GB2202336A

GB2202336A - Improvements relating to testing of coated fabrics

Info

Publication number: GB2202336A
Application number: GB08705196A
Authority: GB
Inventors: John Musgrove; Robert Anthony Scott
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 1987-03-05
Filing date: 1987-03-05
Publication date: 1988-09-21
Also published as: GB8705196D0

Abstract

Apparatus for cycling a coated fabric sample 2 in the crumpling mode, comprises first and second support members 1 and 3 supporting respective ends 2a and 2b at the fabric sample 2 stitched along a seam 25 to form a cylinder. A drive motor 5 oscillates the support shaft 11 for the first support member 1 in the translational direction parallel to the axis of the cylinder 2 by means of a drive transmission 6 - 12 and a drive motor 13 drives the second support member 3 for angular oscillation about the axis of the cylindrical sample 2 by means of a transmission 14 - 20. Respective speed controllers 21 and 22 enable the speeds of the motors 5 and 13 to be adjusted independently of one another so as to allow only random location of the creases and substantially to avoid regularly repeating location of the creases in the crumpled sample. A single motor may be used, an infinitely variable gear box being provided in one of the drive means. A pressure test is performed on the sample 2 to determine the integrity of its coating after testing. <IMAGE>

Description

'IMPROVEMENTS RELATING TO TESTING OF COATED FABRICS' The present invention relates to a method of and an apparatus for testing coated fabrics, in particular to test the permanence of the coating despite repetitive crumpling and creasing of the fabric as is likely to be encountered by the fabric when incorporated in a garment.

Accordingly the present invention provides a device for repetitively crumpling a sample of a fabric, and means for substantially avoiding the creases in the fabric always occurring at the same location in the fabric sample during the crumpling test.

A preferred aspect of the present invention provides a device for crumpling repetitively a cylindrical fabric sample comprising a first member having a circular formation for supporting one end of a cylindrical sample of fabric, a second member having a circular formation for supporting a second end of a sample so supported by the first member, means for repetitively oscillating the first member in the translational direction towards and away from the second member, and means for driving the second member.

for angular oscillation about the axis of the circular formation thereof, the two driving means being arranged to effect oscillatory drive with different respective frequencies.

Preferably the, two oscillation frequencies of the drives are arranged so as not to be harmonics one of the other.

In an advantageous embodiment the drive means comprise two separate electric motors each having a respective speed control to allow adjustment of the speeds to avoid the frequent repetition of the location of creases formed in the cylindrical sample.

In order that the present invention may more readily be understood the following description is given, merely by way of example, with reference to the accompanying drawing in which the sole Figure shows a schematic view of a crumpling device in accordance with the present invention.

Subsequently the cylindrical fabric sample subjected to crumpling in the apparatus shown in the drawing will be subjected to a quantitative test of the integrity of a coating, for example by hydrostatic testing to see what pressure is needed to force water through the pores of the coated fabric sample when laid flat.

The crumpling device shown in the drawings comprises a first circular support member 1 having a periphery on which one end 2a of a cylindrical fabric sample 2 can be supported.

A second similar circular support member 3, coaxial with the first member 1, is able to support the opposite end 2b of the cylindrical fabric sample in a similar manner.

First drive means generally indicated 4, for translationally oscillating the first support member 1, comprise an electric motor 5 connected by a belt drive 6 to a crank wheel 7 supporting an eccentric crank pin 8 on which one end of a crank arm 9 is connected. The other end of the crank arm 9 is pinned at 10 to a translating support shaft 11 of non-circular cross-section supported in a fixed bearing sleeve 12 for translational oscillation.

A second drive means generally designated 4' is provided for effecting angular oscillatory drive of the second support member 3 and comprises an electric motor 13 driving a crank disc 14 having a crank pin 15 to which one end of a crank arm 16 is connected. The other end of the crank arm 16 is pinned at 17 to a lever 18 extending transversely from one end of a rotary shaft 19 supported by bearings 20 and carrying, at the end opposite the lever 18, the second support member 3.

A first controller 21 can be used to adjust the speed of rotation of the electric drive motor 5 of the first drive means 4 and has a digital indicator 23 for indicating the number of cycles of the first drive means 4.

Likewise a second controller 22 can be used for controlling the speed of operation of the drive motor 13 of the second drive means 4' and includes a digital indicator 24 showing the number of cycles of the second drive means 4'.

In use of the apparatus illustrated in the drawing, a rectangular sample of fabric is rolled into a cylindrical form such as is shown at 2 in the drawing, and the edges brought into contact with one another are stitched along the seam 25. The two ends 2a and 2b of the thus formed cylinder are then placed around the respective support members 1 and 3 and are clamped in place by clamps, not shown. The purpose of these clamps is to ensure that during rightward and leftward oscillation of the first support member 1, and during rotational oscillation of the second support member 3, the sample remains attached to the support member and, in the case of the second support member 3, there is no rotational slip between the end 2b of the sample and the support member 3 therefor.

Speeds of operation of the two drive motors 5 and 13 are then selected so as to ensure that there is no identity of drive frequency of the two drive means 4 and 4' and hence there will be no regular patterning of the creases formed in the sample during the combined twisting and compression of the cylindrical sample.

The sample is then run in this manner for the required number of cycles as specified by an appropriate test schedule, and at the end of the test the sample is then removed from the support members 1 and 3 and the seam 25 is opened so as to allow the sample to be laid flat on a test bed for subjecting it to a hydrostatic test to see what is the pressure supported by the sample when applied to one face thereof.

The coating of the sample may be one which renders the sample waterproof, or may be some other form of coating such as a flame-resist coating or a chemical-resist coating which tends to fill the pores of the fabric sample and whose integrity can be measured in terms of a hydrostatic pressure supported by the fabric. If the crumpling of the fabric has caused cracking of the coating and possible peeling of the coating away from the fabric, then this will show up in the form of a reduced hydrostatic pressure supported by the sample under test.

Although in the preferred embodiment described above there is a pair of separate drive motors each having a separate speed control in order to avoid regular patterning of the creasing of the material being cycled, other means may be provided for varying the frequency, for example by means of an infinitely variable gear box in the drive to one of the two drive means where they are both driven by the same drive motor. In this way it is possible to select a gear ratio on the infinitely variable gear box which substantially avoids patterning at regular intervals.

The advantage of having two separate drive motors with separate speed controls is that if there is no accurate monitoring of the speed of both motors, then it will only be a random chance of there being any coincidence of the creases, and the randomness is improved where one or both of the motors can drift somewhat in its operating speed in a random manner.

Claims

1. A device for repetitively crumpling a sample of a fabric, and means for substantially avoiding the creases in the fabric always occurring at the same location in the fabric sample during the crumpling test.

2. A device for crumpling repetitively a cylindrical fabric sample comprising a first member having a circular formation for supporting one end of a cylindrical sample of fabric, a second member having a circular formation for supporting a second end of a sample so supported by the first member, means for repetitively oscillating the first member in the translational direction towards and away from the second member, and means for driving the second member for angular oscillation about the axis of the circular formation thereof, the two driving means being arranged to effect oscillatory drive with different respective frequencies.

3. Apparatus according to claim 2, wherein the first and second drive means include respective drive motors which are controllable in a manner such that the speed of one is independent of the speed of the other.

4. Apparatus according to claim 2, and including a common drive motor to the first and second drive means, with an infinitely variable gear box between the common drive motor and one of said first and second drive means.

5. Apparatus according to claim 3 and including respective controllers indicating the number of cycles executed by the respective one of the first and second drive means and including means for adjusting the speed of the respective drive motors independently in the speed of operation of the other said drive motor.

6. Apparatus according to any one of claims 3, 4 and 5, wherein the drive motors are unstabilized and are therefore subject to variation of operating speed in continuous use.

7. Apparatus for repetitively crumpling a fabric sample, substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.

8. A method of testing a coated fabric for permanence of the coating, comprising taking a rectangular sample of the fabric, forming it into a cylinder by joining opposed parallel edges thereof, attaching the cylinder by its ends to first and second drive members, driving the first drive member for translational oscillation towards and away from the second drive member along the axis of said cylindrical sample, driving the second drive member for angular oscillation about the axis of the cylindrical sample attached thereto, ensuring that the speeds of operation of the first and second drive members are different in such a manner that repetition of the location of the creases at regular intervals in the cycling fabric in use of the apparatus is substantially avoided, and subsequently testing the crumpled fabric for its ability to support hydrostatic pressure applied to one side thereof.

9. A method of testing a coated fabric, substantially as hereinbefore described with reference to the accompanying drawing.