Internal Machining of Hydraulic Cylinders with High Pressure Cooling Lubricants

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ECOROLL AG Werkzeugtechnik has developed an innovative process to more efficiently machine hydraulic cylinders. Our new tools with a high pressure internal cooling system as well as a tool interface for an automatic tool exchange make this novel process possible.

To date, the manufacturing of cylinders is performed in two separate steps:

1. Internal machining of cylinders on deep hole drilling machines.
2. Machining of cylinder ends and external surfaces on a lathe.

Latest ECOROLL tools and a quick change interface for BTA-tools now allow complete machining on a lathe. In the first instance, the cylinders made of cold drawn tubes are pre-machined by a skiving head. Cylinders made of hot-rolled steel tubes are counter bored before skiving process. After an automatic tool exchange, the cylinders are finish machined by roller burnishing. The tools are equipped with an internal high pressure cooling lubricant supply in order to ensure intensive cooling and lubrication as well as efficient chip removal and cleaning of the surface.

Advantages of complete machining

- Reduces side times and simplifies material flow.
- Machining after all welding work is completed improves quality and geometry.
- Investment costs for a deep hole drilling machine can be eliminated.
- Enables economic manufacturing of small batches.
- For cylinders with through and stepped bores.

Short description

Tool interface (1):
Contrary to BTA threads, tools are inserted into the bushing mounted on the boring bar without any rotation. The bushing is then rotated 40° to thighten up the connection. After that the tool is ready to use right away. To disconnect, the bushing is rotated in opposite direction. The tool can be changed manually as well as by an automatic tool change unit or a robot. The interface`s passageway can manage all process media, like cooling lubricants with chips or a control hydraulic unit. The interface is suitable for CNC lathes as well as deep hole drilling machines.

Counter boring tool (2):
Coolant splushing of knives through nozzels. High pressure leads to high velocity of cooling lubricant. This results in improved cooling and a more efficient chip removal.

Skiving tool (3):
Coolant splushing same as counter boring tool. Skiving knives switch to working position after activating the cooling lubrication pump. After releasing cooling lubricant pressure, knives retract. There is no need for a separate control hydraulic unit.

Roller burnishing tool (4):
Internal coolant supply through nozzels positioned towards bore wall ensures efficient cleaning of surface before roller burnishing.

Combined skiving and roller burnishing tool (5):
For long cylinders with through bores of larger batches, combined tools with high pressure internal coolant supply and automatic tool control system are available.



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