JP2000351411A - Stacker crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve carrying capacity of a stacker crane by preventing the occurrence of an excessive load even if the stacker crane is driven at a high speed. SOLUTION: One end of a mast is fixed to a lower carriage, and the other end is elastically connected to an upper carriage 6. The upper carriage 6 is composed of a traveling unit 8 and a connecting unit 10, the mast 12 is fixed to the connecting unit 10, and both units are connected via a spring 34 and a damper 30 to thereby obtain a stacker crane capable of traveling at a high speed and imparting no excessive load to a connecting part of the mast 12 and the upper traveling carriage 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement of a stacker crane.

[0002]

2. Description of the Related Art In an automatic warehouse, a stacker crane is used as a transfer device, and a column-shaped mast is provided on a lower truck, and a lifting platform is moved up and down along the mast. The height of this mast amounts, for example, to 30 m and is therefore extremely heavy. For these reasons, the stacker crane is also heavy and slow.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the carrying capacity of a stacker crane by preventing the stacker crane from being overdriven even when driven at high speed.
~ 3). It is an additional object of the present invention to provide a specific mechanism for transmitting thrust to a mast. An additional object of the invention according to claim 3 is to absorb vibration of the mast.

[0004]

In the stacker crane of the present invention, a mast is connected to a pair of upper and lower traveling vehicles to apply a thrust, and the mast is slidably connected to at least one traveling vehicle, and the mast is slidably connected to the sliding amount. The thrust is applied from the one traveling vehicle.

[0005] Preferably, the mast is elastically connected to the one traveling carriage. Also preferably, the mast is connected to the one traveling vehicle via a damper.

[0006]

According to the first aspect of the present invention, since the thrust is applied to the mast by the upper and lower traveling vehicles, the speed of the stacker crane can be increased. Here, it is impossible to drive the upper and lower trucks completely in synchronization. According to the first aspect of the present invention, since the mast is slidably connected to at least one of the traveling vehicles, the control error of the upper and lower traveling vehicles is absorbed by the sliding of the mast, and the connection between the traveling vehicle and the mast is impossible. Will not join. The traveling bogie on the side where the mast is slidably connected applies thrust to the mast according to the amount of sliding,
For example, if the slide amount is 0, almost no force is applied, and the vehicle travels with the thrust from the other traveling vehicle. For these reasons, the stacker crane can be run at a high speed, and the connection between the mast and the traveling trolley is not forced.

According to the second aspect of the present invention, since the mast is elastically connected, an elastic force corresponding to the sliding amount can be applied to the mast as a thrust. According to the third aspect of the present invention, the mast is prevented from vibrating by providing the damper, and the vibration of the mast can be quickly converged, especially when the mast is stopped, thereby shortening the time until transfer.

[0008]

1 to 4 show a stacker crane 2 according to an embodiment.
FIG. 5 shows the control of the upper and lower traveling motors, and FIG. 6 shows the traveling pattern of the stacker crane 2. FIG. 1 shows an overall image of the stacker crane 2.
Reference numeral 6 denotes an upper carriage, which comprises a traveling unit 8 and a connection unit 10 elastically connected to the traveling unit 8. Reference numeral 12 denotes a lattice mast 12, for example, three pillar members 14, 14, 1
4 are connected by a breath 15 to form a lattice structure, and have a height of, for example, 30 m, and are fixed to the lower carriage 4 and the connection unit 10. Reference numeral 16 denotes an elevating table which moves up and down along the lattice mast 12, and 18 denotes an elevating drive unit. Reference numeral 19 denotes a laser distance meter which detects the absolute positions of the carts 4 and 6. Reference numeral 20 denotes an upper rail, reference numeral 21 denotes a lower rail, and the stacker crane 2 is for transporting articles in, for example, an automatic warehouse.

FIG. 2 shows the traveling unit 8 and the connecting unit 1.
0 shows an elastic connection with 0. The upper end of the lattice mast 12 is fixed to the connection unit 10, and the traveling unit 8 travels along the upper rail 20 and connects these units elastically, thereby eliminating the forcing applied to the connection portion.
The traveling unit 8 is provided with guide rollers 22, 23, 24, which are guided by the upper rail 20,
In step 5, the traveling wheels 26 are driven to travel. For example, a pair of dampers 30, 30 provided in the connection unit is connected to the arm 28 provided in the traveling unit 8 to prevent the mast 12 from vibrating. An electromagnetic damper, an oil damper, or the like is used for the damper 30, and as shown in FIG. 3, a bar-shaped member 31 at the tip of the damper 30 is made to contact the plate-shaped member fixed to the arm 28 so as to be movable up and down and left and right. This is a mast 12
This is because even if there is a deformation such as bending, the contact position between the rod-shaped member 31 and the plate-shaped member 29 only moves, so that no excessive force is applied.

The traveling unit 8 is provided with an arm 32, and springs 34, 34 such as a spring coil, a laminated leaf spring, and a ring spring of the connection unit 10 are connected to the arm 32 from both sides. Therefore, the force (thrust in the traveling direction) in the direction of the rail 20 applied from the traveling unit 8 to the connection unit 10 is applied in accordance with the displacement of the spring 34. This thrust need not necessarily be proportional to the displacement. When the springs 34, 34 have high vibration damping properties or large friction against displacement, the springs 34, 34 serve as dampers, and the dampers 30, 30 are unnecessary. Conversely, if the dampers 30, 30 have spring properties at both ends of the stroke, for example, the spring 34 need not be provided. 36 is a detection arm of the traveling unit 8, and 38, 38 are limit switches for detecting the position of the detection arm 36, as long as they can detect that the displacement between the upper and lower units 8, 10 is equal to or more than a predetermined value. good. Numeral 40 denotes a sheave of a hoisting wire 42 of the elevator.

FIG. 4 shows the mounting of the lift 16 on the mast 12. The mast 12 is composed of, for example, three column members 14, two of which are also used as guide rails,
The sixth guide roller 44 moves up and down so as to sandwich the column member 14 from both sides. Then, a transfer means such as a slide fork 48 is mounted on the loading platform 46 of the lifting platform 16.

FIG. 5 shows a control system for the upper and lower carriages 4 and 6. Reference numeral 50 denotes a control unit, the input of the target value of which is Vref and the output thereof is V0, and 52 is a traveling motor provided on the lower bogie 4. Numerals 54, 56 and 58 denote differentiators, and 60 denotes a PI amplifying unit for obtaining a control amount in PI control (proportional and integral control) for the output Δx (position of the upper bogie 6−position of the lower bogie 4) of the differentiator 54. It is. The positions of the upper and lower trolleys 4 and 6 are obtained by the laser distance meter 19 and input to the differentiator 54,
Reference numeral 62 denotes a control amount of the PI amplification unit
Or a switch for selecting whether to add to the upper traveling motor 25. In the embodiment, the position of the upper and lower carriages 4 and 6 can be aligned in any case by adjusting the motor on the leading side to the side on which the motor is relatively slowed down and delayed. The limit switch 38 is used as an emergency switch, and when the displacement between the traveling unit 8 and the connection unit 10 exceeds the allowable limit value, the control unit 50 sets the traveling target speed to 0 and stops.

In the case of FIG. 5, the target value of the speed determined from the running pattern stored in advance is set to Vref, and the control unit 50 is determined based on, for example, the difference from the actual position obtained from the actual position obtained by the lower laser range finder. Outputs the output V0. Next, the difference unit 54 checks which of the upper trolley 6 and the lower trolley 4 is advanced (Δx> 0 if the upper trolley is advanced, ΔX <0 if the upper trolley is delayed), and the control amount according to the displacement Δx. To PI
Using the switch 62, the control is performed by using the switch 62 to relatively reduce the speed of the advancing side and eliminate the displacement Δx with the lagging side. Control is given by equation (1) or (2)
Indicated by Vup = V0−Kp · Δx−Ki∫Δx (Δx> 0) (1) Vdown = V0 + Kp · Δx + Ki∫Δx (Δx <0) (2) where Vup is the target speed of the upper bogie 6 and Vdown is the lower bogie 4
Target speed. Further, a control based on the output V0 is applied to the motor on the side of delay. ∫ is an integral symbol, Kp is a constant for proportional control, and Ki is a constant for integral control.

Instead of the control shown in FIG. 5, control may be added so that the position error Δx between the upper and lower carriages 4 and 6 is eliminated on the upper carriage 6 side. The control in this case is represented by the equation (3), and control is applied to the lower traveling motor 52 by a difference between the speed determined from the position obtained by the laser distance meter and the target speed Vref. The upper traveling motor 25 to which a proportional integral control for eliminating the displacement Δx is added as a control amount Vup. Vup = V0−Kp · Δx−Ki∫Δx (3)

In the embodiment, the mast 12 has a lattice structure to reduce the weight. The use of the pair of upper and lower trolleys 4 and 6 speeds up the stacker crane 2. Accordingly, a considerable force acts between the connection unit 10 and the traveling unit 8, but these are absorbed by the springs 34, 34, and the vibration of the lattice mast 12 is absorbed by the dampers 30, 30. Conversely, the traveling unit 8 transmits thrust to the connection unit 10 via the springs 34, 34, and this force is applied to the mast 1
Balance with the inertial force and air resistance acting on the upper part of 2.

FIG. 6 shows the speed pattern of the stacker crane 2 and the displacement of the springs 34,34. Since the stacker crane 2 is lightweight and has a high thrust, it accelerates at, for example, about five times the conventional acceleration (area P1), travels at about twice the speed of the conventional (area P2), and has about five times the conventional speed. Decelerate at deceleration (region P3) and run at a low speed in a small section (region P4)
And then stop. Accordingly, if the connection unit 10 is fixed to the traveling unit 8 so as not to be displaced, a large force is applied between them. On the other hand, since the connection unit 10 is elastically connected to the traveling unit 8, it is possible to prevent excessive force between the two, and the damper 30 prevents vibration of the lattice mast 12 due to high-speed traveling, high acceleration, and high deceleration.

In the region P1, a force necessary for accelerating the mast 12 and a thrust corresponding to the air resistance are applied via a spring 34 to the region P1.
In the area 2, the thrust corresponding to the air resistance is applied via the spring 34, in the area P3, a braking force corresponding to the difference between the inertial force due to the deceleration and the air resistance is applied, and in the area P4, the error of the deceleration control is eliminated.
To stop at the target shelf. For these reasons, it is possible to eliminate the excessive force applied to the upper bogie 6 and to shorten the traveling time of the stacker crane 2 to improve the transport capacity.

[Brief description of the drawings]

FIG. 1 is a side view of a stacker crane according to an embodiment.

FIG. 2 is a side view showing an upper bogie of the stacker crane according to the embodiment.

FIG. 3 is a diagram showing a connection between a damper and a traveling unit according to the embodiment.

FIG. 4 is a diagram showing attachment of a lifting platform to a mast in the embodiment.

FIG. 5 is a block diagram showing control of upper and lower bogies in the stacker crane according to the embodiment.

FIG. 6 is a characteristic diagram showing a traveling pattern of a stacker crane and a displacement of a mast with respect to an upper bogie.

[Explanation of symbols]

 2 Stacker crane 4 Lower trolley 6 Upper trolley 8 Traveling unit 10 Connection unit 12 Lattice mast 14 Column member 15 Breath 16 Elevating stand 18 Elevating drive unit 19 Laser distance meter 20,21 Rail 22,23,24 Guide roller 25 Traveling motor 26 Traveling wheel 28, 32, 36 Arm 30 Damper 34 Spring 38 Limit switch 40 Sheave 42 Wire 44 Guide roller 16 Loading bed 48 Slide fork 50 Control unit 52 Lower motor 54, 56, 58 Differentiator 60 PI amplification unit 62 Switch

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Claims (3)

[Claims] 1. A mast of a stacker crane is connected to a pair of upper and lower traveling vehicles to apply thrust, and the mast is slidably connected to at least one traveling vehicle.
A stacker crane that applies a thrust according to the sliding amount from the one traveling vehicle. 2. The stacker crane according to claim 1, wherein said mast is elastically connected to said one traveling vehicle. 3. The stacker crane according to claim 1, wherein the mast is connected to the one traveling vehicle via a damper.