Overview
AXRY bearings can be equipped with inductive angle measuring systems. These systems are available in incremental (MI) or absolute (MA) versions, as single- or multi-head systems with various accuracy grades.
By mounting the measuring ring directly onto the bearing ring, concentricity errors relative to the axis (table) are minimized, achieving the highest accuracies of a few arc seconds.
myonic supplies only the "mechanical part", i.e. the bearing including the mounted measuring ring and the threads in the outer ring for axial or radial scanning-head mounting.
Advantages
In cooperation with Heidenhain (AMO), myonic supplies bearing-integrated absolute and incremental angle measuring systems. The measuring ring is mounted directly onto the bearing. As standard, the measuring ring is mounted on the inner ring, since the inner ring is fitted to the shaft.
Thanks to myonic's extremely precise manufacturing tolerances, the seat surface on which the measuring ring is mounted runs almost perfectly concentric to the table center. This increases system accuracy and thus the overall accuracy of the axis. Because measurement is taken close to the workpiece, deviations caused by torsion or tilting are almost completely avoided.
AMO Measuring System Advantages
- Inductive system - No magnetic or optical components used
- High accuracy / high speed - Suitable for ultra-precision and high-speed applications
- Direct mounting - No separate bearing required (no additional friction/heat, maximum hollow shaft)
- No encapsulation required - Standard IP67 protection rating
- Resistant to electromagnetic interference - The measuring unit is non-magnetic and fully resistant to electromagnetic interference fields
Open System
myonic has developed a new generation of absolute measuring heads and has deliberately designed this development as an open system. All manufacturers and users can procure these systems directly from Heidenhain (AMO).
This guarantees unrestricted access to these systems for all users. When selecting the measuring head, there is no need to be tied to a single roller bearing manufacturer.
Measuring Accuracy
System Accuracy
The accuracy of the angle measuring device when fully assembled on the AXRY bearing alone.
Main influencing factors:
- Pitch accuracy of the measuring ring (±3 μm or ±5 μm)
- Eccentricity error of the measuring ring (1/2 of the inner ring radial runout)
- Interpolation error of the measuring head (IPF-AMO)
Total Accuracy
The accuracy of the angle measuring device when fully assembled on the machine axis.
Main influencing factors:
- Deformation of the axis (tilting, etc.)
- Form and dimensional deviations of the customer's axis and surrounding structure
- Installation errors
Practical application accuracy: The larger the bearing, the easier it is to achieve high system accuracy. Using multi-head solutions, accuracies of better than ±1 arc second have been achieved in real-world applications. The measuring heads are available for different input frequencies to meet both ultra-precision and high-speed application requirements.
Available Systems
The measuring systems can be installed on most axial-radial bearings of the AXRY-NGX / AXRY-NGS and AXRY-EX construction series.
Incremental Systems (MI)
- Single- and multi-head solutions
- Miniature measuring head with external electronics
- Or measuring head with integrated electronics
Absolute Systems (MA)
- Single- and multi-head solutions
- Modular measuring head
- Axial or radial mounting
- For radial mounting, the measuring head is mounted on the seat surface of the bearing outer ring, with no complex air-gap adjustment required
Note: Because the measuring ring height is 10 mm (incremental) or 14 mm (absolute), the overall height of small and medium-sized bearings increases. See the product tables for details.
Function: Incremental vs. Absolute Systems
The measuring ring permanently mounted on the bearing contains a measuring track and a reference track. The measuring track is the measuring body, onto which a high-precision periodic pitch is etched by photolithography. These scale marks or increments are counted by the measuring head as they pass, but the absolute position is unknown.
Incremental Systems
In incremental systems, the absolute position is obtained via distance coding on the reference track. By passing 2 adjacent reference marks, the system can determine the absolute position. The required angle depends on the size; it is typically less than 30°.
Absolute Systems
In absolute systems, a second absolute pitch division runs parallel to the incremental pitch division, continuously providing the control system with a constant absolute position.
| Characteristic | Incremental (MI) | Absolute (MA) |
|---|---|---|
| Encoding method | Incremental counting + distance-coded reference | Absolute position encoding |
| Position at power-up | Reference travel required (<30°) | Immediately known |
| Measuring ring height | 10 mm | 14 mm |
| Maximum accuracy | ±2 μm arc length | ±1 μm arc length |
Connection to Control System
myonic works closely with Heidenhain (AMO) on all measuring-system electronics. This enables efficient connection to a wide variety of control systems, cable outlets, cable lengths, threading, and so on. Prototype solutions can be implemented at short notice.
The best expertise on both the mechanical and electronic sides is available from a single source.
Delivery Condition
myonic supplies only the "mechanical part", i.e. the bearing including the mounted measuring ring and the threads in the outer ring for axial or radial scanning-head mounting.
Standard Configuration
- The bearing is ready for the installation of up to 2 measuring heads (mountable axially or radially on the outer ring)
- The required mounting threads are located in the outer ring (2 each for axial and radial)
Measuring Head Procurement
The measuring heads can be procured directly from Heidenhain (AMO).
Optional Configuration
If required, the bearing can be supplied prepared only for measuring-ring installation.