Abstract: For a compact shield segment erector translation agency structure, flexible operation and high reliability, designed an easy to install, and has a good sealing performance roller bearings ; detailing the structural characteristics of the bearing and lubrication, sealing performance .
Keywords : roller bearings ; Shield ; translation agencies
Segment erector is an important part of the shield device , installed in the tail shield, is a dedicated device assembling pieces of concrete tunnel wall , lining the job. Its main function is to shield tunneling devices with the continuous , stable , fast and accurately precast concrete tunnel wall pieces assembled as required in the excavation of the tunnel wall around [1 ] , the formation of the lining to support just excavation of the tunnel surface , which directly affects the quality of assembly groundwater infiltration and surface subsidence . Segment erector translation agencies responsible for implementing the concrete wall piece in the tunneling direction forward and backward movements, requires its rotating flexible , stable , precise guidance .
An installation location
1, intermediate between the two beams along the axial direction of the shield and the shield is fixed parallel to the cantilever mounted housing , respectively, the left and right ends of the intermediate beam 2 fixed to the cantilever in order to increase stiffness of the structure [ 2 ] . Cross roller mounted on the fixed bearing plate as a support body of the translation mechanism in the cantilever beam , the lower surface of the roll while in contact with the side surface of the track. Roller bearings on the one hand to support translational mechanism moves along the tunneling direction on the track ; hand as a guide , control pan mechanism moves on both sides of the rail , in order to achieve segment erector shield forward direction along the translational and orientation.

2 Structure
Roller bearings in the translation mechanism is necessary to bear the weight of the work and the impact mechanism , while also giving a guide mechanism when moved in the direction of tunneling , i.e., the need to withstand the load bearing direction and two in the two directions to achieve the rotation . The cross roller bearing is constituted by two axes intersect at large , small roller bearings consists of a 90 ° bearing ( Figure 2 ) . Cylindrical roller bearings mounted on a large surface of the shaft seat , mainly used to bear the weight of translational mechanism and impact loads, double row full complement cylindrical roller wheel bearings. Small U -shaped groove roller bearing shaft seat is located within the outer assembly is mounted on the shaft seat interspersed mandrel guide for implementing agencies on both sides of pan , four -row full complement cylindrical roller wheel bearings. Meanwhile, in order to facilitate the installation, the mounting flange and shaft seat design as a whole , and ultimately the formation of a built-in mounting flange cross roller bearings .

Large roller bearing type of bearing design and generally , it is only by the force of the outer ring 1 or 2 in the angular position in the work process , in addition to the regular occurrence of deformation of the bearing contact with the same , but there is still the outer ( or even the entire bearing) bending. The bearing force , the bearing outer ring due to bending deformation caused by the load distribution is changed , so that the carrying capacity is reduced. Therefore, ensuring the basic premise of the rated load , the bearing for maximum resistance to bending deformation, i.e., to obtain a thickness of the outer wall thickness of the roller bearing is an important feature of the design . Play a guiding role in the small roller bearings smaller force to ensure the accuracy of the design guide points .
Through the entire bearing shaft flange mounted on the seat pan mechanism of shield segment erector . Flange shaft seat and opened a number of sink holes threaded holes for the installation and positioning of the bearing . Mounting surface of the shaft seat has a circular groove digging , while reducing the weight bearing ; hand reduces the processing area of ​​the mounting surface , reducing the processing difficulty , shown in Figure 3 . Cylindrical surface of the shaft seat and large roller bearing inner ring fitted , as well as two of the cylindrical surface of the cylindrical bore for interspersed mandrel ; another seat opened transverse axis screw holes for connecting door.

Mandrel shaft seat interspersed with small roller bearings with external components . Both ends of the arc-shaped mandrel , which is consistent with the curvature radius of curvature of the cylindrical shaft housing to the large roller bearing inner ring with the installation . Two circular arc direction along the end face of the mandrel to facilitate the processing tank shaft seat has an arc -shaped oil tank through ; and its internal and external circular hole tank connected to the end face , in order to ensure smooth entry into the small oil roller bearings inside . Figure 4 shows the structure of the mandrel .

Currently the mounting flange and the shaft seat on the shield machine translation of foreign bodies is widely used in the separation of the bearings , and bearing guide cylinder is mounted by a pivot movement of the shaft seat on the side of the cantilever to complete . But the existence of the bearing structure of the following disadvantages: (1 ) needs to be installed in a shaft holder integrally welded mounting flange , difficult to install and remove inconvenient ; difficult ( 2 ) of the guide face of the processing cylinder accuracy is poor, greater friction , smooth motion is not enough to guide precision is also affected.
3 lubrication and sealing
Transverse axis circular groove seat has two countersunk screw holes for mounting the oil bearing grease cup , screw holes opened towards the end of the cylindrical surface of the circular groove hole. Arc injected into a large tank of oil on the one hand its internal roller bearings lubricated by a large roller bearing inner hole on the other hand into the interior of the small roller bearings for lubrication on the mandrel through the hole .
As shown in Figure 5, the big wheel bearing inner ring and the outer diameter surface of the outer diameter surface of the door there are processing tank, tank installation O -ring . O -ring in contact with a large roller bearing outer wall , forming a contact seal to prevent oil outflow . Collar connected via screw shaft seat, wheel bearing wall acts as a big , big wheel bearings from the shaft to prevent the seat off.

Small roller bearing retainer is stepped thin-walled structures . On the one hand the formation of small roller bearings with labyrinth seals stepped outer wall , to prevent small roller bearing lubricant outflow ; hand it is located between the seat and the small shaft roller bearings , roller bearings for positioning small , reducing its rocky ledge , thus ensuring segment erector movement smooth and precise.
4 Conclusion
( 1 ) shield segment erector translation agencies roller bearings mounting flange and shaft seat will be made whole, to overcome the shortcomings of the current foreign welding required to install this type of bearing , to achieve repeated removal and installation of bearings , the structure is more reasonable , compact, and improves the overall strength.
( 2 ) The bearing is mounted on the spindle bearings on both sides of the small roller guided translation agencies , reducing the friction torque , improve their flexibility and guide precision turning .
( 3 ) Design of a novel arrangement of the hole , which can provide lubrication for the large and small roller bearings, bearing reliability and improved maintainability .