guidelines for planning and setting up very narrow aisle ... · pdf fileguidelines for...

Guidelines for planning and setting up very narrow aisle warehouses

Floor.................................................................................................6Specifications for the floor ...................................................................7Height differences and evenness tolerances ......................................8

Racking..........................................................................................14Assembly tolerances for racks and permissible deformations .........16Safety distances in the rack ...............................................................18

Guide.systems...............................................................................19Mechanical guide: rail guidance ........................................................20 a.) Design and assembly of guide rails ..................................... 20 b.) Overview of rail types ......................................................... 22Inductive wire guidance .....................................................................24 a.) Laying an inductive guide wire ........................................... 24 b.) Entering and exiting the aisle/changing aisles ................... 26 c.) Frequency generator ............................................................ 27

Driver.assistance.system..............................................................281. Systems for determining vehicle position .....................................29 a.) Magnets ..................................................................................30 b.) Reflected light sensors ...........................................................31 c.) Bar code ..................................................................................32 d.) RFID .........................................................................................322. Safety functions in the very narrow aisle......................................33 a.) End of aisle protection ......................................................... 33 b.) Height-dependent cut-off ......................................................34 c.) VNA navigation .......................................................................35

Personnel.protection.systems......................................................37Legal regulations ................................................................................38Stationary protection ..........................................................................38Mobile protection ...............................................................................39

Standards......................................................................................41

Table of contents

3

4

Guidelines.for.planning.and.setting.up.very.narrow.aisle.warehouses

Narrow aisle warehouses have a particularly high space utilisation rate through very low spatial requirements and high lift heights. These aspects require special attention in planning and implementation.

These guidelines provide you with a tool which should help you in building the most economical, safe, and functional narrow aisle warehouse. They also utilize your floor space and spatial resources efficiently and ensure optimum implementation for truck, racking, and flooring interfaces in your premises.

Our recommendations and directives in the following should prevent bad investment as well as deficiencies in construction, leading to professional solutions.

6

The floor

High rack storage areas where man-down narrow aisle trucks are used are technically advanced systems today. The use of high-level order pickers, racking trucks and order picking trucks in such warehouses not only requires technically highly developed industrial trucks, but also floors of above average quality. They must be ca-pable of carrying loads, level, and horizontal, and meet the strictest tolerances for travel paths of the VDMA directive (the tolerances according to DIN 18202 apply for all remaining surfaces).

Only compliance with the VDMA directive requirements can guaran-tee the full performance of the trucks and their associated productiv-ity. Testing the floor surface for evenness should be done directly after installing the floor, and before beginning any subsequent work. Proof of compliance with the tolerances is provided by the floor installer or a neutral surveyor office(also see: www.VDMA.org/Branchen/Logistiksysteme).

7

Specifications for the floor.

The following listed values and tolerance ranges are essential for permissible driving speeds, diagonal driving heights, a smooth ride, and positioning accuracy for the trucks used. Therefore, pay special attention to the “floor tolerances”. To avoid possible misunderstand-ings, we recommend you to make these directives part of your agreement with the floor installer and racking manufacturer.

Sub-flooring: •. The supporting subsoil is designed according to DIN EN 1045 part 1

and two using a concrete quality of at least B25 and DIN 18202.

Use-surface.(top.layer):•. .The load group II (middle) DIN EN 18560, part 7, table 1 (resist-

ant against oils and grease) requires an approx. 10–30 mm thick industrial flooring.

•. .The surface must be anti-skid (approx. µ 0.5), anti-slip, free of fluids, dirt, and oil films and must not exhibit plastic deformation under load in order to achieve the braking distances according to ISO 6292. The resistance to earth RE must be a maximum of 10^6 ohm (per DIN EN 1081).

•. .Make sure that the overall traffic surface never exceeds the allowed tolerances and meets the required level of technology (honing the floor finish over levelled guide rails typically does not guarantee the necessary floor tolerances for trucks).

•. .Discontinuities in the flooring, such as channels or shafts, require a minimum spacing of 200 mm to the travel paths and should be avoided in the aisle whenever possible.

Grinding.the.floorMilling or grinding individual travel paths in the aisle to achieve the necessary evenness standards is permissible for inductive or mechanical guidance, assuming it does not result in any visual or tangible height differences.

Linde VNA Directives // Floors

Sub-concrete

Iron reinforcement

8

a b

dz

Z

Table.1:.Permissible height differences crosswise to the travel path

Lift.height.(m) Zslope dz.=.Z.x.Zslope

bis 6 2.0 Z x 2.0 mm/m

10 1. 5 Z x 1.5 mm/m

15 1.0 Z x 1.0 mm/m

Lift heights >_ 6 m require interpolation (see Fig. 2)

ZslopePermissible slope crosswise to the path between the middle of the load wheels of the industrial truck (a, b) in mm/m (the value of Zslope is specified dependent on the lift height)

ZDimension between the centres of the load wheels of industrial trucks (a, b) in m

dZMaximum permissible height differences between the centres of load wheels of industrial trucks (a, b)

Evenness tolerances

This specification is based on the VDMA directive “Flooring for use by very narrow aisle industrial trucks”. Stricter requirements apply for travel paths in very narrow aisle warehouses than in all other areas of the warehouse. Tolerances per the VDMA directive must be com-plied with (see tables 1+2+3) in very narrow aisles and everywhere travelled with an increased load. The evenness of other surfaces must meet those tolerances of DIN 18202, Tab. 3, line 3.

Specifications for evenness for the very narrow aisle range are de-fined for three different areas:a.) height differences crosswise to the travel pathb.) height differences longitudinally along the travel pathc.) rippled variations in height differences

These three factors have a decisive influence on the driving per-formance and non-compliance can lead to a reduction in handling performance.

Height.differences.crosswise.to.the.travel.path

The following tolerances crosswise to the travel path apply per VDMA, deviating from DIN 18202 (see Tab. 1):


Fig.1:.Diagram, height difference crosswise to the travel path

Height difference = dzTrack width = ZLoad wheels = a, b

9

Fig..2:.Example for determining Zslope

Fig..3:.Example for determining dZ

Example.for.determining.Zslope:Assumption: lift height = 8 m; travel path Z = 1.5 mCalculation of Z slope using Fig. 2:Lift height = 8 m; Z slope = 1.75 mm/mCalculation of dz using Fig. 3:dz = Z x Z slope = 2.625 mm

The maximum permissible height difference (dz) in this casemust not exceed 2.625 mm.


5

2 0.5

2

2

1.0

1.25

1.5

1.75

2.625

1.75

3

4

1.5

2

1

1

0.5

0

8 10

1.51 2

15

2.5

T lift height (m)

Z (m)

Zslope

Zslope (mm/m)

dZ (mm)

10

Point X

Hx

Track width

Ast

Ast

Hx = height of point X above the floor

Ast = aisle width

X

+ dz

– dz

Zero line

Delta X

Delta X

b1 = safety distance

After determining the maximum permissible height difference dz, the lateral deviation of the truck at a specific height can be calculated using a formula.

The.general.formula.for.determining.the.lateral.deviation(see.Fig..4):Lateral deviation at the maximum height = Delta X = dz (mm/m) x Hx (m)

Example.calculation.for.lift.height.10.m.and.track.width.1.0.m.(see.Fig..5):A lift height of 10 m and a track width of 1.0 m produces a dz value of 1.5 mm/mHx = height of point X = 10 mDelta X = 1.5 mm/m = 15 mm lateral deviation of point X


Fig..4:.Determining the lateral deviation of point X Fig..5:.Example calculation for lift height + 6.0 mand track width up to 1.0 m

11

Example:The inside micrometer below a 2 m long straight edge must not be greater than 3 mm (see Fig. 6).

Evenness.tolerances.longitudinally.along.the.travel.path

The evenness tolerances per VDMA longitudinally along the travel path are the following (see Tab. 2):

Table.2:.Evenness tolerances longitudinally along the travel path

Testing the evenness is done per DIN 18202.


Fig..6:.Example of evenness tolerances longitudinally along the travel path

Distance.between.measurements.l Gap.under.the.ruler.t

1 m 2 mm

2 m 3 mm

3 m 4 mm

4 m 5 mm

l = 2 m

t = 3 mm

12

Ripple.variations.for.industrial.flooring.in.very.narrow.aisle.warehousesIn addition to the requirements for absolute height differences in very narrow aisles, there are also requirements for regularly reoccur-ring uneven surfaces.

No rippled uneven surfaces or regular changes in lateral inclination may occur, as they lead to the industrial trucks swinging. Ripple vari-ations are defined by the height differences between two adjacent points along the travel path and are measured in “ripple variation factor Fx”. This is determined from a series of height differences of multiple adjacent readings according to a specified algorithm. The smaller the Fx value, the larger the ripple variation at greater ampli-tudes or the more uneven the floor.

In the VDMA directives, the calculation of this key figure is described in detail; a table calculation is also offered for download, enabling automatic calculation from the raw data.

The directive and the calculation tool mentioned can be found on the home page of the VDMA (www.vdma.org/Branchen/Logistiksys-teme).

The ripple variation factor Fx calculated in this way must be complied with as per table 3.

Table.3:.Ripple variation factor Fx

Lift.height.(m) Fx.or.O/-FX

15 >_ 525

10 >_ 400

up to 6 >_ 300

Lift heights > 6 m require interpolation (see Fig. 5)


13

Measuring.procedure.for.ripple.variation.The exact measuring method is defined in the VDMA directive as mentioned. You can find assistance in determining Fx in the schematic drawing below (see Fig. 7).

Example.calculation:Assumption: lift height = 8 m; travel path Z = 1.5 mCalculation of Z slope using Fig. 2: 1.75 mm/mCalculation of dz using Fig. 3: Z x Z slope = 2.625 mmCalculation of Fx using Fig. 6: Fx >_ 350


Fig..7:.Example for determining Fx

5 8 10 15

400

450

500

550

350

300

250

Lift height (m)

Fx

14

The racking

Racking systems available on the market can be adapted exactly to the most varied requirements and room characteristics. Thus, the weights and load dimensions used, the loading equipment, and the industrial trucks used are the most important parameters for design-ing racking. Today, pallet racks are primarily used for very narrow aisle systems. They have the advantage that they can be used both manually and automatically, and facilitate direct access to all items and also order picking.

15

Linde VNA directives // Racking

Pallet racks consist of vertical racks and horizontal bridge pieces (DIN EN 15620). Support beams, grating, steel panels, or particleboard can be placed on these, depending on application profile. If the distance between the inside of the stored loads for double racks is less than 100 mm, a push-through guard is mounted for protection.

Free-standing pallet racks are not permanently joined to the building. They can be set up flexibly, and can be used later for other applica-tions by switching them around.

DIN EN 15512 “Stationary racking systems made of steel – adjustable pallet racks – basis for static measurement” forms the basis for static verification when building such racks.

Requirements for fire protection are an another important factor when building racking storage. We recommend early contact with

the responsible agencies, construction companies, and with your insurance partner, and taking into account the spatial requirementsfor fire protection measures in terms of safety distances in the racking.

Please also note the regulations for the load capacity of the floor. Flooring in storage facilities and the trucks used must meet the re-quirements of DIN EN 15635, DIN EN 15512 and DIN EN 15629 so that net weight and loads can be supported safely.

The p and d stations are normally formed from the overhanging sup-port of the last rack. The use of centering aids at the p and d stations is required for partial and fully automatic rack operation. Thus the loads from the industrial trucks with freely moveable feeder can be deposited in a specified position on the p and d station for the man-down narrow aisle truck.

16


Assembly tolerances for racks and permissible deformations

Per DIN EN 15620 pallet racks for very narrow aisle trucks are divided into two different classes:

Rack.class.300A:Man-down narrow aisle truck with “man up” operation.

Rack.class.300B:Man-down narrow aisle truck with “man down” operation.

The assembly tolerances are shown in Fig. 8, the associated toler-ance description per DIN EN 15620 can be found in table 4.

Fig..8:.Rack assembly tolerances

Front view

Top view

Side view

Side view detail

CX CZ

M

D DE

GY

JZ

GY

JX

Y-direction

E1

H1

H

HB

H1A

X-direction Z-direction

Detail

A

F1 F

F

A1(n)

B1B0

B2 B3 Bn

HY

X-direction

Z-di

rect

ion

GZ

17


Table.4:.Installation tolerances and permissible deformations of the racks according to DIN EN 15620

*The greater of the following values is valid a H/500 is also permitted, provided the overhang of the pallet skids or blocks at the front bars is 75 mm or more and the skids or blocks are supported by the beams.

Horizontal.tolerances.for.the.XZ.plane.(mm)

Measurement.specification.and.description.of.the.cross.deviation Building.cross.deviation.for.racking.class.300

A Deviation from the nominal size of the access width between two support uprights in any beam height

+- 3

A1 Deviation from the nominal value for the total length of the racking, cumulative number “n” for the fields, measured as close as possible to the base plate

+- 3 n

B Misalignment of the supports in transverse direction, speed, cumulative for the Number “n” the fields measured approximately at ground level. For this class 300A applies only to the support uprights. Class 300B applies to the support uprights and the rear pillars.

+- 10 or for class 300A: +- 1,0 n for class 300B: +- 0,5 n*

B0 Deviation from the nominal size of the racking front at the transfer aislethe respective „reference line of the racking system Z ‚ measured near ground level

+- 10

CX Deviation from the perpendicular of the frame in the X direction +- H/500

CZ Deviation from the perpendicular of the frame in the X direction without fixed Hub: +- H/500with fixes Hub: +- H/750a

D Deviation from the nominal depth of the racking(Single or double frame)

Single frame: +- 3Double frame: +- 6

E Deviation from the nominal size for the aisle width about ground level +- 5

E1 Deviation from the nominal size for the width between the rails + 50

E2 Deviation between the supports on one side of the guide rail +- 5

F Deviation from the nominal size of the aisle straightness measured approximately at ground level with respect to the “reference line aisle system X” or according to the specifications of the truck supplier

+- 10

F1 Deviation measured between next to each other uprights around Ground level in the Z direction +- 5

GZ Straightness of the beam in the Z direction +- A/400

JX Straightness of the beams in the X direction between supports ina distance HB from each other

+- 3 or +- HB/750*

JZ Initial curvature of a stator frame in the Z direction +- H/500

M Deviation limits for the upper guide rail Is set by the truck supplier or the author of the specification

TW Beam rotation in the middle of the field 1° per m

Vertical.tolerances.in.the.Y.direction.(mm)

Measurement.specification.and.description.of.the.cross.deviation Mounting.tolerances.for.racking.class.300

GY Straightness of the beam in the Y direction +- 3 or +- A/500*

H1 Deviation of the top level of any beam over the H1 lower support level 300A: +- 5 or +- H1/500300B: +- 3 or +- H1/1000*

H1A Deviation of the top edge of the lower beam on each upright against ground level +- 7

H3 Deviation limits for the upper guide rail, if available If available, set by the supplier or manufacturer of the truck

HY Deviation of the heights of the load unit between the front and rear beam in one compartment

+- 10

H Height from the top of the foot stand level to top of the racking support

HB Height from the top stand level to the next higher stand level

18

X X1

Z

Y

Safety distances in the rack

Free compartment dimensions are the distances between the loads within the rack. A distinction is made between distances between stored pallets and the next rack bridge piece (dimension Y) and be-tween stored pallet and upright or the next standing pallet (dimen-sion X) or also between the pallet backs to each other (dimension Z). The more generous these values are measured to be, the faster the pallets can be stored and removed.

Thus it is advisable at higher productivity to design the safety dis-tances larger than the defined minimum distances.

Minimum.distances.to.be.observed:Dimension X (distance from pallet to upright): 75 mm- For rack class 300B starting at 12 m lift height: 100 mmDimension X1 (distance from pallets to each other): 75 mm- For rack class 300B starting at 12 m lift height: 100 mmDimension Y (distance from pallet to bridge piece): 75 mm- For rack class 300B starting at 6 m lift height: 100 m- For rack class 300B starting at 9 m lift height: 125 m- Linde recommendation: minimum distance + 25 mmDimension X (distance from back of pallets to each other): 100 mm(also take into account here the space requirement for sprinkler pipes)


Fig..9:.Minimum distances

19

The guide systems

To take optimum advantage of the spatial requirements in the very narrow aisle, the appropriate industrial trucks make work easier with very short distances to the rack. DIN EN 1726 part 2 prescribes a minimum distance of 90 mm between the supported load and the pallet in the rack. Depending on parameters such as pallet size, truck type, and guide system, larger distances are also needed sometimes. Basically, there are two different guide systems: inductive wire guid-ance enables driving speeds up to 9 Km/h. Load pick up from the floor is straight forward with inductive guidance. Mechanical guide systems have high driving speeds up to 12 Km/h. Load pick up from the floor is only possible with small rails and special forks.

20

F F

Ast

Distance between the guide rails -b26-

Truck width over the guide rollers -b6-

Sub-concrete

Iron reinforcement2.5 mm 2.5 mm

Mechanical guide: rail guidance

The mechanical guide has rollers attached to the truck and steel profiles mounted to the floor to guide the industrial truck. The later-ally mounted rollers hold the truck between the profiles in the aisle centre.

Fig.10 shows the minimum width of the aisle (Ast) taking into consid-eration the relevant parameters.

Ast.Aisle width, clear width between the loads or between the racks

F.=.Ast/2Permissible deviation of the aisle width from the centre line to 20 m- F = +- 5 mm

b26Clear width between the rails

b6Truck width over guide rollers b6 = b26 – 5 mmPermissible deviation:- over the entire length: -0/+5 mm- over 1 meter length: -0/+2 mm

Linde VNA directives // Guide systems

Fig..10:.Minimum aisle width

21

a21/a23

min. 50 mm

Safety.distances.with.mechanical.guide

Distance.from.guide.rail.to.load.wheelA minimum distances of 50 mm is prescribed between guide rail and load wheel for the mechanical guide. In terms of safety and handling performance, a safety distance of 100 mm (see Fig.11) is preferable.

Distance.of.supported.load.to.pallet.in.the.rack.(a21/a23)DIN EN 1726 part 2 prescribes a minimum distance of 90 mm bet-ween the supported load and the pallet in the rack. Depending on parameters such as pallet size, truck type, and guide system, larger distances are sometimes needed also. The difference in lift height guarantees maximum handling performance with maximum safety.

For mechanical guides, the following applies:Lift height < 7 m -> a21/a23 = min. 90 mmLift height > 7 m -> a21/a23 = min. 120 mm


Fig..11:.Safety distance

22


Rail.guidance.typesThere are multiple types of rail guidance. The most commonly used profiles used in the market are L rails with a profile height of 100 mm (high rails) or 50 mm (low rails). Additionally, other heights can be implemented up to the smallest possible rail height of 38 mm. The profile rails can be both free standing as well as integrated in a concrete base (cast guide rail).

Design.and.assembly.of.guide.railsTo make it easier to adjust the tracks of the truck in the very narrow aisle, the start of the aisle has a entry funnel of approx. 300 mm in length with an opening angle of 15°. The strongest horizontal force is achieved in this funnel and the first meters afterwards, the approx. 2500 mm long single track area. This force of up to 2500 kg occurs in the single track area, as the industrial truck is only guided with the front rollers. Then the rear rollers get into the rail guidance and thus the forces are reduced as the aisle is travelled to approx. 400 – 1000 kg.

To ensure secure track adjustment, we recommend using a funnel with a high profile. The guide rails are anchored in the floor after being installed. The different effects of force in the driving area and single track area require different dowelling distances. In the driving area, the distance is 500 mm. In the single track area, it is recom-mended to reduce it to approx. 300 mm for the first 4 dowels. This dowel spacing also applies to the front of the rail for the changeover aisle (see Fig. 13). The guide rail should be 8 mm to avoid deforma-tions due to lateral forces.

Due to the different heights of guide rails, the side guide rollers on the industrial truck require different heights:

40 – 65 mm for high guide rails20 – 23 mm for low guide rails

Height of non-cast guide rails

Height of cast guide rails

Low guide rails

Fig..12:.The different rail guidance systems

23

b26

Ast

500 mm

500 mm

300 mm

300 mm

300 mm

300 mm

300 mm

15°


Fig..13:.Design and assembly of guide rails

24

Rack Frequency generator

Return of an inductive guide wire

Inductive wire guidance

The inductive wire guidance replaces the guide rails. A wire loop routed in the floor epitomises the guide line. The guide wire is fed from a frequency generator with AC (low voltage). The magnetic field formed around the guide wire is scanned by antennas. The downstream electronics evaluate the signals and control the servo unit. This makes the truck always move centred over the guide wire.


Laying.an.inductive.guide.wire

The guide wire is laid as a closed loop, and its beginning and end are connected to the frequency generator. An uneven number of aisles requires installation of an additional return (see Fig. 14).

Technical.dataStandard frequency: 6.25 HzCurrent strength: 80–120 mA(additional frequencies and current strengths on request)

Tolerances with inductive wire guidance

Fig..14:.Laying inductive guide wires

= Ideal wire guidance

= Maximal permissible deviation± 5 mm

Distance between two guide wires with the same frequency: min. 1200 mm

25

Guide wire10 mm

50 mm 6 mm

Iron reinforcement

Sub-concrete

Transmitting antennas (coil)

Receiver antennas

140 mm


Tolerance.with.inductive.wire.guidance

Deviation of the guide wire from the theoretical centre line over the entire aisle length +- 5 mm (see Fig. 14) is within the tolerance range. In order for these deviation tolerances to be achievable per DIN 15185 part 1, the guide wire should be routed after the racks are assembled.

Distances.for.inductive.guide.wire

As a rule, the distance from the steel reinforcement to the guide wire (c) must be at least 50 mm. A lower distance between reinforcement and guide wire is possible but must be determined using field meas-urement. Metal (cable ducts, expansion joint angle, etc.) must be kept at least 200 mm away from the left and right of the guide wire.

Safety.distanceWith inductive wire guidance a minimum distance of 140 mm is required (see Fig. 15) between load and truck cabin.

Distance.between.two.guide.wiresof the same frequency: min. 1200 mm(see Fig. 16). If this distance is not met, the magnetic fields may mal-function (exception: return lines that are not used as a travel path).

Fig..15:.Minimum distance

Fig..16:.Functional principle

26

Select the changeover aisle to be 1000 mm larger than with the mechanical guide

Optimum tracking angle 45°

Maximum tracking angle 60°

Position of the inductive guide wire

500 mm minimum distance between sensor and end of guide wire


Entering.and.exiting.the.aisle/changing.aisles

Entering.the.aisleWith inductive wire guidance, the changeover aisle width com-pared to the alternative rail guidance must be enlarged by approx. 1000 mm (see Fig. 17).

In the changeover aisle, the forklift truck driver drives the truck at a sharp angle in the direction of the guide wire and switches to

automated operation. The smaller the tracking angle, the faster the truck lines up (displayed by an optical and acoustic message). The guide wire should be pulled in as far as possible in the changeover aisle. The minimum dimension here is a truck length plus 500 mm (see Fig. 17).

Exit.from.the.aisleAfter exiting out of the aisle, the driver switches back to manual mode and the truck can be driven again freely.

Fig..17:.Entering the changeover aisle

27

Frequency.generator

The frequency generator has connections for a max. of 8 separate loops with each up to 2000 m summing up to a total of 16000 m. It feeds the guide wire with high frequency AC. If a single driving loop is damaged this loop then fails entirely. Therefore it is recommended to reduce downtimes by splitting of the wire guidance in a ware-house in different loops.

A protected, easily accessible position in the storage area should be selected for assembly of the frequency generator. If there is a power failure, an independent power source (buffer battery) can be used as emergency power supply and sustain operation for approx. 2 ad-ditional hours.

The supply voltage is 230 V AC at 50 Hz or 115 V AC voltage at 50 Hz. The frequency can be specified between 300 Hz and 20 kHz in 10 Hz steps. Either 35 mA, 80 mA or 100 mA can be selected as adjustable loop current.


28

The driver assistance system

Driver assistance systems support the driver when operating the truck and are especially used for safety in storage areas. Part of the driver assistance system is the end of aisle safety functions, height-dependent shut-off, as well as the Linde navigation system. Whereas end of aisle safety features and driving speed reduction are pre-scribed by DIN 15185 part 1 or DIN 15185 part 2, the Linde naviga-tion system is a supplementary system, which can increase both the handling performance as well as avoid incorrect storage.

29

Linde VNA directives // Driver assistance system

Systems for determining position

GeneralAssistance systems in very narrow aisles such as traction and lift cut-outs can be implemented with different systems. The currently available systems are magnet operated switches, reflected light sen-sors, bar codes and RFID Tags. Whereas magnets and reflected light sensors can be used for traction and lift cut- outs, the functionality of bar codes and RFID is expanded somewhat further and can be used with VNA navigation.

In the following, we would like to provide a brief overview of the various systems. Each of these systems has advantages and disad-vantages so that no general recommendation can be given.

End.of.the.aisle.safety.features

Lift.and..raction.cut-outs

VNA.navigation

Magnets x x

Reflected light sensors

x x

Bar codes x x x

RFID x x x

30

Open end of aisle

Middle of aisle

Vmax

VmaxVred

Vred

S

A

SS

N

150

300

1000

NN

Star

t of

the

rac

k

Ais

le d

etec

tion

wit

h in

duct

ive

guid

ance

usi

ng r

eflec

tor

(A o

r al

tern

ativ

e B

)

Tem

pora

ry s

top

V-Ch

eck/

B

egin

ning

of

aisl

e en

d zo

ne

Beg

inni

ng o

f ai

sle

end

zone

Tem

pora

ry s

top

Abs

olut

e st

op w

ith

posi

tion

ing

mov

e

Closed end of aisle

Drive direction


MagnetsLinde magnets are very small (31 mm diameter, 25 mm height) and thus very simple and cost-effective to install. Two magnets are installed in the floor at approx. 6 cm distance, one behind the other. Depending on if the south pole or the north pole magnet is driven over first, the truck detects in which direction the truck is moving and thus, if and how the truck must brake. To be able to represent different functions, there is also the option to place the magnets 150 mm or 300 mm off centre. Magnets are ideal in storage areas where simple traction and lift reductions are necessary.

Fig..20:.End of aisle safety features using floor magnets

31

Open end of aisle

Specify on site

Middle of aisle

Vmax

VmaxVred

Vred

A

1000

L rac

k

Star

t of

the

rac

k

Ais

le d

etec

tion

wit

h in

duct

ive

guid

ance

usi

ng a

refl

ecto

r (A

or

alte

rnat

ive

B)

Beg

inni

ng o

f ai

sle

end

zone

Beg

inni

ng o

f ai

sle

end

zone

Abs

olut

e st

op w

ith

posi

tion

ing

mov

e

V ch

eck/

tem

pora

ry s

top

Closed end of aisle

Drive direction

A

D

ACB


Reflected.light.sensorsLinde reflectors are attached at eye level to the uprights. Attachment to the racks is cost-effective and fast. The reflectors are grouped into A, B, C, D. These each have a different function:

A reflector: aisle detection, or beginning of the aisle end zoneB reflector: aisle detection (alternative when A reflector is not possible).C reflector: testing the reduced target speedD reflector: absolute stop with positioning move

Fig..21:.End of aisle safety features using reflected light sensors

32


Bar.codesLinde bar codes are attached approx. 50 cm above the floor on all rails. The truck scans the bar code and can determine its exact position in the storage area. Exactly determining a location makes it possible to assign various reactions from the truck to a location. In this way, the most varied and complicated truck functions such as lift and driving restrictions can be implemented. Exactly determining a location is also the basis for Linde‘s very narrow aisle navigation system as it supports the driver during storage and removal of the correct pallets and avoids errors.

RFIDLinde RFID tags are especially small and can be installed very quickly and easily in the floor with a standard drilling machine. They work at a frequency which enables fast reading and writing on the tags. Even if the tags get wet, they are protected and retain their function. The truck reads the RFID tags and can exactly determine its position in the storage area. Exactly determining a location makes it possible to assign various reactions for the truck to a location. In this way, the most varied and complicated truck functions such as lifting and driv-ing restrictions can be implemented. Exactly determining a location is also the basis for Linde‘s very narrow aisle navigation system as it supports the driver during storage and removal of the correct pallets and avoids errors.

33

End of the aisle safety features

End of the aisle safety features mean stopping or braking the indus-trial truck without input by the operating person at the end of the very narrow aisle. This measure also applies to cross aisles with the exception of those expressly provided as escape routes which cannot be entered from outside.

Please note that the above mentioned “End of the aisle safety fea-tures” system is an emergency solution. There are other braking op-tions (depending on model) available to the driver such as generator brakes, reverse current braking, and the mechanical braking on the drive wheel.


Zones.and.functions

Driving.speed.reduction.From the beginning of the aisle end zone to the end of aisle, the speed is reduced from Vmax to Vred = 2.5 km/h.When driving out of the aisle Vred = 2.5 km/h.

Driving.stop

Temporary.stopAt the beginning of the aisle end zone the truck is braked to a stand-still. After 2 seconds, there is a new drive release in the direction of the end of aisle with Vred = 2.5 km/h.

Absolute.stopBraking with absolute stop is done when the end of aisle is closed. When braking is finished, the truck is stopped. A positioning move in the direction of the end of aisle can be done using the “Q“ button (acknowledgement button pressed and held) with Vred = 1 km/h.

Speed.checkAdditional control point: testing the reduced target speed Vsoll<Vmax/2 (only for systems with reflected light sensors).

34

Height-dependent cut-offs

When system-dependent components, such as joists, pipes, and cable racks restrict the effective range and height of the industrial trucks, lift-height dependent cut-offs must be provided.

Bridgeable.intermediate.lift.limitationIn this interlock, the lifting movement is always switched off using a switch before reaching the critical overhead clearance. The driver, once he is convinced that the industrial truck is not in the danger area, can continue the lifting movement by pressing an acknowledge button and actuating the lift valve. When the highest height of the industrial truck has exceeded the critical height, driving is only pos-sible at creep speed.


Automatic.lift.or.traction.cut-outThe combination of height query on the lift mast and the systems for determining position (magnets, RFID, etc.) allows this lift or traction cut-out to be automated.

If an industrial truck enters such an area at a height that is currently less than the critical height, he can continue without restriction at the appropriate speed. If the industrial truck enters this area, stops there, and the lifting movement is triggered, this is switched off just before reaching the critical height. Bypassing this cut-off is not pos-sible.

If the industrial truck enters this area at a height that is currently greater than the critical height, the driving movement is braked and the lifting movement is switched off. Driving further is only possible after lowering below the critical height. Lift cut-outs are often com-bined with traction cut-outs.

35

3. Assigned pallet location

2. Diagonal driving in the aisle using a time-optimised path to the pallet storage location

1. Locating the truck using RFID tags or bar code

VNA navigation

Using Linde’s very narrow aisle navigation system can increase han-dling performance and at the same time, ensure secure storing and removing of stock by preventing errors. Additionally, the navigation system makes the work easier for the driver and also makes it pos-sible for new drivers to quickly work efficiently.

Operation of the very narrow aisle navigation is fast, precise, and simple at the same time. The basis for all functions of Linde’s very narrow aisle navigation system is the exact determination of the truck’s position. Determining position can be done using RFID tags and using bar codes (see Fig. 18).


The truck receives its transport or picking order via data transmission from the warehouse management system on its truck terminal. Using the navigation system, the truck can move in the fastest possible way from its current position to the required pallet storage loca-tion. The driver only has to steer using the drive and lift lever. This ensures that the driver has both hands within the truck contours and thus cannot be injured. The truck moves in an ideal curve to the specified pallet storage location. Storing or removing the pallet in the wrong location is ruled out.

Fig..18:.Functional principle VNA navigation

36


This combination of position detection and detecting the required pallet storage location makes the system efficient and prevents incorrect storage.

Optimised operation using position navigation saves time by up to 25%. The green line in Figure 19 shows the fastest route with the lowest energy and time consumption.

Fig..19:.Time savings with VNA navigation

37


Personnel protection systems

To be able to operate a very narrow aisle warehouse, measures to protect personnel in storage areas must be taken in Germany in accordance with BetrSichV. The following two options can be considered as standard: stationary and mobile protection. Stationary protection uses a photosensor system which is mounted on the rack, and which can distinguish between people and industrial trucks. Mobile protection uses sensors mounted directly on the truck which warning the driver as soon as someone or something is too close to the vehicle.

38

Photosensors for truck detection

Photosensors for personnel detection

Controller

Controller

Legal.regulations

In accordance with the workplace regulation 1.8. , pathsways, point (3) a side clearance for pedestrians on each side of the industrial truck in a VNA aisle should be guaranteed . Although a defnite value is not given the clearance taken as a guideline is 50cm on each side which is derived from the DIN EN 349.

In BetrSichV, basic options to protect persons in very narrow aisle warehouses are described as technical or structural measures. Struc-tural measures typically do not suffice, thus only a technical solution is offered. There is a distinction here between stationary (photo-sensor equipment on the very narrow aisle entrances) or mobile (systems installed on the truck) systems.

If you operate a very narrow aisle warehouse or want to start opera-tion in a new very narrow aisle warehouse the protective measures should be on an up to date standard. In germany they should meet the performance level b.

Stationary.protection

Each access of the very narrow aisle is individually protected with a photosensor system. Emergency exits and access doors are normally protected by swinging doors.

Linde VNA directives // Personnel protection systems

Fig..22:.Truck detection Fig..23:.Personnel detection

39


Mobile protection

The industrial truck is equipped with laser sensors on both sides. These monitor the travel path and detect when a person is in the warning field or the alarm field. If a person is detected in the warn-ing field, the speed is automatically reduced to creep speed (max. 2.5 km/h). If a person is detected in the alarm field, a alarm is triggered and the truck is braked automatically until standstill. For reasons of safety, the alarm can only be reset by the driver after the truck is completely at a standstill. The monitoring equipment is not active outside the very narrow aisles.

Assembly of the scanner For reasons of space, the scanner can only be attached in most cases to the front side behind the fork. This means that if the fork is low-ered, there is no view and thus also no safety function. In this case, the industrial truck may only drive at creep speed (max. 2.5 km/h). A magnet operated switch on the lift mast will determine if the scanner has an unencumbered view. The scanner is then activated. If there are no other speed limitations (cross aisles or the end of the very narrow aisle), the industrial truck can move at maximum speed in the very narrow aisle.

“Person authorisation” mode of operationIn the “Person authorisation” mode of operation, the aisle is free for access by persons, and every attempt at truck entry would immediately trigger an visual and acoustic alarm. This alarm can only be reset by an authorised person using a key switch, who can see what is happening in the aisle.

“Truck authorisation” mode of operationIn the standard “Truck authorisation” mode of operation, the truck is automatically detected when entering the aisle. In this mode of operation, if a person enters the aisle, a visual and acoustic alarm is triggered. This alarm can only be reset by an authorised person using a key switch, who can see what is happening in the aisle.

Truck detection by wide-angle photosensorsIn this solution, two wide-angle transmitters are attached on the left and right of the industrial truck and a receiver with two receiving elements is attached to the rack. The two transmitters detect the industrial truck, regardless if it enters the very narrow aisle forwards or backwards.

40


Laser scanner

Alarm field

Warning field

Additional functionIn order to have fully functioning mobile personal protection meas-ures, e.g. detection of drive direction, end of aisle, cross aisles, or exiting aisle, additional elements are required.

Drive direction sensorA drive direction sensor is attached on one of the two non-driven trailing wheels. This detects the direction of movement as well as the speed and performs a distance measurement.

Position detectionPosition detection can be performed using reflected light sensors with coded reflection marks on the rack or using aisle magnets with magnet operated switches. The first coding is located on the access to the very narrow aisle. When this coding is detected, the protection system is initialised, i.e. the drive direction sensor starts the distance measurement and determines the drive direction. The protective fields are activated.

Additional functionsTo increase safety, additional functions are implemented using the drive direction sensor. At commissioning, the braking distance of the industrial truck is measured from full speed to standstill. Braking dis-tance and delay are then saved in the controller. During each braking process the actual braking distance is measured and compared with the stored braking distance. The driver is notified of diminishing braking efficiency via the terminal. Afterwards, the truck can only be operated at creep speed for safety reasons.

Fig. 24: Mobile protection

Cited standards

• DIN EN 1045 Part 2: Concrete, reinforced and prestressed concrete structures - Part 2: Concrete - Specification, properties, production and conformity

• DIN EN 1045 Part 3: Concrete, reinforced and prestressed concrete structures - Part 3: Execution of structures

• DIN 18202: Tolerances in building construction - Buildings

• DIN EN 18560 Part 7: Floor screeds - Part 7: Heavy-duty screeds (industrial screeds)

• DIN 15185 Part 1: Warehousesystems with guided industrial trucks; requirements on the ground, the warehouse and other require-ments

• DIN 15185 Part 2: Industrial trucks - Safety requirement - Part 2: Use in narrow aisles

• DIN EN 1081: Resilient floor coverings - Determination of the electrical resistance

• DIN EN 15620: Steel static storage systems - Adjustable pallet racking - Tolerances, deformations and clearances

• VDMA directive “Floors for use with very narrow aisle industrial trucks”

• DIN EN 15635: Steel static storage systems - Application and maintenance of storage equipment

• DIN EN 15512: Steel static storage systems - Adjustable pallet racking systems - Principles for structural design

• DIN EN 15629: Steel static storage systems - Specification of storage equipment

• DIN EN 1726 Part 2: Safety of industrial trucks - Self-propelled trucks up to and including 10000 kg capacity and tractors with a drawbar pull up to and including 20000 N - Part 2: Additional requirements for trucks with elevating operator position and trucks specifically designed to travel with elevated loads

• ISO 6292: Powered industrial trucks and tractors — Brake performance and component strength

• DIN EN ISO 13849 Part 1: Safety of machinery - Safety-related parts of control systems - Part 1: General principles for design

• DIN EN 349: Safety of machinery - Minimum gaps to avoid crushing of parts of the human body

Additional standards

• DIN 15184: Power operated industrial trucks; industrial trucks for rack operation, technical safety requirements and testing

• FEM 9.831 Calculation principles of storage and retrieval machines. Tolerances. Deformations and clearances in the high-bay ware-house

• FEM 10.3.01 Pallet racks, tolerances, deformations, and clearances

Linde VNA directives // Standards

Standards

Linde Material Handling ranks among the world’s leading manufacturers. This position has been justly earned. Linde trucksexcel not only with their recognized innovative technology but especially their low energy and operating costs, which can beas much as 40% less than competitors.

High quality in production is matched by the standard of the services we provide. With a comprehensive network of local sales partners, we are at your call around the clock and around the world.

Your local Linde partner offers you a complete single-source package. From qualified pre-sales consulting through the saleto after-sales service; including finance packages matched to your business requirements. Leasing, rental or hire purchase.Flexibility is maintained in your operational and decision-making processes.

Linde Material Handling GmbH, Postfach 10 0136, 63701 Aschaffenburg, GermanyPhone +49.60 21.99-0, Fax +49.60 21.99-15 70, www.linde-mh.com, [email protected]

Engineered for your Performance

Prin

ted

in G

erm

any

. 031

.e.0

,1.1

012.

IndE

.DD

guidelines for planning and setting up very narrow aisle ... · pdf fileguidelines for...

Documents