Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
  • B66C6/00—Girders, or track-supporting structures, specially adapted for cranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
  • B66C9/00—Travelling gear incorporated in or fitted to trolleys or cranes
  • B66C9/16—Travelling gear incorporated in or fitted to trolleys or cranes with means for maintaining alignment between wheels and track
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
  • B66C13/00—Other constructional features or details
  • B66C13/18—Control systems or devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
  • B66C15/00—Safety gear
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
  • B66C19/00—Cranes comprising trolleys or crabs running on fixed or movable bridges or gantries

Definitions

• a hoisting apparatus movable on rails and a method for controlling thereof
• the invention relates to a hoisting apparatus movable on rails and a method for controlling thereof.
• Hoisting apparatuses moving on rails include, for example, bridge cranes intended to move on rails raised above ground level, or gantry cranes intended to move on rails arranged at ground level.
• Bridge or gantry cranes typically have one or more main girders, said one or more main girders forming the frame structure of the crane, with at least one hoisting unit being arrangeable to be supported by it, the hoisting unit comprising a trolley and at least one hoist adapted it.
• each end trolley has at least one wheel whereby a crane may be adapted to move supported by said wheels and along the aforementioned essentially parallel rails, said rails running in an essentially transverse direction in relation to the longitudinal direction of the main girder and form the runway of the crane.
• a bridge or gantry crane further includes at least one travelling appa- ratus adapted to at least one end trolley to move said main girder along the rails, the travelling apparatus typically comprising an electric motor connected to a wheel of the end trolley by means of an axle.
• a crane further includes at least one control device to control the travelling speed of the main girder of the crane on said rails, by controlling the operation of said at least one travelling apparatus.
• a problem in using bridge or gantry cranes is driving the crane aslant, that is, a situation where the main girder of the crane does not run straight, that is, at an essentially right angle to the rails.
• Such a situation may be caused by, for example, the rails having bends or the distance between the rails being indefinite or varying.
• Such a situation may also result from the manufacturing tolerances of the crane itself, the manufacturing tolerances of the runway formed by the rails, or in outdoor cranes, in particular, from the changes caused by temperature changes in the dimensions of the crane or runway.
• Driving a crane aslant may also be caused by the load of the crane being on either end of the main girder, whereby the main girder end under load may move more slowly than the other end due to uneven load distribution of the crane.
• the flanges of the crane wheels hit the rail edges, which causes wear on both the crane wheels and the rails forming the runway for the crane, and causes additional strain on the structure of both the crane and the runway.
• the FI publication 100594 B shows a solution for preventing driving a crane aslant.
• the distance of a specific part of a crane edge is measured from a rail, and the goal is to keep said distance constant by controlling the speeds of the opposite ends of the main girder of the crane so that the distance of the specific part of the crane edge from the rail may be set as desired so that the crane moves straight on the rails.
• the FI publication 105266 B sets forth a solution where the main girder is fixed at one of its ends to an end trolley at the end of the main girder in question so that the main girder is able to both move in its longitudinal direction in relation to said end trolley and to rotate in relation to said end trolley in the horizontal plane.
• the joint in question compensates for form and dimension variations in the structure of the crane itself and in the runway structure, and a fixed joint between the end trolley and the main girder at the opposite end of the main girder alone guides the direction of the crane according to its rail.
• the invention is based on measuring the tensile force present in connection with a girder and/or an end trolley of a hoisting apparatus as the hoisting apparatus is moving along its runway, and controlling, on the basis of the measured tensile force, at least one travelling device to control the travel speed of at least one end of the girder of the hoisting apparatus.
• Said tensile force present in connection with the girder and/or end trolley may, depending on the implementation of the hoisting apparatus, be present either on the girder or the end trolley, or both on the girder and end trolley, or at the joint between the girder and end trolley, or in connection with said joint.
• the solution put forth is not dependent on the position of the hoisting device on the runway or the manu- facturing tolerances of the hoisting device and runway, but exclusively on the tensile forces that at least one girder and/or at least one end trolley connected to the ends thereof in the hoisting apparatus are subjected to.
• Figure 1 is a schematic front view of a bridge crane
• Figure 2 is a schematic bottom view of the bridge crane of Figure 1;
• Figure 3 is a schematic view of a bridge crane and arrangements adapted thereto to detect tensile forces present in driving the bridge crane aslant and to control the bridge crane, as seen from below the crane,
• Figure 4 is a schematic view of a measuring arrangement to detect the tensile forces present when driving a bridge crane aslant
• Figures 5 and 6 are schematic views of a second bridge crane and a measuring arrangement adapted thereto to detect the tensile forces present when driving a bridge crane aslant, with Figure 5 showing the crane from below and Figure 6 showing the crane as seen from its end,
• FIG. 7 is a schematic view in block diagram form of an adjustment system to control the speed of the bridge crane of Figure 3,
• Figure 8 is a schematic view in block diagram form of an adjustment system to control the speed of the bridge crane of Figure 5,
• Figures 9, 10 and 11 are schematic views of examples of situations of driving aslant a bridge crane and correcting the driving aslant
• Figures 12 and 13 are schematic views of yet another measurement arrangement adapted to a bridge crane to detect driving aslant of the crane.
• FIG. 1 is a schematic front view of a bridge crane 1, and Figure 2 is a schematic bottom view of the bridge crane 1 of Figure 1.
• the bridge crane 1 forms a hoisting apparatus moving on rails.
• the bridge crane 1 comprises a main girder 2 which forms the frame structure of the bridge crane 1, with at least one hoisting unit 3 of the bridge crane 1 being arrangeable to be supported by it, to be used for hoisting a load.
• the hoisting unit 3 comprises a trolley 4 equipped with wheels 6 and having a frame structure comprising longitudinal supports 4'.
• the trolley 4 is adapted to be supported by the main girder 2 through the wheels 6 of the trolley 4.
• the trolley includes a hoist 5 for hoisting and lowering a load moved by the crane.
• the main girder 2 forms a runway for the hoisting unit 3, along which the hoisting unit 3 may be moved by means of a travelling motor 7 of the hoisting unit 3, further included in it.
• the main girder 2 has, as seen in its longitudinal direction, a first end 2' and a second end 2" at its opposite end.
• a first end trolley 8 To the first end 2' of the main girder 2 is connected a first end trolley 8, and a second end trolley 11 is connected to the second end 2" of the main girder 2.
• the end trolleys 8, 11 include wheels 9, 12 by means of which the end trolleys 8, 11 and the main girder 2 are arrangeable to be supported by rails 15, 16 forming the runway of the bridge crane 1.
• the bridge crane 1 may be moved along the rails 15, 16 by means of a travelling motor 10, 13 of the end trolley 8, 11, acting on at least one wheel 9, 12 of the end trolley 8, 11.
• the operation of the travelling motors 10, 13 may be controlled by means of a control unit 14 of the bridge crane 1, according to control messages conveyed through control connections CLIO, CL13.
• the control connection CLIO, CL13 may be, for example, control connections implemented by cables, or, for example, wireless control connections implemented through a transmitter-receiver pair.
• the main girder 2 of the bridge crane 1 shown in Figures 1 and 2 has, at both ends 2', 2", one end trolley 8, 11, and both end trolleys 8, 11 have one travelling apparatus.
• each of the end trolleys of the bridge crane 1, which are separate from each other have at least one travelling apparatus. Large end trolleys may have more than one travelling apparatus.
• the rails 15, 16 disclosed in the above are substantially parallel rails running in a substantially transverse direction in relation to the longitudinal direction of the main girder 2 and forming the runway of the bridge crane 1, on which the bridge crane 1 moves in a direction substantially transverse in relation to the longitudinal direction of the main girder 2.
• the rails 15, 16 may be supported either to the ceiling, wall, or frame structure of a building, or to be supported by ground-based pillars.
• the bridge crane 1 described in the above forms a hoisting apparatus arranged to move on rails.
• the bridge crane 1 typically comprises one hoisting unit 3, only, but unlike in the figures, there may be more than one of said hoisting units 3 in one bridge crane 1.
• the bridge crane 1 may comprise, unlike in the figures, at least two substantially parallel main girders, whereby said main girders together form the supports and the runway for at least one hoisting unit 3 of the bridge crane 1.
• the bridge crane 1 may comprise, unlike in the figures, more than one end trolley 8, 11 at the ends 2, 2" of said at least one main girder 2, for example two end trolleys, separate from each other, placed successively in the direction of the rails 15, 16.
• FIG 3 is a schematic view of a bridge crane 1 and arrangements adapted thereto to detect tensile forces present in driving the bridge crane 1 aslant and to control the bridge crane, as seen from below the crane,
• the bridge crane 1 has drifted aslant for the reason that the travelling speed of the second end 2" of the main girder 2 of the bridge crane 1 and the second end trol- ley 11 connected thereto on the runway formed by the rails 15, 16 has been greater than the travelling speed of the first end 2' of the main girder 2 and the first end trolley 8 connected thereto, when it is assumed that the travelling direction of the bridge crane 1 was in the direction of the arrow A.
• At least one tensile force affecting the hoisting apparatus is measured with at least one measuring member of tensile force, caused by the hoisting apparatus drifting aslant on its runway.
• the hoisting apparatus is the bridge crane 1
• the main girder 2 and/or end trolleys 8, 11, or the connection between the main girder 2 and/or the end trolleys 8, 11 may be subjected to said tensile forces.
• Said at least one tensile force may be measured either from the main girder 2, end trolley 8, 11, or the connection between the main girder 2 and the end trolley 8, 11.
• the control device of the hoisting apparatus such as the control unit 14 of the bridge crane 1, is adapted to control at least one travelling apparatus of the hoisting apparatus, that is, in the examples described in the figures, the travelling motor 8 and/or travelling motor 11 to control the travelling speed of at least one end, so the first end 2' and/or the second end 2", of the main girder 2.
• Figure 3 is a schematic view of three alternative embodiments for measuring the tensile forces that the bridge crane 1 is subjected to.
• the embodiments in question are primarily alternatives to each other, but each disclosed embodiment may also be used together with at least one of the other embodiments.
• the measuring members of tensile force are placed at the joint 17, 18 between the end 2', 2" of the main girder 2 and the end trolley 8, 11.
• Figure 3 schematically shows a first tensile force measuring member FMl placed at the joint 17 between the first end 2' of the main girder 2 and the first end trolley 8 to measure the tensile force Fl creat- ed at the joint 17 between the first end 2' of the main girder 2 and the first end trolley 8 when the main girder 2 bends or rotates in a substantially horizontal plane in relation to the end trolley 8.
• a similar second tensile force measuring member FM2 may be placed at the joint 18 between the second end 2" of the main girder 2 and the second end trolley 11 to measure the tensile force F2 created at the joint 18 between the second end 2" of the main girder 2 and the second end trolley 11 when the main girder 2 bends or turns in relation to the end trolley 11 in a substantially horizontal plane in case no sliding joint 24, to be disclosed below in connection with Figures 5 and 6, between the main girder and end trolley is used.
• the measured tensile forces Fl, F2 are transmitted to the control unit 14 which, on the basis of them, controls the operation of the travelling motors 10, 13 to control the travelling speed of the end trolleys 8, 11 so that the drifting of the bridge crane 1 into a harmfully intense situation of being driven aslant is prevented and the bridge crane 1 movement is corrected to be straight.
• Figure 4 is a schematic view of a potential practical solution for placing the first tensile force measuring member FM1, FM2 to the joint 17, 18 between the end 2', 2" of the main girder 2 and the end trolley 8, 11.
• Figure 4 shows the joint 17 between the first end 2' of the main girder 2 and the first end trolley 8 on the front side of the main girder 2.
• a similar joint may be used at the joint 18 between the second end 2" of the main girder 2 and the second end trolley 11, not shown in Figure 4.
• Said joint comprises a bottom disc 19 in the main girder 2 of the bridge crane 1, which has a flange 20 extending at least partly in the direction of the end trolley 8, the flange being fastened in some way on the end trolley 8, by a bolt and nut fastening, for example, arranged in a fastening opening 21.
• Figure 4 shows one fastening opening 21, only, but in practice there are usually more of them.
• a first tensile force measuring member FM1 arranged substantially parallel to the main girder 2 and whose first fastener 22 is arranged in the end trolley 8 and a second fastener 23 arranged in a protrusion portion 20' in the flange 20, the protrusion portion 20' being directed away from the main girder 2 and extending beyond the dimensions of the end trolley 8.
• Said first tensile force measuring member FM1 is adapted to measure the tensile force that is indicative of the force that resists the rotation at the joint 17 between the main girder 2 and the end trolley 8 in relation to an imaginary vertical rotation axis Y when the bridge crane 1 is about to drift aslant on its runway.
• a similar measuring arrangement may be arranged at the joint 18 between the second end 2" of the main girder 2 and the end trolley 11 for a second tensile force measuring member FM2 in case no sliding joint 24, to be disclosed below in connection with Figures 5 and 6, between the main girder and end trolley is used.
• the measured at least one tensile force Fl, F2 is transmitted to the control unit 14 which, on the basis of it/them, controls the operation of the travel- ling motors 10, 13 to control the travelling speed of the end trolleys 8, 11 so that the drifting of the bridge crane 1 into a harmfully intense situation of being driven aslant is prevented and the bridge crane 1 movement is corrected to be straight.
• the tensile force measuring members FM1, FM2 may be based on a strain gauge arrangement, for example.
• Figure 4 is a schematic view of just one possible joint between the main girder 2 and the end trolley 8, but said joint may be implemented in a number of different ways.
• the measuring members of tensile force are placed at the main girder 2, next to the joint 17, 18 between the end 2', 2" of the main girder 2 and the end trolley 8, 11.
• Figure 3 schematically shows a third tensile force measuring member FM3 placed at the main girder 2, next to the joint 17 between the first end 2' of the main girder 2 and the first end trolley 8 to measure the tensile force F3 created next to said joint 17 on the main girder 2.
• a similar fourth tensile force measuring member FM4 may also be similarly placed at the main girder 2, next to the joint 18 between the second end 2" of the main girder 2 and the second end trolley 11 to measure the tensile force F4 created next to said joint 18 on the main girder 2 in case no sliding joint 24, to be disclosed below in connection with Figures 5 and 6, between the main girder and end trolley is used.
• the measured at least one tensile force F3, F4 is transmitted to the control unit 14 which, on the basis of it/them, controls the operation of the travelling motors 10, 13 to control the travelling speed of the end trolleys 8, 11 so that the drifting of the bridge crane 1 into a harmfully intense situation of being driven aslant is prevented and the bridge crane 1 movement is corrected to be straight.
• the tensile force measuring members FM3, FM4 may al- so be based on a strain gauge arrangement, for example.
• the measuring members of tensile force are placed on the axles of the wheels 9, 12 of the end trolleys 8, 11.
• Figure 3 schematically shows a fifth tensile force measuring member FM5, which is placed on the axle of a wheel 9 in the first end trolley 8 to measure the tensile force F5 affecting the axle of said wheel 9.
• a similar sixth tensile force measuring member FM6 may be placed on an axle of a wheel 12 in the second end trolley 11 to measure the tensile force F6 that the axle of said wheel 12 is subjected to in case no sliding joint 24, to be disclosed below in connection with Figures 5 and 6, between the main girder and end trolley is used.
• Said fifth tensile force measuring member FM5 and sixth tensile force measuring member FM6 may also be based on a strain gauge arrangement, for example.
• the measured at least one tensile force F5, F6 is transmitted to the control unit 14 which, on the basis of it/them, controls the operation of the travelling motors 10, 13 to control the travelling speed of the end trolleys 8, 11 so that the drifting of the bridge crane 1 into a harmfully intense situation of being driven aslant is pre- vented and the bridge crane 1 movement is corrected to be straight.
• Figure 5 is a schematic view of another bridge crane 1 and an arrangement adapted thereto to detect driving the bridge crane 1 aslant and to control the bridge crane 1, as seen from below the crane.
• Figure 6 is a schematic view of the bridge crane according to Figure 5 and an arrangement adapted thereto to measure tensile force.
• the bridge crane 1 shown in Figure 5 comprises at the first end 2' of the main girder 2, a sliding joint 24 between the first end 2' of the main girder 2 and the first end trolley 8 to connect together the first end 2' of the main girder 2 and the first end trolley 8 so that the main girder 2 is able to both move in its lon- gitudinal direction and to rotate in relation to said end trolley 8 in the substantially horizontal plane.
• a bridge crane 1 end provided with a sliding joint 24 is self- aligning. If the wheels of the end trolley 8 are mutually parallel, then when the first end trolley 8 has once set itself in the direction of the runway, it will travel in this direction all the time hardly ever touching the rail 15 with its flanges.
• One such solution is shown in the FI publication 105266 B.
• Figure 6 shows a solution in which tensile measurement is arranged at the end of a bridge crane 1 provided with a sliding joint 24, the measurement being indicative of the tensile force F7 created between the main girder 2 and the first end trolley 8 in a driving aslant situation of Figure 5.
• This tensile force F7 is indicative of the force by which force the driving aslant forces that are present in the fixed joint between the second end 2" of the main girder 2 and the end trolley 11 affect the end trolley 8, provided with the sliding joint 24, with the main girder 2 as the lever arm, at the first end 2' of the main girder 2.
• the solution according to Figure 6 includes a seventh tensile force measuring member FM7, which is arranged at the end of the bridge crane 1 provided with the sliding joint 24.
• the tensile force meas- uring member FM7 is arranged between a first fastener 25 supported to the first end 2' of the main girder 2 and a second fastener 26 supported to the first end trolley 8 so that the tensile force measuring member FM7 measures the tensile force F7 created between the main girder 2 and the first end trolley 8, in the di- rection of the runway of the bridge crane 1, so in the example of Figure 6 substantially in the direction of the rail 15, at the bridge crane 1 end provided with the sliding contact 24.
• the tensile force F7 is the result of a disadvantageous, such as wrong or unequal, speed of the end trolley 8 compared with the speed of the end trolley 11 connected with a substantially rigid or fixed joint to the second end 2" of the main girder 2.
• the measured tensile force F7 is transmitted to the control unit 14 which, on the basis of it, controls the operation of the travelling motors 10, 13 to control the travelling speed of the end trolleys 8, 11 so that, based on said tensile force F7 measurement, the drifting of the bridge crane 1 into a harmfully intense situation of being driven aslant is prevented and the bridge crane 1 movement is corrected to be straight.
• the first end 2' of the main girder 2, provided with the sliding joint 24, is travelling at the same speed as the second end 2" of the main girder 2 and there is no driving aslant present in such a case.
• FIG 7 is a schematic view, in the form of a block diagram, of an adjustment system to control the travelling speed of a bridge crane 1 according to Figure 3, provided with substantially fixed joints between the ends 2', 2" of the main girder 2 and the end trolleys 8, 11 of the bridge crane 1.
• the adjustment system according to Figure 7 includes a measuring block M to determine the tensile forces Fl, F2 that the bridge crane is subjected to, presuming there is available both the tensile force Fl measurable at the first end 2' of the main girder 2 and the tensile force F2 measurable at the second end 2" of the main girder 2.
• the inputs to the measuring block M are the tensile forces Fl, F2 measured from the measuring members FM1, FM2.
• the measured tensile forces Fl, F2 are compared to each other.
• the tensile forces Fl and F2 may be added together, whereby the result is the sum Fsum of said forces, for which the value aimed at is zero.
• the sum of the tensile forces is zero, it would be an indication that the bridge crane 1 is moving straight.
• the measured tensile forces Fl, F2 it may also be deduced which of the ends 2', 2" of the main girder 2 of the bridge crane 1 is lagging behind the end moving further ahead and by how much.
• the adjusting system of Figure 7 further includes a control or adjustment block CO to control the speed of the bridge crane 1.
• the operator of the bridge crane 1 may choose a travelling speed for the bridge crane 1, used for a specific bridge crane 1 usage situation, from a limited number of preset standard travelling speeds.
• the set value VSET of the desired speed of the bridge crane 1 which then corresponds to the chosen travelling speed of the bridge crane 1 in each case, and which by default is the same for both ends 2', 2" of the main girder 2.
• the sum FSUM of the measured tensile forces described in the above, or alternatively the measured tensile forces Fl, F2 as such may be the second input to the control block CO.
• the control block CO determines, based on said inputs, such a first speed control signal Vco_io for the first travelling motor 10 moving the first end 2' of the main girder 2, and such a second speed control signal Vco_i3 for the second travelling motor 13 moving the second end 2" of the main girder 2, so that the travelling speed V 2 _2" of the first end 2' of the main girder 2 and the travelling speed V 2 _ 2 '' of the second end 2" of the main girder 2 make a bridge crane 1 that may be about to drift aslant to turn straight.
• the first speed control signal Vco_io and the second speed control signal Vco_i3 are typically equal, whereby the bridge crane 1 is moving substantially straight on its runway, and the measured tensile forces Fl, F2 measured at the ends 2', 2" of the main girder 2 are substantially zero or inconsequential.
• the travelling speed of the ends 2', 2" of the main girder 2 of the bridge crane 1 is controlled as an open control loop solution so that is it assumed that the first speed control signal Vco_io supplied to the travelling motor 10 moving the first end 2' of the main girder 2, and the second speed control signal Vco_i3 supplied to the travelling motor 13 moving the second end 2" of the main girder 2 produce, through the operation of the travelling motors 10, 13, the desired travelling speeds of the bridge crane 1 at the first end 2' and the second end 2" of the main girder 2.
• the control block CO determines on the basis of the set value VSET of the desired speed of the bridge crane 1, on the basis of the sum FSUM of the meas- ured tensile forces, or alternatively directly on the basis of the measured tensile forces Fl, F2, and on the basis of actual travelling speeds V 2 _ 2 ', V 2 _ 2 ' of the ends 2' of the main girder 2, the speed control signals Vco_io, Vco_i3 for the travelling motors 10, 13 so that the possible difference between the desired travelling speed of the ends 2', 2" of the main girder 2 of the bridge crane 1, indicated by the speed set value VSET, and the measured actual travelling speeds V 2 _ 2 ', V 2 _ 2 " approaches zero.
• a dedicated set value or reference value for the tensile force to be measured is not necessary, because the desired value for the force is, by default, zero.
• Figure 8 is a schematic view, in the form of a block diagram, of an adjustment system to control the travelling speed of a bridge crane 1 according to Figure 5, provided with a sliding joint 24 at the first end 2' of the main girder 2.
• the adjustment system according to Figure 8 includes a measurement block M to measure the tensile force F7 affecting the sliding joint 24 of the bridge crane 1.
• the adjusting system of Figure 8 further includes a control or adjustment block CO to control the speed of the bridge crane 1.
• a control or adjustment block CO to control the speed of the bridge crane 1.
• VSET the set value of the desired speed of the bridge crane 1
• the second input to the control block CO is the tensile force F7 measured in the above from the sliding joint 24 of the first end 2' of the main girder 2.
• the control block CO determines, based on said inputs, such a first speed control signal Vco_io for the first travelling motor 10 moving the first end 2' of the main girder 2, and such a second speed control signal Vco_i3 for the second travelling motor 13 moving the second end 2" of the main girder 2, so that the travelling speed V 2 _ 2 ' of the first end 2' of the main girder 2 and the travelling speed V 2 _2'' of the second end 2" of the main girder 2 make a bridge crane 1 that may be about to drift aslant to turn straight.
• the first speed control signal Vco_io and the second speed control signal Vco_i3 are typically equal, whereby the bridge crane 1 is moving substantially straight on its runway, and the measured tensile force F7 measured at the first end 2', 2" of the main girder 2, provided with the sliding joint, is substantially zero or inconsequential. So, a dedicated set value or reference value for the tensile force to be measured is not necessary, because the desired value for the force is, by default, zero.
• the travelling speed of the ends 2', 2" of the main girder 2 of the bridge crane 1 may be controlled as an open con- trol loop solution so that is it assumed that the first speed control signal Vco_io supplied to the travelling motor 10 moving the first end 2' of the main girder 2, and the second speed control signal Vco_i3 supplied to the travelling motor 13 moving the second end 2" of the main girder 2 produce, through the operation of the travelling motors 10, 13, the desired travelling speeds at the first end 2' and the second end 2" of the main girder 2.
• the control block CO determines on the basis of the set value VSET of the desired speed of the bridge crane 1, on the basis of the measured tensile force F7 and on the basis of the actual travelling speeds V 2 _ 2 ', V 2 _ 2 ' of the ends 2' of the main girder 2, speed control signals Vco_io, Vco_i3 for the travelling motors 10, 13 so that the possible difference between the desired travelling speed of the ends 2', 2" of the main girder 2 of the bridge crane 1, indicated by the speed set value VSET, and the measured actual travelling speeds V 2 _ 2 ', V 2 _ 2 " approaches zero.
• the functions shows in Figures 7 and 8 are implemented in the control unit 14 of the bridge crane 1, or controlled by it.
• One or more tensile forces are measured substantially continuously at such a sampling frequency that the driving aslant of the crane may be prevented.
• the speed control signals Vco_io, Vco_i3 are fed to the travelling motors 10, 13, or to control units arranged in connection with them, through control connections CLIO, CL13.
• the control or adjustment functions of the control block may be implemented in a plurality of ways.
• the con- trol block CO may include, for example, a P controller comprising a proportional part, only, or a PI controller comprising both a proportional part and an integrat- ing part, the operating principles of which are known per se to a person skilled in the art. Controller solutions of other types, too, are possible.
• the travelling motor of the end of the main girder 2, which is lagging behind may be controlled to speed up, and the control motor of the end of the main girder 2, which is leading, to slow down.
• the travelling motor of the end of the main girder 2, which is lagging behind may be controlled to speed up, and the travelling motor of the end of the main girder 2, which is leading, to maintain its current speed.
• the travelling motor of the end of the main girder 2, which is lagging behind may be controlled to maintain its current speed, and the travelling motor of the end of the main girder 2, which is leading, to slow down.
• Figures 9, 10 and 11 are schematic views of examples of situations of driving aslant a bridge crane and correcting the driving aslant.
• the top image shows the position of the ends 2', 2" of the main girder 2 of the bridge crane 1 on a runway formed by the rails 15, 16 in meters (position (m))
• the centre image shows the travelling speed V 2 _2', V 2 _ 2 " of the ends 2', 2" of the main girder 2 in metres per minute (speed (m/min))
• the bottom image the measurements by the strain gauge sensors at the ends 2', 2" of the main girder 2 as seconds of time (Time(s)).
• the bridge crane 1 has been deliberately driven aslant, which is indicated by the fact that the positions of the ends 2' 2" of the main girder 2 differ from each other at the beginning of the time axis.
• the bridge crane 1 has not had a load and a P- type controller has been used for control.
• the bridge crane 1 has not had a load and a Pi-type controller has been used for control.
• the bridge crane 1 has had a load of 1.2 tons and a Pi-type controller has been used for control.
• Figures 9, 10 and 11 show that in each situation of driving the bridge crane 1 aslant, it turns to move straight on its runway and the tensile forces go very near to zero or inconsequential.
• Figures 9 and 10 show that with a control solution provided with a PI controller, the driving aslant of a bridge crane 1 may be corrected to some extent faster than with a control solution provided with a P controller, only.
• Figure 11, for its part, shows that the swaying of a load causes tensile forces at the ends 2', 2" of the main girder 2, which may continuously be measured with strain gauge sensors. Despite of the load swaying, the driving aslant of the bridge crane 1 can be corrected, after which the bridge crane 1 moves straight on its runway all the time.
• Figures 12 and 13 show a further solution to detect the driving aslant of a bridge crane 1.
• the position of the end trolleys 8, 11 in relation to each other on the rails 15, 16 is examined.
• a distance sensor 27 which is emitting laser light has been arranged in the second end trolley 11 and which is adapted to point towards a reflector 28 installed on the first end trolley 8 at an angle of 45 degrees in rela- tion to the distance sensor 27.
• the beam of light 29 emitted by the distance sensor 27 points at the centre of the reflector 28.
• the distance between the distance sensor 27 and the reflector 28 which in Figure 12 corresponds to a situation in which the angle of driving aslant is zero, in other words, the bridge crane 1 is moving perfectly straight. If the bridge crane drifts aslant as in Figure 13, the point on the reflector 28, at which the beam of light 29 emitted by the distance sensor 27 meets the reflector 28, deviates from the centre point of the reflector 28. In such a case, the distance between the distance sensor 27 and the reflector 28 is also shorter or longer when compared to a situation in which the bridge crane 1 is travelling straight. The change in the distance is proportional to the angle of driving aslant.
• a position-sensitive photodetector may be used, measuring the position of the beam of light 29 in the lateral direction.
• the hoisting apparatus may also be a travelling gantry crane, in which case the end trolleys of the crane are arranged to move on rails installed on the floor of a building or on the ground, and at least one main girder of the gantry crane is raised up to a distance from the plane formed by the floor or ground, by substantially vertical frame structures formed between the ends of the main girder and the end trolleys.
• the solution set forth in the claims and the embodiments in the above may also be implemented on gantry cranes, as disclosed in the above.
• the hoisting apparatus arranged to move on rails may also be a hoisting unit arranged to move supported by at least two main girders of bridge or gantry cranes, at a distance from each other.
• the solution set forth in the claims and the embodiments in the above may also be implemented on hoisting units of the type referred to, as disclosed in the above, by placing measuring members of tensile force on, for example, supports 4' belonging to the frame structure of a trolley 4, to the connection of the supports 4' and the end trolley of the trolley 4 comprising the wheels 6 of the trolley 4, or to the axles of the wheels 6 of the trolley 4.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Automation & Control Theory (AREA)
• Machines For Laying And Maintaining Railways (AREA)
• Control And Safety Of Cranes (AREA)
• Carriers, Traveling Bodies, And Overhead Traveling Cranes (AREA)

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Cited By (4)

Citations (3)

• 2016
  • 2016-11-16 FI FI20165861A patent/FI20165861L/sv not_active Application Discontinuation
• 2017
  • 2017-11-16 WO PCT/FI2017/050789 patent/WO2018091782A1/en active Application Filing

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