SNR_SNS by jlhd32

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									                                                                                                   500-5E0




    SNR/SNS
    Ultra-heavy Load Type for Machine Tools Model SNR/SNS

    Caged Ball LM Guides - Ultra-heavy Load Type for Machine Tools Model SNR/SNS

    Caged Ball LM Guide
    Ultra-heavy Load Type for Machine Tools Model SNR/SNS
0




                                                                                         90
                                                                                             °
                              LM block




                                                                                             °
                                                                                         40
                Endplate
                                                                     Radial Type Model SNR
                                                                          Cross section




                                                                                             50°
               End seal


                 LM rail




                                                                                         °
                                                                                         40
                                                     Ball cage

                                            Ball                     4-Way Type Model SNS
                                                                         Cross section


* For the ball cage, see A1-106.


Structure and Features                                                 A1-125

Types and Features                                                     A1-126

Rated Loads in All Directions                                          A1-129

Equivalent Load                                                        A1-129

Service Life                                                            A1-76

Radial Clearance Standard                                               A1-89

Accuracy Standards                                                      A1-95

Shoulder Height of the Mounting Base and the Corner Radius             A1-309

Error Allowance in the Parallelism between Two Rails A1-315/A1-316
Error Allowance in Vertical Level between Two Rails A1-318/A1-319
Dimensional Drawing, Dimensional Table, Example of Model Number Coding  B1-26
Standard Length and Maximum Length of the LM Rail  B1-42


A1-124
                                                                                                                               500-5E0

                                                                                              Features of Each Model
                                                           Ultra-heavy Load Type for Machine Tools Model SNR/SNS


Structure and Features
Balls roll in four precision ground raceways on the LM rail and LM block, and ball cages and end-
plates incorporated in the LM block allow the balls to circulate. Use of the ball cage eliminates friction
between balls and increases grease retention, thus to achieve low noise, high speed and long-term
maintenance-free operation.




                                                                                                                                    LM Guide
The raceways are ground into deep grooves that have a radius closer to that of the balls than in the
conventional design, using special equipment and an extremely precise cutting technique.This
design allows high rigidity, high vibration/impact resistance and high damping capacity, all of which
are required for machine tools, thus making these models capable of bearing ultra-heavy loads.
* Due to the extremely high rigidity of the LM guides used in SNR/SNS models, the construction is highly tolerant of the effects
  of mounting face misalignment and installation errors. Where such effects arise, there is a risk of reduced operating life and/
  or malfunction. Contact THK when considering the use of these products.
[Improved Damping Capacity]
While the machine tool (equipped with NR or NRS) is not cutting a workpiece during operation, the
LM Guide travels normally and smoothly. While the machine tool is cutting the workpiece, the cutting
force is applied to the LM Guide to increase and the contact area between the balls and the raceway,
allowing an appropriate mixture of rolling and sliding motions to be achieved. Accordingly, the friction
resistance is increased and the damping capacity is improved.
Since the differential slip during the rolling and sliding motion is insignificant, it causes little wear and
does not affect the service life.
[Highly Rational LM Guide]
The excessively large differential slip occurring in a Gothic-arch groove does not happen with these
models. They smoothly travel and achieve high positioning accuracy during fast feeding.During the
cutting operation, appropriate slip occurs according to the cutting load, the rolling resistance is
increased and the damping capacity is increased. Thus, models NR and NRS are highly rational LM
Guides.
[High Rigidity]
To improve the rigidity of the LM block and the LM rail, which may have reduced overall rigidity of the
LM Guide in the reverse radial and lateral directions, THK made full use of FEM to achieve optimal
design within the limited dimensional range.
Since THK provides two identically sized models with different characteristics, namely the radial
model SNR and four-way model SNS, users can select the model that best suits their specifications.
[Ultra-heavy Load]
Since the curvature of the raceway is approximated to the ball diameter, the ball contact area under
a load is increased and the LM Guide is capable of receiving an ultra-heavy load.




                                                                                                                      A1-125
                                                                                   500-5E0




Types and Features

Models SNR-R/SNS-R                                 Specification Table   B1-26/B1-28
With this type, the LM block has a smaller width
(W) and tapped holes.
Used in places where the space for table width
is limited.




Models SNR-C/SNS-C                                 Specification Table   B1-30/B1-32
The flange of the LM block has tapped holes.
Can be mounted from the top or the bottom.
Can also be used in places where the table can-
not have through holes for mounting bolts.




Models SNR-RH/SNS-RH (Build to Order) Specification Table                B1-34/B1-36
The dimensions are almost the same as that of
LM Guide models SHS and HSR, and the LM
block has tapped holes.




A1-126
                                                                                                500-5E0

                                                                       Features of Each Model
                                             Ultra-heavy Load Type for Machine Tools Model SNR/SNS




Models SNR-CH/SNS-CH (Build to Order) Specification Table                           B1-38/B1-40
The dimensions are similar to that of LM Guide
models SHS and HSR, and the flange of the LM
block has tapped holes.




                                                                                                     LM Guide
Models SNR-LR/SNS-LR                                          Specification Table   B1-26/B1-28
The LM block has the same cross-sectional
shape as models SNR-R/SNS-R, but has a
longer overall LM block length (L) and a greater
rated load.




Models SNR-LC/SNS-LC                                          Specification Table   B1-30/B1-32
The LM block has the same cross-sectional
shape as models SNR-C/SNS-C, but has a
longer overall LM block length (L) and a greater
rated load.




                                                                                         A1-127
                                                                        500-5E0




Models SNR-LRH/SNS-LRH (Build to Order) Specification Table   B1-34/B1-36
The LM block has the same cross-sectional
shape as models SNR-RH/SNS-RH, but has a
longer overall LM block length (L) and a greater
rated load.




Models SNR-LCH/SNS-LCH (Build to Order) Specification Table   B1-38/B1-40
The LM block has the same cross-sectional
shape as models SNR-CH/SNS-CH, but has a
longer overall LM block length (L) and a greater
rated load.




A1-128
                                                                                                                              500-5E0

                                                                                        Features of Each Model
                                                       Ultra-heavy Load Type for Machine Tools Model SNR/SNS


Rated Loads in All Directions
Model SNR/SNS is capable of receiving loads in
four directions: radial, reverse radial and lateral                                  CL      C
directions. Their basic dynamic load ratings are                                PL   C0L     C0     PR
represented by the symbols in the radial direc-                       CT                                       CT
                                                                      C0T                                      C0T




                                                                                                                                 LM Guide
tion indicated in Fig.1, and the actual values are
provided in the specification tables for SNR/                         PT                                   PT
SNS. The values in the reverse radial and lat-
eral directions are obtained from Table1 and
                                                                                        Fig.1
Table2 below.


 Table1 Basic Load Ratings of Model SNR in All Directions     Table2 Basic Load Ratings of Model SNS in All Directions
                                       SNR                                                               SNS
       Direction           Basic dynamic    Basic static            Direction           Basic dynamic          Basic static
                            load rating     load rating                                  load rating           load rating
    Radial direction           C                C0               Radial direction             C                C0
Reverse radial direction    CL=0.64C        C0L=0.64C0       Reverse radial direction      CL=0.84C        C0L=0.84C0
   Lateral directions       CT=0.47C        C0T=0.38C0          Lateral directions         CT=0.84C        C0T=0.84C0



Equivalent Load
When the LM block of model SNR receives a reverse radial load and a lateral load simultaneously,
the equivalent load is obtained from the equation below.
                                                                      Table3 Equivalent Factor of Model SNR
     PE      X•PL Y•PT                                                   PE                        X                  Y
     PE   : Equivalent load                   (N)            Equivalent load in reverse
                                                                                                   1              1.678
            : Reverse radial direction                            radial direction
                                                             Equivalent load in lateral
            : Lateral direction                                      direction
                                                                                                0.596                 1
     PL   : Reverse radial load               (N)
     PT   : Lateral load                      (N)
     X, Y : Equivalent factor        (see Table3)

When the LM block of model SNS receives a radial load and a lateral load, or a reverse radial load
and a lateral load, simultaneously, the equivalent load is obtained from the equation below.
                                                                      Table4 Equivalent Factor of Model SNS
     PE      X•PR (PL) Y•PT                                          (When radial and lateral loads are applied)
     PE   : Equivalent load                  (N)                         PE                        X                  Y
            : Radial direction                                 Equivalent load in the
                                                                                                   1              0.935
                                                                  radial direction
            : Reverse radial direction                        Equivalent load in lateral
            : Lateral direction                                                                   1.07                1
                                                                     direction
     PR : Radial load                        (N)
                                                                     Table5 Equivalent Factor of Model SNS
     PL   : Reverse radial load              (N)               (When reverse radial load and lateral load are applied)
     PT   : Lateral load                     (N)
                                                                         PE                        X                  Y
     X, Y : Equivalent factor                                Equivalent load in reverse
                                                                                                   1                 1.02
                         (see Table4 and Table5)                  radial direction
                                                             Equivalent load in lateral
                                                                                                0.986                 1
                                                                     direction


                                                                                                                     A1-129
                                                             500-5E0




Service Life
For details,see A1-76.

Radial Clearance Standard
For details,see A1-89.

Accuracy Standards
For details,see A1-95.

Shoulder Height of the Mounting Base and the Corner Radius
For details,see A1-309.

Error Allowance in the Parallelism between Two Rails
For details, A1-315 and A1-316.

Error Allowance in Vertical Level between Two Rails
For details, A1-318 and A1-319.




A1-130
                                                   500-5E0

                          Features of Each Model
Ultra-heavy Load Type for Machine Tools Model SNR/SNS




                                                        LM Guide




                                            A1-131

								
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