JPH036437A - Method and apparatus for testing strength of film structure - Google Patents

Abstract

PURPOSE:To test accurately a fatigue strength in relation to a bending stress by making a tape-shaped film structure run while winding it on an appropriate number of guide members at a specified angle so that the total sum of winding angles be a specified number of degrees. CONSTITUTION:A film structure 1 is held by a capstan 2 and a pinch roller 3 between and driven to run and is led into a strength testing element 6. In the testing element 6, guide rollers 7 for a fatigue test numbering 100 or more, for instance, are juxtaposed so that they are positioned in two rows, in the front and the rear, alternately. The surface and rear of the structure 1 led in are wound on the rollers 7 alternately at an angle of 90 or more degrees so that the total sum of winding angles is 1,800 degrees or above, together with the ones of other guide rollers, and the structure is made to run continuously in this state. A bending fatigue strength is tested in the course of this running. On the occasion, the tensions of the structure 1 on the entrance and exit sides are detected by entrance-side and exit-side tape tension sensors 5 and 8 respectively, the tension in the course of running is adjusted, and the strength of a repeated bending stress applied in the course of running of the structure on the rollers 7 is adjusted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method and apparatus for testing the strength of a film structure, and more specifically relates to a method for testing the strength of a film structure, and more specifically, a method for testing the strength of a film structure. The present invention relates to a method for testing the fatigue strength of film structures, particularly against bending stress, and a test device therefor.

[Conventional technology]

Generally, a magnetic layer is provided on the back of a base film such as polyethylene terephthalate film by applying a magnetic paint or vacuum-depositing a ferromagnetic metal, and then a top coat layer is provided on top of the magnetic layer. Multilayer film structures such as magnetic tapes, which are formed by providing a back coat layer on the back side of a base film, are susceptible to repeated bending stress during use. For this reason, this type of film structure is required to have excellent bending fatigue strength, with less fatigue due to bending stress, particularly in the magnetic layer formed on the surface of the base film.

Therefore, in multilayer film structures such as magnetic tapes, it is necessary to sufficiently strengthen the strength by examining fatigue, etc. against bending stress. A tensile test was conducted on the film structure using Autograph AGS-50A manufactured by Seisakusho Co., Ltd., or a sliding test was conducted in which a spherical slider was repeatedly slid on the film surface using HE ID0N-21 manufactured by Shinkan Kagakusha Co., Ltd. It is common practice to test the strength of film constructs.・ [Problem to be solved by the invention] However, in conventional tensile tests, only tensile stress can be applied, and in sliding tests, it is dominated by friction and wear between the slider and the film surface. It is difficult to evaluate the bending fatigue strength due to the large amount of bending stress, and these conventional methods involve repeatedly applying tensile and compressive stress to the film structure due to bending, to accurately evaluate the fatigue strength of the film structure against bending stress. cannot be evaluated.

[Means to solve the problem]

This invention has been made as a result of various studies in view of the current situation, and involves wrapping a tape-shaped film structure around an appropriate number of guide members at an angle of at least 90 degrees. By continuously running the film while wrapping it so that the total angle is 1800 degrees or more, it is possible to accurately test the fatigue strength of the film structure against bending stress.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an explanation will be given based on FIG. 1 showing an embodiment of the strength testing apparatus for a film structure according to the present invention.

In FIG. 1, reference numeral 1 denotes a film structure formed into a loop by processing it into a tape shape, which is held between a capstan 2 on the left side and a pinch roller 3, and is driven and run in the direction of arrow A. 4, an inlet tape tension sensor 5, and then introduced into a strength testing section 6.

The strength test section 6 is constructed by arranging a large number of fatigue test guide rollers in two rows, which are alternately arranged in front and back. It is continuously run while being wound around guide rollers 7 alternately at an angle of 180 degrees, and during this running, bending stress is repeatedly applied to test the bending fatigue strength. After the bending fatigue strength test, the tape passes through the output side tape tension sensor 8, passes through the guide roller 9, is held between the right capstan 10 and the pinch roller 11, and is driven and driven. At this time, the tape-like film structure 1 to be tested for bending fatigue strength in the strength testing section 6 has an entrance tape tension sensor 5 detecting the tape tension on the entry side to the strength testing section 6, and an exit tape The tension sensor 8 detects the tape tension on the exit side, adjusts the tension during running, and adjusts the strength of the repeated bending stress that the tape receives while running while being wrapped around a large number of guide roughs for fatigue testing. .

Here, in the strength test section 6, the winding angle when winding around the large number of fatigue test guide rollers 7 is set so that the fatigue strength test can be performed against sufficient bending stress.
It is preferable to wrap it around each fatigue test guide roller 7 at an angle of at least 90 degrees, so that the sum of these wrapping angles together with the wrapping angle with other guide rollers is 1800 degrees or more, In addition, the number of guide rollers 7 for fatigue testing that are arranged in two rows alternately in the front and back rows in the strength testing section 6 is such that more efficient fatigue strength tests can be performed. Preferably, a guide roller 7 is incorporated, for example 100
It is preferable to incorporate more than one guide roller 7 for fatigue testing. Furthermore, it is preferable that the strength testing section 6 individually prepare guide roller rows corresponding to the widths of the tape-like film structures 1, each having a different width, so that the entire guide roller row can be removed and replaced.

The tape-shaped film structure 1 which is held between the right capstan 10 and the pinch roller 11 and is driven and run is further moved to the slide rail 13 via the guide roller 12.
Movement adjustment guide roller 1 movably attached to the top
4, by moving the movement adjustment guide roller 14 in the left and right direction, the loop length of the traveling tape-like film structure 1 is adjusted. Then, the tape-shaped film structure 1 whose loop length has been adjusted is further run between a pair of optical sensors 17 via guide rollers 15 and 16. At this time, when the marker 18 attached to a part of the tape-like film structure 1 formed in a loop shape passes between the pair of optical sensors 17, the light is reflected or transmitted by the marker 18, and the number of passes is is counted. However,
With this marker 18, the number of times the tape-shaped film structure 1 formed in a loop shape is traveled is known, and the number of repetitions of bending stress is displayed and further controlled.

The tape-shaped film structure 1 that has passed between such a pair of optical sensors 17 further passes through guide rollers 19 and 20 and reaches a tension roller 21, where the tape-shaped film structure 1 is loosened by the tension roller 21. is absorbed. Then, further via the guide roller 22,
It is held between the left capstan 2 and the pinch roller 3,
It is driven.

Note that the guide rollers 4, 9, 12, 15, 16, 19. It is preferable to use one with a diameter as large as possible, for example, one with a valence of 50 or more.

Further, the guide member for fatigue tests is not limited to the guide roll for fatigue tests, but any guide member used as a guide member such as a guide pin for fatigue tests can be used. Furthermore, the tape-like film structure 1 is not limited to magnetic tape.
Various industrial films such as wrapping films and ink ribbons can be applied, and fatigue strength tests on bending stress of these industrial films are performed.

The strength testing device for a film structure of the present invention is constructed as described above, and the strength testing device of the present invention shown in FIG. 1 will be used to test the fatigue strength of a videotape against repeated bending. did.

The videotape used for this fatigue strength test was on a polyethylene terephthalate film with a thickness of 8 μm.
Co-Ni alloy was vacuum-deposited under various conditions to form ferromagnetic metal thin film layers with different shapes and distributions of fine magnetic domain particles, and then cut into 8 pieces with a length of 2 m.
Five types of loop-shaped video tapes were prepared. The ferromagnetic metal thin film layer of each of these video tapes was bonded to a non-magnetic stainless steel pin (sus3o3: surface finish J).
All friction coefficients were 0.22 when they were brought into contact with and slid against (IS Rt: 0.2 μm).

In addition, in the strength testing apparatus shown in FIG. 1, as the strength testing section 6, guide rollers 7 having a diameter of 3M are arranged in two rows, front and rear, alternately arranged in 51 pieces. After each loop-shaped videotape 1 is loaded, the videotape 1 is rotated while alternately changing its contact surface from front to back, except for the guide rollers 7 for fatigue testing on the entry and exit sides of the videotape 1 in the strength testing section 6. , the two sets of capstans and pinch rollers 2, 3, and 1 are set so that they are wound at a winding angle of 180 degrees and run, and the reading value of the entry side tension sensor 5 is 150 g.
0.11, each looped videotape 1 at 2m/sec
The loop-shaped videotape 1 was subjected to a fatigue strength test against repeated bending by driving and running at a speed of c. The results of this fatigue strength test were evaluated by reading the number of runs at the time when cracks or peeling occurred in the ferromagnetic metal thin film layer of each of the five types of video tapes.

In addition, the same five types of video tapes were wound into an 8 mm cassette and an 8 mm VTR (SONY: CCD-v8) was created.
A still (still image state) test was conducted, and the signal output was 3D.
The still execution time up to the time when B decreased was measured.

Figure 2 shows the relationship between the fatigue strength test results for each of the five video tapes and the still test results. (0) indicates the ferromagnetic metal thin film layer of each of the five video tapes. The number of runs at the zero point when cracking or peeling occurs is shown, and (△) shows the still execution time until the signal output drops by 3 dB.

〔Effect of the invention〕

As is clear from FIG. 2, the results of the fatigue strength test of each videotape correspond well with the results of the still test, and this shows that the method and apparatus for testing the strength of film structures of the present invention It can be seen that the fatigue strength corresponding to the bending stress of a film structure such as a videotape can be accurately tested.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of the strength testing device for a film structure of the present invention, and Fig. 2 shows the number of runs measured by the strength testing device for a film structure of the present invention and the times when the same videotape was subjected to a still test. FIG.

Claims (1)

[Claims] 1. A film structure processed into a tape shape is wound around an appropriate number of guide members at an angle of at least 90 degrees or more so that the sum of the wrapping angles is 1800 degrees or more. A strength testing method for a film structure 2, characterized in that the film structure is run continuously while the film structure is being run continuously, and the fatigue against bending stress of the film structure is examined to test the strength. An appropriate number of guide members for winding the traveling film structure at an angle of at least 90 degrees are arranged in parallel along the traveling path so that the total winding angle is 1800 degrees or more. A strength testing device for a film structure consisting of a strength testing section for examining the fatigue of the structure against bending stress.