KR20240036538A - Composite cutting tool and method for manufacturing resin sheet using the same - Google Patents

Abstract

(Problem) To provide a composite cutting tool that can cut even thick workpieces without problems, and a method for manufacturing resin sheets using such a composite cutting tool with high efficiency and ease.
(Solution) A composite cutting tool according to an embodiment of the present invention includes a main body that rotates around a rotation axis; A cutting blade formed on the outer periphery of the main body and having a blade tip, an inclined surface, and a relief surface; A part of the relief surface of the cutting edge has a polishing portion formed as a protrusion with a file-shaped surface. The method for manufacturing a resin sheet according to an embodiment of the present invention includes forming a workpiece by stacking a plurality of resin sheets, and cutting the outer peripheral surface of the workpiece with the above-mentioned composite cutting tool.

Description

Composite cutting tool and method for manufacturing a resin sheet using the same {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 producing a resin sheet using the same.

Various resin sheets are widely used depending on the purpose. After the resin sheet is cut into a predetermined shape, the outer peripheral end surface may be subjected to finishing processing. In such finishing processing, cutting using an end mill may be performed. Cutting with an end mill is usually performed on a workpiece in which multiple resin sheets are overlapped. Here, considering manufacturing efficiency, it is preferable to cut a thick workpiece. However, when cutting a thick workpiece, if the endmill is tilted, there may be a portion of the workpiece that the endmill does not contact. Therefore, there is a problem that the holding state of the end mill on the machine tool must be precisely adjusted and the thickness of the work must be kept below a certain value, resulting in insufficient manufacturing efficiency.

Japanese Patent Publication No. 2009-196015

The present invention was made to solve the above-described conventional problems, and its main purpose is to provide a composite cutting tool that can cut even thick workpieces without problems, and to manufacture resin sheets with high efficiency and ease using such a composite cutting tool. It's about providing a method.

A composite cutting tool according to an embodiment of the present invention includes a main body that rotates around a rotation axis; a cutting blade formed on the outer periphery of the main body and having a blade tip, an inclined surface, and a relief surface; A portion of the relief surface of the cutting edge has a polishing portion formed as a protrusion having a file-shaped surface.

In one embodiment, the protrusion height (H) of the polishing portion is 0.1 μm to 150 μm. Here, the protrusion height (H) is expressed as H=R2-R1, R1 is the distance from the rotation axis to the blade tip, 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 facing the rotation direction of the polishing unit and the R1 satisfy the following equation (1):

L≥0.1×R1···(1).

In one embodiment, the composite cutting tool has a height (Ph) of residual material per pitch of 0.03 μm to 280 μm. Here, the pitch (P) is expressed by the following equation (2), and the height of the remaining material (Ph) for each pitch is expressed by the following equation (3):

P=F/(S×N)···(2)

Ph=arcsin(P/2×R1)···(3)

In equation (2), F is the feed speed (mm/min) of the composite cutting tool, S is the rotation speed (rpm) of the composite cutting tool, and N is the number of cutting edges of the composite cutting tool.

In one embodiment, the polishing portion includes diamond particles.

In one embodiment, the composite cutting tool has a rake angle θ1 of -30° to 45° and a blade tip angle θ2 of 20° to 100°. Here, the inclination 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 inclined plane in a cross section perpendicular to the rotation axis; The blade tip angle is the angle formed by a straight line extending from the blade tip along an inclined plane and a straight line extending from the blade tip along a relief surface in a cross section perpendicular to the rotation axis.

According to another aspect of the present invention, a method for manufacturing a resin sheet is provided. The manufacturing method includes forming a workpiece by overlapping a plurality of resin sheets, and cutting the outer peripheral surface of the workpiece with the composite cutting tool.

In one embodiment, the thickness of the workpiece is 30 mm or more.

In one embodiment, the resin sheet includes an adhesive 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.

According to the embodiment of the present invention, a composite cutting tool that can cut even thick workpieces without problems can be realized. By using such a composite cutting tool, a method for manufacturing resin sheets with high efficiency and simplicity can be realized.

1A is a schematic plan view of a composite cutting tool according to one embodiment of the present invention as seen from the rotation axis direction.
Figure 1B is a schematic perspective view of the composite cutting tool of Figure 1A.
Figure 2 is a schematic plan view showing the detailed structure of a composite cutting tool according to one embodiment of the present invention.
Figure 3 is a schematic cross-sectional view of main parts for explaining the uneven depth and pitch of the surface of the polishing part in the composite cutting tool according to one embodiment of the present invention.
4(a) to 4(e) are schematic plan views of main parts showing modified examples of the polishing portion in the composite cutting tool according to the embodiment of the present invention.
Figure 5 is a schematic perspective view for explaining the outline of end surface processing of a resin sheet in the manufacturing method according to the embodiment of the present invention.
6(a) and 6(b) are schematic plan views for explaining an example of end surface processing when the resin sheet includes a polarizer in the manufacturing method according to the embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Additionally, for ease of viewing, the drawings are shown schematically, and the ratios and angles of length, width, thickness, etc. in the drawings are different from those in reality. Additionally, in order to make it easier to understand the detailed shapes and the meanings of symbols in the drawings, there are cases where shapes do not correspond exactly between drawings.

A.Composite cutting tools

1A is a schematic plan view of a composite cutting tool according to one embodiment of the present invention as seen from the rotation axis direction; Figure 1B is a schematic perspective view of the composite cutting tool of Figure 1A. The composite cutting tool 20 of the illustrated example includes a main body 22 rotating around a rotation axis 21; A cutting edge 23 formed on the outer periphery of the main body 22 and having a blade tip 23a, an inclined surface 23b, and a relief surface 23c; A portion of the relief surface of the cutting edge 23 has a polishing portion 24 formed as a protrusion with a file-shaped surface.

The composite cutting tool 20 is integrally formed of hard metal materials such as cemented carbide and high-speed tool steel, and has a substantially cylindrical shaft shape centered on the rotation axis 21. In the composite cutting tool in the illustrated example, one end (the upper end in the illustrated example) where a cutting edge is not formed is a cylindrical shank portion 25. Both ends of the composite cutting tool may be shank portions. The shank portion 25 of the composite cutting tool is held on the main axis of a machine tool such as a machining center and rotated around the rotation axis 21, so that the cutting edge in contact with the object cuts the object. When one end becomes a shank portion, the composite cutting tool remains cantilevered on the machine tool; When the end becomes a shank portion, the composite cutting tool is maintained in a double-armed state on the machine tool.

The cutting edge 23 is formed on the outer periphery of the main body 22 as described above. The cutting edge 23 has a blade tip 23a, an inclined surface 23b, and a relief surface 23c. The inclined surface 23b is a wall surface facing the rotation direction T of the cutting edge 23. The inclined surface 23b in the illustrated example defines a hollow circular arc on the opposite side of the rotation direction T in a cross section perpendicular to the rotation axis, and is directed toward the outer circumference side opposite to the rotation direction T. It is extended. The relief surface 23c is the outer peripheral surface of the cutting edge 23, and intersects the inclined surface 23b to define the edge 23a. The relief surface 23c is also substantially the outer peripheral surface of the composite cutting tool 20. The relief surface 23c is preferably roughened. As the roughening treatment, any suitable treatment may be employed. A representative example is blasting. By performing a roughening treatment on the relief surface, when the object to be cut (typically a resin sheet) includes an adhesive layer and/or an adhesive layer, adhesion of the adhesive and/or adhesive to the cutting edge is suppressed, and as a result, Blocking can be suppressed. In this specification, “blocking” refers to the phenomenon in which the resin sheets in the work are bonded to each other with an adhesive on the end surface, etc., in the case where the resin sheet includes an adhesive layer and/or an adhesive layer, and the adhesive attached to the end surface, etc. The cutting residue contributes to the adhesion of the resin sheets.

As the number of cutting edges (the number of teeth of a composite cutting tool), any appropriate number of teeth can be adopted depending on the purpose. The number of blades may be 1, 2, 3, 4 as shown in the example, or 5 or more. Preferably, the number of blades is 2 or 4. With this configuration, the rigidity of the blade is secured, a pocket is secured, and cutting waste can be discharged satisfactorily. When the number of blades is plural (two or more), the plurality of cutting edges may be formed at equal intervals in the circumferential direction as shown, or may be formed at unequal intervals in the circumferential direction, although not shown. Additionally, when the number of blades is plural (two or more), the rotation trajectories of the plurality of cutting edges around the rotation axis 21 typically coincide with each other.

Depending on the purpose, the cutting edge may have a twist angle (Θ) of 0° or may have a specific twist angle. In other words, the cutting edge may be a straight blade or a twisted blade depending on the purpose. The twist angle (Θ) of the cutting edge may be, for example, 0° to 65°, for example, 10° to 55°, for example, 20° to 50°, or for example, 30°. It may be ∼45°. In addition, in this specification, “twist angle of 0°” means that the blade tip 23a extends in a direction substantially parallel to the rotation axis 21. In addition, “0°” means substantially 0°, and includes cases where the angle is slightly distorted due to processing errors, etc.

FIG. 2 is a schematic plan view of the main portion showing the detailed structure of the composite cutting tool 20. As shown in Fig. 2, the inclination angle θ1 of the cutting edge is preferably -30° to 45°, more preferably -10° to 30°, and still more preferably 0° to 20°; The blade tip angle (θ2) is preferably 20° to 100°, more preferably 30° to 90°, and still more preferably 45° to 80°. If the rake angle θ1 and the blade tip angle θ2 of the cutting edge are within this range, the machining surface by the cutting edge is smoothed, so there is an advantage that subsequent machining by the polishing unit becomes more uniform. In this specification, the “rake angle” refers to the straight line connecting the rotation axis 21 and the blade tip 23a and the straight line extending from the blade tip 23a along the inclined surface 23b in a cross section perpendicular to the rotation axis. is an angle; “Blade tip angle” is the angle formed by a straight line extending from the blade tip 23a along the inclined surface 23b and a straight line extending from the blade tip 23a along the relief surface 23c in a cross section perpendicular to the rotation axis. . In addition, when the inclined surface defines a circular arc in the cross section in the direction perpendicular to the rotation axis as in the example shown, the line extending along the inclined surface is a tangent to the inclined surface extending from the blade tip. In addition, the relief surface is the outer peripheral surface of the cutting edge, and defines a circular arc in the cross section in the direction perpendicular to the rotation axis, so the line extending along the relief surface is actually a tangent to the relief surface extending from the edge of the blade. Additionally, a negative rake angle means that, in a cross section perpendicular to the rotation axis, the straight line extending from the blade tip along the inclined surface is closer to the rotation direction (T) than the straight line connecting the rotation axis and the blade tip (left side of Figure 2). It means the case in .

In the embodiment of the present invention, the polishing portion 24 is formed on a part of the relief surface 23c as described above. The polishing portion 24 is formed as a protrusion having a file-shaped surface. The polished portion 24 (substantially its surface) typically contains diamond particles. With this configuration, a stripe-shaped surface with appropriate surface roughness and surface hardness can be formed. The polishing unit 24 can typically function as a rotating grindstone. When a plurality of cutting edges are formed, a polishing portion is typically formed on each cutting edge. That is, typically the number of cutting edges and the number of polishing parts are the same. Additionally, the polishing portion is typically formed at a position corresponding to each cutting edge. Additionally, when a plurality of polishing portions are formed, the rotation trajectories of the plurality of polishing portions around the rotation axis 21 typically coincide with each other, as in the case of cutting edges.

The protrusion height (H) of the polishing portion 24 is preferably 0.1 μm to 100 μm, more preferably 1 μm to 50 μm, and still more preferably 5 μm to 30 μm. If the protrusion height (H) of the polishing section is within this range, there is an advantage that the resin sheet does not melt or break on the surface processed by the polishing section and a uniform processing surface is obtained. Here, the protrusion height (H) of the polished portion is expressed as 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 polished portion (protrusion) 24. R1 is the radius of the rotation orbit of the cutting edge 23, and R2 is the radius of the rotation orbit of the polishing unit 24. Therefore, the protrusion height (H) of the polishing part is the difference between the turning radius of the polishing part and the turning radius of the cutting edge. In the example of the illustration, in a cross section perpendicular to the rotation axis, the walls on both sides of the polishing unit may extend radially with respect to the rotation axis, or may extend outward so as to be substantially perpendicular to the outer periphery (clearance surface) of the cutting edge. Additionally, in the cross section of the polishing section in the illustrated example in a direction perpendicular to the rotation axis, the surface of the polishing section is substantially flat and substantially coincides with the rotation orbit of the polishing section.

The width (W) (mm) of the polishing portion 24 along the outer peripheral direction of the composite cutting tool 20 is preferably R1 (mm) or less, more preferably 0.5 × R1 (mm) or less, and even more preferably Typically, it is 0.3×R1(mm) or less. The lower limit of the width (W) of the polished portion may be, for example, 0.01 × R1 (mm). If the width W of the polishing section is within this range, there is an advantage that the polishing section is less likely to be clogged with cutting debris and the processing quality can be maintained constant over a long period of time. In other words, the above advantages can be obtained by adjusting the width of the polishing section according to the outer diameter of the composite cutting tool.

The position at which the polished portion 24 is formed on the relief surface 23c of the cutting edge 23 can be appropriately set depending on the purpose. In one embodiment, the distance (L) (mm) from the blade tip 23a to the wall surface facing the rotation direction of the polishing unit 24, and the distance (R1) (mm) from the rotation axis 21 to the blade tip 23a ) satisfies the following equation (1):

L≥0.1×R1···(1).

The distance (L) is preferably 0.1 x R1 to 1.0 x R1, and more preferably 0.15 x R1 to 0.8 x R1. If the distance L and the distance R1 have this relationship, there is an advantage that the accumulation of debris on the surface of the polishing part is small and the processing quality can be maintained constant over a long period of time. In other words, the above advantages can be obtained by defining the position at which the polished portion is formed according to the outer diameter of the composite cutting tool in this relationship.

The surface roughness of the surface of the polishing unit 24 is the number of file blades, and is preferably #60 or more, more preferably #100 or more, and even more preferably #200 or more. The surface roughness refers to the number of file blades, and is preferably #2000 or less, more preferably #1200 or less, and even more preferably #800 or less. If the surface roughness of the polishing section is within this range, the resin sheet will not melt or break on the machined surface by the polishing section, and there will be little clogging of the polishing section with cutting debris, and the processing quality can be maintained consistently over a long period of time. There is an advantage to doing this. In addition, the smaller the number of file blades, the coarser the mesh. The count can be adjusted by the amount and size of diamond particles, etc.

Figure 3 is a schematic cross-sectional view of the main portion for explaining the uneven shape of the file-shaped surface of the polishing unit 24. The depth D of the unevenness of the file-shaped surface of the polishing portion 24 is, for example, 1 μm to 120 μm. The lower limit of the depth (D) is preferably 5 μm or more, and more preferably 10 μm or more. The upper limit of the depth (D) is preferably 50 μm or less, and more preferably 35 μm or less. The pitch p of the unevenness of the file-shaped surface of the polishing portion 24 is, for example, 1 μm to 250 μm. The lower limit of the pitch (p) of the unevenness is preferably 5 μm or more, and more preferably 10 μm or more. The upper limit of the pitch (p) of the unevenness is preferably 100 μm or less, and more preferably 60 μm or less. If the concavo-convex shape of the surface of the polishing section is configured in this way, the resin sheet will not melt or break on the machined surface by the polishing section, and there will be less clogging of the polishing section with cutting debris, and the processing quality will be maintained constant over a long period of time. There is an advantage to being able to do this.

The outer diameter of the composite cutting tool can be appropriately set depending on the purpose. More specifically, the outer diameter of the composite cutting tool is preferably 0.5 mm to 30 mm, more preferably 0.8 mm to 25 mm, and even more preferably 1 mm to 20 mm. If the outer diameter of the composite cutting tool is within this range, it can be processed without problems using a machine tool capable of general end mill processing. Additionally, the outer diameter of the composite cutting tool is twice the above-mentioned R2 (i.e., the diameter of the rotation orbit of the polishing unit).

In one embodiment, the height (Ph) of the remaining material for each pitch of the composite cutting tool is preferably 0.03 μm to 280 μm, more preferably 0.1 μm to 100 μm, and even more preferably 0.2 μm to 10 μm. It is ㎛. If the height (Ph) of the remaining material is within this range, there is an advantage that the resin sheet does not melt or break on the machined surface by the polishing unit, and a uniform machined surface is obtained. Here, the pitch (P) is expressed by the following equation (2), and the height of the remaining material (Ph) for each pitch is expressed by the following equation (3):

P=F/(S×N)···(2)

Ph=arcsin(P/2×R1)···(3)

In equation (2), F is the feed speed (mm/min) of the composite cutting tool, S is the rotation speed (rpm) of the composite cutting tool, and N is the number of cutting edges of the composite cutting tool.

The shape of the polishing unit 24 (outline shape defining the surface of the polishing unit) viewed from the direction of the rotation axis may be any appropriate shape depending on the purpose, etc. Figures 4(a) to 4(e) are schematic plan views of main parts showing representative modifications of the polishing unit, respectively. The polishing portion in FIG. 4 (a) has a substantially flat surface along the outer circumference from the wall facing opposite to the rotation direction to a predetermined portion in the rotation direction in a cross section in a direction perpendicular to the rotation axis, and from the predetermined portion facing in the rotation direction. The protrusion height is gradually decreasing across the wall. In the cross section of the polishing part in Fig. 4(b) in the direction perpendicular to the rotation axis, the protrusion height gradually decreases from the wall facing away from the rotation direction to the wall facing the rotation direction. In the cross-section of the polishing part in FIG. 4(c) in the direction perpendicular to the rotation axis, the protrusion height gradually decreases at a first inclination angle from the wall facing opposite to the rotation direction to a predetermined portion in the rotation direction, and the rotation direction is changed from the predetermined portion. The protruding height across the facing wall gradually decreases to a second inclination angle that is larger than the first inclination angle. In the cross section of the polishing portion in Fig. 4(d) in a direction perpendicular to the rotation axis, the wall surface facing the rotation direction extends toward the outside (protruding side) so as to face the opposite side to the rotation direction. In the cross section of the polishing portion in Fig. 4(e) in a direction perpendicular to the rotation axis, the intersection of a line defining the surface of the polishing portion and a line defining a wall surface facing the rotation direction has a chamfered shape. These modifications may be appropriately combined. For example, in the modified example of FIGS. 4(a) to 4(d), the intersection of the line defining the surface of the polishing section and the line defining the wall surface facing the rotation direction may be in a chamfered shape; Also, for example, in the modified example of FIGS. 4(a) to 4(c), the wall surface facing the rotation direction may be extended toward the outside (projection side) so as to face the opposite side to the rotation direction. These modifications can be appropriately selected depending on the protrusion height (H) of the polishing portion, the position at which the polishing portion is formed (distance (L)), the height of the remaining grinding portion (Ph), etc. For example, the modification of Figure 4(b) may be useful when the protrusion height H of the polishing portion is large; A variation of Figure 4(c) may be useful when the distance L is large; The modified example of Figure 4(d) may be useful when the height of the remaining material (Ph) is small; The modified example of FIG. 4(e) may be useful when the height (Ph) of the remaining material is large. Additionally, the modified example of FIG. 4(a) may be useful when the protrusion height (H), distance (L), and height of remaining material (Ph) are all of intermediate size.

B. Resin sheet

The resin sheet may be any suitable resin sheet that can be subjected to end surface processing. The resin sheet may be a film comprised of a single layer, or may be a laminate. Specific examples of resin sheets include optical films, insulation sheets, resin windows, surface protection films, fiber-reinforced plastic (FRP) sheets, packaging films, and food films. In one embodiment, the resin sheet includes an optical film. Optical films require precise edge processing compared to other resin sheets or films, so the effect of the embodiment of the present invention is significant. Specific examples of optical films include polarizers, retardation films, polarizers (typically a laminate of a polarizer and a protective film), conductive films for touch panels, surface treatment films, and laminates obtained by laminating them appropriately depending on the purpose (e.g. , a circularly polarizing plate for anti-reflection, and a polarizing plate with a conductive layer for a touch panel). In one embodiment, the resin sheet includes an adhesive layer and/or an adhesive layer. Accordingly, the resin sheet may be, for example, an optical film including an adhesive layer and/or an adhesive layer. In the case of an optical film containing an adhesive layer and/or an adhesive layer, the effect of the embodiment of the present invention becomes more significant.

C. Manufacturing method of resin sheet

Hereinafter, a manufacturing method in the case of employing a polarizing plate with an adhesive layer as an example of the resin sheet will be described. It is obvious to those skilled in the art that the planar shape of the polarizing plate on which the adhesive layer is formed is not limited to the planar shape in the illustrated examples. Additionally, it is obvious to those skilled in the art that embodiments of the present invention can be applied to any suitable resin sheet other than a polarizing plate on which an adhesive layer is formed. That is, embodiments of the present invention can be applied to the production of any suitable resin sheet having any suitable shape.

C-1. Formation of work

Figure 5 is a schematic perspective view for explaining the outline of end surface processing of a resin sheet (here, a polarizing plate with an adhesive layer) in the manufacturing method according to the embodiment of the present invention. A work W is shown in this drawing. As shown in FIG. 5, the work W is formed by overlapping a plurality of polarizing plates on which an adhesive layer is formed. When forming a work, the polarizing plate with the adhesive layer is typically cut from a raw roll into an arbitrary appropriate size and shape. Specifically, the polarizing plate with the adhesive layer formed may be cut into a rectangular shape, may be cut into a shape similar to a rectangular shape, or may be cut into an appropriate shape (for example, circular) depending on the purpose. In the illustrated example, the polarizing plate on which the adhesive layer is formed is cut into a rectangular shape, and the work W has outer peripheral surfaces (cutting surfaces) 1a and 1b opposing each other and outer peripheral surfaces (cutting surfaces) 1c and 1d perpendicular to them. I have it. Cutting is done by any suitable means. Specific examples of cutting means include punching with a punching blade (for example, a Thompson blade) and laser irradiation. In one embodiment, a release liner may be temporarily attached to the surface of the adhesive layer of the polarizing plate with the adhesive layer, and/or a surface protection film may be temporarily attached to the surface of the polarizing plate with the adhesive layer opposite to the adhesive layer.

The total thickness of the workpiece is, for example, 3 mm or more, preferably 5 mm or more, more preferably 10 mm or more, further preferably 30 mm or more, and particularly preferably 60 mm or more. According to the embodiment of the present invention, by using the composite cutting tool as described in item A above, cutting (typically end surface machining) can be performed without problems even on such thick workpieces. As a result, a resin sheet (here, a polarizing plate with an adhesive layer formed thereon) can be manufactured with high efficiency and simplicity. Meanwhile, the total thickness of the workpiece is preferably 150 mm or less, and more preferably 100 mm or less. The upper limit of the total thickness of the workpiece may be mainly due to constraints in the configuration of the machine tool. In addition, according to the embodiment of the present invention, the effect becomes significant when the workpiece is thick, but it goes without saying that the effect can be carried out without problems even when the workpiece has a normal thickness (for example, 10 mm or less).

The work W is preferably clamped from the top and bottom by clamping means (not shown). The clamp means (for example, a jig) may be made of a soft material or a hard material. When composed of a soft material, its hardness (JIS A) is preferably 60° to 80°. If the hardness is too high, marks from the clamping means may remain. If the hardness is too low, positional misalignment may occur due to deformation of the jig, and cutting precision may become insufficient.

C-2.End surface machining by composite cutting tool

Next, a predetermined position on the outer peripheral surface of the work W is cut (end surface machining) using the composite cutting tool 20. The composite cutting tool 20 is typically held in a machine tool (not shown), is rotated at high speed around the rotation axis of the composite cutting tool, and is sent in a direction intersecting the rotation axis, bringing the cutting edge into contact with the outer peripheral surface of the work W. It is used by inserting and inserting. That is, cutting is typically performed by bringing the cutting edge of a composite cutting tool into contact with the outer peripheral surface of the workpiece W and cutting into it. Furthermore, according to an embodiment of the present invention, cutting by the cutting edge is followed by polishing (cutting) by a polishing unit whose rotational orbit radius is larger than that of the cutting edge. By additionally performing cutting by such a grinding unit, end surface machining can be performed without problems even on thick workpieces (in more detail, there is no residual cutting due to the cutting edge not contacting the workpiece, and evenly throughout the thickness direction of the workpiece). You can. In addition, cracking of the polarizing plate (typically a polarizer) on which the adhesive layer is formed, contamination of the cutting edge, and blocking can be suppressed. In particular, the progression of cracks over time can be well suppressed. Additionally, when a release liner and/or a surface protection film are temporarily attached to the polarizing plate on which the pressure-sensitive adhesive layer is formed, their lifting can be suppressed. Here, blade contamination of the cutting edge refers to a phenomenon in which the adhesive of the adhesive layer adheres to the cutting edge and the cutting performance (processing performance) deteriorates beyond the allowable range. Blocking is as described above.

Conditions for end surface machining using a composite cutting tool can be appropriately set depending on the type of resin sheet, desired shape, etc. For example, the rotational speed (number of rotations) of the composite cutting tool is preferably 100 rpm to 50,000 rpm, more preferably 1,000 rpm to 30,000 rpm, and even more preferably 2,000 rpm to 20,000 rpm. Also, for example, the feed speed of the composite cutting tool is preferably 100 mm/min to 5,000 mm/min, more preferably 200 mm/min to 4,000 mm/min, and even more preferably 300 mm/min to 3,000 mm/min. It's a minute. If the rotation speed and feed speed of the composite cutting tool are within this range, end surface machining can be performed without problems even on thick workpieces. The number of cuts on the end surface of the work (resin sheet) by the composite cutting tool may be 1 cut, 2 cuts, 3 cuts, or more.

The composite cutting tool may be maintained in a cantilevered or double-beamed state on the machine tool. By maintaining it in a cantilevered state, in-plane and up-down movement of the composite cutting tool becomes easy. As a result, when non-linear cutting (processing) becomes necessary, such cutting becomes easy. In addition, cantilever is easier to manufacture composite cutting tools. On the other hand, by maintaining the double beam state, backlash (irregularities when the cutting surface is viewed from the horizontal direction) of the cutting surface can be suppressed. Additionally, by maintaining the two-arm beam state, the stress applied to the cutting edge of the composite cutting tool during cutting can be reduced. As a result, the durability of the composite cutting tool can be improved, and thus the stability and reliability of end surface machining by the composite cutting tool can be improved.

The end surface machining of the resin sheet using a composite cutting tool may be performed on the entire outer peripheral surface of the resin sheet, or may be performed 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 illustration), the end surface machining with a composite cutting tool is preferably performed only in the direction of the absorption axis of the polarizer. Figures 6(a) and 6(b) are schematic plan views for explaining an example of a specific sequence of end surface processing of a resin sheet containing a polarizer (here, a polarizing plate with an adhesive layer formed thereon). In this embodiment, the polarizing plate on which the adhesive layer is formed is typically cut into a rectangular shape so that the absorption axis A of the polarizer is in the short side direction, as shown in Fig. 6(a).

Next, as shown in Fig. 6(a), the end surface of the short side is processed using an end mill. The end mill may have any appropriate configuration depending on the purpose, type of resin sheet containing the polarizer, etc. For example, an end mill may have the same structure as a composite cutting tool except that it does not form a polished part, and may have a completely different structure as a whole (e.g., outer diameter, number of teeth, twist angle, rake angle, edge angle). It's okay to have it. Conditions for end surface machining by an end mill can be appropriately set depending on the purpose, etc. The outer diameter of the end mill may be, for example, 0.5 mm to 30 mm, or, for example, 1 mm to 20 mm. The rotational speed (number of rotations) of the end mill may be, for example, 100 rpm to 50,000 rpm, for example, 1,000 rpm to 35,000 rpm, or for example, 2,000 rpm to 20,000 rpm. Additionally, the feed speed of the end mill may be, for example, 100 mm/min to 5,000 mm/min, or, for example, 300 mm/min to 3,000 mm/min. The number of cuts on the end surface of the short side of the work (resin sheet containing a polarizer, here, a polarizing plate with an adhesive layer) by an end mill may be 1 cut, 2 cuts, 3 cuts or more. The illustrated example schematically shows two cuts of rough processing and finishing processing. Rough processing and finishing processing may be performed under the same conditions or may be performed under different conditions.

Next, as shown in FIG. 6(b), end surface processing of the long side is performed using a composite cutting tool. The configuration of the composite cutting tool is as described in section A above, and the conditions for end surface machining by the composite cutting tool are as described above. By performing such end surface machining, even thick workpieces can be subjected to end surface machining without problems. In addition, cracking of the polarizing plate (typically a polarizer) on which the adhesive layer is formed, contamination of the cutting edge, and blocking can be suppressed. Additionally, when a release liner and/or a surface protection film are temporarily attached to the polarizing plate on which the pressure-sensitive adhesive layer is formed, their lifting can be suppressed. When machining the entire outer circumference of a polarizing plate with an adhesive layer formed using an end mill, residual cutting often occurs due to the cutting edge not contacting the workpiece. When machining the entire outer circumference of a polarizing plate on which an adhesive layer is formed using a composite cutting tool, the machined edge surface in a direction parallel to the absorption axis may become weak to impact due to heat shock and cracks may occur. However, when the resin sheet does not contain a polarizer, this problem does not substantially occur even if the entire outer circumference of the resin sheet is machined with a composite cutting tool.

Example

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The evaluation items in the examples are as follows.

(1)Crack

The polarizing plate with the adhesive layer obtained in the Examples, Comparative Examples, and Reference Examples was attached to a glass plate (thickness 1.1 mm) through the adhesive layer to serve as a test sample.

(1-1) Cracks by heat shock test

The test sample was subjected to a heat shock test in which 300 cycles were maintained at -40°C for 30 minutes and then held at 85°C for 30 minutes, and the state of crack generation after the test was observed using an optical microscope (5x magnification). . Specifically, the number and length (μm) of cracks were investigated and evaluated based on the following criteria.

A: The number is 10 or less, and the maximum length is 500㎛ or less.

B: Number is 10 or less, but maximum length exceeds 500㎛

C: The number exceeds 10, and the maximum length exceeds 500 μm.

(1-2) Cracks caused by heating tests

The test sample was subjected to a heating test at 105°C for 1000 hours and evaluated in the same manner as (1-1).

(2) Restlessness

The amount of lifting of the surface protection film and release liner in the polarizing plate with the adhesive layer obtained in the Examples, Comparative Examples, and Reference Examples was measured with a loupe or microscope. The maximum value of the amount of lifting in one workpiece was taken as the amount of lifting, and it was evaluated based on the following criteria.

A: Lifting amount is 300㎛ or less

B: Lifting amount exceeds 300㎛ and is less than 500㎛

C: The amount of lifting exceeds 500㎛

(3)Blade contamination

The state of contamination by adhesive on the cutting edge of the composite cutting tool after end machining in Examples and the cutting edge of the end mill after end machining in Comparative Examples and Reference Examples was observed and evaluated based on the following criteria.

A:Contamination has not been substantially confirmed.

B: Contamination was confirmed, but no problems occurred in processing.

C: Significant contamination was confirmed, and problems arose in processing.

(4)Blocking

The states of the workpieces after end surface processing in Examples, Comparative Examples, and Reference Examples were observed and evaluated based on the following criteria.

A: Separation from the workpiece to the polarizing plate on which each adhesive layer was formed was easy.

B: Separation from the work to the polarizing plate on which each adhesive layer was formed was possible, but the separation operation was difficult.

C: The work was completely block-shaped, and separation into the polarizing plate on which each adhesive layer was formed was impossible.

<Example 1>

According to the conventional method, in order from the viewing side, surface protection film (60㎛)/cycloolefin-based protective film (47㎛)/polarizer (5㎛)/cycloolefin-based protective film (24㎛)/adhesive layer (20㎛)/ A polarizing plate on which an adhesive layer having the structure of a release liner was formed was produced. In addition, as the surface protection film, a surface protection film having a structure of PET base material (50 μm)/adhesive layer (10 μm) was used. The polarizing plate on which this adhesive layer was formed was punched into a 5.7-inch size (approximately 140 mm in length and 65 mm in width). Here, punching was performed so that the absorption axis direction of the polarizer was horizontal (short side direction). A plurality of polarizing plates with a punched adhesive layer were stacked to form a work. The total thickness of the work was 45 mm. The end surface of the short side (absorption axis direction of the polarizer) was processed using an end mill while the obtained workpiece was clamped (jig). Specifically, an end mill with an outer diameter of 9 mm, two blades, and a torsion angle of 45° was used, and each short side was subjected to two end milling operations: rough machining and finishing machining. The cutting amount for rough machining was 0.2 mm, and the cutting amount for finishing machining was 0.1 mm. In both rough and finish machining, the feed speed of the end mill was 1,000 mm/min and the rotation speed was 35,000 rpm. Next, end surface processing of the long side (direction perpendicular to the absorption axis direction of the polarizer) was performed using the composite cutting tool of the embodiment of the present invention. The composite cutting tool used was one in which a polished portion with a protruding height of 20 μm was formed on the relief surface of the cutting edge of the end mill. The protruding surface of the polishing portion had a file shape (or a grindstone shape) containing diamond particles. The distance (L) from the edge of the cutting blade to the wall facing the rotation direction of the polishing unit was 0.9 mm, and the distance (R1) from the rotation axis to the edge of the blade had the relationship of L = 0.167 × R1. The end surface processing of the long side was performed twice under the same conditions. Specifically, the feed speed of the composite cutting tool was 1,000 mm/min, the rotation speed was 8,000 rpm, and the amount of cutting per time was 0.1 mm. In this way, a polarizing plate with an adhesive layer formed thereon was obtained. In end surface machining, there is no need to precisely adjust the holding state of the end mill or composite cutting tool machine tool, and uniform cutting was realized throughout the entire thickness direction of the workpiece. The evaluations (1) to (4) above were performed on the polarizing plate on which the obtained adhesive layer was formed. The results are shown in Table 1.

<Example 2>

A polarizing plate with an adhesive layer formed was obtained in the same manner as in Example 1 except that the thickness of the workpiece was changed to 60 mm. In end surface machining, there is no need to precisely adjust the holding state of the end mill or composite cutting tool machine tool, and uniform cutting was realized throughout the entire thickness direction of the workpiece. The same evaluation as Example 1 was performed on the obtained polarizing plate with the adhesive layer formed thereon. The results are shown in Table 1.

<Comparative Example 1>

The entire side (entire outer circumference) of the workpiece formed in the same manner as in Example 1 was end milled using only an end mill. Specifically, the entire outer circumference of the work was provided for two rounds of end surface machining, rough machining and finishing machining, using the technique of writing in one stroke. The conditions for rough processing and finishing processing were the same as in Example 1. Next, only the long side was edge-processed using a rotary grindstone (#400). The rotation speed of the rotary grindstone was 1,000 rpm and the feed speed was 500 mm/min. In this way, a polarizing plate with an adhesive layer formed thereon was obtained. During end mill machining, a cutting defect occurred in a portion of the workpiece (the upper or lower portion in the thickness direction). Cutting defects were significant on the long side. The same evaluation as Example 1 was performed on the obtained polarizing plate with the adhesive layer formed thereon. 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 cutting defects were confirmed in end surface machining. The same evaluation as Example 1 was performed on the obtained polarizing plate with the adhesive layer formed thereon. The results are shown in Table 1.

<Evaluation>

As is clear from Table 1, it can be seen that the composite cutting tool of the embodiment of the present invention can cut even thick workpieces without problems.

The composite cutting tool according to the embodiment of the present invention can be suitably used in the production of resin sheets (particularly, end surface processing in production). The resin sheet may be, for example, an optical film.

W walk
20 composite cutting tools
21 rotation axis
22 main body
23 cutting edge
23a blade tip
23b slope
23c clearance
24 Polishing section

Claims (1)

a main body rotating around a rotation axis;
a cutting blade formed on the outer periphery of the main body and having a blade tip, an inclined surface, and a relief surface;
A composite cutting tool having a polishing portion formed as a protrusion having a file-shaped surface on a portion of the clearance surface of the cutting edge.