Cutting device and cutting method for cutting sheet material into dumbbell shapes

Abstract

To provide a cutting device and a cutting method which cut a test piece simply, easily, moreover, with a shortened tact time, efficiently and with high dimensional accuracy.SOLUTION: A cutting device is placed with sheet material 6 on a bearing base 5 and cuts the sheet material into a dumbbell shaped test piece 7 with a cylindrical punch-cutting tool 1. The cylindrical punch-cutting tool 1 is a single-edge cutter provided with an outside blade surface 11 on an outer circumferential surface of a lower end part, has a modifying blade surface 12 which modifies a cutting direction of the sheet material 6, and has, on a top edge of the outside blade surface 11 and the modifying blade surface 12, a blade tip 10 which cuts out the sheet material 6 into a dumbbell shape. An uneven interval (L2) being an interval between a cylindrical inner circumferential surface 14 and the blade tip 10 of the punch-cutting tool 1 is 1 / 4 or less of a single edge interval (L1) being an interval between a cylindrical outer circumferential surface 13 and the blade tip 10, and the blade tip 10 of the single blade is positioned deviated outward from the cylindrical inner circumferential surface 14 of the punch-cutting tool 1.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for cutting sheet materials such as rubber and plastic into dumbbell-shaped test pieces for use in tensile tests, impact tests, and the like. [Background technology]

[0002] Materials used for various purposes undergo various tests such as tensile tests and impact tests based on JIS. For example, rubber used in tires is made into rubber sheets of a specified thickness and cut into dumbbell-shaped test pieces for tensile tests and impact tests. The sheet material is cut to dimensions that comply with JIS standards for thickness and external dimensions before being used for tensile tests.

[0003] A cutting device that cuts sheet material into a dumbbell shape has been developed (see Patent Document 1). The cutting device described in Patent Document 1 is described in the "Solution" section of the publication as having the following structure. The test piece punching device is made up of a slide base arranged on a base so as to be slidable back and forth, a rotation base arranged on the slide base so as to be horizontally rotatable, a clamp mechanism that fixes and holds a sheet material on the rotation base, and a cutter device located above the rotation base and attached to the base for punching the sheet material. The cutter device has a lifting cylinder fixed to the base and having a cylinder rod that can be extended and retracted downward, and a thin-bladed punching blade attached to the lower end of the cylinder rod and extending in the longitudinal direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-210899 A Summary of the Invention [Problem to be solved by the invention]

[0005] The cutting devices described in the above publications cut the sheet material with a single linear punching blade, so both sides of the test piece must be cut separately. In particular, to cut a dumbbell-shaped test piece, either the sheet material or the punching blade must be rotated 180 degrees to cut twice, making the cutting device extremely complicated and lengthening the takt time, which is a drawback in that it is not possible to mass-produce efficiently. Furthermore, since both sides of the dumbbell shape are cut separately, in order to achieve high accuracy in the dimensional error of the cut dumbbell shape, the cutting device must also be highly accurate, which is a drawback that the cost of the device becomes significantly high.

[0006] Furthermore, conventional cutting devices use thin-blade punching blades to increase the dimensional accuracy of the cut test pieces, which has the drawback of short blade life and time-consuming maintenance such as blade replacement. Although the life of the punching blade can be extended by making it thicker, when a thick sheet material is cut into a dumbbell shape with a thick punching blade, the cutting surface of the blade edge shifts in the width direction of the test piece, making it impossible to cut to accurate dimensions.

[0007] The present invention was developed with the aim of eliminating the above-mentioned drawbacks, and an important object of the present invention is to provide a cutting device and cutting method for cutting sheet material into dumbbell shapes that can cut test pieces simply, easily, efficiently by shortening the takt time using a cutting device of simple structure, and that can cut test pieces with high dimensional accuracy. [Means for solving the problem]

[0008] According to one embodiment of the present invention, a cutting device for cutting a sheet material into a dumbbell shape places the sheet material on a receiving table and cuts it into dumbbell-shaped test pieces with a cylindrical punching blade. The cylindrical punching blade is a single-edged blade having an outer blade surface on the outer peripheral surface of the lower end, a correction blade surface on the inner peripheral surface of the single blade for correcting the cutting direction of the sheet material, and a blade tip on the tip edge between the outer blade surface and the correction blade for punching the sheet material into a dumbbell shape, and the offset distance (L2) between the cylindrical inner peripheral surface of the punching blade and the blade tip is ¼ or less of the single-blade distance (L1) between the cylindrical outer peripheral surface and the blade tip, and the blade tip of the single blade is offset outward from the cylindrical inner peripheral surface of the punching blade.

[0009] According to another aspect of the present invention, a cutting device for cutting sheet material into a dumbbell shape comprises a receiving table having a cutting surface on which the sheet material to be cut into test pieces is placed and cut, a cylindrical punching blade that reciprocates toward the cutting surface to cut the sheet material on the cutting surface into dumbbell-shaped test pieces having chucking areas at both ends of a central test area, a drive mechanism that reciprocates the punching blade in a direction perpendicular to the surface of the receiving table, a flat pusher that is arranged inside the cylindrical inner surface of the cylindrical punching blade so as to be able to move back and forth relatively to the inside, and an elastic body that elastically protrudes the flat pusher from the tip of the punching blade. The cylindrical punching blade is a single-edged blade with an outer blade surface on the outer peripheral surface of the lower end, and the inner peripheral surface of the single blade has a correction blade surface that corrects the cutting direction of the sheet material, and the tip edge between the outer blade surface and the correction blade surface has a blade tip that punches the sheet material into a dumbbell shape, and the blade tip of the single blade is offset outward from the cylindrical inner peripheral surface of the punching blade. The drive mechanism includes upper and lower tables that reciprocate the punching blade and the flat pusher. The punching blade is fixed to the upper and lower tables in a non-reciprocating state, but the flat pusher is connected to the upper and lower tables via an elastic body so as to be freely reciprocating. The flat pusher has a flat pressing surface that presses the sheet material on the surface facing the cutting surface, and a slit gap is provided between the inner peripheral surface of the punching blade and the outer peripheral surface of the flat pusher, allowing the flat pusher to reciprocate relative to the punching blade. The flat pusher is arranged such that the punching blade is pushed out by the elastic body at a non-cutting position of the sheet material, and the pressing surface protrudes from the cutting edge of the punching blade.

[0010] In one embodiment of the present invention, a cutting method for cutting a sheet material into a dumbbell shape involves placing the sheet material to be cut into test pieces on the cutting surface of a receiving table, and using a punching blade to cut the sheet material into dumbbell-shaped test pieces having chucking areas at both ends of a central test area, and cutting the sheet material into a dumbbell shape by the following methods (A) to (F). (A) The punching blade is a single-edged blade having a dumbbell-shaped cutting edge at the tip and an outer cutting surface on the outer peripheral surface of the lower end, the inner peripheral surface of the single blade has a correcting blade surface which corrects the cutting direction of the sheet material, and the tip edge of the outer cutting surface and the correcting blade surface has a cutting edge which punches the sheet material into a dumbbell shape, the distance (L2) between the cylindrical inner peripheral surface of the punching blade and the cutting edge is 1 / 4 or less of the distance (L1) between the cylindrical outer peripheral surface and the cutting edge, and the cutting edge of the single blade is offset outward from the cylindrical inner peripheral surface. (B) The surface of the sheet material is pressed with a pressure plate and cut with the punching blade. (C) Inside the cylindrical punching blade, the surface of the sheet material is pressed with the pressing surface of a flat pusher to cut it. (D) The punching blade and the flat pusher are moved back and forth via an elastic body on an upper and lower table that reciprocates the punching blade to press the sheet material. (E) The flat pusher has a width smaller than that of the dumbbell-shaped cylindrical punching blade, and has a slit gap between it and the inner surface of the punching blade, causing it to reciprocate inside the punching blade. (F) The flat pusher has a pressing surface positioned at a position protruding from the tip of the punching blade when the punching blade is in a non-cutting position where it is not cutting the sheet material, and when the punching blade is in a state where it is cutting the sheet material, the flat pusher presses the inside of the punching blade to cut it. Effect of the Invention

[0011] The cutting device and cutting method described above have the advantage that they can use a cutting device of simple structure to simply, easily, and efficiently cut dumbbell-shaped test pieces from sheet material while shortening the takt time, and furthermore, can cut the test pieces with high dimensional accuracy. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic front view of a cutting device according to a first embodiment of the present invention. [Diagram 2] 2 is a front view showing a blade unit of the cutting device shown in FIG. 1. [Diagram 3] FIG. 3 is a bottom view of the blade unit shown in FIG. 2. [Figure 4] 4 is a vertical cross-sectional view of the blade unit shown in FIG. 2, which corresponds to the cross-section taken along line IV-IV in FIG. 3. [Diagram 5] 3. FIG. 4 is a vertical cross-sectional view of the blade unit shown in FIG. 2, which corresponds to the cross section taken along line VV in FIG. [Figure 6] 6 is a vertical cross-sectional view of the blade unit shown in FIG. 2, which corresponds to the cross section taken along line VI-VI in FIG. [Figure 7] FIG. 4 is an enlarged cross-sectional view of a main portion showing a state in which a punching blade cuts a sheet material. [Figure 8] 2 is a perspective view showing an example of a test piece to be cut by the cutting device of FIG. 1. [Figure 9] FIG. 11 is a bottom view showing another example of the blade unit. [Figure 10] FIG. 10 is a vertical cross-sectional view of the blade unit shown in FIG. 9. [Figure 11] FIG. 11 is an enlarged cross-sectional view of a main part showing a state in which a punching blade of a cutting device according to a second embodiment of the present invention cuts a sheet material. [Figure 12] FIG. 11 is an enlarged cross-sectional view of a main portion showing a state in which a punching blade of a conventional cutting device cuts a sheet material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In one embodiment of the present invention, a cutting device for cutting a sheet material into a dumbbell shape places the sheet material on a receiving table and cuts it into dumbbell-shaped test pieces with a cylindrical punching blade. The cylindrical punching blade is a single-edged blade having an outer blade surface on the outer peripheral surface of the lower end, a correction blade surface on the inner peripheral surface of the single blade for correcting the cutting direction of the sheet material, and a blade tip on the tip edge between the outer blade surface and the correction blade surface for punching the sheet material into a dumbbell shape, and the offset distance (L2) which is the distance between the cylindrical inner peripheral surface of the punching blade and the blade tip is 1 / 4 or less of the single-blade distance (L1) which is the distance between the cylindrical outer peripheral surface and the blade tip, and the blade tip of the single blade is offset outward from the cylindrical inner peripheral surface of the punching blade.

[0014] In the above-mentioned cutting device, the punching blade is a single-edged blade with a cylindrical inner peripheral surface being a nearly vertical surface and an outer blade surface being provided on the outer peripheral surface. Furthermore, a correction blade surface is provided on the inner peripheral surface of the single blade, and the tip edge between the outer blade surface and the correction blade surface is a dumbbell-shaped blade tip. Furthermore, the distance (L2) between the cylindrical inner peripheral surface and the blade tip of the punching blade is 1 / 4 or less of the distance (L1) between the cylindrical outer peripheral surface and the blade tip, and the blade tip is offset from the cylindrical inner peripheral surface to the outside. Since the above-mentioned punching blade can punch a dumbbell-shaped test piece from the sheet material in a single punching process, there is no need to cut both sides of the test piece in two steps as in the conventional cutting device. In addition, there is no need to rotate the sheet material or the punching blade 180 degrees to cut both sides of the dumbbell shape, and a dumbbell-shaped test piece can be efficiently punched out of the sheet material in a single punching process.

[0015] Furthermore, the above punching blade has a unique blade edge shape in which the cutting edge of the single blade is biased from the inner peripheral surface to the outer peripheral surface, so that the test piece can be punched into a dumbbell shape with high dimensional accuracy. This is because the cutting edge can prevent the single blade from cutting into the inside of the sheet material, more precisely, in the direction narrowing the width of the dumbbell shape, during the process of cutting the sheet material. The punching blade that cuts the sheet material in this state can correct the cutting direction of the cutting edge to a direction perpendicular to the surface of the sheet material by the cutting edge provided on the inner peripheral surface of the single blade.

[0016] The enlarged cross-sectional view of FIG. 7 shows the state where the blade tip 10 cuts the sheet material 6. This figure shows the pressing forces F1 and F2 acting on the outer blade surface 11 and the correcting blade surface 12 at the timing when the blade tip 10 cuts the sheet material 6 by biting into it. As shown in this figure, when the single-edged blade tip 10 bites into the sheet material 6, a lateral force F1 is generated on the outer blade surface 11, and a force acting to bite into the sheet material 6 in a direction narrowing the width of the dumbbell shape acts. Furthermore, when the single-edged blade tip 10 bites into the sheet material 6, a lateral force F2 is generated on the single-edged blade tip 10 by the correcting blade surface 12 provided on the inside, and acts in a direction widening the width of the dumbbell shape. The force F1 acting on the outer blade surface 11 to narrow the width of the dumbbell shape and the force F2 acting on the correcting blade surface 12 to widen the width of the dumbbell shape are balanced with each other, so that the dumbbell shape is cut to an accurate width.

[0017] Furthermore, the above punching blades have an offset distance (L2) between the correcting blade faces on the inner peripheral surface of the blade edge, which is less than 1 / 4 of the single blade distance (L1) between the outer blade faces. When the blade edge bites into the sheet material to cut it, the direction in which the blade edge penetrates the sheet material is particularly strongly affected by a small area of ​​the blade edge. Therefore, by providing a small correcting blade face on the inner peripheral surface of the single blade, the blade edge can penetrate in a direction perpendicular to the sheet material surface and cut the test piece while maintaining a constant width.

[0018] Furthermore, in the above punching blade, the correcting blade surface provided on the inside of the cutting edge is smaller than the outer blade surface, and the cylindrical inner peripheral surface is a nearly vertical surface, so that the cut test piece can be smoothly inserted into the inside of the punching blade. The test piece smoothly inserted into the inside of the punching blade is not strongly pressed in the width direction. Therefore, after being punched into a dumbbell shape, the test piece is not deformed or altered by being inserted into the cylindrical inner peripheral surface, and can be smoothly pushed out of the punching blade.

[0019] In another embodiment of the cutting device for cutting a sheet material into a dumbbell shape according to the present invention, the effective inclination angle of the correction blade surface is set to 5 degrees or less.

[0020] In this specification, the substantial inclination angle of the correcting blade surface means the inclination angle (α) of the distance (L2) between the cylindrical inner surface and the cutting edge relative to the vertical width (H) of the correcting blade surface, i.e., tan α=L2 / H, as shown in the enlarged cross-sectional view of FIG. 7.

[0021] In another embodiment of the present invention, a cutting device for cutting a sheet material into a dumbbell shape has a vertical width (H) of a correction blade surface of 5 mm or less.

[0022] In another embodiment of the present invention, a cutting device for cutting a sheet material into a dumbbell shape has a punching blade that is a hardened metal plate having a thickness of 2 mm or more.

[0023] In another embodiment of the cutting device for cutting a sheet material into a dumbbell shape according to the present invention, the inclination angle of the correction blade surface increases toward the cutting edge of one of the blades.

[0024] Another embodiment of the present invention provides a cutting device for cutting sheet material into a dumbbell shape, comprising a receiving table having a cutting surface on which the sheet material to be cut into test pieces is placed and cut, a cylindrical punching blade that reciprocates toward the cutting surface to cut the sheet material on the cutting surface into dumbbell-shaped test pieces having chucking areas at both ends of a central test area, a drive mechanism that reciprocates the punching blade in a direction perpendicular to the surface of the receiving table, a flat pusher that is arranged inside the cylindrical inner surface of the cylindrical punching blade so as to be able to move back and forth relatively to the inside, and an elastic body that elastically protrudes the flat pusher from the tip of the punching blade. The cylindrical punching blade is a single-edged blade with an outer blade surface on the outer peripheral surface of the lower end, and the inner peripheral surface of the single blade has a correction blade surface that corrects the cutting direction of the sheet material, and the tip edge between the outer blade surface and the correction blade surface has a blade tip that punches the sheet material into a dumbbell shape, and the blade tip of the single blade is offset outward from the cylindrical inner peripheral surface of the punching blade. The drive mechanism includes upper and lower tables that reciprocate the punching blade and the flat pusher. The punching blade is fixed to the upper and lower tables in a non-reciprocating state, but the flat pusher is connected to the upper and lower tables via an elastic body so as to be freely reciprocating. The flat pusher has a flat pressing surface that presses the sheet material on the surface facing the cutting surface, and a slit gap is provided between the inner peripheral surface of the punching blade and the outer peripheral surface of the flat pusher, allowing the flat pusher to reciprocate relative to the punching blade. The flat pusher is arranged such that the punching blade is pushed out by the elastic body at a non-cutting position of the sheet material, and the pressing surface protrudes from the cutting edge of the punching blade.

[0025] The enlarged cross-sectional view of FIG. 12 shows a state in which a conventional cutting device cuts a sheet material 96. This figure is a cross-sectional view showing a state in which a sheet material 96 that is not pressed by a pressing plate is cut. This figure shows a state immediately before a punching blade 91 starts cutting the sheet material 96. Cutting of the sheet material 96 does not start immediately after the blade tip 92 of the punching blade 91 comes into contact with the sheet material 96, but as shown in this figure, cutting starts from a state in which the blade tip 92 presses and compresses the sheet material 96 with a predetermined pressure. The sheet material 96 pressed by the blade tip 92 is in a state in which both sides of the blade tip 92 are elastically expanded, so that when cutting of the sheet material 96 starts in this state, the width (W') of the cut test piece 97 becomes wider. This is because the substantial width (W') of the expanded sheet material 96 becomes wider than the distance (D) between the blade tips on both sides.

[0026] The cutting device according to the above embodiment of the present invention has a feature that the flat pusher presses and cuts the sheet material with the inside of the dumbbell-shaped punching blade, so that the dumbbell-shaped test piece can be punched out with extremely high accuracy. This is because the flat pusher 21 presses and cuts the sheet material 6 in a flat state, as shown in the enlarged cross-sectional view of FIG. 11. In particular, the above cutting device has a slit gap between the cylindrical inner peripheral surface of the punching blade and the outer peripheral surface of the flat pusher, and the flat pusher is disposed in a position where the punching blade does not cut the sheet material, i.e., where the blade tip does not contact the sheet material and protrudes from the blade tip of the punching blade. Therefore, when the blade tip of the punching blade cuts the sheet material, the sheet material is held in a flat state, and in particular, the inside of the blade tip of the punching blade, which is a dumbbell-shaped cylinder, is held in a flat state, and the sheet material is cut without expanding, so that the width of the test piece can be cut with extremely high accuracy.

[0027] In particular, in the above cutting device, the flat pusher is shaped so that the surface facing the cylindrical inner peripheral surface of the punching blade conforms to a dumbbell shape, and the flat pusher presses the sheet material with the inside of the blade. Therefore, the sheet material that tends to expand into a curved shape when pressed against the blade can be held flat and cut, so that dumbbell-shaped test pieces can be cut with extremely high precision, especially with high precision in width. Since an error in the width of the test piece reduces the precision of the tensile strength, the above device that can cut the width of the test piece with high precision realizes the feature that the tensile strength of the test piece can be measured with a high precision using a testing machine.

[0028] Furthermore, in the above cutting device, when the punch blade is in a position not cutting the sheet material, the flat pusher is pushed out into the elastic body and the pressing surface is positioned in a protruding position from the tip of the punch blade, so that the tip of the punch blade is covered by the flat pusher to protect the tip and can be used safely by preventing the operator from accidentally touching the tip.

[0029] In another embodiment of the present invention, a cutting device for cutting sheet material into a dumbbell shape has a punching blade which has a test area cutting blade for cutting a test area of ​​a dumbbell-shaped test piece and a chuck area cutting blade for cutting the chuck area, and a planar pusher which has a narrow pressing portion located inside the test area cutting blade and a wide pressing portion located inside the chuck area cutting blade, and the slit gap between the test area cutting blade and the narrow pressing portion is 0.1 mm or more and 2 mm or less.

[0030] The above-described cutting device has a slit gap between the test area cutting blade of the punching blade and the narrow pressing portion of the flat pusher, so that the narrow pressing portion of the flat pusher can be smoothly reciprocated along the cylindrical inner surface of the punching blade, thereby enabling the lateral width of the test area cut by the test area cutting blade to be adjusted with extremely high precision.

[0031] In another embodiment of the present invention, a cutting device for cutting a sheet material into a dumbbell shape has a flat pusher with a dumbbell-shaped outer shape that fits the cylindrical inner peripheral surface of a punching blade.

[0032] In the cutting device described above, the flat pusher can punch out the overall outer shape of the test piece with high dimensional accuracy, and the cut test piece that has been guided to the cylindrical inner surface can be smoothly pushed out by the flat pusher.

[0033] In another embodiment of the cutting device for cutting a sheet material into a dumbbell shape according to the present invention, the cylindrical inner peripheral surface of a punching blade serves as a guide tube for reciprocating a flat pusher.

[0034] The cutting device described above has an advantage that the flat pusher can be reciprocated with a simple structure without the need for a dedicated guide for reciprocating the flat pusher.

[0035] A cutting device for cutting sheet material into a dumbbell shape according to another embodiment of the present invention further includes an outer pusher arranged so as to be relatively reciprocatable outside the cylindrical outer circumferential surface of the cylindrical punching blade, and an elastic body that elastically protrudes the outer pusher from the cutting edge of the punching blade. The outer pusher is connected to the upper and lower tables so as to be reciprocatable via the elastic body, and has a flat pressing surface that presses the sheet material on the surface facing the cutting surface. The outer pusher is arranged in a position where the pressing surface protrudes from the cutting edge of the punching blade, with the punching blade being pushed out by the elastic body at a non-cutting position of the sheet material.

[0036] The cutting device described above is provided with an outer pusher on the outside of the outer periphery of the punching blade, and the outer pusher presses the sheet material to hold it in a flat state before cutting, so that the sheet material being cut by the blade edge is prevented from deforming outwardly, and the width of the test piece can be cut with high precision. Furthermore, since the outer pusher is connected to the connecting base via an elastic body, when the blade edge of the punching blade is in a state where it is cutting the sheet material, the sheet material is pressed with a predetermined pressing force via the elastic body, and cutting can be performed in a state where deformation of the sheet material is prevented.

[0037] Furthermore, in the above cutting device, when the punch blade is in a position not cutting the sheet material, the outer pusher is pushed out into the elastic body and the pressing surface is positioned in a protruding position from the tip of the punch blade, so that the tip of the punch blade is covered by the outer pusher to protect the tip and can be used safely by preventing the operator from accidentally touching the tip.

[0038] In another embodiment of the present invention, a cutting device for cutting sheet material into a dumbbell shape has an outer pusher that is frame-shaped with a punching blade located inside, and its inner shape is a dumbbell shape that fits along the cylindrical outer peripheral surface of the punching blade. A reciprocating gap is provided between the inner peripheral surface of the outer pusher and the outer peripheral surface of the punching blade, allowing the outer pusher to move back and forth relative to the punching blade.

[0039] In the cutting device described above, a reciprocating gap is provided between the inner peripheral surface of the outer pusher and the outer peripheral surface of the punching blade, so that the outer pusher can be smoothly reciprocated along the cylindrical outer peripheral surface of the punching blade while reliably pressing the sheet material with the outer pusher on the outside of the punching blade to hold it in a flat state. In particular, by making the inner shape of the frame-shaped outer pusher a dumbbell shape that fits the cylindrical outer peripheral surface of the punching blade, the sheet material can be cut while being ideally pressed with the outer pusher over the entire outside of the punching blade.

[0040] In another embodiment of the present invention, a cutting device for cutting a sheet material into a dumbbell shape has a flat pusher with a dumbbell-shaped outer shape that conforms to the cylindrical inner peripheral surface of the punching blade, and a gap for the punching blade to pass through is formed between the outer peripheral surface of the flat pusher and the inner peripheral surface of the outer pusher. past The width (d) of the gap is set to be greater than the thickness of the punching blade and equal to or less than 8 mm.

[0041] In the above cutting device, the width of the passage gap formed between the outer peripheral surface of the flat pusher and the inner peripheral surface of the outer pusher is made larger than the thickness of the punching blade, so that the flat pusher and the outer pusher can be smoothly reciprocated relative to the punching blade while the width of the passage gap is set to 8 mm or less, thereby reliably preventing the operator's fingertips from entering the passage gap and preventing the operator from accidentally touching the blade edge, thereby allowing for safe use.

[0042] In another embodiment of the cutting device of the present invention for cutting sheet material into a dumbbell shape, the pressing force with which the elastic body elastically presses the flat pusher is set to a pressing force that maintains the surface of the sheet material, which is the surface to be cut in the test area of ​​the punching blade, substantially flat in a cutting state in which the punching blade cuts the sheet material.

[0043] In one embodiment of the present invention, a cutting method for cutting a sheet material into a dumbbell shape is a cutting method in which the sheet material to be cut into test pieces is placed on the cutting surface of a receiving table, and a punching blade is used to cut the sheet material into dumbbell-shaped test pieces having chucking areas at both ends of a central test area, and the sheet material is cut into a dumbbell shape by the following methods (A) to (F). (A) The punching blade is a single-edged blade having a dumbbell-shaped cutting edge at the tip and an outer cutting surface on the outer peripheral surface of the lower end, the inner peripheral surface of the single blade has a correcting blade surface which corrects the cutting direction of the sheet material, and the tip edge of the outer cutting surface and the correcting blade surface has a cutting edge which punches the sheet material into a dumbbell shape, the distance (L2) between the cylindrical inner peripheral surface of the punching blade and the cutting edge is 1 / 4 or less of the distance (L1) between the cylindrical outer peripheral surface and the cutting edge, and the cutting edge of the single blade is offset outward from the cylindrical inner peripheral surface. (B) The surface of the sheet material is pressed with a pressure plate and cut with the punching blade. (C) Inside the cylindrical punching blade, the surface of the sheet material is pressed with the pressing surface of a flat pusher to cut it. (D) The punching blade and the flat pusher are moved back and forth via an elastic body on an upper and lower table that reciprocates the punching blade to press the sheet material. (E) The flat pusher has a width smaller than that of the dumbbell-shaped cylindrical punching blade, and has a slit gap between it and the inner surface of the punching blade, causing it to reciprocate inside the punching blade. (F) The flat pusher has a pressing surface positioned at a position protruding from the tip of the punching blade when the punching blade is in a non-cutting position where it is not cutting the sheet material, and when the punching blade is in a state where it is cutting the sheet material, the flat pusher presses the inside of the punching blade to cut it.

[0044] In another embodiment of the present invention, a cutting method for cutting sheet material into a dumbbell shape involves cutting the surface of the sheet material by pressing it with a pressure plate connected to an upper and lower base via an elastic body, and the pressure plate presses the sheet material with a flat pusher and an outer pusher that presses the outside of a punching blade to cut the sheet material.

[0045] In another embodiment of the cutting method for cutting a sheet material into a dumbbell shape according to the present invention, the outer pusher is formed in a frame shape.

[0046] In another embodiment of the present invention, a method for cutting a sheet material into a dumbbell shape includes pressing the sheet material with a flat pusher and an outer pusher to hold the sheet material in a substantially flat state and cutting the sheet material into a dumbbell shape with a punching blade.

[0047] The present invention will be described in detail below with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "upper", "lower", and other terms including these terms) are used as necessary, but the use of these terms is for the purpose of facilitating understanding of the invention with reference to the drawings, and the meanings of these terms do not limit the technical scope of the present invention. In addition, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or members. Furthermore, the embodiments shown below are specific examples of the technical ideas of the present invention, and do not limit the present invention to the following. Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended to be illustrative and not to limit the scope of the present invention. Furthermore, the contents described in one embodiment or example can be applied to other embodiments or examples. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated to clarify the explanation.

[0048] (Embodiment 1) The cutting device 100 shown in Figure 1 for cutting sheet material into dumbbell-shaped test pieces includes a receiving table 5 having a cutting surface 50 on which sheet material 6 to be cut into test pieces is placed and cut, a cylindrical punching blade 1 that reciprocates toward the cutting surface 50 to cut the sheet material 6 on the cutting surface 50 into dumbbell-shaped test pieces, and a drive mechanism 4 that reciprocates the punching blade 1 in a direction perpendicular to the surface of the receiving table 5.

[0049] Furthermore, the cutting device 100 preferably includes a pressing plate 2 for holding the sheet material 6 to be cut by the punching blade 1 in a flat state and cutting it, as shown in Figs. 2 to 7. The pressing plate 2 presses the sheet material 6 with its flat lower surface to hold it in a flat state at the timing when the sheet material 6 is cut by the punching blade 1. The cutting device 100 with the pressing plate 2 can cut the test piece with high dimensional accuracy, but the cutting device 100 can also punch the sheet material 6 into a dumbbell-shaped test piece without necessarily providing the pressing plate 2. The dumbbell-shaped test piece 7 has a narrow test area 7X in the center and wide chucking areas 7Y at both ends of the test area 7X, as shown in Fig. 8. The test piece 7 has the chucking areas 7Y at both ends chucked by a test machine, and the tensile strength of the test area 7X cut to a specific width (W) is measured.

[0050] (Pedestal 5) The receiving stand 5 is made of metal and is arranged in a horizontal position with the cutting surface 50 on the upper surface as a smooth plane. However, the receiving stand 5 may be made entirely or with a surface made of plastic or rubber. As shown in FIG. 1, the metal receiving stand 5 has a buffer sheet 51 placed on the cutting surface 50. The buffer sheet 51 can punch the sheet material 6 into a dumbbell shape while preventing damage to the cutting edge 10 of the punching blade 1. The buffer sheet 51 is a plastic sheet with a thickness of 1 mm to 5 mm. The receiving stand 5 with the buffer sheet 51 laminated on the upper surface can neatly cut the entire circumference of the test piece 7 from the sheet material 6 by pressing the cutting edge 10 of the punching blade 1 against the buffer sheet 3 or inserting the cutting edge 10 of the punching blade 1 into the surface of the buffer sheet 3 in a state in which the sheet material 6 is punched by the punching blade 1. However, it is not necessary to place a plastic buffer sheet 51 on the upper surface of the receiving base 5. Instead of the plastic buffer sheet 51, a buffer sheet 51 other than plastic that is cut by the cutting edge 10 but does not damage the cutting edge 10 of the punching blade 1, for example a metal softer than the receiving base 5 such as brass or lead, can be laminated, or the sheet material 6 can be punched and cut by bringing the punching blade 1 close to or in contact with the cutting surface 50 of the receiving base 5 without laminating the buffer sheet 51.

[0051] (Drive mechanism 4) The driving mechanism 4 holds the punching blade 1 in a horizontal position and reciprocates it vertically to cut the sheet material 6 placed on the cutting surface 50 of the stand, thereby punching out a dumbbell-shaped test piece 7. The driving mechanism 4 includes an upper and lower table 41 to which the punching blade 1 is fixed, and a cylinder 42 that reciprocates the upper and lower table 41 up and down. The punching blade 1 is fixed in a vertical position to the underside of the upper and lower table 41, and the cylinder 42 reciprocates up and down to punch out the sheet material 6 placed on the receiving table 5 into a dumbbell-shaped test piece 7. Furthermore, the cutting device 100 includes a pressing plate 2, which is connected to the upper and lower table 41 via an elastic body 20.

[0052] (Punching knife 1) As shown in Figs. 2 to 7, the punching blade 1 is cylindrical and cuts the sheet material 6 into a dumbbell shape with a blade tip 10 at the lower end edge, and is preferably made of a metal plate with a thickness of 2 mm or more. The punching blade 1 is made of a steel material that can be hardened, and carbon steel, which has excellent workability, is preferable. The carbon content of the carbon steel is adjusted to an optimum value taking into account the required hardness and brittleness. The metal plate of the punching blade 1 can be made hard by increasing the carbon content. However, since a high carbon content makes the steel brittle, the carbon content of the steel material processed into the blade is, for example, 0.4% or more and 1.4% or less, preferably 0.45% or more and 0.7% or less.

[0053] As shown in the enlarged cross-sectional view of FIG. 7, the punching blade 1 has a single-edged cutting edge 10 formed by grinding the tip of a cylindrical metal plate with a whetstone or a file. The single-edged cutting edge 10 is produced by grinding and polishing the outer peripheral surface of the lower end of the cylindrical metal plate to form an outer cutting surface 11. Furthermore, the punching blade 1 has a correction cutting surface 12 formed by grinding and polishing the inner peripheral surface of the single blade to correct the cutting direction of the sheet material 6. The tip edge of the outer cutting surface 11 and the correction cutting surface 12 of the punching blade 1 forms the cutting edge 10, and the sheet material 6 is punched out into a dumbbell shape with this cutting edge 10. The punching blade 1 has the single-edged cutting edge 10 positioned offset outward from the cylindrical inner peripheral surface 14. The cutting edge 10 is positioned such that the offset distance (L2) between the cylindrical inner peripheral surface 14 and the cutting edge 10 is ¼ or less of the single-edged distance (L1) between the cylindrical outer peripheral surface 13 and the cutting edge 10.

[0054] The eccentric distance (L2) of the blade tip 10 is set to a distance that cuts the width of the test piece 7 to be cut into a dumbbell shape to the most accurate dimension. In particular, the eccentric distance (L2) of the blade tip 10 is set to a distance that cuts the width of the test area 7X of the test piece 7 to be cut into a dumbbell shape to an accurate dimension without deviation in the thickness direction. The eccentric distance (L2) of the blade tip 10 acts to widen the width of the dumbbell shape as the blade tip 10 cuts into the sheet material 6. With a single blade in which the blade tip is disposed on the cylindrical inner peripheral surface and the eccentric distance (L2) is set to 0, the width of the test piece 97 to be cut into a dumbbell shape gradually narrows as it cuts into the sheet material (see FIG. 12). The chucking areas provided at both ends of the test area are chucked by the testing machine, and the test area is broken to measure the tensile strength. For this reason, it is extremely important that the width (W) of the test area of ​​the dumbbell-shaped test piece is cut with high accuracy. The eccentric distance (L2) provided on the punching blade 1 prevents the width (W) of the test area 7X from gradually narrowing as the cutting edge 10 of the single-edged blade digs into and cuts the sheet material 6. The single-edged punching blade 1 can increase the eccentric distance (L2) to widen the width of the test piece 7 which narrows as the cutting edge 10 digs into and cuts the sheet material 6. If the eccentric distance (L2) is too large, the width of the test piece 7 will widen as it is cut, so the single-edged punching blade 1 has an eccentric distance (L2) that is ¼ or less of the single-edged distance (L1). However, if the eccentric distance (L2) is too small, the width of the cut test piece 7 will gradually become narrower. Therefore, for example, taking into consideration the material and thickness of the sheet material 6 to be cut, the eccentric distance (L2) is set to be 1 / 10 or more of the blade distance (L1), preferably 1 / 8 or more and 1 / 4 or less.

[0055] The eccentric distance (L2) can be adjusted by the actual inclination angle and vertical width (H) of the correction blade surface 12. The single-edged punching blade 1 preferably has the actual inclination angle of the correction blade surface 12 of 5 degrees or less, the vertical width (H) of 50 mm or less, and the cutting edge 10 disposed at the aforementioned position. The above-described punching blade 1 can cut a plastic plate of thickness 4 mm into a dumbbell-shaped test piece 7 of accurate width, for example, with a metal plate thickness of 3 mm, an eccentric distance (L2) of 0.5 mm, and a single-blade distance (L1) of 2.5 mm.

[0056] The effective inclination angle of the correcting blade surface 12 means the inclination angle (α) of the distance (L2) between the cylindrical inner peripheral surface 14 and the cutting edge 10 relative to the vertical width (H) of the correcting blade surface 12, i.e., tan α=L2 / H, as shown in the enlarged cross-sectional view of Fig. 7. The correcting blade surface 12 can be a flat blade surface with a constant inclination angle (α), but preferably has a shape in which the inclination angle (α) gradually increases toward the cutting edge 10, as shown in Fig. 7.

[0057] (Press plate 2) The cutting device 100 includes a pressing plate 2 that prevents deformation of the sheet material 6 and cuts the sheet material 6 with high dimensional accuracy. The pressing plate 2 presses the sheet material 6 against the cutting surface 50, and prevents deformation of the sheet material 6, particularly swelling at the side of the blade tip 10, at the timing when the punching blade 1 cuts the sheet material 6, thereby improving the dimensional accuracy of the test piece 7. The pressing plate 2 shown in Figs. 2 to 6 includes a flat pusher 21 located inside the cylindrical inner peripheral surface 14 of the punching blade 1, and an outer pusher 22 located outside the cylindrical outer peripheral surface 13. The cutting device 100 in Fig. 1 presses the sheet material 6 on the inside and outside of the blade tip 10 with the flat pusher 21 and the outer pusher 22, but the pressing plate 2 does not necessarily need to press both sides of the blade tip 10. Although not shown, the dimensional accuracy of the test piece can be improved by providing only a flat pusher or only an outer pusher.

[0058] The present invention does not specify the material of the sheet material 6 to be cut into the test pieces 7, but when observing microscopically the moment when the sheet material 6 is cut, the cutting is performed in a state where the blade tip 10 locally presses the surface of the sheet material 6, creating a linear indentation. No matter how sharp the blade tip 10 is, it is not possible to maintain the surface of the sheet material 6 in a completely flat state, in other words, to start cutting from the moment the blade tip 10 comes into contact with the surface of the sheet material 6.

[0059] The test piece 7 is produced by cutting a sheet material 6, which is mainly made of soft plastic, hard plastic, rubber-like elastomer, or the like. Rubber-like elastomers and soft plastics are pressed by the blade tip 10 during cutting and are significantly deformed, so if the test piece 7 is cut without preventing deformation, the dimensional error of the test piece 7 will be large. Hard plastics are less deformed during cutting than soft plastics and rubber-like elastomers, so the dimensional error of the test piece 7 can be reduced, but the dimensional error of the test piece 7 becomes a problem in tensile tests with higher accuracy.

[0060] The pressing plate 2 reciprocates in conjunction with the reciprocating motion of the punching blade 1, pressing the surface of the sheet material 6 to be cut into a flat surface to prevent deformation during cutting by the blade edge 10. The flat pusher 21 and outer pusher 22 of the pressing plate 2 are connected to the upper and lower bases 41 of the drive mechanism 4 via the elastic body 20. The upper and lower bases 41, which reciprocate up and down, connect the flat pusher 21 and outer pusher 22 via the elastic body 20.

[0061] 1, the driving mechanism 4 of the cutting device 100 has a cylinder 42 with a rod 42a extending and retracting in a vertical position with the rod 42a facing downward, and the lower end of the rod 42a is connected to the center of the upper and lower base 41. Furthermore, the driving mechanism 4 has a pair of guide mechanisms 43 facing both ends of the upper and lower base 41, and a guide rod 43a inserted into a guide tube portion 43b is arranged in a vertical position, and the lower end of the guide rod 43a is connected to both ends of the upper and lower base 41. With the cylinder 42 extending and retracting the rod 42a, the driving mechanism 4 reciprocates up and down while maintaining the upper and lower base 41 in a horizontal position.

[0062] The upper and lower bases 41 include a base plate 30 which connects the punching blade 1 and the pressure plate 2, and a main body 45 which connects the base plate 30 in a detachable manner. The base plate 30 is a flat metal plate, and as shown in Figures 2 and 4, a connecting part 31 which is detachably connected to the main body 45 is fixed to the upper surface, and the punching blade 1 and the pressure plate 2 are connected to the lower surface. The punching blade 1 is fixed to the base plate 30 by welding, and the pressure plate 2 is connected to the base plate 30 via an elastic body 20. This structure allows the punching blade 1 and the pressure plate 2 to be connected to the base plate 30 as a blade unit 3, which can be conveniently replaced.

[0063] (Blade unit 3) 2 to 6 show the blade unit 3, with FIG. 2 being a front view, FIG. 3 being a bottom view, FIG. 4 being a vertical longitudinal section view, FIG. 5 being a cross-sectional view of the test area 7X in the center of the test piece 7, and FIG. 6 being a cross-sectional view of the chucking area 7Y at the end of the test piece 7. The blade unit 3 shown in these figures includes a base plate 30 having a connecting portion 31 fixed to the upper surface thereof, a cylindrical punching blade 1 fixed to the lower surface of the base plate 30, a flat pusher 21 arranged so as to be relatively movable back and forth inside the cylindrical inner peripheral surface 14 of the punching blade 1, and an outer pusher 22 arranged so as to be relatively movable back and forth outside the cylindrical outer peripheral surface 13 of the punching blade 1. The flat pusher 21 is connected to the base plate 30 via an elastic body 20, and the flat pusher 21 is elastically protruded from the cutting edge 10 of the punching blade 1. The outer pusher 22 is connected to a base plate 30 via an elastic body 20, and the outer pusher 22 is elastically protruded from the cutting edge 10 of the punching blade 1.

[0064] (Flat Pusher 21) The flat pusher 21 shown in Figs. 2 to 6 has a dumbbell-shaped outer shape that fits the cylindrical inner peripheral surface 14 of the punching blade 1 and is slightly smaller than the inner shape of the punching blade 1, which is a dumbbell-shaped cylinder. The punching blade 1 is equipped with a test area cutting blade 1X that cuts the test area 7X of the dumbbell-shaped test piece 7, and a chucking area cutting blade 1Y that cuts the chucking area 7Y. The flat pusher 21 is equipped with a narrow pressing part 21X located inside the test area cutting blade 1X and a wide pressing part 21Y located inside the chucking area cutting blade 1Y. The flat pusher 21 has a pressing surface 21a on its lower surface, is located inside the punching blade 1, and reciprocates vertically relative to the punching blade 1. The flat pusher 21 is disposed in a protruding position where the punching blade 1 is pushed out by the elastic body 20 at a non-cutting position of the sheet material 6, and the pressing surface 21a is positioned from the cutting edge 10 of the punching blade 1. A narrow slit gap 33 is provided between the flat pusher 21 and the cylindrical inner peripheral surface 14 of the pushing punching blade 1. The flat pusher 21 can reciprocate up and down relative to the punching blade 1, using the punching blade 1 as a guide cylinder.

[0065] The flat pusher 21 can punch the test piece 7 into a dumbbell shape with higher accuracy by narrowing the slit gap 33 with the punching blade 1. By narrowing the slit gap 33, the outer periphery of the flat pusher 21 can be brought closer to the side of the blade tip 10. This flat pusher 21 prevents deformation of the sheet material 6 on the side of the blade tip 10, and increases the dimensional accuracy of the test piece 7. However, if the slit gap 33 is too narrow, it becomes difficult for the flat pusher 21 to smoothly reciprocate inside the cylindrical inner peripheral surface 14. Therefore, the slit gap 33 between the flat pusher 21 and the cylindrical inner peripheral surface 14 is preferably 0.1 mm or more and 2 mm or less, and more preferably 0.2 mm or more and 1 mm or less. The dumbbell-shaped flat pusher 21 can punch out the entire outer periphery of the test piece 7 with high dimensional accuracy, and further has the advantage that the test piece 7 that has been cut and inserted into the cylindrical inner surface 14 can be smoothly pushed out of the punching blade 1 by the elastic body 20.

[0066] The dimensions of the test piece 7 are specified in ISO standards. For example, ISO 974:2000 states: The width of the test area 7X in the center of the test piece 7 is specified to be 2.50 mm, the total length to be 20 mm, the thickness to be 2.5 mm, and the dimensional accuracy of the test area 7X to be 2.50±0.05 mm.

[0067] FIG. 12 shows an enlarged cross-sectional view of a conventional single-edged test area cutting blade 91 with a blade distance (D) of 2.5 mm cutting a rubber-like sheet material 96 having a thickness of 2.5 mm. As shown in this figure, the blade edge 92 immediately before cutting the sheet material 96 locally presses the surface of the sheet material 96 in a linear shape to press it into a groove. In this state, the outer blade surface 93 of the single blade presses the sheet material 96. Since the direction of the blade edge 92 of the single blade is inclined inward as shown by arrow A, the friction resistance between the sheet material 96 and the blade edge 92 is smaller in the direction shown by arrow B than in the opposite direction, and the sheet material 96 pressed by the outer blade surface 93 is pressed into the inside of the test area cutting blade 92, and the area that will be the test area 97X of the test piece 97 after being cut is deformed into a curved shape as shown in FIG. The actual width (W') of the test area 97X deformed into a curved surface is wider than the 2.5 mm inner width of the blade tip 10. When the blade tip 10 cuts the sheet material 6 in this state, the width (W') of the cut test area 97X becomes wider than 2.5 mm. In the inventor's tests, when a rubber sheet having a thickness of 2.5 mm is cut with a single-edged punching blade 91 having an inner width of 2.5 mm, the width of the test area 97X of the test piece 7 becomes wider than 2.55 mm, resulting in a dimensional error that exceeds the ISO standard.

[0068] The enlarged cross-sectional view of the main part in FIG. 7 shows a state in which the flat pusher 21 presses the inner side of the test area cutting blade 1X and cuts it with the cutting edge 10 of the single blade. As shown in this figure, when the flat pusher 21 presses the sheet material 6 and cuts the sheet material 6 with the cutting edge 10 of the single blade, the width of the test area 7X of the cut test piece 7 is almost equal to the inner width of the cutting edge 10, which is 2.5 mm, and falls within the range of 2.5±0.05 mm of the ISO standard. Furthermore, the width (W) of the test area 7X of the test piece 7 can be cut with higher accuracy by setting the pressure with which the flat pusher 21 presses the sheet material 6 to an optimal value. The optimal pressure with which the flat pusher 21 presses the sheet material 6 is set to a pressure that can hold the sheet material 6 inside the test area cutting blade 1X in a substantially flat state at the timing when the cutting edge 10 of the single blade cuts the sheet material 6. The sheet material 6 exhibits incompressible physical properties, with its volume not substantially changing when pressed in the thickness direction. Therefore, the pressure with which the flat pusher 21 presses the sheet material 6 is set to a pressure below the limit pressure at which the sheet material 6 is pressed too hard and does not undergo any material change, such as "whitening," for example, 80% or less of the limit pressure, preferably 50% or less, and capable of maintaining the surface of the sheet material 6 to be cut in a flat state. For example, the flat pusher 21 that presses the rubber-like elastic sheet material 6 presses the sheet material 6 while it is positioned on the same plane as the blade edge 10 with a pressure of, for example, 0.1 kg / cm 2 More than 10kg / cm 2 As described below, the sheet material 6 is held flat and can be cut with high dimensional accuracy without altering the material.

[0069] The flat pusher 21 does not necessarily have to have a dumbbell-shaped outer shape. The test piece 7 requires high dimensional accuracy in the width of the test area 7X. This is because the tensile strength of the sheet material 6 is measured by detecting the tensile strength of the test area 7X. If the width of the test area 7X of the test piece 7 is narrower than the standard dimension, the tensile strength of the sheet material 6 is detected weakly and an accurate tensile strength cannot be measured. For this reason, it is particularly important that the cutting device 100 cuts the width of the test area 7X of the test piece 7 with high dimensional accuracy. The width of the chucking area 7Y chucked by the testing machine does not necessarily require high dimensional accuracy. This is because the chucking area 7Y of the test piece 7 is sufficient as long as it has a width that allows reliable chucking.

[0070] (Another example of a flat pusher) The pressing plate 2A of the blade unit 3A shown in the bottom view of Fig. 9 has an overall width of the flat pusher 21A that is a rectangle with a width slightly narrower than the inner width of the test area cutting blade 1X that cuts the test area 7X of the test piece 7. The punching blade 1 has a test area cutting blade 1X that cuts the test area 7X of the test piece 7 and a chucking area cutting blade 1Y that cuts the chucking area 7Y, and cuts the sheet material 6 into a dumbbell shape by making the interval between the test area cutting blades 1X narrower than the interval between the chucking area cutting blades 1Y. At the boundary between the test area cutting blades 1X and the chucking area cutting blade 1Y, the interval gradually widens from the test area cutting blade 1X to the chucking area cutting blade 1Y.

[0071] The flat pusher 21A in FIG. 9 is composed of a narrow pressing part 21XA located inside the test area cutting blade 1X and a wide pressing part 21YA located inside the chucking area cutting blade 1Y. The flat pusher 21A in FIG. 9 is rectangular in shape with the narrow pressing part 21XA and the wide pressing part 21YA having the same width. This flat pusher 21A approaches the inside of the test area cutting blade 1X to improve the dimensional accuracy in the width direction of the dumbbell-shaped test area 7X cut by the test area cutting blade 1X. The flat pusher 21A having the above shape is connected to a base plate 30 via a support plate 36 arranged on the upper surface of the flat pusher 21A so that it can reciprocate up and down inside the cylindrical punching blade 1, as shown in FIG. 9 and FIG. 10. The support plate 36 in the figure is a metal plate with a dumbbell-shaped bottom, and a flat pusher 21A, which is placed inside the test area cutting blade 1X, is fixed to the underside of the narrow central portion 36a, and the wide portions 36b at both ends are connected to the base plate 30 via connecting rods 31 and elastic bodies 20.

[0072] The width of the flat pusher 21A, which has an overall rectangular shape, is preferably such that the slit gap 33 between the test area cutting blade 1X of the punching blade 1 is 0.1 mm or more and 2 mm or less, more preferably 0.2 mm or more and 1 mm or less. This flat pusher 21A presses the sheet material 6 close to the inside of the test area cutting blade 1X, so that the punching blade 1 can cut the test area 7X of the test piece 7 with high dimensional accuracy. The flat pusher 21A in FIG. 9 has an overall rectangular shape with the same width and is shaped to approach the inside of the test area cutting blade 1X, but the flat pusher 21 can also cut the test area 7X of the test piece 7 with high dimensional accuracy by narrowing the slit gap 33 between the test area cutting blade 1X and widening the slit gap 33A between the chucking area cutting blade 1Y.

[0073] (Outer Pusher 22) The outer pusher 22 shown in Figs. 2 to 6 has a frame shape in which the punching blade 1 is disposed, and its inner shape is a dumbbell shape that conforms to the cylindrical outer circumferential surface 13 of the punching blade 1, specifically, an inner shape that is slightly larger than the outer shape of the punching blade 1, which is a dumbbell-shaped cylinder. The outer pusher 22 has a pressing surface 22a on the lower surface, is located outside the punching blade 1, and reciprocates vertically relative to the punching blade 1. The outer pusher 22 is pushed out by the elastic body 20 at a non-cutting position of the sheet material 6, and the pressing surface 22a of the outer pusher 22 is disposed at a protruding position from the blade tip 10 of the punching blade 1. In addition, a reciprocating motion gap 34 is provided between the inner circumferential surface of the outer pusher 22 and the outer circumferential surface of the punching blade 1 to allow the outer pusher 22 to reciprocate relative to the punching blade 1.

[0074] The frame-shaped outer pusher 22 connects a pair of vertical frames 22m and a pair of horizontal frames 22n at right angles. The vertical frames 22m on both sides widen the width of the area facing the test area cutting blade 1X of the punching blade 1, and the inner peripheral surface of this portion is close to the outer surface of the test area cutting blade 1X. The horizontal frames 22n on both ends have the same width. The outer pusher 22 has a rectangular outer shape and the four corners are cut to provide curved portions, thereby improving safety. Similarly to the outer pusher 22, the base plate 30 also has a rectangular outer shape and the four corners are cut to provide curved portions, thereby improving safety. In the blade unit 3 shown in the figure, the outer shapes of the base plate 30 and the outer pusher 22 are almost the same.

[0075] In the pressing plate 2 shown in FIG. 3, the outer shape of the flat pusher 21 is a dumbbell shape that fits the cylindrical inner peripheral surface 14 of the punching blade 1, and the inner shape of the frame-shaped outer pusher 22 is a dumbbell shape that fits the cylindrical outer peripheral surface 13 of the punching blade 1, and a passing gap 32 for the punching blade 1 is formed between the outer peripheral surface of the flat pusher 21 and the inner peripheral surface of the outer pusher 22. As shown in FIG. 3, the passing gap 32 is formed in a dumbbell shape having a predetermined width (d) when viewed from the bottom, and the sheet material 6 can be punched out while the cylindrical punching blade 1 passes through this passing gap 32. The width (d) of the passing gap 32 is larger than the thickness of the punching blade 1 and is 8 mm or less, preferably 5 mm or less. In this way, by making the width (d) of the passing gap 32 8 mm or less, it is possible to reliably prevent the fingertips of the operator from entering the passing gap 32, and to prevent the operator from accidentally touching the blade tip 10, thereby enabling safe use. 3, the width (d) of the passage gap 32 is uniform, but the width (d) of the passage gap 32 can be changed depending on the region. In particular, by narrowing the width (d) of the passage gap 32 in the region facing the test region cutting blade 1X of the punching blade 1, the dimensional accuracy of the lateral width of the test region 7X of the test piece 7 can be improved.

[0076] The pressing plate 2 consisting of the flat pusher 21 and the outer pusher 22 can be made of, for example, a plastic plate or a metal plate. For example, a plate material made by molding engineering plastic to a predetermined thickness can be used as the plastic pressing plate 2. For such a plastic plate, nylon, which has high strength and high versatility, such as MC nylon, can be used. However, plastics other than nylon can also be used. In particular, by using a plastic pressing plate 2, the overall thickness can be made thick while still being lightweight. In addition, the flat pusher 21 and the outer pusher 22, which are formed thick, can reliably cover the cutting edge 10 of the punching blade 1 while elastically protruding from the cutting edge 10, preventing the worker from touching the cutting edge 10 and allowing for safe use. The plastic pressing plate 2, which will be described in detail later, can be made 5 mm to 20 mm thick, preferably 8 mm to 15 mm thick, taking into account the amount of protrusion from the cutting edge 10, thereby improving safety while ensuring strength.

[0077] The blade unit 3 described above narrows the slit gap 33 inside the test area cutting blade 1X, thereby increasing the dimensional accuracy of the width of the test area 7X of the test piece 7 to be cut. Also, by bringing the center of the vertical frame 22m of the outer pusher 22 close to the outside of the test area cutting blade 1X, the surface of the sheet material 6 can be pressed while cutting in the area close to the outside of the test area cutting blade 1X, so that the width of the test area 7X can be cut with high dimensional accuracy. The outer pusher 22 pushes the sheet material 6 punched into the test piece 7 downward to separate it from the punching blade 1.

[0078] The flat pusher 21 and the outer pusher 22 are connected to a base plate 30 to which the punching blade 1 is fixed, forming a blade unit 3. The blade unit 3 connects both the flat pusher 21 and the outer pusher 22 to the base plate 30 so that they can reciprocate in the up and down direction relative to the punching blade 1. The flat pusher 21 and the outer pusher 22 are connected to the base plate 30 via a connecting rod 23 and an elastic body 20. The flat pusher 21 has both ends connected to the base plate 30 by a pair of connecting rods 23, and reciprocates in a horizontal position. The outer pusher 22 has both ends and both sides connected to the base plate 30 by connecting rods 23, and reciprocates in a horizontal position. As shown in FIG. 3, by connecting the outer pusher 22 to the base plate 30 at four points, i.e., the front, rear, left and right, by the connecting rods 23, the outer pusher 22 can reciprocate in a stable horizontal position without wobbling.

[0079] (Connecting rod 23, stopper 24) The connecting rod 23 has its lower end fixed to the flat pusher 21 and the outer pusher 22, and its upper end inserted into the through hole 30a of the base plate 30 so as to be freely reciprocable. The connecting rod 23 has a stopper 24 at its upper end, which contacts the upper surface of the base plate 30 to determine the protruding positions of the flat pusher 21 and the outer pusher 22 from the blade tip 10. The protruding positions of the flat pusher 21 and the outer pusher 22 are set, for example, at about 2 mm or more and 10 mm or less, and preferably 3 mm or more and 8 mm or less, from the blade tip 10.

[0080] The connecting rod 23 has a screw portion 23a at its tip, and the stopper 24 is screwed into the screw portion 23a as a nut 24a, which connects the flat pusher 21 and the outer pusher 22 to the base plate 30 with a simple structure, and the protruding position can be easily adjusted to an optimal position. The screw portion 23a of the connecting rod 23 can be inserted from bottom to top into the insertion holes 25 provided in the flat pusher 21 and the outer pusher 22. The screw portion 23a of the connecting rod 23 has a recess 26 on the lower surface of the flat pusher 21 and the outer pusher 22 so that the screw head 23b does not protrude from the lower surface of the flat pusher 21 and the outer pusher 22, and the screw head 23b is guided into the recess 26. The nut 24a of the stopper 24 is screwed into the screw portion 23a of the connecting rod 23 protruding from the base plate 30. The stopper 24 can be configured as a double nut by screwing multiple nuts 24a into it, so that it does not move back and forth. By adjusting the screwed position of the nut 24a of this connecting rod 23, the protruding positions of the flat pusher 21 and the outer pusher 22 from the blade tip 10 can be set to optimal values.

[0081] (Elastic body 20) The elastic body 20 is a compression spring, a coil spring 20a, which is disposed between the base plate 30 and the flat pusher 21 and outer pusher 22, with a connecting rod 23 inserted to prevent misalignment. The elastic body 20 is a compression spring, a coil spring 20a, which elastically pushes the flat pusher 21 and outer pusher 22 from the blade tip 10. The coil spring 20a of the elastic body 20 is disposed between the flat pusher 21 and outer pusher 22 and the base plate 30 in a compressed state. The spring constant of the elastic body 20 can be increased to increase the pressure with which the flat pusher 21 and outer pusher 22 press the sheet material 6. For example, when the flat pusher 21 and outer pusher 22 press the sheet material 6 to cut it, the pressure with which the surface of the sheet material 6 is pressed flatly can be set to an optimal value by adjusting the spring constant of the elastic body 20 and the position at which the stopper 24 compresses the elastic body 20.

[0082] Furthermore, the blade unit 3 shown in FIG. 4 has a through hole formed in the base plate 30 as an air hole 35. This is to allow the flat pusher 21, which reciprocates inside the cylindrical punching blade 1, to move smoothly. When the flat pusher 21 is pushed inside the punching blade 1, the blade unit 3 exhausts the air inside through the air hole 35 to the outside, and when the flat pusher 21 pushed inside the punching blade 1 is pushed out toward the opening side, the blade unit 3 draws in the air outside through the air hole, allowing the flat pusher 21 to reciprocate smoothly. In particular, the flat pusher 21 can reciprocate smoothly along the inner surface of the punching blade 1 while narrowing the slit gap 33 provided between the flat pusher 21 and the punching blade 1.

[0083] The cutting device 100 described above punches out the sheet material 6 and cuts it into dumbbell-shaped test pieces 7 in the following steps. (1) The cylinder 42 moves the vertical stand 41 to the raised position and connects the blade unit 3 to the vertical stand 41. (2) The sheet material 6 is placed on the cutting surface 50 of the receiving table 5. (3) The vertical platform 41 is lowered by the cylinder 42. (4) As the upper and lower tables 41 descend, the flat pusher 21 and the outer pusher 22 come into contact with the surface of the sheet material 6 at a position where the cutting edge 10 of the punching blade 1 approaches the sheet material 6 . When the upper and lower platforms 41 are further lowered in this state, the elastic body 20 is compressed, and the flat pusher 21 and the outer pusher 22 press the surface of the sheet material 6 . The flat pusher 21 presses the surface of the sheet material 6 with a pressure that keeps the surface flat when the sheet material 6 is cut by the blade tip 10. The flat pusher 21 presses the sheet material 6 with the inside of the blade tip 10 of the elastic body 20, and prevents the inside of the blade tip 10 from deforming and keeps it flat when the blade tip 10 cuts the sheet material 6.

[0084] (5) In this state, when the upper and lower tables 41 are further lowered, the cutting edge 10 bites into the surface of the sheet material 6 and starts cutting, as shown in the enlarged cross-sectional view of FIG. 7. At this timing, the sheet material 6 inside the cutting edge 10 is pressed by the flat pusher 21 and held in a flat state. The cutting edge 10 cuts the sheet material 6 held in a flat state, and cuts it into a dumbbell shape with accurate dimensions. The outer pusher 22 presses a position away from the outer peripheral surface of the cutting edge 10. Therefore, the sheet material 6 on the outer surface of the cutting edge 10 is deformed into a protruding shape as shown in FIG. 7. The deformation of the sheet material 6 outside the cutting edge 10 has little effect on the dimensional accuracy of the dumbbell shape, especially the dimensional accuracy of the width of the test area 7X. (6) Furthermore, the upper and lower tables 41 are lowered and the cutting edge 10 of the punching blade 1 is moved vertically to cut the sheet material 6 into a dumbbell shape with high dimensional accuracy.

[0085] (Embodiment 2) The cutting device of the above-mentioned embodiment 1 shows an example of using a cylindrical punching blade 1 having an outer blade surface 11 on the outer peripheral surface of the tip and a correction blade surface 12 on the inner peripheral surface of a single blade as the punching blade. However, as shown in FIG. 11, the cutting device can also be configured such that the cylindrical punching blade 1B is a single-edged punching blade 1B having an outer blade surface 11 on the outer peripheral surface of the tip and a vertical inner surface, and a flat pusher 21 is arranged on the inside of the cylindrical punching blade 1B via an elastic body 20 so as to be freely reciprocable. A cutting device of this configuration can also punch out dumbbell-shaped test pieces with extremely high accuracy, since the flat pusher 21 presses and cuts the sheet material 6 inside the dumbbell-shaped punching blade 1. In particular, by bringing the outer peripheral surface 21b of the flat pusher 21 close to the inner peripheral surface 14 of the single-edged punching blade 1B and narrowing the slit gap 33, the sheet material 6 can be cut at a position very close to the outer peripheral edge of the pressing surface 21a of the flat pusher 21 that presses the sheet material 6 into a flat shape, and the blade tip 10 is prevented from curving the surface of the sheet material 6 when cutting the sheet material 6, allowing the width of the test piece to be cut with extremely high precision. [Industrial Applicability]

[0086] INDUSTRIAL APPLICABILITY The present invention can be suitably used as a cutting device and cutting method for cutting sheet materials such as rubber and plastic into dumbbell-shaped test pieces for use in tensile tests, impact tests, and the like. [Explanation of symbols]

[0087] 100...Cutting device 1, 1B...Punching blade 1X…Test area cutting blade 1Y…Cutting blade in chucking area 2, 2A…Press plate 3, 3A…Blade unit 4. Driving mechanism 5…Pedestal 6…Sheet material 7...Test piece 7X…Test area 7Y: Chucking area 10…Cutting edge 11...Outer blade surface 12…Corrected blade surface 13...Cylindrical outer surface 14...Cylindrical inner surface 20...Elastic body 20a...coil spring 21, 21A…Flat pusher 21a...Pressing surface 21b...Outer surface 21X, 21XA... Narrow pressing section 21Y, 21YA...Wide pressing section 22…Outer pusher 22a...Pressing surface 22m…vertical frame 22n…Horizontal frame 23…Connecting rod 23a…Threaded part 23b…Screw head 24…Stopper 24a…Nut 25...Through hole 26…Recess 30…Base plate 30a…Through hole 31...Connection part 32...Passing gap 33, 33A…Slit gap 34…Reciprocating motion gap 35…Air vent 36…Support plate 36a...Narrow part 36b…Wide section 41…Upper and lower stand 42…Cylinder 42a…Rod 43...Guide mechanism 43a…Guide rod 43b...Guide tube part 45…Main body 50…Cut surface 51...Buffer sheet 91...Punching knife 92…Cutting edge 93...Outer blade surface 96...Sheet material 97...Test piece 97X…Test area

Claims

1. A cutting device for cutting a sheet material into a dumbbell shape, the sheet material being placed on a receiving table and cut into a dumbbell-shaped test piece with a cylindrical punching blade, The cylindrical punching blade is A single-edged blade with an outer blade surface on the outer periphery of the lower end. The inner peripheral surface of the blade has a correction blade surface for correcting the cutting direction of the sheet material, The outer blade surface and the correction blade surface have a blade tip at a tip edge for punching a sheet material into a dumbbell shape, The eccentric distance (L2) between the cylindrical inner peripheral surface of the punching blade and the blade tip is 1 / 4 or less of the single-edged distance (L1) between the cylindrical outer peripheral surface and the blade tip, 1. A cutting device for cutting sheet material into a dumbbell shape, comprising: a cutting edge of one blade that is offset outward from the cylindrical inner peripheral surface of the punching blade.

2. A cutting device for cutting the sheet material according to claim 1 into a dumbbell shape, A cutting device for cutting a sheet material into a dumbbell shape, wherein a substantial inclination angle of the correction blade surface is 5 degrees or less.

3. A cutting device for cutting the sheet material according to claim 1 or 2 into a dumbbell shape, A cutting device for cutting sheet material into a dumbbell shape, characterized in that the vertical width (H) of the correction blade surface is 5 mm or less.

4. a receiving table having a cutting surface on which a sheet material to be cut into test pieces is placed and cut; Reciprocating motion toward the cut surface, The sheet material having the cut surface is A cylindrical punching blade for cutting a dumbbell-shaped test piece having a chucking area at both ends of a central test area; a drive mechanism for reciprocating the punching blade in a direction perpendicular to the surface of the receiving base; a flat pusher arranged inside the cylindrical inner peripheral surface of the punching blade so as to be capable of relatively reciprocating motion; an elastic body that elastically protrudes the flat pusher from the cutting edge of the punching blade, The cylindrical punching blade is A single-edged blade with an outer blade surface on the outer periphery of the lower end. The inner peripheral surface of the blade has a correction blade surface for correcting the cutting direction of the sheet material, The outer blade surface and the correction blade surface have a blade tip at a tip edge for punching a sheet material into a dumbbell shape, The cutting edge of the single blade is offset outward from the cylindrical inner peripheral surface of the punching blade, The drive mechanism includes: A vertical stand is provided for reciprocating the punching blade and the flat pusher, The punching blade is fixed to the upper and lower tables in a state where it does not reciprocate. The flat pusher is connected to the upper and lower bases via the elastic body so as to be freely reciprocating; The planar pusher comprises: a flat pressing surface that presses the sheet material on a surface facing the cut surface; Between the inner peripheral surface of the punching blade and the outer peripheral surface of the flat pusher, A slit is provided so that the flat pusher can reciprocate relative to the punching blade, The planar pusher is a cutting device for cutting sheet material into a dumbbell shape, characterized in that the punching blade is pushed out by the elastic body at a non-cutting position of the sheet material, and the pressing surface is positioned in a protruding position from the tip of the punching blade.

5. A cutting device for cutting the sheet material according to claim 4 into a dumbbell shape, The punching blade is A test area cutting blade that cuts a test area of ​​a dumbbell-shaped test piece; a chucking area cutting blade for cutting the chucking area, The planar pusher is A narrow pressing portion located inside the test area cutting blade; A wide pressing portion is provided on the inside of the chucking area cutting blade, A cutting device for cutting sheet material into a dumbbell shape, characterized in that a slit gap between the test area cutting blade and the narrow pressing portion is 0.1 mm or more and 2 mm or less.

6. A cutting device for cutting the sheet material according to claim 4 or 5 into a dumbbell shape, The outer shape of the flat pusher is a dumbbell shape that fits along the cylindrical inner peripheral surface of the punching blade, A cutting device for cutting sheet material into a dumbbell shape, wherein the cylindrical inner peripheral surface of the punching blade is a guide tube for reciprocating the flat pusher.

7. 7. A cutting device for cutting a sheet material into a dumbbell shape according to claim 5 or 6, further comprising: an outer pusher arranged on the outside of the cylindrical outer peripheral surface of the punching blade so as to be capable of reciprocating relative thereto; an elastic body that elastically projects the outer pusher from the cutting edge of the punching blade, The outer pusher is connected to the upper and lower bases via the elastic body so as to be freely reciprocating; The outer pusher is a flat pressing surface that presses the sheet material on a surface facing the cut surface; The outer pusher is a cutting device for cutting sheet material into a dumbbell shape, characterized in that the punching blade is pushed out toward the elastic body at a non-cutting position of the sheet material, and the pressing surface is positioned in a protruding position from the tip of the punching blade.

8. A cutting device for cutting the sheet material according to claim 7 into a dumbbell shape, The outer pusher is a frame-shaped member in which the punching blade is disposed, and the inner shape of the frame is a dumbbell shape that fits along the cylindrical outer peripheral surface of the punching blade. A cutting device for cutting sheet material into a dumbbell shape, characterized in that a reciprocating gap is provided between the inner surface of the outer pusher and the outer surface of the punching blade, allowing the outer pusher to move back and forth relative to the punching blade.

9. A cutting device for cutting the sheet material according to claim 8 into a dumbbell shape, The outer shape of the flat pusher is a dumbbell shape that fits along the cylindrical inner peripheral surface of the punching blade, a gap for passing the punching blade is formed between an outer circumferential surface of the flat pusher and an inner circumferential surface of the outer pusher; A cutting device for cutting sheet material into a dumbbell shape, characterized in that the width (d) of the passage gap is greater than the thickness of the punching blade and is 8 mm or less.

10. A cutting device for cutting the sheet material according to any one of claims 4 to 9 into a dumbbell shape, A cutting device for cutting sheet material into a dumbbell shape, characterized in that the pressing force with which the elastic body elastically presses the flat pusher is a pressing force that maintains the surface of the sheet material, which is the surface to be cut in the test area of ​​the punching blade, substantially flat when the punching blade is in a cutting state cutting the sheet material.

11. A cutting method for cutting a sheet material into a dumbbell shape, comprising the steps of: placing the sheet material to be cut into a test piece on a cutting surface of a receiving table; and using a punching blade to cut the sheet material into a dumbbell-shaped test piece having a chucking area at both ends of a central test area, the method comprising the steps of: A cutting method for cutting a sheet material into a dumbbell shape, comprising cutting the sheet material by any of the following methods (A) to (F). (A) the punching blade, The tip has a dumbbell-shaped cutting edge. A single-edged blade with an outer blade surface on the outer periphery of the lower end. The inner peripheral surface of the blade has a correction blade surface for correcting the cutting direction of the sheet material, The outer blade surface and the correction blade surface have a blade tip at the tip edge thereof for punching the sheet material into a dumbbell shape, The distance (L2) between the cylindrical inner peripheral surface of the punching blade and the blade tip is The distance (L1) between the cylindrical outer peripheral surface and the cutting edge is 1 / 4 or less, A blade having a cutting edge of one edge, the cutting edge being offset outward from the cylindrical inner peripheral surface, is used. (B) The surface of the sheet material is pressed with a pressure plate and cut with the punching blade. (C) Inside the cylindrical punching blade, the surface of the sheet material is pressed with the pressing surface of a flat pusher to cut it. (D) the punching blade and the flat pusher, The punching blade is reciprocated by an upper and lower table via an elastic body to press the sheet material. (E) the planar pusher, The width is smaller than the width of the punching blade, which is a dumbbell-shaped cylinder, A slit gap is provided between the inner peripheral surface of the punching blade and the punch reciprocates inside the punching blade. (F) the planar pusher, In a non-cutting position where the punching blade does not cut the sheet material, The pressing surface is disposed at a position protruding from the cutting edge of the punching blade, When the punching blade is cutting the sheet material, The flat pusher presses and cuts the sheet material inside the punching blade.

Images