▶ Products : LM Guide >THK LM Guide > Actuator type KR > Types and Features

     The one-piece structure of the LM Guide, with highly rigid, U-shaped outer rails on both sides of the inner block
and the Ball Screw in the center of the inner block, provides high rigidity and excellent accuracy, and
requires minimal installation space. Ball trains are arranged at a contact angle of 45° in relation to one another
so that each train of balls bears an equal load rating on the inner block in all four directions: radial,
reverse-radial, and the two lateral directions. Thus, this type can be used in any installation direction.

▶ Model-Number Coding

▶ Load Rating and Permissible Moment in Various Directions

Load rating

●LM Guide
 Type KR can bear loads in all four directions: radial, reverse-radial, and the two lateral directions. The basic load ratings
of type KR are equivalent to one another in all four directions (radial, reverse-radial, and the two lateral directions).
The values are given in Table 2.

●Ball Screw
 Because of the construction that Ball Screw is driven through the inner block, type KR can bear an axial load.
The values of basic load rating are presented in Table 2.

●Support Bearing

 Due to its construction, in which an angular bearing is assembled in housing A, type KR can bear an axial load.
The values for the basic load rating are given in Table 2.

Table 2 Load Rating

Unit : N

             Notes:

 

        The load rating of the LM Guide is the value per inner block.

        The balls in the precision-grade Ball Screw (grade P) include spacer balls at a ratio of 1:1
        for models KR33 and KR 4610, and 2:1 for models KR4620, KR55, and KR65.

▶Permissible moment (LM Guide)

       The LM Guide of type KR can bear loads in all four directions with a single inner block. Table 3 gives the values for the
    static permissible loads in directions M_A, MM_B, and M_C.

Note:

The values for types KR-B and D are those for two inner blocks used closely liked together.

▶ Accuracy Standards

The accuracy of type KR comprises positioning-accuracy reproducibility, positioning accuracy, backlash, and running parallelism.

1. Positioning-Accuracy Reproducibility

    Move the inner block from a starting point and stop it at a given point, measuring the stopped position.
Repeat this measurement in the same direction as above seven times each in the middle of the stroke and at both ends.
Take the maximum values at each stopping position as the measurements being sought.
Divide the maximum difference among these maximum values by 2. Define the value thus obtained as the positioning-accuracy reproducibility, attaching "±" thereto.

2. Positioning Accuracy

   Using the maximum stroke as the reference length, measure the distance actually traveled from the reference position,
and determine the maximum difference between a measurement and target value.
Express the positioning accuracy using the absolute value of this maximum difference.

3. Backlash

Using the feeder, move the inner block slightly. Define the reading of the test indicator at this time as the reference position.
Without using the feeder, apply a load to the inner block in order to move it from this reference position in the same direction
as above (table-feeding direction). Release the load and allow the inner block to return. Measure the distance
between the returned-block position and the reference position.

Measure the same in the middle of the stroke and at both ends. Take the maximum of the measurements thus obtained
as the backlash.

4.. Running parallelism

Place a straight edge on a surface plate to which a unit of type KR is mounted. Using a test indicator, measure the parallelism
over the entire inner-block stroke. Take the maximum of the measurements within the stroke as the parallelism.

※ The accuracy of type KR is divided into three grades: normal (no symbol), high (H), and precision (P).
The standards for these grades are as specified below.
 

   The evaluation methods for accuracy grades must conform to THK Standards.
The starting torque must be measured with lithium soap-based grease No. 2 sealed in.
For models KR20 and 26, however, the grease to be sealed in must be AFA Grease.

▶ contamination protection

Cover and bellows (optional)

For type KR, we can provide contamination protection parts such as a dedicated cover and bellows.

 Cover

Bellows

Note: The bellows length can be obtained using the calculation shown below.

• With the aid of an intermediate plate available from us, grease can be fed through the grease nipple
  without removing the bellows. If you require an intermediate plate, please contact us.
• In installation directions other than horizontal (e.g., vertical and wall-hung), the expansion ratio differs.
  If you are using such an installation direction, please contact us.

▶ Bellows Dimension Table

• Block-A type

• Block-B type

• Block-C type

• Block-D type

▶ Precautions on Use

Maximum running velocity and production-limit length

The maximum running velocity of type KR is restricted by the Ball Screw critical speed and DN value,
regardless of the motor maximum speed. Keep this in mind when using this type, particularly at high speed.
The production-limit length is expressed as the outer-rail length.

▶ Sensor

Sensor (optional) Optional sensors available for type KR include proximity sensors and photosensors.
Products with sensors come with the dedicated sensor rail and sensor dog.

▶ XY Bracket

The brackets required to mount LM Guide Actuator type KR have been standardized. Made of aluminum, the brackets are
lightweight in order to minimize inertia.

          Sample Combination