GB2201796A - Fastener cycling machine and method - Google Patents

Abstract

A machine which simulates use of a hook/mushroom and pile tape fastener such as that sold under the trade name Velcro, by driving under known pressure two adjacent drums 11, 12 around which the complementary halves of the fastener are fixed and counting the number of revolutions. Lower drum 11 is driven by motor 13 and upper drum 12 is carried by counterweighted lever 14. Weights 16 load drum 12. The direction of rotation may be periodically reversed. The upper drum may be slightly larger than the lower drum to ensure that the same sections of hook tape do not always make contact with the same sections of pile tape. Shear and peel strength tests are performed on the two cooperating loops of fastener before and after the above test. <IMAGE>

Description

FASTENER CYCLING MACHINE AND METHOD Touch and close fasteners are well known, particularly fasteners comprising two pieces of tape or fabric, e.g. a hook or mushroom tape and a pile tape such as that sold under the trade name Velcro. Typically, the hook or mushroom tape is a woven nylon or polyester fabric into which are woven hook shaped or mushroom shaped locking elements manufactured from polyester, nylon or polypropylene. The pile tape into which the hook or mushroom locking elements become entangled when the two halves of the fastener are closed together, is typically a polyester or nylon warp pile fabric or raised knitted structure.

Touch and close fasteners such as this are particularly useful in clothing since they may be dyed to various shades, and are light and washable; tape fasteners are not uni-directional in their opening and closing action.

However, after the fastener has been closed and re-opened many times, as it would be during normal use, the strength of the fastener reduces. To assess the sheer strength and peel strength of touch and close fasteners standard tests are carried out. A measurement of the durability of the fastener may be obtained by re-testing the fastener after it has been fastened and peeled apart many times e.g. 5000 times, and comparing the results of tests done before and those done after this extensive use of the fastener.

The present invention relates to a machine to simulate use of a touch and close fastener by fastening it and peeling it apart a measureable number of times under a known force.

One aspect of the present invention provides apparatus for cyclicly fastening and peeling apart a touch and close fastener, the apparatus comprising a first drum and a second drum, means for fixing the complementary parts of the fastener around the first and second drums respectively, means for applying an adjustable contact force between the drums, means for rotating at least one of the drums when the drums are in contact with one another, and rotation measuring means.

Preferably the first drum is driven by the rotating means and the second drum is freely rotatable.

Preferably the two drums are mounted one directly on top of the other, the second drum above the first drum.

Preferably the upper drum is counter-balanced e.g. by attaching the axle of the upper drum to one end of a pivoted arm on the other end of which is a movable weight such that the fastener wound around the upper drum touches, but brings no pressure to bear on, the fastener wound around the lower drum. Measurable amounts of pressure may then be added to the upper drum by the addition of weights to its axle.

A second aspect of the present invention provides a method of testing a touch and close fastener comprising testing the strength of the unused fastener, fixing the complementary parts of the fastener around the first and second drums of a cycling apparatus as described above, cycling the fastener a measured number of times, removing the fastener from the drums and retesting the strength of those parts of the fastener which have been subjected to the cycling.

Several methods may be used to attach the fastener half to a said drum. In a preferred method, the drum has a slot in its curved side and the fastener is held onto the slotted drum. A loop is formed of the fastener e.g. in the case of a tape fastener of the hook/mushroom and pile type, a length of tape is stitched face side to face side to form a continuous loop which is slightly larger than the circumference of the drum on which the fastener is to be held. This loop is then slipped around the drum with the hooks/mushrooms facing outwards and the excess loop is clamped into the slot in the drum so that the main part of the loop is held firmly around the drum.

The fastener may additionally be held to the drum using double sided adhesive tape, preferably in addition to the fastener loop and slot method described above.

The apparatus is particularly suitable for use with hook/mushroom and pile type of tape fastener, and preferably the hook/mushroon tape is fixed to the upper drum and the pile tape is fixed to the lower drum.

The quality of a hook/mushroom and pile type of tape fastener may preferably be tested in the following way. One sample comprising both hook/mushroom tape and pile tape is taken from every hundred rolls of tape produced. The peel strength of the tape fastener is then measured, using the method described hereafter. The lengths of tape used in this peel strength test are then fixed to the drums of the cycling apparatus, the hook tape preferably being fastened to the upper drum and the pile tape to the lower drum. The counter-balanced upper drum is then loaded with one kilogram per total width of the tape on the upper drum in centimeters. The lower drum is then driven at e.g. 60 rpm with the direction of rotation reversed every 30 seconds.

The fastener tape on the lower drum contacts the fastener tape on the upper drum such that rotation of the lower drum causes corresponding rotation of the upper drum and the tape fastener is closed and fastened and peeled apart as the two drums rotate.

The number of cycles of the drums is counted, regardless of direction of rotation, and when this number has reached a set target e.g. 50.00 rotations, the tapes are removed from the drum and the peel strength test is repeated. If the loop and slot means is used to fasten the tape around a drum then the repeated peel strength test should only be carried out on those areas of the fastener which have been subjected to the cyclic fastening and peeling process i.e. not those areas of the fastener which were within the slot during the cycling process.

From the same sample roll the shear strength of another section of tape is tested by the standard shear strength test described hereinafter, these sections of tape are then subjected to the cycling process described above, and the shear strength retested for those areas which have been subjected to the cycling process.

Typically a hook/mushroom and pile type of tape fastener is required to have a peel strength when new of at least 2 N/cm and at least 1 N/cm after 5000 opening and closing cycles, and a shear strength of at least 8 N/cm2 2 when new and at least 5 N/cm2 after 5000 opening and closing cycles.

The present invention will be further described with reference to the attached drawings in which Figure 1 shows the arrangement of hook and pile .type of tape fastener when being tested for peel strength; Figure 2 shows the arrangement of hook and pile tvpe of tape fastener when being tested for shear strength; and Figure 3 shows a preferred embodiment of the cycling machine of the present invention.

In the standard test for measuring peel strength, four lengths of hook tape each 615 mm long are each stitched face side to face side to form four separate loops each 595 mm in circumference, and similarly four lengths of pile tape each 590 mm long are stitched to form four separate loops 570 mm in circumference.

The pile tape 1 is placed on a bench with the pile uppermost and the hook tape 2 is then placed on top of this so that a 50 mm overlap is formed. The two tapes are then locked together by rolling a steel roller five times in each direction over the overlap. The two loops of tape which are locked together are then mounted in clamps 3 as shown in Figure 1 with the overlap equidistant between the two clamps. Force is then applied parallel to the jaws of the clamps and perpendicular to the plane of the overlap and the peel strength at a constant rate of extension of 200 mm/min is measured and the median value in N/cm width of tape is recorded for the first 40 mm of the overlap. The mean of 20 such results, five results from each of the four pairs of tape is then calculated.

The standard test for measuring the shear strength of a hook and pile type of tape fastener comprises forming four loops of hook tape and four loops of pile tape as described for the peel strength test. A pile tape 1 and a hook tape are fastened together with a 50 mm overlap as described for the peel strength test, and these two attached loops are then mounted in clamps 4 as shown in Figure 2. Force is then applied parallel to the overlap of the loops such that a constant rate of extension of 200 mm/min is obtained and the maximum force required to disengage the entire overlap is recorded. The mean value of force in N/cm for 20 results (5 results from each of the four pairs of loops) is calculated. The loops are then subjected to 5000 oDening and closing cycles on a cycling machine and the shear strength is then measured again using this test.

The apparatus shown in Figure 3, the touch and close cycling machine, comprises a lower drum 1 around which the pile tape 1 is fixed, a motor 13 which drives the lower drum, an upper drum 12 around which the hook tape 2 is fixed, a pivoted arm 14 which on one side of the pivot holds the axle of the upper drum 12 and on the other side of the pivot carries a counter-balance weight 15.

The counter-balance 15 is adjusted such that the hook tape fixed around the upper drum is in contact with the pile tape around the lower drum, but brings no pressure to bear on the lower drum; weights 16 are then loaded onto the upper drum e.g. to an amount of 1 kg/cm width of fastener. The lower drum is then driven, preferably at 60 rpm with the direction of rotation reversed every 30 seconds. A counter (not shown) counts the number of cycles of the lower drum regardless of direction of rotation. Rotation of the lower drum drives the upper drum through the contact between the two halves of the fastener. Preferably the two drums are of similar, but not exactly equal diameter e.g. the upper drum may have a diameter which is 1-28 larger than the lower drum so that, as the drums rotate, the same sections of hook tape are not always in contact with the same sections of pile tape, to ensure even wearing of the tapes. If the loops of tape used in the peel strength and shear strength tests are of the standard length i.e. 595 and 570 mm in circumference then suitably the lower drum is 160 mm in diameter and the upper drum is 162.5 mm in diameter.

The surfaces of both drums are scored with lines parallel to the direction of rotation of the drums so that it can be seen whether the tape has slipped sideways during the cycling process and this can be corrected for.

Claims (16)

1. Apparatus for cyclicly fastening and peeling apart a touch and close fastener, the apparatus comprising a first drum and a second drum, means for fixing the complementary parts of the fastener around the first and second drums respectively, means for applying an adjustable contact force between the drums, means for rotating at least one of the drums when the drums are in contact with one another, and rotation measuring means.

2. Apparatus as claimed in claim 1 in which the means for fixing the complementary parts of the fastener include a slot in the respective said drum.

3. Apparatus as claimed in claim 2 in which the fastener is held onto the slotted drum by forming a loop of the fastener around the drum and clamping the excess fastener into the slot.

4. Apparatus as claimed in any one of the preceding claims in which the first drum is driven by the rotating means, and the second drum is freely rotatable.

5. Apparatus as claimed in claim 4 in which the first drum may be driven in either direction.

6. Apparatus as claimed in any one of the preceding claims in which the second drum is arranged above the first drum.

7. Apparatus as claimed in any one of the preceding claims in which the surface of at least one drum is scored with lines parallel to the direction of rotation of the drum.

8. Apparatus as claimed in any one of the preceding claims in which the first drum and the second drum are of different diameters.

9. Apparatus as claimed in claim 8 in which the larger diameter is 1 to 2% larger than the smaller diameter.

10. Apparatus for cyclicly fastening and Peeling apart a touch and close fastener constructed and arranged to operate substantially as hereinbefore described with reference to figure 3.

11. A method of testing a touch and close fastener comprising testing the strength of the unused fastener, fixing the complementary parts of the fastener around the first and second drums of an apparatus as claimed in claim 1, cycling the fastener a measured number of times, removing the fastener from the drums and retesting the strength of those parts of the fastener which have been subjected to the cycling.

12. A method according to claim 11 which further comprises laundering the fastener between the first and second testing for strength.

13. A method as claimed in any one of claims 11 or 12 in which the fastener half is held onto a drum by double sided adhesive tape.

14. A method as claimed in any one of claims 11 to 13 in which a hook/mushroom and pile type of tape fastener is fixed around the drums.

15. A method as claimed in claim 14 in which the pile tape is fixed around the first drum and the hook/mushroom tape is fixed around the second drum.

16. A method of testing a touch and close fastener, substantially as hereinbefore described with reference to the accompanying drawings.