Dynamic Seal Test Rig DYDIP
The dynamic seal test rig DYDIP has been developed to measure the frictional force of translational hydraulic rod seals at different operating points. On the test rig, the chamber pressure and relative speed can be varied according to any movement pattern. A wedge-shaped gap reduces the effect of the operating pressure on the force sensor so that the frictional force of a single seal can be measured.
Mode of operation
The test rig consists of two cylinders: An operating cylinder and a test cylinder. The operating cylinder is a differential cylinder that is used to move the chamber of the test cylinder and thus to specify the movement pattern within the sealing contact. The test cylinder is a double rod cylinder with a split rod. Both parts of the rod are connected to the frame of the test rig. The upper rod is also connected to a force sensor. The split rod enables the force sensor to record only the force of the seal of the upper rod, but not the force of the seal of the lower rod. Since the pressure force acting on the front surface of the split piston rod would superimpose the frictional force in the measurement signal of the force sensor, there is a wedge-shaped gap between the two rods. This gap significantly reduces the fluid pressure acting on the front surface, which in turn reduces the force of the chamber pressure acting on the force sensor.
Operational parameters and spec-ifications
The test rig is operated by a hydraulic power unit with an 11 kW electric motor, which supplies the operating cylinder and provides the pressure within the test chamber. In total, speeds of up to 160 mm/s at chamber pressures between 6 and 150 bar can be achieved with the current setup. The standard diameter of the rod acting as the counter surface of the seal is 40 mm. The fluid in the test rig is a mineral oil of type HLP 46.
Results
With the control of the test rig arbitraty movement patterns such as sinusoidal movements and constant speeds can be set. The sensor system of the test rig records the movement speed of the operating cylinder, the signal at the force sensor and the pressure within the test chamber. In addition, the temperature in the oil circuit can also be monitored.