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EP-4737845-A2 - SLEW BEARING WITH LOAD MONITORING

EP4737845A2EP 4737845 A2EP4737845 A2EP 4737845A2EP-4737845-A2

Abstract

A slew bearing for rotatably supporting an object on a base about a slew axis. The slew bearing comprises a stationary ring and a rotary ring part. The stationary ring part is provided with a stationary raceway member forming a stationary raceway surface oriented substantially perpendicular to the slew axis. The rotary ring part is provided with a rotary raceway member forming a rotary raceway surface. Rolling elements are provided between the stationary raceway surface and the rotary raceway surface. The slew bearing further comprises an elastically compressible resilient insert sandwiched either between the rotary raceway member and the rotary ring part or between the stationary ring part and the stationary raceway member. The slew bearing further comprises an axial load sensor for monitoring an axial load on the slew bearing by measuring a distance over the resilient insert.

Inventors

  • ROMEIJN, ERIC

Assignees

  • Itrec B.V.

Dates

Publication Date
20260506
Application Date
20230725

Claims (15)

  1. Assembly for supporting an object, e.g. a pile gripper, on a rail whilst the object moves along the rail, wherein the assembly comprises a load bearing housing for carrying the object, wherein the assembly comprises an endless chain of rolling elements, which are arranged for recirculating along a closed path around a raceway member (34) and a central body (35) of the assembly which central body (35) is attached to or integral with the load bearing housing, the path including: - a work portion defined by a flat load bearing surface of the raceway member of the assembly, in which work portion an operative set of the rolling elements engages the rail, and - a return portion defined by a return surface of the central body of the assembly in which a remaining set of the rolling elements is free from the rail, e.g. the return portion having a section which is parallel to the work portion, wherein the assembly comprises an elastically compressible resilient insert (38), e.g. containing a plastic material, which resilient insert (38) is sandwiched between the central body (35) and the raceway member (34) above the work portion, so that the central body (35) is resiliently supported on the operative set of the rolling elements via the resilient insert (38) and the raceway member (34), wherein the assembly further comprises a load sensor (40) for monitoring a load on the assembly by measuring a distance between the central body (35) and the raceway member (34) through the resilient insert (38), wherein the load sensor (40) is provided in the central body (35), e.g. opposite the raceway member (34) relative to the resilient insert (35), preferably wherein the resilient insert (38) is made of a composite material, e.g. a fiber reinforced plastic material.
  2. Assembly according to claim 1, wherein the raceway member and/or the resilient insert are each embodied in the form of a plate, preferably wherein the raceway member has a smaller thickness than the raceway member, e.g. corresponding to around 55 - 65% of a thickness of the raceway member.
  3. Assembly according to one or more of the preceding claims, wherein the central body comprises a recess inside which the resilient insert and the raceway element are contained and axially enclosed, e.g. such that the raceway element is flush with the longitudinally adjacent return surface of the central body.
  4. Assembly according to one or more of the preceding claims, wherein at a front and rear side of the load bearing surface, the return surface runs upwardly directly from the load bearing surface, preferably wherein a frontmost and/or rearmost section of the raceway member slants slightly upwards towards the return surface.
  5. Assembly according to one or more of the preceding claims, wherein the assembly further comprises a second endless chain of linear recirculating rolling elements, arranged for recirculating along a second closed path defined by the assembly, the two paths being laterally juxtaposed and parallel to one another, the second path including a work portion that is defined by a second load bearing surface of a second raceway member and in which an operative set of the rolling elements engages the rail, and a return portion that is defined by a second return surface of the central body and in which a remaining set of the rolling elements is free from the rail, wherein the central body is resiliently supported on the respective operative portions of the rolling elements of both endless chains via the respective raceway members, a elastically compressible resilient slide ring, e.g. containing a plastic material, being sandwiched between the central body and the second raceway member.
  6. Assembly according to one or more of the preceding claims, wherein the housing is provided, at least around the work portion of the recirculating rolling elements, with one or more seals, e.g. between one or more bottom surfaces of the assembly, e.g. bottom surfaces of walls of the assembly, which together axially enclose the work portion, and the upper surface of the rail, wherein the seals, e.g. together with the walls, define between the load bearing surface and the upper surface of the rail a grease chamber for the operative set of the recirculating rolling elements, e.g. wherein the seals are in a cross-section thereof substantially V-shaped.
  7. Assembly according to one or more of the preceding claims, wherein the housing comprises a front and rear vertical end wall which extend laterally respectively at the front and rear side of the assembly, and a front and rear guide wall which are attached to respectively the front and rear end wall and define respectively a front and rear section of the return portion of the closed path opposite the return surface, e.g. wherein the attachment is established via one or more elongate mounting elements, e.g. one or more bolts, screws or similar, which extend perpendicularly through the end walls and longitudinally protrude into the guide walls.
  8. Assembly according to one or more of the preceding claims, wherein the housing comprises a second front guide wall and a second rear guide wall, which are attached to respectively the front and rear end wall and define respectively a front and rear section of the return portion of the second closed path opposite the second return surface.
  9. Assembly according to one or more of the preceding claims, wherein the housing further comprises a front and/or rear frame which protrude respectively from the front and/or rear end wall in a frontward and/or rearward direction, wherein the front and/or rear scraper is mounted underneath the respective frame at a longitudinal end thereof.
  10. Assembly according to one or more of the preceding claims, wherein the rolling elements each rotate around a respective roller axis of which head ends run over respective treads formed by vertical protrusions from the central body extending longitudinally along the closed path at respective lateral sides of the closed path.
  11. Assembly according to one or more of the preceding claims, wherein the assembly further comprises left upper and lower and right upper and lower longitudinal wall parts which form upper and lower vertical protrusions from the central body at the left and right ends thereof, and which extend longitudinally over at a least length of the closed path, e.g. wherein the left upper and lower longitudinal wall parts are interconnected, and the right upper and lower longitudinal wall parts are interconnected, via one or more elongate mounting elements, e.g. one or more bolts, screws or similar, which vertically extend inside the respective upper and lower longitudinal wall parts and through the respective lateral end of the central body, e.g. multiple elongate mounting elements being distributed longitudinally along the wall parts.
  12. Assembly according to one or more of the preceding claims, wherein the assembly further comprises intermediate upper and lower longitudinal wall parts which form upper and lower vertical protrusions from the central body in between the two closed paths, and which extend longitudinally over at least a length of the closed path, e.g. wherein the intermediate upper and lower longitudinal wall parts are interconnected via one or more elongate mounting elements, e.g. one or more bolts, screws or similar, which vertically extend inside the respective upper and lower longitudinal wall parts and through a central part of the central body, e.g. multiple elongate mounting elements being distributed longitudinally along the wall parts, preferably wherein the longitudinal wall parts are connected to the end walls via one or more elongate mounting elements which extend perpendicularly through the end walls and longitudinally protrude into the longitudinal wall parts.
  13. Assembly according to one or more of the preceding claims, wherein the assembly comprises multiple load sensors for monitoring a load on the assembly by measuring a distance between the central body and the raceway member, wherein the multiple axial load sensors are distributed on the central body.
  14. Method for supporting an object, e.g. a pile gripper on a rail whilst the object moves along the rail wherein use is made of the assembly according to one or more of the claims 1 - 13.
  15. Method according to claim 14, wherein the method comprises: - monitoring a load on the resilient insert using the load sensor by measuring a local compression on the resilient insert by measuring the distance between the central body and the raceway member through the resilient insert.

Description

The invention relates to a slew bearing for rotatably supporting an object on a base about a slew axis. For example, the slew bearing supports a crane or a crane part. The slew bearing could also support an excavator, e.g. a backhoe dredger. The base can, for example, be embodied as a tub, a column, or a pedestal. The invention further relates to a crane or backhoe dredger provided with the slew bearing, a vessel comprising the crane or backhoe dredger, and to a method for hoisting an object with the crane on the vessel. For example, WO2008088213A2 describes a hoisting crane comprising a vertical column, a jib, and a jib connection member to which the jib is connected pivotably. The crane further comprises a slew bearing extending around the column and carrying the jib connection member rotatable about the column. For example, in WO2019027325A1 the slew bearing comprises an elastically compressible resilient insert containing a plastic material, which insert is sandwiched between the rotary raceway member and the rotary ring part, so that the rotary ring part is resiliently supported on the rollers of the slew bearing via the rotary raceway member and the resilient insert. Axial load components on the slew bearing arise from the weight of the crane or crane part, and loads applied to the crane when performing a hoisting operation. When performing a hoisting operation, not only axial load components arise, but also radial load components and momentum loads. When hoisting a load with a slewable hoisting crane, e.g. the crane of WO2008088213A2 or WO2019027325A1, the heavy load is supported by the crane offset from the center of the slew bearing and that causes the slew bearing to experience axial, radial, and momentum loads which are unevenly distributed over the slew bearing. During slewing of the crane, e.g. with the load to be lifted suspended from the crane, the load distribution on the slew bearing also moves along with the slew motion. Systems are known to monitor load(s) acting on a slew bearing. For example, EP1528356B discloses a slew bearing and a monitoring apparatus for monitoring the slew bearing. The monitoring apparatus comprises sensors for detecting relative movements of the bearing rings with respect to each other. In particular, the tilting of the bearing rings can be monitored or determined on the basis of determined radial and axial movements. The sensors are non-contact displacement sensors which may be aligned radially and scan peripheral surfaces of the bearing rings, with the two sensors being arranged inside a bearing ring with the head of the sensors arranged in the sealed bearing gap of the slew bearing. A downside of known slew bearings and accompanying monitoring solutions is that they are susceptible to breaking or malfunctioning during use. For example, the system of EP1528356B performs the measurements using non-contact displacement sensors provided in one bearing ring to measure through the bearing gap to the other bearing ring. In practice, the bearing gap is partly filled with oil, grease and/or other products (e.g. contaminants from outside and/or (metallic) particles due to wear) which may prevent the sensors from functioning properly. It is an object of the invention to provide an improved slew bearing. It is a further object of the invention to provide a slew bearing that allows for an improved monitoring of load on the slew bearing. It is a further object of the invention to provide an alternative slew bearing. The invention provides a slew bearing according to claim 1. The slew bearing is configured for rotatably supporting an object on a base about a slew axis. For example, the object is a crane or a part of a crane, e.g. a crane boom or jib. For example, the base may be mounted on the hull of a vessel so that the slew bearing may be used to support a crane on a vessel for use in offshore operations. The base may further be provided on the shore, e.g. on a vehicle or on the ground, for supporting a crane, via the slew bearing, for onshore operations. The base, preferably, is a circular base having similar circular dimensions to the slew bearing. The slew bearing, for example, may have an inner diameter of more than 5 meters, e.g. more than 10 meters, e.g. more than 15 meters, e.g. more than 20 meters. The slew bearing comprises: a stationary ring part connected or connectable to the base, anda rotary ring part connected or connectable to the object which is rotatable around the slew axis. The stationary ring part is configured to remain stationary relative to the base to which the stationary ring part is connected or connectable. The rotary ring part is configured to be rotatably relative to the base to which the stationary ring part is connected or connectable. Thus the rotary ring part is configured to rotate relative to the stationary ring part, for example to allow a crane, supported by the rotary ring part, to be rotatable, around the slew axis. In practical embo