MEASURING DEVICE AND METHOD FOR DETERMINING PROPERTIES OF A VISCOELASTIC MATERIAL

Abstract

A measuring device, in particular a measuring device of the type of a rheometer, and a method determines properties of a viscoelastic material, which has been introduced or can be introduced into a temperature-regulated sample space between an upper chamber half provided with a sensor and a lower chamber half that can be rotated relative to the upper chamber half. The lower chamber half is driven or can be driven by a motor and is connected with at least one slip ring (that creates an electric path into the interior of the sample space on the lower chamber half, so that the lower chamber half can be rotated, with reference to the upper chamber half, about an angle of rotation over 360°.

Claims

1. A measuring device for determining properties of a viscoelastic material comprising: (a) an upper chamber half; (b) a sensor provided in the upper chamber half; (c) a lower chamber half rotatable relative to the upper chamber half; (d) a temperature-regulated sample space arranged between the upper chamber half and the lower chamber half for receipt of the viscoelastic material; (e) a motor for driving the lower chamber half; and (f) at least one slip ring connected with the lower chamber half; wherein the at least one slip ring creates an electric path into an interior of the sample space so that the lower chamber half can be rotated, with reference to the upper chamber half, about an angle of rotation over 360°.

2. The measuring device according to claim 1, wherein the lower chamber half can be rotated, with reference to the upper chamber half, any selected number of rotations and about any selected angle of rotation.

3. The measuring device according to claim 1, wherein a plurality of slip rings are provided, wherein each slip ring of the plurality of slip rings creates an electric path into the interior of the sample space.

4. The measuring device according to claim 1, wherein the at least one slip ring creates an electric path for regulating temperature in the interior of the sample space.

5. The measuring device according to claim 1, wherein the at least one slip ring is arranged on a drive shaft of the motor between the lower chamber half and the motor.

6. The measuring device according to claim 1, wherein the at least one slip ring is arranged on a rotational axle of the lower chamber half.

7. The measuring device according to claim 1, wherein the sensor (is a torque sensor or a combined torque/force sensor.

8. A method for determining properties of a viscoelastic material comprising: (a) introducing the viscoelastic material into a temperature-regulated sample space between an upper chamber half provided with a torque sensor or a combined torque/force sensor and a lower chamber half that is rotatable via a motor relative to the upper chamber half; (b) creating an electric path into an interior of the sample space by connecting the lower chamber half with at least one slip ring; and (c) rotating the lower chamber half, with reference to the upper chamber half, about an angle of rotation over 360°, so as to determine using the sensor at least one torque on the upper chamber half during the rotation of the lower chamber half.

9. The method according to claim 8, wherein the lower chamber half is rotatable, with reference to the upper chamber half, any selected number of rotations and about any selected angle of rotation.

10. The method according to claim 9, wherein the lower chamber half, with reference to the upper chamber half, is rotated, during the measurement, until a constant value of the torque occurs, derived from torque values measured as a function of time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

[0032] In the drawings, wherein components that are the same or functionally equivalent are provided with the same reference symbols,

[0033] FIG. 1 shows a measuring device according to the invention, in a perspective side view;

[0034] FIG. 2 shows a detail of the measuring device according to the invention, from FIG. 1, in a sectional view;

[0035] FIG. 3 shows a further detail of the measuring device according to the invention, from FIG. 1, in a sectional view;

[0036] FIG. 4 shows a measurement diagram when using the method according to the invention; and

[0037] FIG. 5 shows a further measurement diagram when using the method according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0038] In FIG. 1, an embodiment of a measuring device 2 according to the invention is shown in a perspective side view. The representation according to FIG. 1 should be understood as being merely an example, wherein only those components of the measuring device 2 are shown that are relevant for explaining the invention. The measuring device 2 is of the type of a rheometer and comprises an upper chamber half 4, which is fastened to a traverse 8 in a freely movable manner, by way of a closure system 6, using a closing cylinder.

[0039] Furthermore, the upper chamber half 4 is connected with a sensor 28 shown in FIG. 2 in the interior of the housing, for determining the torque or a force and the torque. It is true that the upper chamber half 4 is movable with reference to the mounting plate 10 and the longitudinal struts 12, but it is held in its position by the traverse 8. Opposite the upper chamber half 4, a lower chamber half 14 is arranged, which is connected with an electric motor 20 by way of a drive shaft 16.

[0040] The lower chamber half 14 can be rotated with reference to the further mounting plates 22 and/or the further longitudinal struts 24. On the drive shaft 16, multiple slip rings 26 are arranged, which each create an electric path to the lower chamber half 14. The designation as an upper chamber half 4 or lower chamber half 14, in each instance, refers to their position relative to one another, as well as to the usual arrangement in the case of a rheometer 2, but not to an absolute position in space. Of course, the two chamber halves can also be arranged differently.

[0041] The upper chamber half 4 and the lower chamber half 14 together form a measuring chamber having a cavity, called sample space in the following, in its interior. A viscoelastic material is introduced into the sample space, in order to determine its material properties. By means of deflection of the lower chamber half 14, using the electric motor 20, a torque as a function of time can be determined by way of the sensor 28, as a jump response, so that a determination of the viscosity of the introduced material is possible.

[0042] During the measurement, the measuring device 2 is kept at a fixed temperature by means of a regulator. The connections for electric lines required for the lower chamber half 14 are made available by means of the slip ring 26. The slip ring 26 allows rotation of the lower chamber half 14, without having to take into consideration cables that wind up. It is therefore possible to select the deflection of the lower chamber half 14 without the restrictions known from the state of the art.

[0043] In FIG. 2, the structure of the measuring device 2 is shown once again in a more detailed sectional representation. One can see that the lower chamber half 14 and the upper chamber half 4 together form a closed chamber system. Likewise, the sample space 30 can be seen, as can the sensor 28.

[0044] In FIG. 3, a further detail representation of the measuring device 2 is shown in the region of the slip ring 26. For transmission of multiple electric signals, multiple conductor rings 32 can be seen here, which are mechanically connected with the rotating lower chamber half 14. An electric connection with the stationary connectors 34, which do not move relative to the other components, is produced in a manner usual in the field, by way of a slip or brush contact 36. Corresponding rotating connectors 38, which are arranged in the region of a top side in FIG. 3, can create a connection to the sample space 30 in the region of the lower chamber half 14, by way of one or more cables.

[0045] In this way, it is possible to increase the size of the deflection of the lower chamber half 14, in almost any desired manner, and, in particular, to expand it to include deflections of greater than 360°.

[0046] The need for an increase in the deflection of the lower chamber half 14 is explained using the example of the measurement diagram of FIG. 4. FIG. 4 shows the typical progression of the viscosity 40 as a function of time. In this regard, the maximum deflection is limited to 360°. One can see that the viscosity does not achieve a constant value, which would be necessary for a viscosity determination by means of the jump response.

[0047] In comparison to FIG. 4, two measurements (viscosity progressions) 42 and 44 are shown in FIG. 5, wherein the measurement with the reference number 42 is restricted to 360°, and for the measurement with the reference number 44, ten rotations, i.e. a deflection of 3600° was selected. It can be seen that a constant progression occurs for the viscosity only after approximately 5 rotations. This plateau value corresponds to the actual viscosity of the material being investigated. In the case of the progression according to the measurement having the reference number 42, this value cannot be determined or would have to be estimated.

[0048] The characteristics indicated above and in the claims, as well as those that can be derived from the figures, can be advantageously implemented both individually and in various combinations. The invention is not restricted to the exemplary embodiments described, but rather can be modified in many ways, within the scope of the ability of a person skilled in the art.

[0049] Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.