AU8160087A

AU8160087A - Device for placing in a substance for checking the viscosity and elasticity thereof

Info

Publication number: AU8160087A
Application number: AU81600/87A
Authority: AU
Inventors: Leif Rune Bohin; Sven-Erik Larsson
Original assignee: BOHLIN REOLOGI AB
Current assignee: BOHLIN REOLOGI AB
Priority date: 1986-10-27
Filing date: 1987-10-27
Publication date: 1988-05-25
Also published as: WO1988003264A1; SE8604563L; SE8604563D0; SE454915B

Description

DEVICE FOR PLACING IN A SUBSTANCE FOR CHECKING THE VISCOSITY AND ELASTICITY THEREOF

The present invention relates to a device for placing in a substance for checking the viscosity and elasticity and the rheological properties thereof.

In a number of applications, there is need for checking or measuring the viscosity or the state of solidification and melting, respectively, of a substance when this state changes in consequence of the treatment to which the substance is subjected so that, for example, the treatment can be interrupted or other substances added at the right moment. To this end, a number of instruments have been developed which, in most cases, have a movable part which is inserted in the substance at a predetermined freguency. With such instruments, however, only the surface layer can be checked, and the state in the interior of the substance can only be conjected, and furthermore there is a risk that the check will adversely affect the substance.

To make it possible to check also the interior of a pulverulent or liquid body passing into the solid state, an instrument is required which can make its viscosity-_'sensing movement within the body and which is so designed that it can be retained within the body after the body has passed into the solid state, i. e. it must be harmless to the body and not adversely affect the use thereof. Furthermore, it must be inexpensive. The device according to the invention satisfies these requirements in that it consists at least partly of magnetoelastic material and has a surrounding coil with wires extractable from the substance for connection to a voltage source, and a measuring equipment for measuring changes in the impedance of the coil which are a consequence of the bending of the device, caused by the magnetic field of the coil upon application of a voltage, against the action of said substance. By "substance" are meant in the contex of this invention all gaseous, liquid or granular substances whose viscosity or state of solidification is changed under the action of, for example, heat or pressure, and, in similar manner, solid substances passing into the liquid or gaseous form under such action.

The invention will be described in more detail below, reference being had to the accompanying drawing illustrating embodiments. Fig. 1 is a top plan view of a device designed according to the invention, and Fig. 2 is a lateral view of the device. Fig. 3 illustrates another embodiment of the device according to the in¬ vention.

A few yers ago, a material- was developed which has a very high magnetoelastic coupling factor and which is commercially available int. al. under the trade name METGLAS 2605SC. Another material also recently developed is called supermagnetostrictive and is sold int. al. under the trade name TERFENOL.

Fig. 1 shows a device 10 which consists of a com¬ bination of two foils 11 and 12, of which the foil 11 is made of the above-mentioned supermagnetostrictive material, while the other foil 12 constitutes the carrier and consists of nonmagnetic material, such as aluminium. The foils are interconnected, for example by gluing. In Fig. 11, the device 10 has a central portion 16 merging into two end portions 14, 15, considerably wider than the central portion 16 around which a coil 13 is disposed which is provided with connection wires 17, 18-.

If the connection wires 17, 18 are connected to a voltage source, the coil 13 produces a longitudinal magnetic field in the magnetostrictive foil 11 of the device 10, and due to the lamination the device 10 will bend. If the device 10 is disposed within a substance, the substance will affect the bending, and it will be appreciated that this effect is unambiguously determined by the viscoelastic properties of the substance. The end portions 14, 15 of the device are enlarged to increa the engagement of the substance with the device 10. The bending of the device 10 about the central portion 16 causes the impedance of the coil 13 to change in accordance, with the bending, and by measuring this im¬ pedance, the viscoelasticity of the substance can be determined.

To improve the bending capacity of the device 10, the carrier 12 of nonmagnetic material may be provided with a magnetostrictive foil 11 on opposite sides, in which case one foil has a positive and the other foil a negative magnetostriction. Instead of foils 11 of magnetostictive material, the carrier 12 may have a coating on one or both sides, which is established electrolytically or by spraying.

Fig. 3 illustrates another embodiment of the in¬ vention, in which the device 10 has the same design as the device in Fig. 1, i.e. with a central portion 16 and end portions 14, 15, but lacks a carrier and therefore consists of but one foil of magnetostrictive material, for example METGLAS 2605SC. To achieve bending in this case, terminals 19, 21 are provided on opposite sides of the coil ends, and to these terminals con¬ nection wires 20, 22 are connected. If the coil 13 according to Fig. 3 is connected to a voltage source, whereby the magnetic field in the device 10 is generated, the device 10 will rotate, if the connection wires 20, 22 are at the same time connected to a current source. If the current source is a direct current source, the device will rotate in one direction only, but if it is an alternating current source, the device will rotate back and forth. As in the other case, it is possible, by measuring the impedance, to determine the viscosity of the substance within which the device is disposed. However, rotation of the device can be measured also by instantaneous switching of the wires 20, 22 from the current source to a voltage meter by means of a quick-acting electronic switch (not shown).

The device according to the invention can be manu¬ factured at very low cost and therefore can be used as a throwaway device in, for example, the curing of plastics by placing the device in the plastic masse prior to curing which is then checked by activating the device at regular intervals by connection to the voltage source and the current source, respectively. When the device can no longer move, the plastic is fully cured, and the plastic component can, for example, be removed from the mould. The device is retained in the plastic component, and the wires are cut flush with the surface thereof.

Naturally, the device according to the invention can be used for many other applications where it is desired to carefully check the viscosity or the progress of solidification, for example in the casting of concrete. However, the device may, of course, also be used reversely to check a melting process.

Claims

1. A device for placing in a substance for checking the viscosity thereof, c h a r a c t e r i s e d in that it consists at least partly of magnetoelastic material, i.e. a material having a high magnetoelastic coupling factor, surrounded by a coil 13 which is pro¬ vided with wires (17, 18) extractable from the substance for connection to a voltage source, and a measuring equipment for measuring the change in the impedance of the coil (13) which is a consequence of the bending of the device, caused by the magnetic field of the coil upon application of a voltage, against the action of the substance.

2. A device as claimed in claim 1, c h a r a c t e¬ r i s e d in that it consists of carrier foil (12) of nonmagnetic material, for example aluminium, and a foil (11) of magnetostrictive material affixed to said carrier foil.

3. A device as claimed in claim 1, c h a r a c ¬ t e r i s e d in that it consists of a carrier foil (12) of nonmagnetic material, for example aluminium, wich is coated on opposite side with magnetostrictive material (11) having a positive magnetostriction on one side of the carrier foil (12) and a negative magneto¬ striction on the opposite side the carrier foil.

4. A device as claimed in claim 1, c h a r a c ¬ t e r i s e d in that it has, on both sides of the coil (13), terminals (19, 21) for connection with the magnetoelastic material, the terminals being connected with wires (20, 22) extractable from the substance and connectible to a current source in order to rotate the device by current supply thereto upon application of a magnetic field by means of said coil (13), said rota¬ tion being measurable by switching the wires (20, 22) from the current source to a volt-meter by means of a quick-acting electronic switch.

5. A device as claimed in any one of the preceding claims, c h a r a c t e r i s e d in that it is flat and has a central portion (16) around which the coil (13) is disposed, and end portions (14, 15) far wider than the central portion (16).