WO2006094503A1

WO2006094503A1 - A handling device and a method for handling a test specimen

Info

Publication number: WO2006094503A1
Application number: PCT/DK2005/000166
Authority: WO
Inventors: Jakob NØRGAARD
Original assignee: Pbi Dansensor A/S
Priority date: 2005-03-10
Filing date: 2005-03-10
Publication date: 2006-09-14

Abstract

A holding device (1) for a test specimen (7), said holding device comprising a rigid steel plate (2) and a flexible sheet (3) containing a permanent magnetic material. The flexible sheet (3) is at least partially detachable from said rigid steel plate (2) so as to allow a test specimen (7) to be placed between said rigid steel plate (2) and said flexible sheet (3) . Both of said rigid steel plate (2) and said flexible sheet (3) have a matching aperture (5a, 5b).

Description

A holding device and a method for handling a test specimen.

The present invention relates to a holding de- vice for a test specimen and a method for handling a test specimen.

In devices for testing material properties of test specimens, such as the gas permeability of foils, the foils are typically clamped between two clamping plates in a test apparatus. The clamping plates include sealing means and cavities allowing a gas chamber to be formed on either side of the test specimen. Such devices are generally disclosed in WO- A-03/087782 and WO-A-99/50644. More specifically the present applicant produces the test apparatuses OPT 5000, L-80 and L-100. In these apparatuses the clamping plates are enclosed on three sides, so that the test specimen may be inserted between them from one side only, viz. the front side of the test apparatus. In order to insert and correctly position the sample between the clamping plates, the sample is held in a holding device, which cooperates with a guide means.

Typically the guide means of the test apparatus comprises a flat surface with two parallel vertical walls. The holding device is traditionally a rectangular piece of cardboard with appropriate cut-outs allowing the sealing means of the clamping plates to engage the test specimen held therein, when the holding device has been inserted into the test apparatus guided by said flat surface and said two vertical walls .

The traditional rectangular cardboard holding means generally comprises a piece of cardboard folded once along a centre line to sandwich the test specimen along, the cardboard halves on either side of the centre line being provided with the necessary apertures allowing the sealing means of the clamping plates to engage both sides of the test specimen.

Cutting the test specimen to size and securing it in the cardboard holding means, however, is complicated and cumbersome. Both the cutting and correct placement of the test specimen in the cardboard hold- ing means is performed manually and thus involves not only a risk of in advertent touching and contamination of the test specimen, but also a risk of the mounted test specimen warping, folding or wrinkling.

Both of these risks are undesirable. Contamina- tion of the test specimen is undesirable, because it will influence the measurement. The warping, folding or wrinkling is undesirable because it may influence the engagement of the sealing means and thus introduce leaks, which may also influence the measure- ments.

Also, the cardboard is prone to absorbing humidity, which may render it soft. Though this is not always a problem, it can be, in particular when tests are performed under conditions with a relatively high humidity level.

If the test specimens need not be stored after testing, both the cardboard holding means and the sample are typically just thrown away, as they are not reusable. With the increased focus on the envi- ronment nowadays, such waste is undesirable.

It is the object of the present invention to overcome these problems. According to a first aspect of the present invention, this object is achieved by a holding device for a test specimen, said holding device comprising a rigid steel plate, a flexible sheet containing a per- manent magnetic material, where said flexible sheet is at least partially detachable from said rigid steel plate so as to allow a test specimen to be placed between said rigid steel plate and said flexible sheet, and where both of said rigid steel plate and said flexible sheet have a matching aperture.

This provides a re-usable holding device in which the test specimen may be held firmly by the magnetic forces between the flexible sheet and the rigid steel plate between which it is sandwiched. In particular because of the rigid steel plate this can be done without the test specimen warping, folding or wrinkling. Moreover, as the test specimen is not permanently attached to anything it may easily be dis- posed of in an environmentally friendly manner.

According to a second aspect of the present invention this object is achieved by a method for handling a test specimen, said method comprising providing a rigid steel plate, providing a flexible sheet containing a permanent magnetic material, placing the test specimen between said steel plate and said flexible sheet, introducing said rigid steel plate, said flexible sheet and said test specimen into a testing device. This method allows test specimen to be held firmly and correctly positioned temporarily during measurement using a re-usable holding device. In particular, this can be done without the test specimen warping, folding or wrinkling. Moreover, as the test specimen is not permanently attached to anything, it may easily be disposed of in an environmentally friendly manner. According to a preferred embodiment of the holding device according to the invention, said steel plate is essentially rectangular, and said flexible sheet is permanently attached to said steel plate along one side of said rectangle. This attachment al- lows for good positioning of the flexible sheet with respect to the steel plate.

According to a further preferred embodiment, said matching apertures are circular. Not only are circular apertures easy to manufacture, but they also match in overall shape the o-rings typically used as sealing means of the clamping devices. This again means that least possible material has to be removed from the steel plate, thus compromising its mechanical strength the least possible. According to another preferred embodiment, said rigid steel plate has at least one cut-out not registering with cut-outs or apertures in the flexible sheet. This allows for digital access to the flexible sheet, thereby facilitating the separation of it from the rigid steel plate.

In particular an embodiment wherein said cutouts are apertures is preferred. Having apertures rather than e.g. incisions along the edges of the steel plate is preferable because it provides a straight edge, along which the test specimen may be cut with a knife when the test specimen is placed in the holding device between the rigid steel plate and the flexible sheet. According to yet a further embodiment, said flexible sheet has at least one cut-out not registering with cut-outs or apertures in the steel plate. This allows for access to the test specimen for writ- ing purposes, the rigid steel plate thereby serving as support. Thus, it is possible to write data directly on the sample if it is to be kept after measurement .

According to a preferred embodiment of the method according to the invention, the method further comprises the step of cutting the test specimen along the edges of the steel plate after the test specimen has been placed between said steel plate and said flexible sheet. This allows the test specimen to eas- ily be cut to the shape of the holding device, thus not protruding from the edges and not hindering the insertion of the holding device into the test apparatus. This is advantageous because the test specimen does not have to be handled after having been cut to size.

According to a further preferred embodiment, the method comprises the step of writing directly on said test specimen through an aperture in said flexible sheet using said steel plate as support. This is advantageous in that no other part than the test specimen itself has to be kept after the measurement. Thus the prior art cardboard holding means, which was traditionally used for writing data regarding the test specimen may be entirely omitted. According to a further preferred embodiment, the method further comprises the steps of removing said rigid steel plate, said flexible sheet and said test specimen from said testing device, pressing against said flexible sheet via the test specimen through said cut-out in said steel plate, so as to overcome the magnetic attraction, and separating said flexible sheet from said steel plate, removing said test specimen. This facilitates the removal of the test specimen for storage or disposal thereof, whilst allowing the holding device to be reused.

The invention will now be described in greater detail based on non-limiting exemplary embodiments, and with reference to the drawings. In the drawings, fig. 1 shows a top plan view of the holding device according to the invention, fig. 2 shows a top plan view of the holding device according to fig. 1 but with a test specimen held in the holding device, fig. 3 shows a bottom plan view of the holding device of fig. 1, and fig. 4 shows a cross section of the holding device taken along the line IV-IV in fig. 1. Fig. 1 shows a top plan view of a preferred specimen holding device 1 according to the invention. The overall shape is rectangular but the corners may be rounded in order to make the specimen holding device 1 more comfortable to handle and facilitate the insertion into a test apparatus.

As can best be seen from the cross section in fig. 4 the specimen holding device 1 comprises two layers. For illustration purposes, fig. 4 is not to scale, meaning that the two layers will in practice normally be thinner than illustrated.

The two layers include a rigid steel plate 2 and a flexible sheet 3. Preferably the rigid steel plate 2 and the flexible sheet 3 have congruent rec- tangular overall shapes. The rigid steel plate 2 is made of magnetic steel. The flexible sheet 3 is made of a material with permanent magnetic properties, such as a flexible rubber or polymer with a permanent magnetic filler material. In particular, the flexible sheet may be a layered composite comprising a tough flexible carrier such as a flexible PVC foil, to which a layer of the material with permanent magnetic properties is adhered, e.g. by gluing. In this case, the tough flexible carrier would face away from the rigid steel plate and the material with the permanent magnetic properties would face it. The skilled person, however, will understand that these are only options and that flexible materials with inherent per- manent magnetic properties could be used, e.g. polymer materials with inherent permanent magnetic properties could be used in the future, when these have been fully developed.

Due to the permanent magnetic properties of the flexible sheet 3, it is attracted to the rigid steel plate 2. The thickness and the elasticity of the flexible sheet is chosen so that it will naturally position itself flush along the steel plate 2 without any wrinkles, warps or folds. Apart form the magnetic properties necessary for the mutual attraction between the flexible sheet and the steel plate, the steel plate should preferably also have spring steel properties because it is to be avoided that the steel plate is subjected to permanent deformation during use. If it is deformed, e.g. bent, it may not cooperate properly with the test apparatus. Evidently, in this respect the thickness of the steel plate is also of importance. Hence, it should not be too thin. Also, the steel plate should preferably be corrosion resistant because, as mentioned above, in some applications it may be subjected to humidity. A preferred material fulfilling the above criteria is highly ferritic stainless steel .

It should be noted that the preferred thickness of the flexible sheet 3 and the steel plate 2 depend on the overall dimensions of the specimen holding de- vice 1. In a non-limiting example for the use with existing test apparatuses, the specimen holding device 1 would have a length of 190 mm and a width of 110 mm. The thickness of the flexible sheet would be approximately 1 mm, and the steel plate would have a thickness of approximately 0.5 mm. If not for the constraints set by the existing test apparatuses, steel plates with larger thicknesses than the one exemplified above could be envisaged.

The flexible sheet 3 and the rigid steel plate 2 each have an aperture, 5a and 5b respectively.

These allow access to the test specimen 7 from either side thereof, when a test specimen 7 is placed in the specimen holding device 1 as illustrated in fig. 2. The apertures 5a and 5b are preferably circular. This is because the sealing means of the test apparatus, which have to engage the test specimen 7, usually involve o-rings. Using a corresponding shape for the apertures 5a and 5b rather than e.g. a square preserves a larger area of steel in the steel plate 2, and thus compromises the spring properties and rigidity less.

As can be seen from figs. 1, 3 and 4, the apertures 5a and 5b register with each other. This is achieved by permanently attaching the flexible sheet 3 and the steel plate 2 to each other in an area along one side 8 of the overall rectangular shape. This may be done by gluing or by any suitable method. To place a test specimen between the flexible sheet 3 and the steel plate 2, the flexible sheet 3 is lifted from the steel plate at an appropriate point remote from the area where they are permanently attached. Once lifted at this one point, the magnetic force is reduced and the flexible sheet 3 may be detached from or peeled off the steel plate 2 all the way to the area where they are permanently attached.

The test specimen 7 is then placed flush upon the steel plate 2. When the flexible sheet 3 is re- leased, the magnetic attraction will return it to its natural position flush along the steel plate, the test specimen 7 now being sandwiched between them.

In order to facilitate the initial separation, the steel plate 2 may be provided with further cut- outs at a position remote from the side 8 of the rectangle. These cut-outs are not in register with any cut-outs in the flexible sheet 3. These cut-outs could be incisions in the edge of the steel plate 2, but it is preferred to provide apertures 6 within the circumference to the steel plate 2. The cut-out allows digital pressing on the flexible sheet 3 with a finger of one hand to effect the initial separation, whereupon the flexible sheet is gripped with the same hand or the other, and the flexible sheet 3 peeled off. For removal of a test specimen 7 the separation is the same, except for the fact the digital pressing on the flexible sheet 3 is effected via the test specimen 7. When the test specimen 7 has been placed in the specimen holding device 1 as illustrated in fig 2, it may conveniently be cut to size by cutting along those edges of the specimen holding device 1, where the test specimen 7 protrudes. This is of cause only necessary to the extent that the dimensions of the test specimen 7 exceed the dimensions of the specimen holding device 1, but will usually be more convenient than correctly placing previously prepared test specimens 7, with matching or smaller size than the specimen holding device 1. In this process the edges of the steel plate 2 serve as a means to cut along. Since it is more convenient to cut along a straight edge, it is preferred not to provide the cut-outs for the separation in the edge, but instead as the aforementioned apertures 6 within the circumference.

The flexible sheet 3 preferably also has at least one further cut-out 4, which is not in register with any cut-out in the steel plate 2. This allows access to one side of the test specimen 7 in order to write thereon. Since the cut-out 4 is not in register with any cut-out in the steel plate 2, the steel plate serves as rigid backing when writing on the test specimen 7. Writing directly on the test speci- men 7 may be necessary or at least desirable, because of the absence of the prior art cardboard holding means, which could be used for this. The cut-out 4 may have any desired shape, but as text is usually written in lines, a generally rectangular shape is preferred.

After having placed the test specimen 7 in the holding device 1, cutting it to size if necessary, and optionally having written thereon, the specimen holding device 1 may be inserted in the test apparatus for testing, by gripping it in the area of the side 8 of the rectangular shape and inserting the other end in the test apparatus with the side 9 first.

After testing, the test specimen 7 may be removed from the specimen holding device 1 after separating the flexible sheet 3 and the steel plate 2, as described above, whereupon the test specimen 7 may subsequently be stored or disposed of.

It should be noted that the invention is not restricted to the embodiment described above. Conversely, the above description reflects a preferred embodiment invented for the use with existing appara- tuses, and many modifications will be apparent to the skilled person in order to adapt the invention to other and future test apparatuses. In particular, the skilled person will understand that modifications, which involve dimensions and choice of materials are possible. Also it is to be understood that the flexible sheet 3 and the steel plate 2 may be fully detachable .

It should also be noted that the test specimen need 7 not be a foil and the test not a gas perme- ability test. The specimen holding plate could be used for other applications, where a thin object such as a foil, a textile or a plate has to be held for testing or inspection.

Finally, in respect of the above it should be noted that neither rigid nor flexible are to be understood in an absolute sense, but rather in relation to each other so as to distinguish the properties of the flexible sheet 3 and the rigid steel plate 2 from each other.

Reference numerals:

1 Specimen holding device

2 Rigid steel plate 3 Flexible sheet

4 Cut-out in flexible sheet 5a Aperture in flexible sheet 5b Aperture in steel plate 6 Cut-out in steel plate 7 Test specimen

8 Side of rectangle

9 Side of rectangle

Claims

P A T E N T C L A I M S

1. A holding device for a test specimen, said holding device comprising a rigid steel plate, a flexible sheet containing a permanent magnetic mate- rial, where said flexible sheet is at least partially detachable from said rigid steel plate so as to allow a test specimen to be placed between said rigid steel plate and said flexible sheet, and where said both of said rigid steel plate and said flexible sheet have a matching aperture.

2. A holding device according to claim 1, wherein said steel plate is essentially rectangular and said flexible sheet is permanently attached to said steel plate along one side of said rectangle.

3. A holding device according to claim 1, wherein said matching apertures are circular.

4. A holding device according to claim 1, wherein said rigid steel plate has at least one cut- out not registering with cut-outs or apertures in the flexible sheet.

5. A holding device according to claim 4, wherein said cut-outs are apertures.

6. A holding device according to claim 1 wherein said flexible sheet has at least one cut-out not registering with cut-outs or apertures in the steel plate.

7. A method for handling a test specimen, comprising providing a rigid steel plate, said method comprising providing a flexible sheet containing a permanent magnetic material, placing the test specimen between said steel plate and said flexible sheet, introducing said rigid steel plate, said flexible sheet and said test specimen into a testing device.

8. A method according to claim 7, further comprising the step of cutting the test specimen along the edges of the steel plate after the test specimen has been placed between said steel plate and said flexible sheet .

9. A method according to claim 7 or 8, further comprising the step of writing directly on said ^'test specimen through an aperture in said flexible sheet using said steel plate as support.

10. A method according to any one of claims 7 to 9, further comprising the steps of removing said rigid steel plate, said flexible sheet and said test specimen from said testing de- vice, pressing against said flexible sheet via the test specimen through said cut-out in said steel plate, so as to overcome the magnetic attraction, and separating said flexible sheet from said steel plate, removing said test specimen.

11. The use of a holding device according to any one of claims 1 to 6 for the method according any one of claims I₁ 8 or 10.

12. The use of a holding device according to claim 6 for the method according to claim 9.