not the elapsed time t is smaller than one day (see FIG. 8) at the constant speed conveyance start time, and when the determination is NO, that is, when the constant speed conveyance start time tB has passed, In step S7, the linear motor controller 5
2 is turned OFF to stop the operation of the linear motor unit 23, and the pallet P is transported only by driving the servo motor unit 31. Note that the period between the accelerated conveyance start time tA and the constant speed conveyance start time tB has a significance as a synchronization period for synchronizing the drive of the linear motor unit 23 and the drive of the servo motor unit 23.

Next, in step S8, it is determined whether the elapsed time t is smaller than the deceleration conveyance start time tc, and when the determination is No, the deceleration conveyance start time tc has passed, the linear motor unit 23 and the servo motor are activated in step S9. unit 3
1 applies the braking force and starts the attack.

Thereafter, it is determined in step SIO whether the elapsed time t is smaller than the stop time to, and when the determination is NO and the stop time to has passed, the linear motor unit 23 and the servo motor unit 31 are activated in step S1+. stop together. As a result of the above, adjacent work stations S
The conveyance of the pallet P by the station controller 51 between T+ and S72 is completed.

Therefore, in the above embodiment, when the pallet P on which the body B is placed is transported between adjacent stations ST+ to ST2, under the control of the station controller 51, the transport initial region, which is the acceleration region at the initial stage of transport, and Conveyance is performed by driving the beam near motor unit 23 and servo motor unit 31 in the final conveyance region, which is a deceleration region at the final conveyance stage, and conveyance is performed by driving the servo motor unit 31 in the intermediate conveyance region, which is a constant speed region in the middle of conveyance. will be held. That is, since the servo motor unit 31 is constantly driven during transport, the linear motor unit 23 is only driven in the low speed region (initial transport region and final transport region).
The servo motor unit 31 with high positioning accuracy compensates for the fact that the overall control is essentially an open loop, and the servo motor unit 31 has high positioning accuracy. There will be no deviation in each shift point from the speed region to the deceleration region (transport final region). This makes it possible to stabilize the conveyance and improve the accuracy of the stop position, thereby improving the control accuracy of the conveyance in general (the initial conveyance region, the final conveyance region, and the intermediate conveyance region).

In addition, as described above, the beam near motor unit 23 and the servo motor unit 31 are
Since conveyance in the low speed region is performed by the sum of the thrust forces, it is possible to effectively improve the acceleration force and deceleration force in these low speed regions.

Furthermore, as described above, transport is performed by driving the linear motor unit 23 and servo motor 31 in the initial transport region and final transport region, and transport is performed by driving the servo motor unit 31 in the middle transport region. Even if the motor 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 transport the system to the first station. This makes it possible to transport the unit 23 (31) when either one of the units 23 (31) is out of order.

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 acceleration area and the deceleration area are all divided between the linear motor unit 23 and the servo motor unit 3.
1, the pallet P on which the body B is placed is transported by driving the pallet P on which the body B is placed, and the transport initial region and the transport final region including at least part of each of the acceleration region and the deceleration region, that is, at least part of the acceleration region and the deceleration region. Of course, the pallet on which the body is placed may be transported by driving the linear motor unit 1 and the servo motor in the initial transport region and final transport region. In addition, the initial conveyance area and the final conveyance area each include a part of the constant speed area during the intermediate conveyance period, and in each of these areas, the pallet on which the body is placed is conveyed by the drive of the linear motor unit and the servo motor unit. You may also do so.

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 conveying device of the present invention, the servo motor unit with high positioning accuracy is constantly driven during conveyance, and the near motor unit is substantially controlled by driving only in the initial and final areas of conveyance. Since it compensates for the oven loop, there will be no misalignment at each shift point.
It is possible to stabilize the conveyance and improve the stop position accuracy, improving the control accuracy of the overall conveyance.In addition, since conveyance is performed by driving the beam near motor unit and servo motor unit in the initial and final stages of conveyance, the conveyance is improved. Acceleration and deceleration forces in the initial and final regions are effectively increased, making it possible to increase the speed of conveyance. In addition, even if the linear motor unit fails, the servo motor unit is constantly driven during transportation, allowing transportation, while even if the servo motor unit fails, the thrust of the linear motor unit can still carry the transport.
It is possible to transport the unit when either one of the units is out of order.

[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. 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 the V-v line 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 equivalent to Fig. 1 showing a conventional example, Fig. 10 is a diagram equivalent to Fig. 8 and Fig. 11 is a diagram corresponding to Fig. 1 in which drive is performed by a linear motor in a low speed region and by a servo motor in a high speed region. FIG. 3 is a characteristic diagram showing thrust-speed characteristics of a beam near motor and a servo motor. A...Transportation device P...Pallet (object to be transported) ST+, ST2...Working station 23...Linear motor unit 31...Servo motor unit 43...Transportation state detection means 51... Station controller (control means) No. 8
Figure 7 Figure 10F Figure 9 Figure 1

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 conveyance state detection means, an initial conveyance area and a final conveyance area including at least a part of each of an acceleration area at the initial stage of conveyance and a deceleration area at the final stage of conveyance are driven by the linear motor unit and the servo motor to detect the conveyed object. transport,
The intermediate conveyance region including at least part of the constant speed region during the intermediate conveyance period includes a control means for controlling the operation of the linear motor unit and the servo motor unit so that the conveyed object is conveyed by driving the servo motor unit. A conveying device characterized by: