Angle measuring systems

• Angle measuring systems are primarily used in the NC units. Units with Hirth gearing do not require an angle measuring system; the precision of the position is achieved by means of the mechanical locking of the Hirth gearing, the angle measuring system is only used for pre-positioning.
• The types of angle measuring systems are categorized into direct or indirect, absolute or incremental systems.
• A direct angle measuring system is flanged directly to the rotary axis of the trunnion or the table and offers the highest degree of precision.
• Positioning precision of less than ± 1 seconds of arc is attained with the direct angle measuring system.
• An indirect angle measuring system is flanged to the free worm shaft end or the motor drive shaft. The reduction ratio from this type of design is taken into account arithmetically in the control of the faceplate position.
• Positioning precision of up to ± 10 seconds of arc is attained with indirect angle measuring systems.
• The repeatability of direct and indirect angle measuring systems is approximately 30% of the positioning accuracy.
• By design, an absolute angle measuring system recognizes its own set position. This is helpful when the faceplate position stored in the control system is lost through a loss of power.
• An incremental angle measuring system counts exponentially from a defined position called the reference point over a bar code. This bar code is proportional to the path covered by the rotation.
• The reference point is normally approached from the clockwise direction in a power-up condition. Clockwise rotation is defined by looking into the table faceplate.
• Standard reference point switch is 24 volt DC. The function N/O or N/C can be specified.