JP2019113399A - Evaluation method of test device and cut-resistant performance - Google Patents

Abstract

To provide a test device 32 which can more accurately grasp the cut-resistant performance of a plate-like test piece 34.SOLUTION: A test device 32 is a test device 32 for evaluating the cut performance of a plate-like test piece 34, and includes a fixing portion 50 for holding the test piece 34 in a state of bending by gripping both ends of the test piece 34, a blade 52 for placing a notch in the test piece 34, and a hitting portion 54 for making the blade 52 hit a surface 76 of the test piece 34 in the curved state. The fixing portion 50 includes a pair of gripping means 56 each for gripping the end of the test piece 34, an actuator 58 for moving one gripping means 56 toward another gripping means 56, and a spacer 60 located on a back surface 74 side of the test piece 34.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a test apparatus and a method of evaluating cut resistance. In particular, the present invention relates to a test apparatus for evaluating cut resistance and a method of evaluating cut resistance using the test apparatus.

  Crawler-type traveling devices are used in agricultural machines such as combine harvesters and construction machines such as backhoes. This traveling device has an endless belt-like elastic crawler (hereinafter, also simply referred to as a crawler).

  FIG. 5 schematically shows an example of the traveling device 4 having the crawler 2. The traveling device 4 is provided with a sprocket 6 and a plurality of rolling wheels 8 in addition to the crawler 2.

  The sprocket 6 is disk-shaped. A large number of teeth 10 are provided on the periphery of the sprocket 6. The wheel 8 is disk-shaped. Like the sprockets 6, no teeth are provided on the periphery of the rolling wheel 8.

  In FIG. 6, the cross section of the crawler 2 along the AA of FIG. 5 is shown. The crawler 2 is provided with a core metal 12, a tensile body 14, a canvas 16 and an elastic member 18 as parts.

  The crawler 2 is provided with a number of core metals 12. Although only a part of the core metals 12 is shown in FIG. 5, these core metals 12 are arranged at a constant pitch in the longitudinal direction of the crawler 2 in the inner part of the crawler 2.

  The tensile body 14 is located outside the core 12. The tensile body 14 includes a plurality of cords 20. These cords 20 are arranged in parallel in the width direction of the crawler 2. Although only a portion of the tensile body 14 is shown in FIG. 5, the tensile body 14 is in the form of an endless belt and extends in the longitudinal direction of the crawler 2.

  The canvas 16 is located outside the tensile body 14. The canvas 16 is a fabric 22. Although only a portion of the canvas 16 is shown in FIG. 5, the canvas 16 is in the form of an endless belt and extends in the longitudinal direction of the crawler 2.

  The elastic member 18 is made of a crosslinked rubber. In the crawler 2, the core metal 12, the tensile body 14 and the canvas 16 are covered with an elastic member 18.

  The crawler 2 structurally comprises an endless belt 24, a number of lugs 26 and a number of guides 28. A number of lugs 26 project outwardly from the endless belt 24. A number of guides 28 project inwardly from the endless belt 24. Of the crawler 2, portions other than the lugs 26 and the guides 28 are endless belts 24.

  The crawler 2 further comprises a number of holes 30. Although only a portion of the holes 30 is shown in FIG. 5, each hole 30 is provided between the core 12 and another core 12 adjacent to the core 12. The teeth 10 of the sprocket 6 enter the holes 30.

  In this traveling device 4, when the sprocket 6 rotates, the teeth 10 that have entered the hole 30 drive the crawler 2. By this drive, the traveling device 4 moves forward. In FIG. 5, the left side is the front side of the traveling device 4.

  By the way, the ground on which the traveling device 4 travels often includes crushed stone and the like. For this reason, it is feared that crushed stone or the like hits the crawler 2 and the surface of the crawler 2 is scratched (also referred to as a cut). It is important to grasp the cut resistance performance of a rubber member such as the crawler 2 because the damage may grow if the damage occurs.

  With regard to the ease of scratching of the rubber member, for example, as in Patent Document 1, it is considered to place a blade on the surface of the rubber member for evaluation.

  In this patent document 1, the rubber sample is pressed by pushing the blade until a cut occurs on the surface of the rubber sample, and the pressing stroke or pushing force at the time the cut occurs or the external work amount until the time the cut occurs is obtained. Evaluation of the chipping resistance performance of is being attempted.

Japanese Patent Application Laid-Open No. 2016-075486

  For example, in the case of evaluating the cut resistance performance of the crawler 2 using the traveling device 4, it is necessary to manufacture the crawler 2, prepare the traveling device 4, and the like. Also this evaluation takes time to get the result. It takes cost and time to evaluate the cut resistance performance by the traveling device 4.

  In the aforementioned Patent Document 1, the blade is pressed without fixing the test piece. When the blade is pressed against the test piece, the test piece is warped, which may make it impossible to clearly grasp the difference between the test piece in the stroke, the pressing force and the external work amount. Since such curling does not occur in the crawler 2 of the traveling device 4, there is a concern that sufficient knowledge can not be obtained even if the cut resistance performance of the crawler 2 is evaluated by the method disclosed in this patent document 1. .

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a test apparatus and an evaluation method of the cut resistance, which can grasp the cut resistance of the plate-like test piece more accurately. To aim.

  The test apparatus according to the present invention is a test apparatus for evaluating the cut resistance performance of a plate-like test piece, and a fixing unit which holds both ends of the test piece and holds the test piece in a curved state. And a blade for making a cut in the test piece, and a striking part for striking the blade on the surface of the test piece in a curved state, wherein each of the fixing parts grips the end of the test piece And an actuator for moving one of the holding means toward the other holding means, and a spacer located on the back side of the test piece.

  Preferably, in this test device, the curvature radius of the surface of the test piece in a curved state is 30 mm or more and 150 mm or less.

  Preferably, in this test apparatus, the striking portion is a pendulum-type hammer, and the hammer includes an arm rotatably supported at one end, and a weight fixed to the other end of the arm. The blade is attached to the weight.

  Preferably, in this test device, an angle between the arm with the weight lifted and the arm with the weight directly below is 10 ° or more and 180 ° or less.

  Preferably, in this test device, the length of the arm is 0.5 m or more and 1.5 m or less.

The evaluation method according to the present invention is a method for evaluating the cut resistance performance of a plate-like test piece using the above-mentioned test apparatus,
A gripping step of gripping both ends of the test piece,
A bending step of bending the test piece;
A striking step is included which strikes the blade on the surface of the test piece in a curved state.

  The test apparatus according to the present invention can set the bending state of the test piece in the same manner as the bending state of the crawler of the traveling device (in particular, the portion in contact with the front wheel). For this reason, according to this test apparatus and the evaluation method using this test apparatus, the cut resistance performance of the crawler can be grasped more accurately and quantitatively. Moreover, since it is not necessary to prepare a traveling device for grasping the cutting resistance performance of the crawler, this test device and the evaluation method using this test device can also shorten the development time and reduce the development cost.

FIG. 1 is a schematic view showing an example of a test apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing a test piece used in the test apparatus of FIG. FIG. 3 is a schematic view showing a state in which the test piece is gripped by the gripping means of the test apparatus. FIG. 4 is a schematic view showing a state in which the test piece is bent. FIG. 5 is a front view showing a part of a traveling device having an elastic crawler. 6 is a cross-sectional view taken along the line AA of FIG.

Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the drawings as appropriate.

  FIG. 1 shows a portion of a test apparatus 32 for evaluating the cut resistance performance of a rubber member such as the crawler 2 shown in FIG. In this test apparatus 32, for example, the test strip 34 shown in FIG. 2 is used. In FIG. 2, the direction indicated by the arrow X is the width direction of the test piece 34, the direction indicated by the arrow Y is the longitudinal direction of the test piece 34, and the direction indicated by the arrow Z is the thickness of the test piece 34. It is

[Test strip 34]
The test piece 34 is plate-shaped. The test piece 34 simulates the crawler 2. The test strip 34 includes a plurality of steel cords 36, a canvas 38 and an elastic member 40.

  In the test piece 34, a plurality of steel cords 36 are arranged in parallel in the width direction. Each steel cord 36 extends in the longitudinal direction of the test piece 34. In the test piece 34, a plurality of steel cords 36 (hereinafter also referred to as a code group 42) arranged in parallel in the width direction correspond to the tensile members 14 in the crawler 2 shown in FIG. As the steel cord 36 of the test piece 34, a steel cord which is adopted for the tensile body 14 of the crawler 2 or which will be adopted as the tensile body 14 is preferably used.

  In the test piece 34, the canvas 38 has a width substantially equal to the width of the cord group 42 described above. The canvas 38 has a length substantially equal to the length of the code group 42 described above. The canvas 38 is a fabric 44. The woven fabric 44 is composed of warp yarns and weft yarns. Of the warp and weft yarns, warp yarns are shown in FIG. The canvas 38 corresponds to the canvas 16 in the crawler 2 shown in FIG. For the canvas 38 of the test piece 34, it is preferable to use the fabric 22 employed for the canvas 16 of the crawler 2 or a fabric equivalent to the fabric to be employed for the canvas 16. In the test piece 34, a plurality of organic fiber cords aligned in the width direction may be used as the canvas 38 in place of the woven fabric 44.

  In the test piece 34, the elastic member 40 covers the cord group 42 and the canvas 38. The elastic member 40 is made of a crosslinked rubber. The elastic member 40 corresponds to the elastic member 18 in the crawler 2 shown in FIG. The elastic member 40 of the test piece 34 is preferably made of a crosslinked rubber which is adopted for the elastic member 18 of the crawler 2 or which will be adopted as the elastic member 18.

  In the test piece 34, in the thickness direction, the upper surface 46 is referred to as a first surface, and the lower surface 48 is referred to as a second surface. As shown in FIG. 2, the canvas 38 is located between the first surface 46 and the cord group 42. In the test piece 34, the canvas 38 is not provided between the cord group 42 and the second surface 48. As described above, this test piece 34 simulates the crawler 2. As shown in FIG. 6, in the endless belt 24 of the crawler 2, the canvas 16 is located closer to the lug 26 than the tensile body 14, and the tensile body 14 is located closer to the guide 28 than the canvas 16. ing. That is, in the test piece 34, the first surface 46 corresponds to the lug 26 side of the crawler 2, and the second surface 48 corresponds to the guide 28 side of the crawler 2.

  In FIG. 2, the solid line LS represents the upper end position of the cord group 42 in the thickness direction of the test piece 34. The double arrow ts is the distance in the thickness direction from the first surface 46 to the upper end position LS. The solid line LC represents the upper end position of the canvas 38 in the thickness direction of the test piece 34. The double arrow tc is the distance in the thickness direction from the first surface 46 to the upper end position LC.

  In the test piece 34, the distance ts and the distance tc are appropriately determined in consideration of the specification of the crawler 2 from the viewpoint of reproduction of the endless belt 24 in the crawler 2. Specifically, the distance ts is preferably 3 mm or more and 13 mm or less. The distance tc is preferably 1 mm or more and 11 mm or less. The thickness, width, and length of the test piece 34 are appropriately determined in consideration of the specifications of the crawler 2. The thickness of the test piece 34 is usually set in the range of 10 to 30 mm. The width of the test piece 34 is usually set in the range of 50 to 100 mm. The length of the test piece 34 is usually set in the range of 100 to 200 mm.

[Testing apparatus 32]
Next, a test apparatus 32 for evaluating the cut resistance performance of the plate-like test piece 34 will be described. The test apparatus 32 includes a fixing portion 50, a blade 52, and a striking portion 54.

[Fixing part 50]
The fixing portion 50 grips both ends of the test strip 34 and holds the test strip 34. The fixing unit 50 includes a pair of gripping means 56, an actuator 58, and a spacer 60.

  Each of the gripping means 56 comprises a clip 62 for gripping the end of the test piece 34, a mount 64 fixed to the frame of the test apparatus 32, and the clip 62 rotatably supported relative to the mount 64. And a rotary connection member 66 connecting the two.

  The actuator 58 moves one gripping means 56 toward the other gripping means 56. The actuator 58 includes a piston 68 and a cylinder 70. The actuator 58 is configured such that the piston 68 reciprocates with respect to the cylinder 70.

  In this test apparatus 32, the mount 64 of the lower gripping means 56 is directly fixed to the frame 72 of the test apparatus 32. Although not shown, the mount 64 of the upper gripping means 56 is indirectly fixed to the frame 72 of the test apparatus 32 via the actuator 58. In this test apparatus 32, when the piston 68 moves downward, the upper gripping means 56 approaches the lower gripping means 56. On the other hand, when the piston 68 moves upward, the upper gripping means 56 separates from the lower gripping means 56.

  The spacer 60 is located on the back surface 74 side of the test piece 34. The test apparatus 32 is configured such that the spacer 60 can be moved in the horizontal direction by a horizontal moving means (not shown) to press the back surface 74 of the test piece 34. It is preferable that the surface of the spacer 60 in contact with the test piece 34 be rounded, in view of the fact that the distortion of the test piece 34 is suppressed by the contact of the spacer 60 with the test piece 34. Although the thickness of the spacer 60 is determined in consideration of the degree of distortion occurring in the test piece 34, this thickness is usually set in the range of 10 to 30 mm. Although the width of the spacer 60 is determined in consideration of the width of the test piece 34, the width is generally set in the range of 50 to 100 mm.

  In this test apparatus 32, as shown in FIG. 3, the ends of the test strip 34 are gripped by the upper and lower clips 62 respectively. Thereby, the test piece 34 is attached to the fixing portion 50. The downward movement of the piston 68 of the actuator 58 causes the upper gripping means 56 to move toward the lower gripping means 56. As a result, the distance between the two gripping means 56 is reduced. Further, in the test apparatus 32, the spacer 60 is moved in the horizontal direction by a horizontal movement means (not shown), and the spacer 60 is pressed against the back surface 74 of the test piece 34. Thereby, as shown in FIG. 4, the test piece 34 is held by the fixing portion 50 in a curved state. In the test piece 34 held in the fixed portion 50 in a curved state, a portion of the surface 76 is stretched and a portion of the back surface 74 is compressed.

[Blade 52]
The blade 52 cuts a test piece 34 held by the fixed portion 50 described above. In the test device 32, the blade 52 is disposed to face the surface 76 of the test piece 34. In this test device 32, the blade 52 is a double-edged blade. The blade 52 is cool. In the test device 32, a single-edged blade may be used as the blade 52. The blade 52 used in the test apparatus 32 is preferably a double-edged blade rather than a single-bladed blade from the viewpoint that distortion generated in the test piece 34 is less likely to be biased when the blade 52 is pressed against the test piece 34.

  In FIG. 1, the angle α is the angle of the cutting edge 78. The double arrow TB is the thickness of the blade 52. In the test apparatus 32, the angle α of the blade edge 78 is set in the range of 20 ° to 40 °. The thickness TB is set in the range of 0.2 mm to 2 mm. The width of the blade 52 is set in the range of 5 mm to 30 mm.

[Strike section 54]
The striking portion 54 strikes the blade 52 onto the surface 76 of the test piece 34 in a curved state. In this test apparatus 32, the striking portion 54 is a pendulum hammer 80. The hammer 80 includes an arm 82 and a weight 84. In the test device 32, the arm 82 is fixed at one end to a frame 72 (not shown) of the test device 32. In this test apparatus 32, one end of the arm 82 is rotatably supported by the frame 72. A weight 84 is fixed to the other end of the arm 82.

  In this test device 32, the above-mentioned blade 52 is attached to the weight 84 with the cutting edge 78 directed to the test piece 34 side. When the weight 84 is lifted upward and dropped, the blade 52 moves toward the test piece 34 while drawing a locus of a circular arc. The blade 52 strikes the surface 76 of the test specimen 34 when the weight 84 is directly below. In the test apparatus 32, the striking portion 54 is not limited to the pendulum hammer 80. For example, the test piece 34 is disposed so that the surface 76 of the test piece 34 faces upward, and the blade 52 attached to the weight 84 is dropped from above the test piece 34 and the blade 52 is hit against the test piece 34 The striking portion 54 may be configured to cause the movement.

[Evaluation method]
The cut resistance performance of the test piece 34 is evaluated as follows using the test piece 34 and the test apparatus 32 described above. A method (hereinafter, also referred to as an evaluation method) for evaluating the cut resistance performance of the plate-like test piece 34 using the test apparatus 32 includes a preparation step, a gripping step, a bending step, and a striking step. .

  In the preparation step, a test piece 34 is prepared. In this preparation step, the rubber composition for the elastic member 40, the cord group 42 and the canvas 38 are combined to obtain a preform of the test piece 34, and then this preform is pressed and heated, as shown in FIG. The test strip 34 shown in FIG. A sample obtained by cutting out a part of the crawler 2 may be used as the test piece 34. In this case, a portion including the one lug 26 and the lug 26 located next to the one lug 26 (the portion indicated by the alternate long and two short dashes line SC in FIG. 5) is cut out. The portion of the endless belt 24 (outer portion of the core metal 12) located on the is subject to evaluation. In FIGS. 5 and 6, the area surrounded by the dotted line RE is the part to be the target of this evaluation. In addition, when obtaining the test piece 34 shown by FIG. 2 from a preformed body, the test piece 34 should just be obtained in the shaping | molding state equivalent to the crawler 2, and a restriction | limiting in particular on the conditions of pressurization and heating of a preformed body. There is no.

  In the gripping step, the test piece 34 obtained in the preparation step is attached to the fixing portion 50. In this gripping step, both ends of the test strip 34 are firmly gripped by the clips 62 so that the end of the test strip 34 does not come off from the clip 62 of the gripping means 56 of the fixed portion 50. When the test piece 34 shown in FIG. 2 is to be evaluated, this test is performed so that the first surface 46 of the test piece 34 is positioned on the blade 52 side as the surface 76 of the test piece 34 in this gripping step. The piece 34 is set to the fixing portion 50. When a sample obtained by cutting out from the crawler 2 is used as the test piece 34, the test piece 34 is set to the fixing portion 50 so that the surface on the side of the lug 26 is positioned on the blade 52 side as the surface 76 of the test piece 34. Ru.

  In the bending step, in a state where both ends of the test piece 34 are held by the holding means 56, the distance between the upper and lower holding means 56 is reduced by the actuator 58, and the spacer 60 is used as a test piece by the horizontal movement means (not shown). It is pressed against the back surface 74 of 34. Thereby, the test piece 34 is bent. In this evaluation method, the test piece 34 is held by the fixing portion 50 in a curved state.

  In the striking step, the height of the weight 84 is adjusted. After adjustment, the weight 84 is released, and the blade 52 set in the weight 84 is struck on the surface 76 of the test piece 34 in a curved state. There is no particular limitation on the position at which the test piece 34 is hit by the blade 52 (hereinafter also referred to as a hit position), but from the viewpoint of effectively reflecting the fact that the test piece 34 is curved. Preferably, the top of the curved portion, indicated by the symbol PT in 4, is set as the striking position of the blade 52.

  The crawler 2 in the traveling device 4 is curved, for example, by a roller 8 located on the front side, as shown in FIG. This curvature causes the portion of the endless belt 24 on the side of the lugs 26 to be stretched. In this test apparatus 32, the surface 76 of the test piece 34, ie, the portion of the first surface 46 is stretched. As described above, the side of the first surface 46 of the test piece 34 corresponds to the side of the lug 26 of the crawler 2.

  The test apparatus 32 for this evaluation method can effectively control the degree of bending of the test piece 34 by adjusting the distance between the gripping means 56. That is, in the test apparatus 32 and the evaluation method using the test apparatus 32, the bending state of the test piece 34 is the curvature of the crawler 2 of the traveling device 4 (in particular, the portion in contact with the front wheel 8). It can be set the same as the state. For this reason, the test apparatus 32 and the evaluation method can apply a force similar to the force acting on the crawler 2 in the traveling state to the portion of the surface 76 of the test piece 34. According to the test apparatus 32 and the evaluation method, the cut resistance performance of the crawler 2 can be grasped more accurately and quantitatively. Further, since it is not necessary to prepare the traveling device 4 for grasping the cut resistance performance of the crawler 2, the test apparatus 32 and the evaluation method can also shorten the development time and reduce the development cost.

  In this test apparatus 32 and the evaluation method, by changing the height at which the weight 84 is released, the speed of the blade 52 striking the test piece 34 is close to the speed at which crushed stone etc. hits the crawler 2 in the running state (570 mm / s It can be adjusted to a range of 4600 mm / s). This contributes to an accurate and quantitative grasp of the anti-cut performance of the crawler 2. In this test apparatus 32 and the evaluation method, as the striking part 54 of the test apparatus 32, as shown in FIG. 1, from the viewpoint of being able to adjust the speed of the blade 52 striking the test piece 34 precisely and easily. A pendulum hammer 80 is preferred.

  In this test apparatus 32, the contour of the surface 76 of the test piece 34 in a curved state is approximated by an arc passing through the apex PT. In FIG. 4, the arrow Rs represents the radius of this arc. The radius Rs is a radius of curvature of the surface 76 of the test piece 34 in a curved state.

  In the test apparatus 32 and the evaluation method, the curvature radius Rs of the surface 76 of the test piece 34 in a curved state is preferably 30 mm or more, and more preferably 150 mm or less. As a result, a force similar to the force acting on the crawler in the traveling state can be exerted on the surface 76 of the test piece 34. In this respect, the curvature radius Rs is more preferably 50 mm or more, and more preferably 125 mm or less.

  In FIG. 5, the arrow Rt is half of the outer diameter of the roller 8 located on the front side of the traveling device 4 on which the crawler 2 to be evaluated is mounted, that is, the radius.

  In this test apparatus 32 and the evaluation method, the ratio of the radius of curvature Rs of the surface 76 of the test piece 34 in a curved state to the radius Rt of the rotating wheel 8 of the traveling device 4 on which the crawler 2 to be evaluated is mounted is 80 % Or more is preferable and 120% or less is preferable. Thereby, in the test piece 34, a state close to the state of the crawler 2 stretched by the front wheel 8 of the traveling device 4 can be reproduced, and the cut resistance performance of the crawler 2 can be more accurately evaluated. . In this respect, the ratio is more preferably 90% or more, and more preferably 110% or less.

  In FIG. 1, the double arrow LA represents the length from the rotation center of the arm 82 to the blade 52 (specifically, the blade edge 78). This length LA is measured along the arm 82. In the present invention, this length LA is the length of the arm 82. This length LA is also referred to as the length of the pendulum.

  In the test apparatus 32 and the evaluation method, the length LA of the arm 82 is preferably 0.5 m or more, and more preferably 1.5 m or less. By setting the length LA to 0.5 m or more, it is possible to adjust the speed of the blade 52 just before striking the test piece 34 at a speed close to the speed at which crushed stone etc. strikes the traveling crawler 2. . On the other hand, when the length LA is set to 1.5 m or less, the test apparatus 32 can be configured with an appropriate size, and good workability can be maintained.

  In FIG. 1, what is indicated by a two-dot chain line is the arm 82 in a state where the weight 84 is directly below. The angle θ is the angle that the arm 82 with the weight 84 lifted up makes with the arm 82 with the weight 84 directly below. The angle θ is measured immediately before lifting the weight 84 and releasing the weight 84.

  In the test apparatus 32 and the evaluation method, the speed of the blade 52 can be adjusted by changing the angle θ. The angle θ is preferably 10 ° or more and 180 ° or less from the viewpoint that the speed of the blade 52 striking the test piece 34 can be adjusted at a speed close to the speed at which crushed stone or the like hits the crawler 2 in a running state. . In other words, this angle θ is preferably set in the range of 10 ° or more and 180 ° or less.

  In the test apparatus 32 and the evaluation method, the mass of the weight 84 of the striking portion 54 affects the speed of the blade 52 striking the test piece 34. The weight of the weight 84 is preferably 20 kg or more and 40 kg or less from the viewpoint that the speed of the blade 52 striking the test piece 34 can be adjusted at a speed close to the speed at which crushed stone etc. hit the crawler 2 in running condition. preferable.

  As apparent from the above description, the test apparatus 32 of the present invention for evaluating the cut resistance performance and the method of evaluating the cut resistance performance using this test apparatus 32 are plate-shaped tests corresponding to the crawler 2 The cut resistance performance of the piece 34 can be grasped more accurately.

  Hereinafter, the present invention will be described in more detail by way of examples and the like, but the present invention is not limited to only such examples.

[Example]
[Test specimen preparation]
Two plate-shaped test pieces (length = 150 mm, width = 65 mm, thickness = 20 mm) were prepared.

  One of the test pieces (hereinafter, test piece A) was composed of a cord group, a canvas and an elastic member, as in the test piece shown in FIG. Although detailed description is omitted, cords, canvas and elastic members generally used in crawlers are used for cords, canvas and elastic members. In this test piece A, the thickness direction distance tc was set to 5 mm. The thickness direction distance ts was set to 7 mm.

  The other test piece (hereinafter, test piece B) had the same specifications as test piece A except that the canvas was not provided. The thickness direction distance ts of the test piece B was set to 7 mm.

[Evaluation of cut resistance]
The cut resistance performance of the test piece A was evaluated using a test device having the basic configuration shown in FIG. The mass of the weight was set to 30 kg. The arm length LA was set to 1.09 m. As the blade, a double-edged blade (angle α = 20 °, thickness TB = 2 mm, width (depth) = 20 mm) was used.

  As shown in FIG. 3, each of both ends of the test strip A was gripped by the gripping means of the test apparatus. This test piece A was set to the fixing portion so that the first surface of the test piece A was located on the blade side. The actuator moved the upper gripping means toward the lower gripping means, and the spacer was pressed against the back of the test piece. This caused the test specimen to bend as shown in FIG. The radius of curvature of the arc representing the contour of the specimen surface in a curved state was set to 110 mm.

  By lifting the weight and releasing the weight, the blade was hit on the portion of the top PT of the test piece in a curved state. The angle θ between the arm with the weight lifted and the arm with the weight directly below was set to 36 °.

  Whether the blade reached the steel cord was judged by the sound at the time of striking. In addition, if the blade did not reach the steel cord without making a noise at the time of striking, the test strip A was replaced with a new separate test strip A. The test was carried out on this new additional specimen A with an angle θ increased by 2 °. The striking of test specimen A by this blade was repeated until the blade reached the steel cord while increasing the angle θ in 2 ° steps. In this test strip A, it was confirmed that the blade reached the steel cord when the angle θ was 44 °.

  The same evaluation was performed on the test piece B. In this test strip B, it was confirmed that the blade reached the steel cord when the angle θ was 38 °.

  Potential energy was calculated from the obtained angle θ, arm length LA, mass of weight and gravitational acceleration. The calculation results are shown as destruction energy in Table 1 below. The larger the value, the better the cut resistance of the test piece.

  As a comparative example, the cut resistance performance of the test pieces A and B was evaluated by the method disclosed in Japanese Patent Application Laid-Open No. 2016-075486. However, the test pieces were warped and the difference due to the presence or absence of the canvas was clarified. Could not confirm. On the other hand, in the evaluation method of the example, as shown in Table 1, it could be clearly confirmed that the difference in the destruction energy is caused by the presence or absence of the canvas. From the above results, the superiority of the present invention is clear.

  The techniques relating to the test apparatus and the evaluation method of cut resistance described above can be applied not only to crawlers but also to evaluation of cut resistance of various rubber products.

2 ... crawler 4 ... traveling device 6 ... sprocket 8 ... rotary wheel 12 ... core metal 14 ... tensile bodies 16 ... canvas 18,40 ... elastic member 24, · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 28 48 ... second surface 50 ... fixing portion 52 ... blade 54 ... hitting portion 56 ... grasping means 58 ... actuator 60 ... spacer 74 ... rear surface 76 ... surface 78 ··· Cutting edge 80 ··· Hammer 82 ··· Arm 84 · · · Weight

Claims (6)

A testing apparatus for evaluating the cut resistance performance of a plate-like test piece,
A fixing portion configured to hold the test piece in a curved state by gripping both ends of the test piece;
A blade for cutting the test piece;
A striking portion for striking the blade on the surface of the test piece in a curved state;
Equipped with
The fixing portion comprises a pair of gripping means each gripping the end of the test strip, an actuator for moving one of the gripping means toward the other gripping means, and a spacer positioned on the back side of the test strip And, test equipment.   The test apparatus according to claim 1, wherein a curvature radius of a surface of the test piece in a curved state is 30 mm or more and 150 mm or less. The striking part is a pendulum-type hammer,
The hammer includes an arm rotatably supported at one end, and a weight fixed to the other end of the arm.
The test apparatus according to claim 1, wherein the blade is attached to the weight.   The test apparatus according to claim 3, wherein an angle formed by the arm in a state in which the weight is lifted with respect to the arm in a state in which the weight is directly below is 10 ° or more and 180 ° or less.   The test apparatus according to claim 3, wherein a length of the arm is 0.5 m or more and 1.5 m or less. A method for evaluating the cut resistance performance of a plate-like test piece using the test apparatus according to any one of claims 1 to 5,
A gripping step of gripping both ends of the test piece, and a bending step of bending the test piece;
And a striking step of striking a blade on the surface of the test piece in a curved state.

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