EP2280898B1

EP2280898B1 - A safety device for cable or chain lifting apparatus

Info

Publication number: EP2280898B1
Application number: EP09745662.8A
Authority: EP
Inventors: Maria Chiara Vinati; Giacomo Vinati
Original assignee: VINATI Srl
Current assignee: VINATI Srl
Priority date: 2008-05-16
Filing date: 2009-04-30
Publication date: 2014-08-27
Anticipated expiration: 2029-04-30
Also published as: EP2280898A1; WO2009138329A1; EP2280898B8; IT1387564B1; ITMI20080901A1

Description

Technical Field

The invention relates to a safety device for cable lifting apparatus, such as overhead cranes, cranes used in the construction industry, truck hoists and chain apparatus, or hydraulic apparatus of like apparatus destined to raise and move heavy loads.

Background Art

As is known, overhead cranes are machines destined to raise and displace materials and goods, both in the open air and in closed environments, and are generally constituted by a bridge that is horizontally mobile along a pair of tracks or running ways and is provided with a crossbar (carriage) on which a hoist is mounted, which hoist can move horizontally along the crossbar and to which hoist a pulley is connected, provided with a hook for gripping and raising objects. Such a device is disclosed in document DE 4238795 A1 .
One or more cables are applied on the hoist, which with a system including pulleys, shunts and hooks enable weights to be raised or displaced.
Notwithstanding the fact that the overhead crane is a raising apparatus subject to specific standards both with regard to construction and to periodic controls, there is still an outstanding technical problem which is substantially connected to the question of safety for the operators using the apparatus.
Safety standards and use manuals prohibit oblique raising of loads and all the lifting means are designed exclusively for lifting loads vertically.
Notwithstanding the above limit to use, there are no systems in existence which prevent the operator from attempting to lift oblique loads.
During use of the lifting hook, the hook can shift considerably from the vertical, giving rise to the possibility of pendulum-like oscillation of the hook and the heavy object which may be hooked up to it and transported, or it can lead to breakage of the cable or structural failure, with a grave risk that the load can get out of control and strike one or more operators, with the concrete likelihood of occasioning a grave or even fatal accident.
The above problems can also result from use of other cable apparatus for raising loads, such as for example cranes for construction use or truck hoists. A first solution to these problems has been provided by the device described in patent application MI2008A000227 , in the name of one of the applicants.
This safety device for lifting apparatus includes means for detecting a displacement from the vertical of at least one of the cables lifting the gripping element for the load, signalling means being associated to the displacement detection means, the signalling means being acoustic and/or visual and/or means for interrupting the lifting or displacing operations designed to intervene if the displacement from the vertical of the cable for which the displacement is detected exceeds at least a first predetermined threshold.
An embodiment of this device includes the use of potentiometer Joysticks and is able to identify an inclination of the cable or chain or hydraulic element or combination of the preceding which are about to operate the lifting, and thus advise via visual, acoustic, software and hardware signallers to prevent if necessary the raising operations, or activate other necessary positioning functions of the lifting means.
A further embodiment described in the above-cited patent application includes the use of accelerometers applicable to the cable with the aim of detecting the displacement from the vertical.
Though the device of the above-cited patent application effectively performs the function of timely signalling a situation of danger, it does not provide all those functions which ideally correspond to the safety requirements provided for in the existing standards, especially the ISO and FEM standards.
Specifically these standards include the use of systems which can verify and measure the effective use made or service life of the lifting apparatus with respect to the theoretical service life provided by the constructor.

Disclosure of Invention

The aim of the present invention is to obviate the above-cited drawbacks by providing a safety device for cable lifting apparatus which provides the operators with complete information on the functioning of the lifting apparatus.
A further aim of the invention is to provide a considerable increase in safety during use of cable lifting plants which is rational, reliable and relatively inexpensive.
The aims of the invention are attained with a safety device designed to be connected to or installed on a cable or chain or hydraulic (or a combination thereof) lifting apparatus, where the above-mentioned apparatus comprises a mobile hoist or lifting apparatus to which is connected, via a cable system, a gripping element for a load, the safety device being characterised in that it is provided with means for detecting any displacement of the load gripping element where the means comprise an accelerometer group, each of which accelerometers is destined to calculate the displacement of the gripping element of the load in relation to a respective perpendicular Cartesian axis (x, y, z), and means for processing the data received from the above-mentioned accelerometers.
The invention also comprises use of means for processing the data collected by the accelerometer group during use of the lifting apparatus.
In a preferred embodiment of the invention, the accelerometers are positioned on the cable anchorage or at the point in which the cable is fixed or immobile, i.e. not running.
In a further embodiment of the invention, when the ends of the cable contemporaneously wind on two rotating drums, the accelerometers are positioned on the highest-positioned fixed return pulley.
The device of the invention is in particular able to define:

the work cycles (with the specification that loading and unloading form a cycle);
the loading regime, i.e. how much load is raised and for how long, deriving from this data that the regime falls within the tables provided by the standards for defining conditions of use of the lifting means and therefore if the load regime is light, moderate, heavy or very heavy, with a consequent determination of the load spectrum defined by the standards;
movement of the lifting apparatus in the space defined by x, y and z; the hours of effective functioning of the lifting apparatus T
the recording of anomalous events, such as earthquakes, overloads etc. Further characteristics of the invention can be found in the dependent claims.

Brief description of the Drawings

Further characteristics and advantages of the invention will emerge from a reading of the following description, provided by way of non-limiting example, with the aid of the figures illustrated in the accompanying figures of the drawings, in which:

Figure 1 is a schematic view of the safety device of the invention, in a vertical load position; and
Figure 2 is a schematic view of the safety device of the invention in a non-vertical load position and in a situation of potential danger.

Best Mode for Carrying Out the Invention

Figures 1 and 2 illustrate the safety device for the cable or chain lifting device of the invention, denoted in its entirety by reference number 10.
Figure 1 schematically illustrates a pulley 11, provided with a hook 12 and destined to raise or lower a load by means of a cable system 13, 14 activated via a hoist or another lifting means 15 mounted on the crossbar 16, in a situation in which the load (not illustrated for the sake of simplicity) is vertical and thus there is no danger of load oscillation. In this figure the cables are represented in a vertical position.
According to the invention a group 20 containing accelerometers on three axes is mounted such as to perceive the displacements of the cable in the various spatial directions taking account of the time and the ambient temperature.
In a preferred embodiment of the invention, the accelerometers are positioned on the cable anchor, i.e. at the point in which the cable is fixed and immobile.
In a further embodiment of the invention, when the ends of the cable wind contemporaneously on two rotating drums, the accelerometers are positioned on the fixed return pulley located in an upper position.
In a preferred embodiment of the invention three single-axis accelerometers can be used, one for each perpendicular Cartesian axis, or a double-axis accelerometer can be used to detect accelerations on the axes X and Y, in conjunction with a single-axis accelerometer for detecting the acceleration with respect to the axis Z.
Alternatively a triple-axis accelerometer can be used, by which is meant a device which comprises three accelerometers, one for each perpendicular Cartesian axis.
The data collected by the accelerometer group 20 is sent in real-time either to an on-board protected processing chip, i.e. contained together with the accelerometers, or, for example via a screened connecting cable 21, to a hardware card 22 with a separate processing chip which processes the data as described herein below.
The hardware card has the function of enabling interfacing and connecting with the accelerometers and/or the relative processing chip, the alarm system managing device and the apparatus lifting or moving devices on which the system is installed or in any case to interface with external systems.
Figure 2 shows the hook in a non-vertical loading position and a situation of potential danger, where by way of example φ denotes the angle of displacement from the vertical.
The device of the invention enables measuring this angle φ in any position in space defined by angle θ, which is variable between 0° and 360°.
Entirely indicative values for the angle φ can be such as to define a first alarm threshold when φ exceeds 4°, and a second greater alarm threshold when φ exceeds 7°.
The device of the invention can also be configured as a kit that can be installed by maintenance operatives and can satisfy the safety requirements provided for in the existing standards, in particular the ISO and FEM standards, the kit being made up of at least:

single-axis, double-axis or triple-axis accelerometer or accelerometers to be applied to the cable anchoring point or another appropriate location on the lifting means;
an interface card for detecting the data from the accelerometers and relative data processing and storing EPROM's;
outputs and relays for connection to overhead crane systems and warning systems;
USB output port for data collection on the part of operators;
USB memory stick for data collection;
PDA devices for data collection;
software programs for the operators, for system programming;
EPROM's for data storing, taking into account the three-month periodic maintenance controls;
reset key for maintenance operators.

The device of the invention can also be configured as a kit that can be installed on the lift means for a period of time in order to determine the load regime and the relative effective use conditions with respect to the theoretical conditions on the basis of which the lift means has been designed.
Once the prescribed time has passed, the kit is de-installed and the data is detected, stored and processed in order to define the exact load regime and the effective use of the lifting means. These data are of extreme interest as far as operator safety is concerned.
It is therefore evident that the invention represents a substantial evolution with respect to the prior art as the concept of detecting with accelerometers the displacements on the three Cartesian axes of the hook of a lifting apparatus.
In general, therefore, it can be said that the device of the invention constitutes a transversal anti-traction system with the main objective of preventing the loads from being raised non-vertically, and thus dangerously. The device of the invention, via detection of the data provided by the accelerometers enables the following operations.
First it enables calculation of the run of the hook based on the principle that the run of the hook determines a variation in the angle φ of the cable anchorage where the accelerometer group is solidly installed.
The variation φ is perceived by the accelerometers and thanks to this datum the position of the hook with respect to axis Z can be determined, given point Z1 (hook completely raised) and the relative angle φ, and given the hook run Cg, the function determining the position of the hook can be derived.
The device can enable the hook to become a manoeuvring system of the lifting apparatus, a follow-me joystick-type function.
In this case, the displacement of the hook decided by the operator is detected by the device positioning the lift hook and thus the overhead crane or the crane such that it follows the displacements of the hook commanded by the operator.
The device can also function as an anti-oscillation system: it can enable the lifting means to prevent the translating load from oscillating, detecting the movements and enabling the lifting means to accelerate or reduce its velocity such that the lifting means is always perfectly placed above the load, preventing the load from oscillating.
The device can enable detection of the breakage or elastic or permanent lengthening of the cables or steel chains by defining property algorithms known as harmonics of breakage and/or of stretching, which developed from experiences relating to evaluation of the breakage or non-elastic lengthening and function over time, all with regard to increased safety.
The device is predisposed, with property algorithms, for detecting various anomalies and specific events such as when the end of the working life of the lifting means is imminent, earthquakes, repeated excess loads, signals of unknown origin and thus meriting analysis, etc.
The device can enable measuring the load by means of property algorithms relating to the directional arrow determined by the load (variation on axis Z), the position in space of the carriage or the hoist (variation on axis X or Y) and the definition of the gauge or gap parameters, as well as to other parameters required for the algorithm.
The device can enable measurement in space of all the positions of the lifting means (overhead crane, carriage, hook etc.), and storing thereof for subsequent processing.
The device of the invention can enable memorisation of all the events necessary for selected time periods.
It is able to record all the events or parameters such as:

translation of the carriage and its position in space;
translation of the bridge and its position in space;
rotation of the turret in the case of construction cranes and its position in space;
inclination of the arm in the case of a truck hoist or forklift trucks and its position in space;
raised weight;
lifting momentum;
unloading momentum
start-up of the lifting apparatus;
shut-down of the lifting apparatus;
duration of daily functioning of the lifting apparatus;
summing of the total daily functioning time for periods or fractions or sums of periods;
total functioning hours in the working life.

By means of clocks the device detects an effective duration of functioning and use of the lifting means.
The device is provided with an actual material button for recalibrating the system with repositioning to ZERO or another value of all systems and relative functioning software. This considerably eases the work of the maintenance operatives who can intervene without the use of computers or other devices.
The device can also transmit data and information through a wireless system or sms text forwarding or data transmission. This is particularly useful for the maintenance operatives. The wireless system and battery pack system is particularly suitable for construction cranes where the carriage translates by means of cables and there is no electric supply line, or on petroleum oil plants or others.
The device can be provided with a USB stick drive or another autonomous system containing processing chips, which enables the data to be collected from the data banks of the system of the invention only by specially programmed and authorised devices.
A further possibility is that of using a PDA on which the software for communicating with the accelerometer group is installed, and with which not only can the data be downloaded, but it is possible to intervene directly on the device to change some parameters. The connection between the device and the PDA can be done via USB, Serial or Wireless.
The advantages of this solution lie in the combination of the portability of the USB stick and the flexibility of use of the PC. Further, the extended functions can interface later on with the resident PC software.
The device can be provided with a display for reproducing and immediately displaying some data such as the alarm codes which cannot wait for the normal maintenance cycle. For example, in a case where there will be a probable breakage of the strand of a cable, of a cracking in the metal or another malfunction the datum is immediately signalled for reasons of operator safety and so on for other malfunctioning of various nature.
The accelerometer device applied to the arms of the truck hoist is able to prevent tilting, interrupting functioning.
The accelerometer device can be further used for anti-explosion or anti-implosion purposes, and for the detecting of anomalous events on tanks of any type, especially in the field of petroleum oil.
The system of the invention duly equipped with a battery pack and wireless or SMS text transmission can be applied on structures which might for unforeseen reasons be subjected to structural deformation, for example pressurised tanks, due to expansion, heat dilation or other reasons. Thus such anomalies can be signalled in good time and prevent damage to systems and in any case to personnel.
Among the advantages of the invention is the possibility of improving use of the overhead crane or crane by optimising service time between planned maintenance operations and according to the load regime and the relative load spectrum set out in the theoretic design use as defined in pursuance of the existing standards.
For determining and comparing the actual service life S and the theoretical service life D there exist various different recording classes.
A first possible method is combined documentation and cycle-counter, where the effective load spectrum factor K_m and the working hours T_i are documented by the user on the basis of a cycle-counter apparatus the overhead crane or the crane must be equipped with.
A less satisfactory method is using simple documentation and known service history (effective hours actually worked).
The effective load spectrum value K_m and the working hours T_i are documented by the user without using a cycle-counter apparatus.
This can even be done using simple documentation and unknown working hours, which means that the effective load spectrum factor K_m and the working hours T_i are not documented by the user.
In all cases the aim is to define the reaching of the theoretical utilisation threshold assigned by the constructor when defining the theoretical class of the apparatus.
The invention enables instrumental registration to be made according to the ideal standard parameters, i.e. the working conditions are automatically recorded by special instrumentation, in which the hours of use between a maintenance operation and the previous operation T_i are calculated, where the load spectrum deduced from the effective load regime is known.
The formula is as follows.
Formulating the hypothesis that the spectrum factor does not vary between one maintenance operation and another, T_i would simply be T, i.e. the total of the working hours.
This enables formulating the following example: in class M4 the ratio would be S=800C/*0.25, i.e. an overhead crane which has performed 3,200 hours of work should undergo a general service as it has reached the theoretical use Limit.
With the system having documentation combined with a cycle-counter, for each documented interval i, the period of use in hourly terms will be multiplied by the empirical factor Ø1 or Ø2.

The formulas according to the type of registration are reported in the following table.

Registration	Working life formula calculation	Ø	ISO standards	FEM standards
Instrumental	$S = \sum_{i = 1}^{R} K_{m} T_{i}$	Ø	1	1
Documented with cycle-counter	$S = \sum_{i = 1}^{R} φ 1 K_{m} T_{i}$	Ø1	1.1	1.2
Documented with hour-counter	$S = \sum_{i = 1}^{R} φ 2 K_{m} T_{i}$	Ø2	1.2	1.4
Documented and unknown service	$S = \sum_{i = 1}^{R} φ 3 K_{m} T_{i}$	Ø2	1.5	-

In brief, in the prior art non-use of automatic instrumentation is penalised. For example, in class M4 the ratio will be: S=800/(1.2*0.25) and an overhead crane which has done 2,667 hours of work under the ISO standards should undergo a general service as it has reached the theoretic use limit.
With documentation and effective working hours provided, and in the absence of a cycle-counter, the 02 coefficient is applied.
For example: in class M4 the ratio will be: S=800/(1.4*0.25) and an overhead crane which has done 2, 286 hours or work under the ISO standards should undergo a general service as it has reached the theoretic use limit.
In a case where documentation and working hours are unknown, i.e. not even the effective working hours have been recorded, which is the normal condition of today, with a grave risk for the operators' lives, the Ø factor is 1.5.

The following table illustrates the registration data of the working conditions in the various cases referred to the example in which the apparatus is classified in class M4:

CLASS	Registration of work condition T4
M4	INSTRUMENTAL (Invention)	DOCUMENTAZION + CYCLE-COUNTERI	DOCUMENTATION AND CYCLE-COUNTER	DOCUMENTATION AND SERVICE UNKNOWN
THEORETICAL WORKING LIFE	3200	2667	2286	2133
LOST HOURS	0	533	914	1067

The device of the invention guarantees a high safety and protection standard for the operators working on the lifting means.
The ability to define the effective service life S with respect to the theoretical life D, which once reached requires a general service of the lifting means to be performed, is clearly a very positive influence on the operators' safety level.
A further advantage is expressed very clearly in the above-reported table, i.e. the use of the instrumentation of the present invention enables a service lift working life to be obtained which is the same as the theoretical life without the disadvantage of the standards which reduce the theoretical life thereof with impacts on the theoretical total of working hours that vary from 10% to 50%.
Obviously modifications or improvements can be made to the invention as described herein above, dictated by contingent or special motives, without the invention's forsaking the ambit of protection as claimed herein below.

Claims

A safety device (10) for applying to a cable or chain lifting apparatus, or a pneumatic apparatus or a combination thereof, wherein the apparatus comprises a mobile hoist or another lifting system (15) to which a gripping element for a load is connected by means of a cable system, wherein the safety device is provided with means for detecting each displacement of the gripping element of the load, the means comprising an accelerometer group (20), each of the accelerometers of the group being destined to calculate a displacement of the gripping element in relation to a respective perpendicular Cartesian axis (x, y, z), and means for processing data obtained by the accelerometers, characterized in that the safety device comprises software means for enabling spatial measurement of all positions of the lifting means (15) and storage thereof for a subsequent treatment.
The safety device of claim 1, characterised in that it comprises use of means for processing the data obtained by the accelerometer group (20) during use of the lifting apparatus.
The safety device of claim 1, characterised in that it enables an interfacing with the lifting means for activating visual and/or acoustic signals and for interacting with all devices present on the lifting means (15).
The safety device of claim 1, characterised in that the accelerometer group (20) is located at a point of the cable in which the cable does not run or wind.
The safety device of claim 1, characterised in that the point of location of the accelerometer group (20) is at an anchoring point of the hoist or other lifting means.
The safety device of claim 1, characterised in that it comprises means for calculating a run of the hook on a basis of a variation of an angle of the anchoring point or the element on which the accelerometer group (20) is solidly installed.
The safety device of claim 1, characterised in that it comprises means for using the displacement data collected via the accelerometer group (20), in a case in which the displacements of the hook are performed by the operator with an aim of positioning the lifting hook and thus an overhead crane or a crane or a truck hoist or a construction crane such that the device follows the displacement of the hook as set by the operator.
The safety device of claim 7, characterised in that it comprises means which function as an anti-oscillation system in order to prevent a translating load from oscillating, the means detecting displacements and enabling the lifting means to accelerate or reduce a velocity thereof such that the lifting means are always positioned perfectly above the load.
The safety device of claim 1, characterised in that it comprises software means for enabling detection of a breakage or an elastic or permanent stretching of the cables or steel chains using algorithms derived from experiences collected on evaluation of breakage of strands or single steel wires or experiential data concerning non-elastic stretching of the overhead crane cables.
The safety device of claim 1, characterised in that it comprises software means for enabling detection of anomalies and specific events such as an approach to end of working life of the lifting means, earthquakes, repeated excess loads, unrecognised signallings and the like.
The safety device of claim 1, characterised in that it comprises software means for enabling measurement of the load relating to the direction determined by the load, a spatial position of the carriage or the hoist, and gauge or gap parameters and other parameters required for an algorithm.
The safety device of claim 1, characterised in that it comprises software means for enabling storage of all events or parameters, as follows:
translation of the carriage and a position in space thereof;

translation of the bridge and a position in space thereof;

rotation of a turret in a case of construction cranes and a position in space thereof;

inclination of an arm in a case of a truck hoist or lift trucks and a position in space thereof;

lifted weight;

lifting momentum;

unloading momentum

start-up of the lifting apparatus;

shut-down of the lifting apparatus;

duration of daily functioning of the lifting apparatus;

summing of a total daily functioning time for periods or fractions or sums of periods;

total functioning hours in a service life;

calculation of a load regime;

detection of a load spectrum;

calculation of use conditions;

calculation of effective service life.
The safety device of claim 1, characterised in that it comprises a button for recalibrating the system with a resetting at ZERO value or another value of all the systems and the relative functioning software.
The safety device of claim 1, characterised in that it comprises means for transmitting the data and information by means of wireless systems or by means of SMS text message or data transmission.
The safety device of claim 1, characterised in that it can be associated to a USB memory stick or another autonomous system containing a processor chip which enables the data memorised by the system to be collected.
The safety device of claim 1, characterised in that it can be associated to a PDA provided with software for communicating with the accelerometer group and with which it is possible to intervene directly on the device to change functioning settings thereof.
The safety device of claim 1, characterised in that it can be provided with a display which can reproduce and immediately display alarm data and codes, attention to which cannot be delayed until a next maintenance service cycle.
The safety device of claim 1, characterised in that it can be applied on arms of a truck hoist in order to prevent tilting thereof by interrupting functioning of the hoist.
The safety device of claim 1, characterised in that it can further be used for anti-explosion or anti-implosion purposes and for detecting of anomalous events on storage tanks of any kind.