JP2000153553A - Patterned roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a desired shape without spending much time for fabricating fine grooves by forming helical groove on the surface of a roll. SOLUTION: Fine grooves are formed, in a single strip or multistrip helical shape, on the surface of a patterned roll 1 and the helical angle is set depending upon the use applications of an optical sheet and the groove is of a V or U-shaped. The matrix of the patterned roll 1 is tool steel with a specified outside dia. and a specified length shaped like a roll. In addition, the surface of the patterned roll 1 is plated with a hard copper, for example, which is somewhat less durable than a non-electrolytic nickel-plated face but reduces the wear of a cutting tool. After cutting the surface, it is treated by plating a non-electrolytic nickel as a protecting film to a specified thickness, on the cut surface, so that the surface hardness and the durability are adequately secured without collapsing the groove shape. Thus a continuous cutting fabrication process can be employed by forming the groove helically and the switching of cutting, rough and finish fabrications for every working pitch and the tool replacement are dispensed with. Consequently, the groove can be fabricated in the continuous cutting mode and also the edge wear of the cutting tool can be reduced and further, the manufacturing time can be shortened significantly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold roll used for manufacturing optical sheets such as a diffusion sheet for a liquid crystal display and a lenticular sheet for a projection television.

[0002]

2. Description of the Related Art An optical sheet made of a plastic substrate such as a diffusion sheet for a liquid crystal display or a lenticular sheet for a projection television is generally manufactured by an extrusion molding method. For example, Japanese Patent Application Laid-Open No. 9-1328 discloses a method for producing an optical sheet by a well-known extrusion molding method. In the conventional manufacturing method as described above, a melt-extruded sheet-like polycarbonate resin is sandwiched between a mold roll and a cooling roll, and a processed fine pattern is transferred to the surface of the mold roll, I have an optical sheet.

[0003] Usually, a mold roll for producing an optical sheet by an extrusion molding method has an outer diameter of 100 to 200 m.
m and a roll base material having a length of about 100 to 600 mm are often used. For the roll base material, an iron-based material is often used, and in order to facilitate cutting of fine grooves in a later process, hard copper plating or electroless nickel having a lower surface hardness than the base material is formed on the base material surface. Surface treatment such as plating is performed. The plating film is formed to have a thickness of about 100 to 300 μm so as not to expose the roll base material in consideration of the cutting process of the fine groove in a later step. However, if pure brass or hard aluminum alloy, which is easy to cut, is used as the base material, it is not necessary to perform plating.

Next, the mold roll is processed into a desired groove shape, groove pitch, groove depth, and groove width by a high-rigidity ultra-precision lathe, and a large number of fine grooves are formed in a ring shape. Usually, this groove is V-shaped or U-shaped, and the groove pitch is 20 to
The groove has a depth of about 100 μm and a depth of about 10 to 100 μm. Since the surface of the processed groove needs to be a mirror surface, a diamond tool 5 as shown in FIG. 2 is used as a cutting tool. A diamond tip 501 is attached to a blade portion of the diamond tool 5, and a tip portion (a groove shape transfer portion) of the diamond tip 501 is attached.
Reference numeral 502 denotes a V-shaped or U-shaped chevron shape corresponding to a desired optical sheet groove shape.

After the cutting, a surface treatment such as electroless bright nickel plating is performed as a protective film on the roll surface.
Used as a mold roll for melt extrusion.

[0006]

However, in the prior art as described above, since the fine pattern formed on the roll surface is a large number of ring-shaped grooves, the roll is cut at every pitch. In this case, intermittent machining for cutting the tool is required, and the machining time per groove requires 5 to 10 seconds, and there is a problem that it takes a lot of time to perform the desired number of groove machining. .

Further, there is also a problem that the load on the tool is large due to the above-mentioned interrupted cutting, the cutting edge wears quickly, and chipping easily occurs. In particular, when the machining amount is large, such as a long roll, a longer machining time is required, so that the cutting edge of the tool is more worn, and the number of times of changing the tool has been increased. On the other hand, rough machining,
At least two stages of finishing processing are required, and in addition to the tool replacement due to the wear of the cutting edge of the tool, the tool replacement and the tool replacement frequency by switching the processing are further increased.
As a result, there is a problem that the positioning accuracy of the cutting edge of the tool is deteriorated due to the tool change, and it is difficult to obtain a desired shape of the bottom shape of the groove to be machined into the roll (a mountain shape in an optical sheet to be transferred). Was.

Accordingly, an object of the present invention is to provide a mold roll capable of obtaining a desired shape without processing the fine grooves in a long time.

[0009]

According to a first aspect of the present invention, there is provided a mold roll used for manufacturing an optical sheet, wherein a groove on a surface of the roll is provided. The invention according to claim 2, characterized in that the groove on the surface of the roll is formed in a multi-layered spiral shape. Features.

An embodiment of the present invention will be described below.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an overall view of a mold roll according to the present invention. The fine grooves on the surface are not formed in a conventional ring shape, but are formed in a spiral shape as shown in FIG. The spiral groove is not limited to a single groove, but may be multiple. However, in this embodiment, the single spiral groove is formed. The helix angle is determined by the use of the optical sheet, and the groove shape is a V-shaped or U-shaped shape. In the present embodiment, a V-shaped groove having a spiral angle of 0.014 ° was machined.

In the present embodiment, a roll-shaped tool steel having an outer diameter of 200 mm and a length of 420 mm is used as a base material of the mold roll. 200 hard copper plating as surface treatment
μm was electrodeposited. The hardness of the plating film is Hv2.
It was 00-230. The copper plating surface is slightly less durable as a mold roll than the electroless nickel plating surface, but has the advantage that wear of the cutting tool can be reduced,
By applying a surface treatment of electroless nickel plating of 1 μm or less as a protective film after the cutting process, it is possible to secure the surface hardness of Hv 400 or more without breaking the groove shape, and to improve the durability of the mold roll. We can cope without problem. Further, in the present embodiment, unlike the conventional intermittent cutting method in which a large number of grooves are formed into a ring shape, a continuous cutting method is used because the grooves are provided in a spiral shape. It is not necessary to perform the notch processing. In addition, since the wear of the cutting edge has been significantly reduced, there is no need to change tools by switching between roughing and finishing processes.
It was possible to machine without having to change tools. .

FIG. 3 shows a vertical axis type processing apparatus used in the manufacturing process of the die roll according to the present invention. The mold roll 1 as a workpiece is attached to a mold roll hire 6, and the mold roll hire 6 is held by an air spindle 7. As described above, the diamond tool 5 is used as the cutting tool, and the diamond tool 5 is attached to the machining tool unit 4, and the machining tool unit 4 is further equipped with the machining tool unit mounting slide 2 ( (Hereinafter called slide). During cutting, the air spindle 7 is driven to rotate the mold roll 1 at a desired rotation speed. On the other hand, by driving the slide 2 in the vertical direction, the diamond tool 5 can be fed at a desired speed. When the tool is replaced, the entire tool unit 4 is replaced.

In the groove machining of the present embodiment, it is important that the rotation of the main shaft of the air spindle 7 and the tool feed by the slide 2 are accurately synchronized with each other. If the feeding unevenness is large, a groove having a stable pitch cannot be obtained, and a desired groove shape cannot be obtained.
Also, when setting the die roll base material in the processing device,
The centering was set within 0.01 mm, and the outer periphery of the die roll base material was processed. After that, the main shaft of the air spindle 7 is rotated so that both the circumferential and axial deflections are 0.1 μm.
The weight was attached to the main shaft so that it was within m. This balancing is a very important task, and without it, a good machined surface cannot be obtained. In the present embodiment, a spiral shape having a groove pitch of 50 μm, a 90 ° V-shaped groove and a depth of 25 μm is formed by changing the spindle speed of the air spindle to 150 rpm, the slide feed speed to 7.5 mm / min,
Processing was performed with a total of four cuts, two times for roughing and two times for finishing.

According to the above-described embodiment of the present invention, the total machining time, which took about 24 hours in the conventional method, is reduced to about 6 hours and 1/4.
Could be shortened.

[0016]

As described above, according to the present invention, since the groove of the die roll is formed in a spiral shape, the groove can be formed by continuous cutting, and the wear of the cutting edge of the tool is reduced.
The manufacturing time of the mold roll can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is an overall view of a mold roll of the present invention.

FIG. 2 is an external view of a cutting tool used for manufacturing a mold roll.

FIG. 3 is a schematic view of a processing apparatus used for manufacturing a mold roll.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Roll with a mold 2 ... Slide to attach a processing tool unit 3 ... Slide fixing base 4 ... Processing tool unit 5 ... Diamond tool 501 ... Diamond tip 502 ... Tool tip ( (Groove shape transfer part) 6 ・ ・ ・ Roll with a mold 7 ・ ・ ・ Air spindle 8 ・ ・ ・ Surface plate

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Claims (2)

[Claims] 1. A mold roll used for manufacturing an optical sheet, wherein a groove is formed in a spiral shape on a surface of the roll. 2. A mold roll used in the manufacture of an optical sheet, wherein grooves are formed in the surface of the roll in a multi-layered spiral shape.