Page 310 - needle bearings

Linear flat rollers
NTN

Linear Flat Rollers

Linear Flat Rollers How to mount
This bearing type composed of a needle roller and flat Theoretically the linear flat roller bearing moves by 1/2
cage assembly (needle rollers are configured in the flat of table moving stroke in same direction as the table
cage) ensures smooth reciprocating motion with less moving direction. The relationship of bed length (L) -
friction coefficient. stroke (S) - cage length (L1) can be expressed in formula
(1). (Fig. 2)
Types
LʹS 2 L ʜʜʜʜʜʜʜʜʜʜʜʜʜʜʜʜʢ1ʣ
For Type FF, the polyamide resin cage has a dovetail
joint groove on its both ends so that several cages can be
jointed together into one unit.
For Type FFʝʝZW, two rows of needle rollers are
L1 S
configured in the cage and the cage has an elastic joint
on its center so as to enable to bend two rows of flat
rollers to any optional angle at the elastic joint by heating
them in oil of 70 to 90˚C. The two roller rows bent to any
optional angle can hold the bent shape unchanged, even
under normal operating temperature, by being cooled S/2
L
down for several seconds, with the bending angle held
unchanged.
Fig. 2
For Type BF, the cage is press-formed from steel plate
and the standard length of the bearing unit is 1000 mm.
For Type RF, the cage is of polyamide resin and the The linear flat roller bearing results in moving deviation
standard length of the bearing unit is 705 mm. The both due to profile deviation of raceway surface, uneven load
are unavailable for cage to cage inter-jointing, but a or vibration. Therefore, the table or the bed must be
bearing unit of any desired length is offerable upon equipped with a stopper at its end portion to prevent over-
request. Feel free to contact NTN for the detailed run of the flat roller bearing. (Fig. 5)
information. Figs. 3 and 4 illustrate application examples of the
linear flat roller bearing unit.
Needle roller tolerance
The needle rollers contained in the flat roller cage are
manufactured within the dimensional tolerance range of 0
to -2 mm against the nominal diameter (Dw).

Raceway surface requirements
Table 1 shows the requirements for raceway surface
applied to the linear flat roller bearings.

Table 1 Raceway surface requirements Fig. 3 General application
Characteristics Tolerance
Surface roughness (max) 0.2a
Surface hardness 1 HRC58ʙ64
Effective hardened layer depth (min) 0.4mm
Mounting accuracy (max) 2 0.1 mm per 1000 mm
1 Where raceway surface hardening not allowed, a quenched spring plate
ɹ may be used.
2 Mounting accuracy is expressed with an inclination value in Fig. 1.

Fig. 4 When overhung load acts on

Inclination
Fig. 1

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