Abstract: The present invention relates to a holder having an actuation unit, particularly as a part of a material testing machine for testing specimens, for example metal test-specimens, which are held at high forces that are particularly due to the type of testing. The actuation unit operates with pressure from a pressure source. A bi-stable fluid control valve is temporarily in a first or in a second state, in particular depending on pressures at actuation sides of the valve. Besides a first actuator, which is responsible for the regular clamping force of the clamping face, to a second actuator is provided. The second actuator may also be referred to as motion unit due to its motion force to the clamping piston. The actuators arrange for a certain de-coupling of the different forces when holding and clamping specimens. Such a circuit offers the desired safety degree.

Abstract: A flow test machine 2 which, for example, is able to be used for viscosity tests on plastics, comprises a test piston 4, a test channel 38, at least one test weight 72 and a drive unit 92. The test piston 4 is able to move through the test channel 38 by means of a weight force 79 of the test weight 72. The test weight 72 is able to be loaded by an actuating additional force 108, 108? by means of the drive unit 92 between a starting position 151 and an end position. The actuating additional force 108 enables a movement of the test piston 4 in the direction of the weight force 79, said movement being accelerated in comparison with an effect of the weight force 79. In a melt viscosity test, after a heating step, a thermoplastic plastic is pressed through a test channel 38 by a test piston 4. In a measurement preparation step and/or a cleaning step, the test mass is lowered along a weight force direction 79 under the influence of an actuating additional force 108, 108?.

Abstract: The present invention relates to a holder having an actuation unit, particularly as a part of a material testing machine for testing specimens, for example metal test-specimens, which are held at high forces that are particularly due to the type of testing. The actuation unit operates with pressure from a pressure source. A bi-stable fluid control valve is temporarily in a first or in a second state, in particular depending on pressures at actuation sides of the valve. Besides a first actuator, which is responsible for the regular clamping force of the clamping face, to a second actuator is provided. The second actuator may also be referred to as motion unit due to its motion force to the clamping piston. The actuators arrange for a certain de-coupling of the different forces when holding and clamping specimens. Such a circuit offers the desired safety degree.

Abstract: A flow test machine 2 which, for example, is able to be used for viscosity tests on plastics, comprises a test piston 4, a test channel 38, at least one test weight 72 and a drive unit 92. The test piston 4 is able to move through the test channel 38 by means of a weight force 79 of the test weight 72. The test weight 72 is able to be loaded by an actuating additional force 108, 108? by means of the drive unit 92 between a starting position 151 and an end position. The actuating additional force 108 enables a movement of the test piston 4 in the direction of the weight force 79, said movement being accelerated in comparison with an effect of the weight force 79. In a melt viscosity test, after a heating step, a thermoplastic plastic is pressed through a test channel 38 by a test piston 4. In a measurement preparation step and/or a cleaning step, the test mass is lowered along a weight force direction 79 under the influence of an actuating additional force 108, 108?.

Abstract: A test-specimen holder for gripping test specimens to perform material tests in the form of compressive and tensile tests has two grabs coaxially aligned relative to each other and capable of gripping the test specimen. The grabs have angled faces on sides facing away from the test specimen gripped between them. Respective hydraulic gripping cylinders are connected to the grabs for shifting same axially and a wedge can engage the angled faces of both grabs. A fluid-operated synchronization cylinder is connected to the wedge for moving the wedge perpendicular to the axis of the grabs into and out of engagement with the angled faces of the grabs. A fluid reservoir is connected through a 4/2 directional control valve with the gripping cylinders for actuating same. An adjustable first pressure-limiting valve and a check valve connected parallel thereto are connected between the 4/2 valve and the synchronization cylinder.

Abstract: The invention relates to a method for measuring the deformation of a specimen without contact with the specimen. The surface of the measured specimen is partly illuminated by a laser light having uniform intensity. A speckle image is produced due to the local quality of the surface and is reproduced via an optical image sent onto a light-sensitive sensor. At least one reference speckle is selected by an evaluator unit from the totality of the speckles of the speckle image. The displacement of the reference speckle on the sensor is evaluated as the measure of the change that occurred in the specimen. In addition, the invention provides a device for performing this method.

Abstract: A test frame has an upper end traverse, a lower end traverse below the upper end traverse, a pair of parallel upright tie rods having upper ends fixed in the upper traverse and lower ends fixed in the lower traverse, and a middle traverse between the upper and lower end traverses. Respective cylinders fixed on the middle traverse surrounding the tie rods are vertically slidable on the tie rods and each define with the respective tie rod a substantially closed chamber. A piston provided on each tie rod inside the respective cylinder subdivides the respective chamber into an upper compartment and a lower compartment. A source of fluid having a high-pressure side and a low-pressure side is connectable by a pair of respective valves to either of the respective compartments. A mechanical controller connected to both valves synchronously operates same to synchronize the position and movements of both cylinders.