JP3397239B2 - Stacker crane - Google Patents

Description

Detailed Description of the Invention

[0001]

This invention relates to improvements in stacker cranes.

[0002]

2. Description of the Related Art A stacker crane is used as a transfer device in an automated warehouse, and a column-shaped mast is provided on a lower carriage to elevate a lifting platform along the mast. The mast is rigid and can reach a height of, for example, 30 m and is therefore extremely heavy. And because of these, the stacker crane also becomes heavy and slow.

[0003]

An object of the present invention is to provide a lightweight and high-speed stacker crane (claims 1 to 3).
It is an additional object of the invention of claim 2 to reduce the weight of the mast and facilitate speeding up of the stacker crane. It is an additional object of the invention of claim 3 to further reduce the weight of the mast.

[0004]

In the stacker crane of the present invention, an upper carriage is provided on the upper part of the mast, and a traveling motor and traveling wheels are provided on each of the lower carriage and the upper carriage, and the target value of the speed determined from the stored traveling pattern is set. To drive according to
While controlling each traveling motor, a control means is provided for at least one of the traveling motors so as to add additional control so that the upper and lower carriages overlap on a vertical line.

Preferably, each of the upper and lower bogies is provided with position recognizing means such as a laser range finder, and the traveling motor of the traveling bogie is controlled according to the traveling motor of the traveling bogie. By doing so, the control means is configured such that the upper and lower carts overlap each other on the vertical line.

Further, preferably, the mast of the stacker crane is constituted by a lattice structure using a plurality of pillar members.

[0007]

In the invention of claim 1, the lower bogie is provided at the lower part of the mast, the upper bogie is provided at the upper part, and the traveling motor and traveling wheels are provided respectively for traveling. Further, the traveling motor is controlled so that the upper and lower carts overlap each other on the vertical line. If the upper and lower bogies overlap on the vertical line, no horizontal force acts on the mast, and the mast can be made lighter. Since the lightweight mast is driven by the upper and lower trolleys, the stacker crane can be speeded up.

According to the second aspect of the present invention, the traveling motors of the trucks on the advancing side are matched with the traveling motors of the trucks on the lagging side so that the upper and lower trucks overlap each other on the vertical line. As a result, the upper and lower carts can always be stacked on the vertical line.

According to the third aspect of the present invention, since the mast is constituted by the lattice structure, the weight of the mast can be reduced and the stacker crane can be further speeded up accordingly.

[0010]

1 to 4 show a stacker crane of an embodiment, and FIG. 5 shows a modification of the control means for the upper and lower traveling motors. Fig. 1 shows an overview of the stacker crane. 2 is a lower truck, 3 and 3 are running wheels, 4 is a lower running motor,
Reference numeral 6 is a laser rangefinder for obtaining the distance from the origin position of the automatic warehouse. Further, 8 is a common power source for the entire stacker crane, and 10 is a lifting drive unit. An upper carriage 12 is provided above the stacker crane, 13 and 13 are its traveling wheels, 14 is an upper traveling motor, and 16 is a laser rangefinder similar to the laser rangefinder 6. A mast 18 with a lattice structure is provided between the upper and lower carts 2 and 12.
Here, it is assumed that the three pillar members 19, 19, 19 are connected by a breath 20. In the embodiment, three pillar members 19, 1
Although 9 and 19 are used, four or the like may be used. Further, 21 is an elevating table, which is moved up and down along the mast 18 by the elevating drive section 10. Reference numeral 22 is a lower rail, 23 is an upper rail, and the stacker crane is used, for example, to convey articles in an automatic warehouse.

In FIGS. 2 and 3, the lifting table 21 to the mast 18 is shown.
And the slide fork 2 installed on the lift 21
4 is shown. The mast 18 is composed of pillar members 19-1 to 19-3. Of these, the pillar members 19-2 and 19-3 also serve as guide rails, and the wheels 21-2 of the lifting platform 21 are the pillar members 1.
It is guided while sandwiching 9-2 and 19-3 from the outside. The slide fork 24 mounted on the elevator 21 has three
The plates 25, 26 and 27 are configured to slide right and left by a chain. 28 and 28 are rollers for traveling provided on the plate 27 at the tip, which may be wheels or balls, and 30 is the plate 27 at the tip. It is a lifter installed in. Since the lifter 30 is provided, it is not necessary to move the plate 27 up and down to reload the articles 34.

The slide fork 24 includes rollers 28, 28.
To run on the rack shelf and load the article 34 to the lifter 30.
Transfer to and from the rack shelves by lifting. Therefore, the load applied to the slide fork 24 is supported by the rack and is not applied to the lift table 21. Therefore, an unbalanced load applied to the mast 18 can be prevented, and the weight of the mast 18 can be reduced. Further, since the lifter 30 at the tip of the slide fork 24 is used for the transshipment of the articles to and from the rack shelves, it is not necessary to slightly move the elevating table 21 up and down to transship the articles. Therefore, the transfer of the article can be speeded up.

In the embodiment, the mast 18 has a lattice structure to reduce the weight. Further, by using the pair of upper and lower carts 2 and 12, the speed of the stacker crane is increased. Then, the upper and lower carriages 2 and 12 are overlapped on a vertical line, in other words, when the mast 18 is not subjected to air resistance, inertial force, or the like, the mast 18 is set to be vertical. As a result, the horizontal force applied to the mast 18 is minimized, and the mast 18 can be further reduced in weight. Along with this, control means for performing synchronous control on the carriages 2 and 12 is required.

FIG. 4 shows a control system for the motors 4 and 14.
Reference numeral 40 denotes a control unit, whose output is V0, 41, 42, 4
Reference numeral 4 is a difference unit, and 43 is an amplification unit for giving a control gain to the output Δx of the difference unit 44 (position of the upper carriage 12-position of the lower carriage 2). Reference numerals 6 and 16 are the laser rangefinders, and obtain the distance between the upper and lower carriages 2 and 12 from the origin position of the automatic warehouse. SW is the position imbalance between the upper and lower carriages 2 and 12 (when Δx is not 0). ) Is a switch for selecting whether to apply control for solving the above problem to the upper motor 14 or the lower motor 4. And in the example,
The motor on the leading side is decelerated and controlled to match the side on the delayed side. By doing so, it is possible to prevent the situation in which the upper and lower carriages 2 and 12 cannot be aligned on the vertical line due to insufficient capacity of one motor in any case.

In the case of FIG. 4, the target value of the speed determined from the traveling pattern stored in advance is Vref, and the difference from the speed determined from the actual position obtained by the lower laser range finder 6 by the control unit 40 is a control value. Let V0. Next, the differencer 44 is used to check which of the upper carriage 12 and the lower carriage 2 is moving. If the upper carriage is moving and Δx is positive, the switch SW is connected to the differencer 42 and the formula (1) Control by. Vup = V0−Kp · Δx−Ki∫Δx (Δx> 0) (1) That is, the lower motor 4 is controlled by the control target value V0, ignoring the mutual relationship with the upper motor 14, Is added with a control amount Vup to which proportional / integral control according to the equation (1) is added so as to eliminate the positional deviation Δx. K
p and Ki are control constants. As a result, the upper carriage 12 is decelerated, the upper and lower carriages 2 and 12 are overlapped on the vertical line, and the mast 18 accurately faces the vertical axis.

On the contrary, when the lower carriage 2 is advancing, Δx becomes negative, the switch SW is connected to the differencer 41 side, the control amount V0 is added to the upper motor 14, and the expression (( As shown in 2), the control amount V0 is obtained by adding the proportional / integral control for eliminating the error Δx to the control amount V0.
add as down Vdown = V0 + Kp · Δx + Ki∫Δx (Δx <0) (2)

Instead of the control of FIG. 4, as shown in FIG.
Control may be added so as to eliminate the positional error Δx between the upper and lower carriages 2 and 12 on the upper carriage 12 side. The control in this case is represented by the equation (3), and the lower motor 4 is controlled by the difference between the speed determined from the position obtained by the laser distance meter 6 and the target speed Vref. A control amount Vup is added to the upper motor 14 to which a proportional / integral control for eliminating the position error Δx between the upper and lower carriages 2 and 12 is added. Even with this method, the upper and lower carts 2 and 12 can be controlled so as to overlap with each other on the vertical line. However, when Δx is larger than the controllable range of the upper carriage 12, even if the upper traveling motor 14 is rotated at full power, the lower carriage 2 is not moved to the upper carriage 1.
When 2 cannot catch up, Δx cannot be canceled while traveling, and it becomes necessary to stop the stacker crane. Vup = V0−Kp · Δx−Ki∫Δx (3)

Although not shown in the figure, the mast 18 is slidably connected to the upper carriage 12 at the upper end in the traveling direction and is fixed to the lower carriage 2 at the lower end. Therefore, even if the vertical positions of the upper and lower bogies 2 and 12 deviate greatly, the connecting portion between the upper bogie 12 and the mast 18 will not be overcompressed.

[Brief description of drawings]

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

FIG. 2 is a view showing how the lifting platform is attached to the mast in the embodiment.

FIG. 3 is a diagram showing a lifting platform in the stacker crane of the embodiment.

FIG. 4 is a block diagram showing control of upper and lower carts in the stacker crane of the embodiment.

FIG. 5 is a block diagram showing a modified example of the control of the upper and lower bogies.

[Explanation of symbols]

2 Lower cart 4,14 Travel motor 6,16 laser rangefinder 8 power supplies 10 Lifting drive 12 Upper trolley 18 masts 19 pillar members 21 Lifting platform 22,23 rail 24 slide forks 25,26,27 plate 30 lifters 40 control unit 41, 42, 44 differentiator 43 Amplifier

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B65G 1/04

Claims (3)

(57) [Claims] 1. A stacker crane in which a mast having a lifting platform is attached to a lower carriage, an upper carriage is provided on the upper part of the mast, and a traveling motor and traveling wheels are provided on each of the lower carriage and the upper carriage. While controlling each of the traveling motors so that the vehicle travels according to the target value of the speed determined from the stored traveling pattern, additional control is performed on at least one of the traveling motors so that the upper and lower carriages overlap each other on the vertical line. A stacker crane, characterized in that it is provided with control means for adding. 2. The position recognizing means is provided on each of the upper and lower bogies, and a traveling motor of the bogie on the moving side is provided.
2. The stacker crane according to claim 1, wherein the control means is configured such that the upper and lower bogies are overlapped on a vertical line by controlling in accordance with a traveling motor of the bogie on the delayed side. 3. The stacker crane according to claim 1, wherein the mast of the stacker crane has a lattice structure.