TWI853315B - Composite cutting tool and method for manufacturing resin sheet using the same - Google Patents

Abstract

The subject of the present invention provides: a composite cutting tool that can cut thick workpieces without defects; and a method for efficiently and simply manufacturing a resin sheet using the composite cutting tool. The solution is: the composite cutting tool of the present invention has: a main body that rotates around a rotation axis; a cutting edge that is arranged on the outer periphery of the main body and has a cutting edge, a front cutting face and a back cutting face; and a grinding portion that is a protrusion with a file-like surface and is arranged on a part of the back cutting face of the cutting edge. The method for manufacturing a resin sheet of the present invention includes the following steps: overlapping a plurality of resin sheets to form a workpiece; and cutting the outer periphery of the workpiece using the composite cutting tool.

Description

Composite cutting tool and method for manufacturing resin sheet using the same

The present invention relates to a composite cutting tool and a method for manufacturing a resin sheet using the same.

Various resin sheets are widely used according to the application. After the resin sheet is cut into a predetermined shape, the outer peripheral end surface is sometimes subjected to finishing. In the finishing, cutting is sometimes performed using an end mill. Cutting using an end mill is usually performed on a workpiece on which a plurality of resin sheets are overlapped. Here, if manufacturing efficiency is considered, it is appropriate to cut a thick workpiece. However, when cutting a thick workpiece, if the end mill is tilted, there may be a portion where the end mill does not contact the workpiece. Therefore, there are problems such as the need to precisely adjust the holding state of the end mill on the working machine and the inability to make the thickness of the workpiece below a certain value, resulting in insufficient manufacturing efficiency. Current technical literature Patent literature

Patent document 1: Japanese Patent Publication No. 2009-196015

Problems to be solved by the invention The present invention is proposed to solve the above-mentioned previous problems, and its main purpose is to provide: a composite cutting tool that can cut thick workpieces without any problems; and a method for efficiently and simply manufacturing resin sheets using the composite cutting tool.

Means for solving the problem The composite cutting tool of the embodiment of the present invention comprises: a main body, which rotates around a rotation axis; a cutting edge, which is arranged on the outer periphery of the main body and has a cutting edge, a front cutting edge and a back cutting edge; and a grinding portion, which is a protrusion having a file-like surface and is arranged on a part of the back cutting edge. In one embodiment, the protrusion height H of the grinding portion is 0.1 μm to 150 μm. Here, the protrusion height H is represented by H=R2-R1, R1 is the distance from the rotation axis to the cutting edge, and R2 is the distance from the rotation axis to the surface of the protrusion. In one embodiment, the distance L from the blade tip to the wall surface of the grinding portion facing the rotation direction and the R1 satisfy the following formula (1): L≥0.1×R1  ･･･(1). In one embodiment, the cutting residual height Ph of each pitch of the compound cutting tool is 0.03μm to 280μm. Here, the pitch P is expressed by the following formula (2), and the cutting residual height Ph of each pitch is expressed by the following formula (3): P=F/(S×N)  ･･･(2) Ph=arcsin(P/2×R1)  ･･･(3) In formula (2), F is the feed speed of the compound cutting tool (mm/minute), S is the number of rotations of the compound cutting tool (rpm), and N is the number of cutting edges of the compound cutting tool. In one embodiment, the grinding portion includes diamond particles. In one embodiment, the front angle θ1 of the composite cutting tool is -30° to 45°, and the blade angle θ2 is 20° to 100°. Here, the front angle is the angle formed by a straight line connecting the rotation axis and the blade tip and a straight line extending from the blade tip along the front blade face in a cross section in a direction perpendicular to the rotation axis; the blade angle is the angle formed by a straight line extending from the blade tip along the front blade face and a straight line extending from the blade tip along the back blade face in a cross section in a direction perpendicular to the rotation axis. According to another embodiment of the present invention, a method for manufacturing a resin sheet is provided. The manufacturing method includes the following steps: overlapping a plurality of resin sheets to form a workpiece; and cutting the outer peripheral surface of the workpiece using the composite cutting tool. In one embodiment, the thickness of the workpiece is greater than 30 mm. In one embodiment, the resin sheet includes a bonding agent layer and/or an adhesive layer. In one embodiment, the resin sheet includes an optical film. In one embodiment, the optical film includes a polarizer.

Effect of the invention According to the embodiment of the present invention, a composite cutting tool can be realized, which can cut even thick workpieces without any problems. By using the composite cutting tool, a method for manufacturing resin sheets efficiently and simply can be realized.

Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to the embodiments. In addition, the accompanying drawings are schematically shown for easy viewing, and the ratios and angles of length, width, thickness, etc. in the accompanying drawings are different from the actual ones. Furthermore, in order to make the meaning of detailed shapes and symbols in the drawings easy to understand, the shapes sometimes do not correspond correctly between the accompanying drawings.

A. Compound cutting tool FIG. 1A is a schematic top view of a compound cutting tool of an embodiment of the present invention viewed from the direction of the rotation axis; FIG. 1B is a schematic three-dimensional view of the compound cutting tool of FIG. 1A. The compound cutting tool 20 of the illustrated example has: a main body 22, which rotates around the rotation axis 21; a cutting edge 23, which is provided on the outer periphery of the main body 22 and has a cutting tip 23a, a front cutting face 23b and a back cutting face 23c; and a grinding portion 24, which is provided as a protrusion having a file-like surface on a part of the back cutting face of the cutting edge 23.

The compound cutting tool 20 is formed integrally of a hard metal material such as a super-hard alloy or a high-speed tool steel, and is in the shape of a roughly cylindrical shaft with a rotating shaft 21 as the center. In the compound cutting tool of the illustrated example, one end (the upper end in the illustrated example) where a cutting edge is not formed is set as a shank 25 which is still cylindrical. Both ends of the compound cutting tool may also be set as shanks. The shank 25 of the compound cutting tool is held on the spindle of a working machine such as a machining center, and by rotating it around the rotating shaft 21, the cutting edge that abuts against an object cuts the object. When one end is set as a shank, the compound cutting tool is held on the working machine in a cantilevered state; and when both ends are set as shanks, the compound cutting tool is held on the working machine in a double-supported state.

As described above, the cutting edge 23 is disposed on the periphery of the main body 22. The cutting edge 23 has a cutting tip 23a, a front cutting face 23b, and a back cutting face 23c. The front cutting face 23b is the wall surface of the cutting edge 23 facing the rotation direction T. In the cross section in the direction perpendicular to the rotation axis, the front cutting face 23b of the illustrated example is an arc that is recessed on the side opposite to the rotation direction T, and the side extends toward the side opposite to the rotation direction T as it moves toward the peripheral side. The back cutting face 23c is the outer peripheral surface of the cutting edge 23, which defines the cutting tip 23a by intersecting with the front cutting face 23b. The back cutting face 23c is substantially also the outer peripheral surface of the composite cutting tool 20. The back cutting face 23c is preferably roughened. As the roughening treatment, any appropriate treatment can be adopted. As a representative example, blasting treatment can be cited. By roughening the back face, when the object to be cut (typically a resin sheet) includes an adhesive layer and/or an adhesive layer, the adhesive and/or the adhesive can be prevented from adhering to the cutting edge, thereby preventing blocking. "Blocking" as described in this specification refers to the phenomenon that when the resin sheet includes an adhesive layer and/or an adhesive layer, the resin sheets in the workpiece are bonded to each other by the adhesive on the end surface, and the cutting chips of the adhesive on the end surface promote the bonding of the resin sheets.

Regarding the number of cutting edges (the number of blades of the composite cutting tool), any appropriate number of blades can be adopted according to the purpose. The number of blades can be 1 blade, 2 blades, 3 blades, 4 blades as shown in the example in the figure, or 5 blades or more. The ideal number of blades is 2 blades or 4 blades. With the above-mentioned structure, the rigidity of the blade can be ensured and the chip groove can be ensured so that the chips can be discharged well. When the number of blades is plural (more than 2 blades), the multiple cutting blades can be formed at equal intervals in the circumferential direction as shown in the example in the figure, or can be formed at unequal intervals in the circumferential direction, but this is not shown. Furthermore, when the number of blades is plural (more than 2 blades), the rotation trajectories of the multiple cutting blades around the rotation axis 21 are typically made consistent with each other.

The helix angle θ of the cutting edge can be either 0° or a specific helix angle, depending on the purpose. That is, the cutting edge can be either a straight edge or a spiral edge, depending on the purpose. The helix angle θ of the cutting edge can be, for example, 0° to 65°, or 10° to 55°, or 20° to 50°, or 30° to 45°. In addition, the "helix angle of 0°" stated in this manual means that the blade tip 23a extends in a direction substantially parallel to the rotation axis 21. In addition, "0°" means substantially 0°, and also includes the situation where a slight angle is twisted due to processing errors, etc.

FIG2 is a schematic top view of the main parts, showing the detailed structure of the composite cutting tool 20. As shown in FIG2, the rake angle θ1 of the cutting edge is preferably -30° to 45°, preferably -10° to 30°, and more preferably 0° to 20°; the tip angle θ2 is preferably 20° to 100°, preferably 30° to 90°, and more preferably 45° to 80°. If the rake angle θ1 and the tip angle θ2 of the cutting edge are within the above range, the machined surface obtained by the cutting edge will be smooth, so there is an advantage that the subsequent processing by the grinding part is further uniform. In this specification, the "front angle" is the angle formed by a straight line connecting the rotation axis 21 and the blade tip 23a and a straight line extending from the blade tip 23a along the front cutting surface 23b in a cross section in a direction perpendicular to the rotation axis; the "tip angle" is the angle formed by a straight line extending from the blade tip 23a along the front cutting surface 23b and a straight line extending from the blade tip 23a along the back cutting surface 23c in a cross section in a direction perpendicular to the rotation axis. In addition, when the front cutting surface defines an arc in a cross section in a direction perpendicular to the rotation axis as shown in the example in the figure, the line extending along the front cutting surface is the tangent of the front cutting surface extending from the blade tip. In addition, the back cutting surface is the outer peripheral surface of the cutting edge, and defines an arc in a cross section in a direction perpendicular to the rotation axis, so the line extending along the back cutting surface is actually the tangent of the back cutting surface extending from the blade tip. Furthermore, a negative (-: minus) rake angle means that, in a cross section perpendicular to the rotation axis, a straight line extending from the cutting edge along the rake face is located on the rotation direction T side (left side in FIG. 2 ) of a straight line connecting the rotation axis and the cutting edge.

In the embodiment of the present invention, as described above, a grinding portion 24 is formed on a portion of the back blade 23c. The grinding portion 24 is configured as a protrusion having a file-like surface. The grinding portion 24 (substantially its surface) typically contains diamond particles. If it is configured as described above, a file-like surface having appropriate surface roughness and surface hardness can be formed. The grinding portion 24 typically functions as a rotating grindstone. In the case where a plurality of cutting edges are provided, the grinding portion is typically provided on each cutting edge. That is, the number of cutting edges is typically consistent with the number of grinding portions. Furthermore, the grinding portion is typically provided at a corresponding position of each cutting edge. In addition, in the case where a plurality of grinding portions are formed, the plurality of grinding portions are the same as the case of the cutting edges, and the rotational trajectories around the rotating shaft 21 are typically consistent with each other.

The protruding height H of the grinding portion 24 is preferably 0.1μm to 100μm, more preferably 1μm to 50μm, and more preferably 5μm to 30μm. If the protruding height H of the grinding portion is within the above range, it has the advantage that the resin sheet will not melt or break in the processed surface formed by the grinding portion, and a uniform processed surface can be obtained. Here, the protruding height H of the grinding portion is expressed by H=R2-R1. R1 is the distance from the rotation axis 21 to the blade tip 23a, and R2 is the distance from the rotation axis 21 to the surface of the grinding portion (protruding portion) 24. R1 is the radius of the rotation track of the cutting edge 23, and R2 is also the radius of the rotation track of the grinding portion 24. Therefore, the protruding height H of the grinding portion is the difference between the rotation radius of the grinding portion and the rotation radius of the cutting edge. In the cross section of the grinding part in the direction perpendicular to the rotation axis, the wall surfaces on both sides of the grinding part can extend radially to the rotation axis or extend outward substantially perpendicular to the outer periphery (flank surface) of the cutting edge. Furthermore, in the cross section of the grinding part in the direction perpendicular to the rotation axis, the surface of the grinding part is substantially flat and roughly consistent with the rotation track of the grinding part.

The width W (mm) of the grinding portion 24 along the outer circumferential direction of the composite cutting tool 20 is preferably less than R1 (mm), more preferably less than 0.5×R1 (mm), and more preferably less than 0.3×R1 (mm). The lower limit of the width W of the grinding portion may be, for example, 0.01×R1 (mm). If the width W of the grinding portion is within the above range, there is an advantage that the grinding portion is less clogged with cutting chips and the processing quality can be maintained at a certain level for a long time. In other words, the above advantages can be obtained by adjusting the width of the grinding portion according to the outer diameter of the composite cutting tool.

The position of the grinding portion 24 in the back face 23c of the cutting edge 23 can be appropriately set according to the purpose. In one embodiment, the distance L (mm) from the blade tip 23a to the wall of the grinding portion 24 facing the rotation direction and the distance R1 (mm) from the rotation axis 21 to the blade tip 23a satisfy the following formula (1): L≥0.1×R1   ･･･(1). The distance L is preferably 0.1×R1～1.0×R1, and more preferably 0.15×R1～0.8×R1. If the distance L and the distance R1 are in the above relationship, there is an advantage that the accumulation of cutting chips on the surface of the grinding portion is small and the processing quality can be maintained at a certain level for a long time. In other words, the above advantages can be obtained by setting the position of the grinding part according to the outer diameter of the composite cutting tool in accordance with the above relationship.

Regarding the surface roughness of the grinding part 24, the file number is preferably above #60, preferably above #100, and more preferably above #200. Regarding this surface roughness, the file number can be preferably below #2000, preferably below #1200, and more preferably below #800. If the surface roughness of the grinding part is within the above range, it has the following advantages: the resin sheet will not melt or break in the processed surface obtained by the grinding part, and the grinding part will be less blocked by cutting chips, and the processing quality can be maintained constant for a long time. In addition, regarding the number of the file, the smaller the number means the coarser the gap between the abrasive particles. The number can be adjusted by the amount and size of the diamond particles.

FIG3 is a schematic cross-sectional view of the main parts, used to illustrate the concave-convex shape of the file-like surface of the grinding portion 24. The depth D of the concave-convex on the file-like surface of the grinding portion 24 is, for example, 1 μm to 120 μm. The lower limit of the depth D is preferably 5 μm or more, preferably 10 μm or more. The upper limit of the depth D is preferably 50 μm or less, preferably 35 μm or less. The spacing p of the concave-convex on the file-like surface of the grinding portion 24 is, for example, 1 μm to 250 μm. The lower limit of the spacing p of the concave-convex is preferably 5 μm or more, preferably 10 μm or more. The upper limit of the spacing p of the concave-convex is preferably 100 μm or less, preferably 60 μm or less. If the concavo-convex shape of the grinding part surface is configured as described above, it has the following advantages: the resin sheet will not melt or be damaged in the processed surface obtained by the grinding part, and the grinding part will be less clogged by cutting chips, so that the processing quality can be kept constant for a long time.

The outer diameter of the compound cutting tool can be appropriately set according to the purpose. More specifically, the outer diameter of the compound cutting tool is preferably 0.5 mm to 30 mm, more preferably 0.8 mm to 25 mm, and more preferably 1 mm to 20 mm. If the outer diameter of the compound cutting tool is within the above range, it can be processed without defects using a working machine that can perform general end milling. In addition, the outer diameter of the compound cutting tool is the value obtained by multiplying the above R2 by 2 times (that is, the diameter of the rotating track of the grinding part).

In one embodiment, the cutting margin height Ph of each pitch of the composite cutting tool is preferably 0.03 μm to 280 μm, more preferably 0.1 μm to 100 μm, and more preferably 0.2 μm to 10 μm. If the cutting margin height Ph is within the above range, the resin sheet will not melt or break in the processed surface obtained by the grinding part, and a uniform processed surface can be obtained. Here, the pitch P is expressed by the following formula (2), and the cutting residual height Ph of each pitch is expressed by the following formula (3): P=F/(S×N)  ･･･(2) Ph=arcsin(P/2×R1)  ･･･(3) In formula (2), F is the feed speed of the compound cutting tool (mm/minute), S is the number of rotations of the compound cutting tool (rpm), and N is the number of cutting edges of the compound cutting tool.

The shape of the grinding portion 24 viewed from the direction of the rotation axis (the outer contour shape of the surface of the grinding portion) can adopt any appropriate shape depending on the purpose, etc. Figures 4(a) to 4(e) are respectively schematic top views of the main parts, showing representative variations of the grinding portion. The grinding portion of Figure 4(a) has a substantially flat surface along the periphery from the wall facing the opposite side of the rotation direction to the predetermined portion in the rotation direction in a cross section in a direction perpendicular to the rotation axis, and the protrusion height gradually decreases from the predetermined portion to the wall facing the rotation direction. The grinding portion of Figure 4(b) has a protrusion height gradually decreases from the wall facing the opposite side of the rotation direction to the wall facing the rotation direction in a cross section in a direction perpendicular to the rotation axis. In the cross section of the grinding portion in FIG4(c) in the direction perpendicular to the rotation axis, the protrusion height gradually decreases at a first inclination angle from the wall facing the opposite side of the rotation direction to the predetermined portion in the rotation direction; and the protrusion height gradually decreases at a second inclination angle greater than the first inclination angle from the predetermined portion to the wall facing the rotation direction. In the cross section of the grinding portion in FIG4(d) in the direction perpendicular to the rotation axis, the wall facing the rotation direction extends toward the opposite side of the rotation direction as it moves toward the outside (protruding side). In the cross section of the grinding portion in FIG4(e) in the direction perpendicular to the rotation axis, the intersection of the line defining the surface of the grinding portion and the line defining the wall facing the rotation direction is in a chamfered shape. These modifications may also be appropriately combined. For example, in the variants of FIG. 4(a) to FIG. 4(d), the intersection of the line defining the surface of the grinding portion and the line defining the wall surface facing the rotation direction may also be chamfered; and, for example, in the variants of FIG. 4(a) to FIG. 4(c), the wall surface facing the rotation direction may also extend toward the side opposite to the rotation direction as it moves toward the outside (protruding side). Such variants may be appropriately selected according to the protruding height H of the grinding portion, the position (distance L) where the grinding portion is set, the cutting residual height Ph, etc. For example, the variant of FIG4(b) may be useful when the protrusion height H of the grinding portion is large; the variant of FIG4(c) may be useful when the distance L is large; the variant of FIG4(d) may be useful when the cutting height Ph is small; the variant of FIG4(e) may be useful when the cutting height Ph is large. Furthermore, the variant of FIG4(a) may be useful when the protrusion height H, the distance L, and the cutting height Ph are all of medium size.

B. Resin sheet As the resin sheet, any appropriate resin sheet that can be used for end surface processing can be cited. The resin sheet can be either a film composed of a single layer or a laminate. As specific examples of the resin sheet, optical films, heat insulation sheets, resin windows, surface protection films, fiber reinforced plastic (FRP) sheets, packaging films, and food films can be cited. In one embodiment, the resin sheet includes an optical film. Optical films require precise end surface processing compared to other resin sheets or films, so the effect brought about by the embodiment of the present invention is significant. As specific examples of optical films, polarizers, phase difference films, polarizing plates (representatively, a laminate of a polarizer and a protective film), conductive films for touch panels, surface treatment films, and laminates formed by appropriately laminating these films according to the purpose (for example, circular polarizing plates for anti-reflection, polarizing plates with conductive layers for touch panels). In one embodiment, the resin sheet includes a bonding agent layer and/or an adhesive layer. Therefore, the resin sheet can be, for example, an optical film including a bonding agent layer and/or an adhesive layer. In an optical film including a bonding agent layer and/or an adhesive layer, the effect brought about by the embodiment of the present invention is more significant.

C. Method for manufacturing resin sheet Below, a method for manufacturing a resin sheet using a polarizing plate with an adhesive layer as an example is described. For a person skilled in the art, it is obvious that the top view shape of the polarizing plate with an adhesive layer is not limited to the top view shape of the example in the figure. In addition, for a person skilled in the art, it is obvious that the embodiment of the present invention can also be applied to any suitable resin sheet other than the polarizing plate with an adhesive layer. That is, the embodiment of the present invention can be used to manufacture any suitable resin sheet having any suitable shape.

C-1. Formation of workpiece FIG. 5 is a schematic three-dimensional diagram for explaining the outline of the end surface processing of the resin sheet (here, the polarizing plate with an adhesive layer) in the manufacturing method of the embodiment of the present invention. In this figure, the workpiece W is shown. As shown in FIG. 5, the workpiece W is formed by overlapping a plurality of polarizing plates with an adhesive layer. Typically, the polarizing plate with an adhesive layer is cut from the original sheet roll into any appropriate size and shape when the workpiece is formed. Specifically, the polarizing plate with an adhesive layer can be cut into a rectangular shape, a shape similar to a rectangular shape, or a shape suitable for the purpose (e.g., a circle). In the example of the figure, the polarizing plate with an adhesive layer is cut into a rectangular shape, and the workpiece W has mutually opposing peripheral surfaces (cutting surfaces) 1a, 1b and peripheral surfaces (cutting surfaces) 1c, 1d orthogonal thereto. The cutting is performed by any appropriate means. As specific examples of the cutting means, punching by a punching knife (such as a Thompson knife) and laser irradiation can be cited. In one embodiment, a peeling liner can also be temporarily attached to the adhesive layer surface of the polarizing plate with an adhesive layer, and/or a surface protection film can also be temporarily attached to the surface of the polarizing plate with an adhesive layer on the opposite side of the adhesive layer.

The total thickness of the workpiece is, for example, more than 3 mm, preferably more than 5 mm, more preferably more than 10 mm, more preferably more than 30 mm, and particularly preferably more than 60 mm. According to the implementation form of the present invention, by using a composite cutting tool as described in the above-mentioned item A, even a workpiece of the aforementioned thickness can be cut without any adverse conditions (representatively, end surface processing). As a result, a resin sheet (here, a polarizing plate with an adhesive layer) can be manufactured efficiently and simply. On the other hand, the total thickness of the workpiece is preferably less than 150 mm, and more preferably less than 100 mm. The upper limit of the total thickness of the workpiece is mainly due to the constraints on the structure of the working machine. In addition, according to the implementation form of the present invention, the effect is remarkable when the workpiece thickness is thick, but of course it can be implemented without any adverse conditions even if the workpiece is of normal thickness (for example, less than 10 mm).

Ideally, the workpiece W is clamped from above and below by a clamping mechanism (not shown). The clamping mechanism (e.g., a clamp) can be made of either a soft material or a hard material. When made of a soft material, its hardness (JIS A) is preferably 60° to 80°. If the hardness is too high, indentations formed by the clamping means may sometimes remain. If the hardness is too low, positional deviations may occur due to deformation of the clamp, and cutting accuracy may sometimes be insufficient.

C-2. End surface processing using a compound cutting tool Next, the compound cutting tool 20 is used to cut a predetermined position on the outer peripheral surface of the workpiece W (end surface processing). Typically, the compound cutting tool 20 is held by a working machine (not shown) and rotated at high speed around the rotating axis of the compound cutting tool, and is used while being fed in a direction intersecting the rotating axis and the cutting edge is brought into contact with the outer peripheral surface of the workpiece W and cuts in. That is, typically, the cutting edge of the compound cutting tool is brought into contact with the outer peripheral surface of the workpiece W and cuts in to perform cutting. Furthermore, according to an embodiment of the present invention, after cutting in using the cutting edge, grinding (cutting) is then performed using a grinding portion whose radius of the rotating track is larger than that of the cutting edge. By additionally performing cutting using the grinding section, even a thick workpiece can be end-face processed without any adverse conditions (more specifically, there is no cutting residue due to the cutting edge not contacting the workpiece, and the workpiece can be processed uniformly in the thickness direction). Furthermore, cracks on the polarizing plate (representatively the polarizer) with an adhesive layer, dirt on the cutting edge, and adhesion can be suppressed. In particular, the development of cracks over time can be well suppressed. In addition, when a peel-off liner and/or a surface protection film is temporarily adhered to the polarizing plate with an adhesive layer, such convexities can be suppressed. Here, cutting edge contamination refers to the phenomenon that the adhesive of the adhesive layer adheres to the cutting edge, causing the cutting performance (processing performance) to exceed the allowable range and decrease. Adhesion is as described above.

The conditions for end surface processing using a compound cutting tool can be appropriately set according to the type of resin sheet, the desired shape, etc. For example, the rotation speed (number of revolutions) of the compound cutting tool is preferably 100rpm to 50,000rpm, more preferably 1,000rpm to 30,000rpm, and more preferably 2,000rpm to 20,000rpm. Also, for example, the feed speed of the compound cutting tool is preferably 100mm/minute to 5,000mm/minute, more preferably 200mm/minute to 4,000mm/minute, and more preferably 300mm/minute to 3,000mm/minute. If the rotation speed and feed speed of the compound cutting tool are within the above range, even thick workpieces can be end surface processed without any problems. The number of times the end face of the workpiece (resin sheet) is cut using the compound cutting tool may be one cut, two cuts, three cuts or more.

The composite cutting tool can be held on a working machine in a cantilevered state or in a doubly supported state. By holding it in a cantilevered state, the composite cutting tool can be easily moved in the plane and in the up and down directions. As a result, when non-linear cutting (processing) is required, the cutting becomes easier. In addition, in the cantilevered state, it is easy to manufacture the composite cutting tool. On the other hand, by holding it in a doubly supported state, the shaking of the cutting surface (the unevenness when the cutting surface is viewed from the horizontal direction) can be suppressed. Furthermore, by holding it in a doubly supported state, the stress acting on the composite cutting tool by the cutting edge during cutting can be reduced. As a result, the durability of the composite cutting tool can be improved, and therefore, the stability and reliability of the end face processing performed using the composite cutting tool can be improved.

The end surface processing of the resin sheet using a composite cutting tool can be performed on the entire outer peripheral surface of the resin sheet or on a portion of the outer peripheral surface. When the resin sheet includes a polarizer (for example, when the resin sheet is a polarizing plate with an adhesive layer as shown in the example of the figure), the end surface processing using a composite cutting tool should be performed only in the absorption axis direction of the polarizer. Figures 6(a) and 6(b) are schematic top views, which are used to illustrate an example of specific steps for end surface processing of a resin sheet including a polarizer (here, a polarizing plate with an adhesive layer). In this embodiment, the polarizing plate with an adhesive layer is cut into a rectangular shape in a manner such that the absorption axis A of the polarizer is in the short side direction, as shown in Figure 6(a).

Next, as shown in FIG6(a), the end face of the short side is processed by an end mill. The end mill can have any appropriate structure according to the purpose and the type of resin sheet including the polarizer. For example, the end mill can have the same structure as the composite cutting tool except that the grinding part is not provided, or it can have a completely different structure as a whole (for example, outer diameter, number of edges, helix angle, rake angle, blade tip angle). The conditions for end face processing using the end mill can be appropriately set according to the purpose. The outer diameter of the end mill can be, for example, 0.5 mm to 30 mm, or 1 mm to 20 mm. The rotation speed (number of revolutions) of the end mill can be, for example, 100 rpm to 50,000 rpm, or 1000 rpm to 35,000 rpm, or 2000 rpm to 20,000 rpm. In addition, the feed rate of the end milling cutter can be, for example, 100 mm/min to 5,000 mm/min, or can be, for example, 300 mm/min to 3,000 mm/min. The number of times the end face of the short side of the workpiece (including the resin sheet of the polarizer, in this case, the polarizer with an adhesive layer) is cut by the end milling cutter can be one cutting, two cuttings, three cuttings or more. The example in the figure schematically shows two cuttings for rough machining and fine machining. Rough machining and fine machining can be performed under the same conditions or under different conditions.

Next, as shown in FIG6(b), the end face processing of the long side is performed using a composite cutting tool. The composition of the composite cutting tool is as described in the above-mentioned item A, and the conditions for the end face processing using the composite cutting tool are as described above. By performing the end face processing, even a thick workpiece can be processed without any defects. Furthermore, cracks in the polarizing plate (representatively, the polarizer) with an adhesive layer, contamination and agglomeration of the cutting edge can be suppressed. In addition, when a peeling liner and/or a surface protection film is temporarily adhered to the polarizing plate with an adhesive layer, such reliefs can be suppressed. When the end milling cutter is used to process the entire periphery of the polarizing plate with an adhesive layer, there are often cases where cutting residue occurs because the cutting edge does not abut the workpiece. When the end milling cutter is used to process the entire periphery of the polarizing plate with an adhesive layer, the end surface processed in the direction parallel to the absorption axis is weak to the impact caused by thermal shock, and cracks may occur. However, when the resin sheet does not include a polarizer, the above problem will not occur even if the composite cutting tool is used to process the entire periphery of the resin sheet.

Implementation Examples The present invention is described in detail below by using implementation examples, but the present invention is not limited to such implementation examples. The evaluation items in the implementation examples are as follows.

(1) Cracks The polarizing plates with adhesive layers obtained in the examples, comparative examples and reference examples were adhered to glass plates (thickness 1.1 mm) through the adhesive layers as test samples. (1-1) Cracks caused by thermal shock test The test samples were subjected to the following thermal shock test: after being kept at -40°C for 30 minutes, they were kept at 85°C for 30 minutes, and the above operation was repeated 300 times; the state of cracks after the test was observed by an optical microscope (magnification 5 times). Specifically, the number and length (μm) of cracks were investigated and evaluated according to the following criteria. A: The number is less than 10 and the maximum length is less than 500μm B: The number is less than 10, but the maximum length exceeds 500μm C: The number is more than 10 and the maximum length exceeds 500μm (1-2) Cracks caused by heating test The above test specimens were subjected to a heating test at 105℃ for 1000 hours and evaluated in the same way as (1-1).

(2) Embossment The embossment amount of the surface protective film and the peeling liner of the polarizing plate with adhesive layer obtained in the embodiment, comparative example and reference example was measured by a magnifying glass or a microscope. The maximum embossment amount of one workpiece was taken as the embossment amount, and the evaluation was performed according to the following criteria. A: Embossment amount is less than 300μm B: Embossment amount exceeds 300μm and is less than 500μm C: Embossment amount exceeds 500μm

(3) Blade contamination The cutting edge of the composite cutting tool after end face processing in the embodiment and the cutting edge of the end milling cutter after end face processing in the comparative example and reference example were observed for contamination caused by adhesives and evaluated according to the following criteria. A: No contamination was substantially confirmed B: Contamination was confirmed, but no problems occurred during processing C: Significant contamination was confirmed, and problems also occurred during processing

(4) Agglomeration The state of the workpiece after end surface processing of the embodiment, comparative example and reference example was observed and evaluated according to the following criteria. A: It is easy to separate from the workpiece to the polarizing plate with adhesive layer attached B: Although it can be separated from the workpiece to the polarizing plate with adhesive layer attached, the separation operation is difficult C: The workpiece is completely in a block and cannot be separated from the polarizing plate with adhesive layer attached

<Example 1> A polarizing plate with an adhesive layer having a structure of surface protection film (60μm)/cycloolefin protective film (47μm)/polarizer (5μm)/cycloolefin protective film (24μm)/adhesive layer (20μm)/peeling liner in order from the viewing side was prepared by a conventional method. In addition, as a surface protection film, a surface protection film having a structure of PET substrate (50μm)/adhesive layer (10μm) was used. The polarizing plate with an adhesive layer was punched into a size of 5.7 inches (about 140mm in length and 65mm in width). Here, punching was performed in a manner that the absorption axis direction of the polarizer was the horizontal direction (short side direction). The workpiece is made by stacking multiple sheets of polarizing plates with adhesive layers after punching. The total thickness of the workpiece is 45mm. While the workpiece is clamped by a clamp (fixture), the end surface of the short side (the absorption axis direction of the polarizer) is processed by an end mill. Specifically, an end mill with an outer diameter of 9mm, double edges, and a helix angle of 45° is used to perform secondary end surface processing on each short side, including rough machining and fine machining. The cutting amount for rough machining is 0.2mm, and the cutting amount for fine machining is 0.1mm. In both rough machining and fine machining, the feed speed of the end mill is 1,000mm/minute and the number of rotations is 35,000rpm. Next, the end face of the long side (in the direction perpendicular to the absorption axis direction of the polarizer) was processed by the composite cutting tool of the embodiment of the present invention. A composite cutting tool was used in which a grinding portion with a protrusion height of 20 μm was provided on the back face of the cutting edge of the above-mentioned end mill. The protruding surface of the grinding portion is a file-like (or rotating grindstone-like) shape containing diamond particles. The distance L from the tip of the cutting edge to the wall surface of the grinding portion facing the rotation direction is 0.9 mm, and has a relationship of L=0.167×R1 with the distance R1 from the rotation axis to the tip. The end face processing of the long side was performed twice under the same conditions. Specifically, the feed speed of the composite cutting tool is 1,000 mm/min, the number of rotations is 8,000 rpm, and the cutting amount per time is 0.1 mm. According to the above operation, a polarizing plate with an adhesive layer was obtained. In the end surface processing, there is no need to precisely adjust the holding state of the end milling cutter and the composite cutting tool on the working machine, and uniform cutting is achieved throughout the thickness direction of the workpiece. The above-mentioned (1) to (4) evaluations were performed on the obtained polarizing plate with an adhesive layer. The results are shown in Table 1.

<Example 2> Except that the thickness of the workpiece was set to 60 mm, a polarizing plate with an adhesive layer was obtained in the same manner as in Example 1. In end surface processing, there was no need to precisely adjust the holding state of the end milling cutter and the composite cutting tool on the working machine, and uniform cutting was achieved throughout the thickness direction of the workpiece. The obtained polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 1> All sides (the entire periphery) of a workpiece formed in the same manner as in Example 1 were subjected to end surface processing using only an end mill. Specifically, the entire periphery of the workpiece was subjected to secondary end surface processing including rough processing and fine processing in a continuous and uninterrupted manner. The conditions for rough processing and fine processing were the same as those in Example 1. Next, only the long sides were subjected to end surface processing using a rotary grindstone (#400). The number of rotations of the rotary grindstone was 1,000 rpm, and the feed speed was 500 mm/min. According to the above operation, a polarizing plate with an adhesive layer was obtained. In the end surface processing of the end mill, poor cutting occurred in a portion of the workpiece (the upper end or the lower end in the thickness direction). The poor cutting was prominent in the long sides. The polarizing plate with the adhesive layer obtained was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Reference Example 1> A polarizing plate with an adhesive layer was obtained in the same manner as in Comparative Example 1 except that the thickness of the workpiece was set to 15 mm. No poor cutting was observed in the end surface processing. The obtained polarizing plate with an adhesive layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Table 1]

<Evaluation> According to Table 1, the composite cutting tool of the embodiment of the present invention can cut thick workpieces without any problems.

Industrial Applicability The composite cutting tool of the embodiment of the present invention can be suitably used for manufacturing resin sheets (especially end surface processing during manufacturing). The resin sheet can be, for example, an optical film.

A: Absorption axis D: Depth H: Projection height L: Distance P: Pitch R ₁ : Distance from the rotation axis to the tool tip R ₂ : Distance from the rotation axis to the surface of the projecting part T: Rotation direction W: Workpiece 1a, 1b, 1c, 1d: Outer surface 20: Composite cutting tool 21: Rotation axis 22: Body 23: Cutting edge 23a: Tool tip 23b: Rake face 23c: Flank face 24: Grinding part 25: Shank θ: Helix angle θ1: Rake angle θ2: Tool tip angle

FIG. 1A is a schematic top view of a composite cutting tool according to an embodiment of the present invention viewed from the direction of the rotation axis. FIG. 1B is a schematic three-dimensional view of the composite cutting tool of FIG. 1A. FIG. 2 is a schematic top view of the main part, showing the detailed structure of the composite cutting tool according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of the main part, used to illustrate the depth and spacing of the concave and convex surfaces of the grinding portion of the composite cutting tool according to an embodiment of the present invention. FIG. 4(a) to FIG. 4(e) are each schematic top views of the main part, showing a variation of the grinding portion of the composite cutting tool according to an embodiment of the present invention. FIG. 5 is a schematic three-dimensional view, used to illustrate the outline of the end surface processing of the resin sheet in the manufacturing method according to an embodiment of the present invention. Figure 6(a) and Figure 6(b) are schematic top views for illustrating an example of end surface processing when the resin sheet includes a polarizer in the manufacturing method of the embodiment of the present invention.

T: Rotation direction

20: Composite cutting tools

21: Rotation axis

22: Subject

23: Cutting edge

23a: Knife tip

23b: Rake face

23c: back blade

24: Grinding Department

Claims (9)

A composite cutting tool comprises: a main body, which rotates around a rotation axis; a cutting edge, which is arranged on the outer periphery of the main body and has a cutting edge, a rake face and a flank face; and a grinding portion, which is a protrusion formed integrally with the main body and is arranged on a part of the flank face of the cutting edge and has a file-like surface, wherein the helix angle of the cutting edge is 10° to 55°, and the grinding portion has a wall surface facing the rotation direction and a wall surface facing the opposite side to the rotation direction in a cross section in a direction perpendicular to the rotation axis, wherein the protrusion height H of the grinding portion is 0.1 μm to 150 μm, and the distance L from the cutting edge to the wall surface of the grinding portion facing the rotation direction and the following distance R1 satisfy the following formula (1):

The aforementioned composite cutting tool is used for cutting optical films, wherein the aforementioned optical films include a bonding agent layer and/or an adhesive layer, and a polarizing element. Here, the protrusion height H is represented by H=R2-R1, where R1 is the radius of the rotation track of the cutting edge, and R2 is the radius of the rotation track of the grinding portion. For example, in the composite cutting tool of claim 1, the cutting residual height Ph of each spacing is 0.03μm~280μm. Here, the spacing P is expressed by the following formula (2), and the cutting residual height Ph of each spacing is expressed by the following formula (3): P=F/(S×N)…(2) Ph=arcsin(P/2×R1)…(3) In formula (2), F is the feed speed of the composite cutting tool (mm/minute), S is the number of rotations of the composite cutting tool (rpm), and N is the number of cutting edges of the composite cutting tool. A composite cutting tool as claimed in claim 1, wherein the wall surface facing the aforementioned rotation direction and the wall surface facing the opposite side to the rotation direction extend radially with respect to the aforementioned rotation axis, or extend outward in a manner substantially orthogonal to the back face of the aforementioned cutting edge. A composite cutting tool as claimed in claim 2, wherein the wall surface facing the aforementioned rotation direction and the wall surface facing the opposite side to the rotation direction extend radially with respect to the aforementioned rotation axis, or extend outward in a manner substantially orthogonal to the back face of the aforementioned cutting edge. A composite cutting tool as claimed in any one of claims 1 to 4, wherein the abrasive portion comprises diamond particles. For a composite cutting tool as claimed in any one of claims 1 to 4, the rake angle θ1 is -30°~45°, and the tool tip angle θ2 is 20°~100°, wherein the rake angle is the angle formed by a straight line connecting the rotation axis and the tool tip and a straight line extending from the tool tip along the rake face in a cross section in a direction perpendicular to the rotation axis; the tool tip angle is the angle formed by a straight line extending from the tool tip along the rake face and a straight line extending from the tool tip along the flank face in a cross section in a direction perpendicular to the rotation axis. For the composite cutting tool of claim 5, the rake angle θ1 is -30°~45°, and the tool tip angle θ2 is 20°~100°, wherein the rake angle is the angle formed by a straight line connecting the rotation axis and the tool tip and a straight line extending from the tool tip along the rake face in a cross section in a direction perpendicular to the rotation axis; the tool tip angle is the angle formed by a straight line extending from the tool tip along the rake face and a straight line extending from the tool tip along the flank face in a cross section in a direction perpendicular to the rotation axis. A method for manufacturing a resin sheet comprises the following steps: overlapping a plurality of resin sheets to form a workpiece; and cutting the outer peripheral surface of the workpiece using a composite cutting tool as in any one of claims 1 to 7. The resin sheet comprises an optical film, and the optical film comprises a bonding agent layer and/or an adhesive layer, and a polarizer. The method for manufacturing a resin sheet as claimed in claim 8, wherein the thickness of the aforementioned workpiece is greater than 30 mm.

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