JP2001163408A - Stacker crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To travel a stacker crane at high speed by vertically driving lightweight carriages and lightening the weight of a lifting guide. SOLUTION: The carriages 4, 6 in the top/bottom of the stacker crane 2 are traveled by belts 22, 24. A traveling guide 8 is supported by the carriages 2, 4 so that a lifting table 10 with a shifter is raised/lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stacker crane in which upper and lower trucks are towed by towing means.

[0002]

2. Description of the Related Art In a conventional stacker crane, the crane travels while being guided up and down by rails, and a traveling motor is arranged on a bogie provided at a lower portion of the crane, so that the crane runs by itself. And the mast of the crane has a height of, for example, 30
m, it requires considerable rigidity and becomes heavier accordingly. For these reasons, the stacker crane is heavy and there is a limit to speeding up.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the weight of a stacker crane so that it can run at a higher speed. Another object of the present invention is to prevent vibration during traveling. Another object of the present invention is to prevent a force exceeding a limit from being applied to the lifting guide.

[0004]

According to the present invention, a stacker crane according to the present invention is provided with an elevating guide disposed between upper and lower bogies to raise and lower the elevating platform. It is characterized by being provided on the upper and lower sides, respectively. The traction means is, for example, a belt conveyor or a chain conveyor.

[0005] Preferably, means for detecting the position of each truck in the running direction is provided, and the upper and lower traction means are controlled so that the upper and lower trucks overlap in the vertical direction. More preferably, the lifting guide is provided so as to be movable in a traveling direction with respect to at least one of the carts,
Each of the towing means is stopped when a deviation of a position in the traveling direction between the carriages exceeds a predetermined value.

[0006]

According to the present invention, since the upper and lower trucks are towed by the pulling means such as a belt conveyor or a chain conveyor, the weight can be reduced as compared with the case where each truck is driven by itself. Furthermore, unlike the case of applying the force from the lower bogie to the upper bogie via the elevating guide to run the whole, the upper and lower bogies apply force to the elevating guide and move it,
The rigidity required for the lifting guide may be low, and the lifting guide can be reduced in weight. For these reasons, the stacker crane becomes lighter as a whole. Further, in the present invention, since the upper and lower carts are respectively driven, it is originally suitable for speeding up. In addition, since the weight of the stacker crane can be reduced, the stacker crane can run at a higher speed. Therefore, according to the present invention, the weight of the stacker crane can be reduced and the stacker crane can be driven at a high speed.

According to the second aspect of the present invention, the displacement of the upper and lower trucks is determined in the traveling direction, and the traction means is controlled so that the displacement in the traveling direction is eliminated and the upper and lower trucks overlap in the vertical direction. Therefore, vibration of the lifting guide and the bogie during traveling can be prevented. According to the third aspect of the present invention, since the lifting guide is provided so as to be movable in at least one of the carts in the traveling direction, the upper and lower carts may not strictly overlap in the vertical direction. When the displacement of the carriage in the traveling direction exceeds a predetermined value, the traction means is stopped, so that the carriage is not damaged beyond the movable range of the lift guide relative to the carriage.

[0008]

1 to 3 show an embodiment. FIG. 1 schematically shows the stacker crane 2, 4 is a lower truck, 6 is an upper truck, and 8 is a lifting guide provided between the trucks 4 and 6. Reference numeral 10 denotes an elevating table, which moves up and down along the elevating guide 8, mounts a transfer device such as a slide fork (not shown), and transfers articles to a shelf or the like. Reference numeral 12 denotes an upper frame for movably attaching the lifting guide 8 to the upper carriage 6, and the lifting guide 8 is rigidly fixed to the lower carriage 4. The elevating guide 8 is composed of, for example, four guide rails 14 and guides a guide roller (not shown) of the elevating table 10 and, for example, winds a pair of ropes 16 attached to the elevating table 10 by a winding motor 18 or the like. It is designed to be raised and lowered.

Reference numerals 20 and 22 denote belt conveyors provided above and below, respectively, and reference numeral 24 denotes a belt wheel thereof. The upper and lower trolleys 4, 6 are, for example, at the position of the center of gravity,
22 and is towed by belt conveyors 20 and 22. Note that a chain conveyor or the like may be used instead of the belt conveyors 20 and 22. Also, in FIG. 1, both the forward side and the backward side of the belt are passed through the carriages 4 and 6, but only one of the forward side and the backward side is fixed to the carriages 4 and 6. Reference numerals 26 and 28 denote guide rails provided at the top and bottom, respectively, and guide the carts 4 and 6 along guide rails 26 and 28 by guide rollers (not shown) or the like. The lower guide rails 26 support the weight applied to the lower carriage 4. Reference numerals 30 and 32 denote laser distance meters for measuring distances from the origins of the carts 4 and 6 in the traveling direction. The method of measuring the positions of the carts 4 and 6 in the running direction is arbitrary, and the position of the carts 4 and 6 may be measured by attaching an encoder or the like to the belt cart 24 or the like. On both sides of the rails 26 and 28, for example, shelves and stations of an automatic warehouse are arranged, and the stacker crane 2 is used as a transport device of the automatic warehouse and the like.

FIG. 2 shows how the upper frame 12 is attached to the upper carriage 6. As described above, the upper carriage 6 travels while being towed by the belt conveyor 22 and the guide rails 28.
The posture is guided by. The upper frame 12 is movably attached to the upper carriage 6 within a predetermined range in the traveling direction, and 34 is a spring such as a spring coil or an air spring.
36 is a damper. The spring 34 allows the upper frame 12
Is maintained at a predetermined position in the traveling direction with respect to the upper carriage 6, and the damper 36 absorbs vibration energy between the upper frame 12 and the upper carriage 6. Thus, the lifting guide 8 is maintained at a predetermined position with respect to the upper carriage 6, and its vibration is prevented. When an air spring or the like is used as the spring 34, the damper 36 is unnecessary. Further, only the damper 36 may be provided without providing the spring 34.

FIG. 3 shows a control system of the stacker crane 2. Reference numerals 40 and 41 are differentiators, 42 and 43 are adders, and 44 is a determination unit for determining whether or not the positional deviation between the upper and lower carriages 4 and 6 in the traveling direction has exceeded a predetermined range.
46 is a lower motor and 48 is an upper motor. In the control system shown in FIG. 3, the control is performed so that the difference between the traveling direction position (hereinafter simply referred to as “position”) and the speed between the upper and lower carriages 4 and 6 is eliminated, and the lower carriage 4 travels in accordance with the speed pattern of the control target. I do.

The lower laser distance meter 30 measures the distance from the origin of the lower carriage 4, and the upper laser distance meter 32 similarly measures the distance from the origin of the upper carriage 6. These positions are denoted by P, and their differential values are denoted by v. Thus, the positions and speeds of the upper and lower carriages 4, 6 are determined. In an ideal state, the positions and speeds of the upper and lower carriages 4 and 6 should match. Then, these differences are obtained by the difference device 40,
The control amount Δ is generated so as to eliminate these differences. For example, when the lower bogie 4 moves forward ahead of the upper bogie 6 and has a higher speed, the energy of the displacement between the upper and lower bogies 4 and 6 is large, and the absolute value of the control amount becomes large to cancel the energy. Further, when the lower bogie 4 is traveling forward of the upper bogie 6, but the speed is lower than that of the upper bogie 6, the absolute value of the control amount Δ becomes smaller. The sign of the control amount Δ is inverted between the upper bogie 6 and the lower bogie 4, and the next adder 42,
Add to 43. This is active control for canceling the difference between the position and the speed in the traveling direction of the upper and lower trolleys 4 and 6. Here, both the difference between the position and the speed are canceled. However, only the difference between the positions is canceled. You may do it.

The judging section 44 detects that the deviation of the distance between the upper and lower carriages 4, 6 exceeds the allowable range, or that the value determined from both the distance deviation and the speed deviation exceeds the allowable range. Generates an emergency stop signal. With this signal, the motor 46 for driving the lower conveyor 20 and the motor 48 for driving the upper conveyor 22 are stopped to prevent damage to the elevating guide 8 and the like.

The stacker crane 2 receives signals from the laser rangefinders 30 and 32 as well as a control terminal (not shown).
A control command to move to a predetermined position and transfer articles to a shelf or the like (not shown) is added. From this control command, a speed pattern during traveling to the destination is determined, and this speed pattern is, for example, a function of the position. In the embodiment, since the lifting guide 8 is rigidly attached to the lower bogie 4, the speed of the lower bogie 4 is compared with a traveling pattern determined from a control target, and a control amount ε is generated so as to cancel a speed error during this period. Then, adders 42 and 43 add a control amount ε for canceling an error from the target traveling pattern to a control amount ± Δ for canceling an error in the position and speed between the upper and lower carriages 4 and 6, and apply these to the motor. In addition to 46 and 48, the conveyors 20 and 22 are driven.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a stacker crane according to an embodiment.

FIG. 2 is a diagram showing attachment of an elevating guide to an upper carriage in the embodiment.

FIG. 3 is a block diagram of a travel control system in the embodiment.

[Explanation of symbols]

 2 Stacker crane 4 Lower trolley 6 Upper trolley 8 Elevating guide 10 Elevating platform 12 Upper frame 14 Guide rail 16 Rope 18 Winding motor 20,22 Belt conveyor 24 Belt wheel 26,28 Guide rail 30,32 Laser distance meter 34 Spring 36 Damper 40, 41 Difference device 42, 43 Adder 44 Judgment unit 46 Lower motor 48 Upper motor

Claims (3)

[Claims] 1. A stacker crane in which an elevating guide is arranged between upper and lower bogies to raise and lower an elevating platform, wherein a pulling means for pulling and running each of the bogies is provided on each of upper and lower sides. A stacker crane. 2. The vehicle according to claim 1, further comprising means for detecting a position in the traveling direction of each of the trucks, and controlling the upper and lower traction means so that the upper and lower trucks overlap in the vertical direction. The stacker crane of claim 1. 3. The method according to claim 1, wherein the lifting guide is provided so as to be movable in at least one of the carts in a traveling direction, and the towing guide is provided when a displacement of the truck in the traveling direction exceeds a predetermined value. 3. The stacker crane according to claim 2, wherein the means is stopped.