self-contained resolvers are used for servomotors as a position feedback system for cantilevers

Blast Hole Drilling Machine

Blast Hole Drilling Machine

Self-contained resolvers control servo motor speeds and are also used as position feedback systems for booms. The resolver returns the exact angular position, e.g. on mobile cranes or mining drills.

Detailed application description

Description of problem:

Tunnel excavation with explosives requires the explosive charges to be placed into blast holes. After the blast, the exact tunnel contour should preferably already exist so that later rework is unnecessary/minimised. Nowadays, blast holes are arranged with centimetre accuracy by blast hole drilling machines with several booms (drills). Owing to the extreme conditions during tunnelling – dust, water, hydraulic oil and in particular severe vibration and shocks – conventional incremental encoders fail after only a short time. Resolvers, on the other hand, offer the required robustness and can help operators stay within a tight budget. Resolvers tend to be mounted in relatively exposed positions due to the overhanging geometry of the machines and because repairs demand easy access. The mechanical strength and tolerance requirements are accordingly higher.

Description of solution:

Robustness and maximum availability, leading to the minimum possible machine and drive downtime, are crucially important – and not only in mining. LTN provides self-contained resolvers enclosed in a housing for additional protection against mechanical or environmental influences. Featuring variable sizes and housing designs, these resolvers achieve protection classes up to IP68 and are capable of withstanding vibration up to 50 G or shocks up to 100 G. By selecting suitable housing geometries, cable guides and connectors can be attached to ensure that signal transmission likewise meets the stringent demands. Special, electroplated enclosure coatings simultaneously protect the system against aggressive agents such as hydraulic oils, salt water or potassium hydroxide solutions.

Thanks to these self-contained and enclosed resolver systems, the drill feeds of tunnelling machines can position their holes with centimetre precision and in doing so help contractors observe budget and time constraints.

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