JPH0453642A - Manufacture of lenticular lens metal mold - Google Patents

Abstract

PURPOSE:To secure the manufacture of a low pitch and high precision lenticular lens by winding a thin shape of nonferrous sheet material on a cylindrical roll so as to make a surface distortion value become within the elastic limit of the shape, and machining it by means of lathe turning. CONSTITUTION:A thin shape consisting of nonferrous sheet material is wound on a cylindrical roll so as to make the surface distortion value become within the elastic limit of the shape, and lathe turning is applied, through which a lenticular lens plane metal mold is manufactured. Since the distortion value at time of cylindrization of the shape is within the elastic range, the shape after subjected to the lathe turning is restored to a plate form owing to its elasticity, and that since plastic working is not added at all, it becomes highly accurate that even a fine variation in a precision lens form is not produced. In addition, there is no fine deformation in lens form, and such a metal mold that is excellent in surface precision being required for a lense metal mold is manufacturable, it is optimum for a low pitch lenticular lens metal mold, especially, manufacturing of the metal mold of less than a pitch of 0.5mm.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a flat mold for forming a lenticular lens sheet used for a projection television screen or the like.

[Prior Art] A general method for manufacturing the above-mentioned flat mold is shown below.

As the cutting tool, a piece of cemented carbide, ceramic, sintered diamond, single crystal diamond, etc. processed into the required shape is used.

As the mold material, non-ferrous metal materials such as copper alloys and aluminum alloys, which have excellent machinability, are used.

The processing method is to use a milling machine, shaper, etc.
A cutting method in which the cutting tool makes reciprocating linear motion on the surface of the material (in machines such as milling machines where the cutting tool clamp part has a rotating main shaft, the main shaft is fixed),
Alternatively, there is a method in which a cylindrical roll is inserted and fixed into a shape material bent into a cylindrical shape (plastic working) using a lathe, and turning is carried out.

Next, the features and problems of the above processing method are shown below.

■ When processing with a milling machine, shaper, etc., the advantage is that it is possible to cut the shape material in a flat state equivalent to the final flat metal mold, and it is possible to process thick-walled shapes. The problem is that the cutting speed is slow (several to tens of m/m1n) and the machining time is enormous due to the intermittent cutting. In addition, the impact on the cutting tool due to interrupted cutting is large, and when a precision cutting tool with a sharp shape is used, the cutting edge is likely to chip.

In particular, a single-crystal diamond cutting tool suitable for cutting precision lens molds cannot actually be used due to its impact resistance.

■ Turning using a lathe is suitable for precision cutting because it is capable of high-speed cutting (several tens to hundreds of m/m1n) and continuous fine cutting in the order of several μm. ing.

Pjil point 1 is that it is necessary to make the mold material cylindrical during cutting, and if a flat mold is ultimately required, it is necessary to deform the mold material from a flat plate to a cylindrical flat plate.

Here, a thickness of 1 to 2 mm has been conventionally used for the shape material, and the shape material is bent and stretched by plastic working before and after turning. Among these plastic working processes, stretching processes in particular tend to cause local deformation of the mold material and minute deformation of the lens shape, and these phenomena become fatal defects in precision lenticular lens molds. In other words, unless the deformation of the mold material due to this plastic working is prevented, it is expected that it will be difficult to support lenticular lens molds that will require increasingly lower pitch and higher precision in the future.

[Problems to be Solved by the Invention] In view of the above circumstances, an object of the present invention is to provide a method for manufacturing a lenticular lens mold with low pitch and high precision.

[Means for solving the problem] A flat metal for a lenticular lens, which is characterized in that a thin profile made of a non-ferrous metal plate is wound around a cylindrical roll so that the amount of surface distortion is within the elastic limit of the profile, and then subjected to turning processing. A method for manufacturing a mold is provided.

In the method for manufacturing a lenticular lens mold of the present invention, single-crystal diamond is preferable as the material for the cutting tool because it reproduces the lens shape and lens surface with high precision.
This does not apply if a cutting tool made of another material can provide sufficient accuracy in terms of shape accuracy and roughness of the cutting surface.

By the way, when using single-crystal diamond, it is preferable to adopt a turning method that allows fine cutting and high-speed continuous cutting as a processing method in order to shorten processing time and is also advantageous in terms of quality. When adopting a turning method that enables fine depth of cut and high-speed continuous cutting, we conducted intensive studies to solve the problems of plastic processing in cylindrical shape material, and as a result we found the following. .

In other words, when a thin-walled profile is wound around a cylindrical roll, if the stress generated in the circumferential cross section is within the elastic limit of the profile, the flatness can be achieved by simply removing the profile from the cylindrical roll after turning, and the lens shape can be improved. It is possible to obtain a lenticular lens mold free of minute changes.

In addition, within the elastic limit mentioned above means that the relationship between stress and strain is linear in the stress strain curve obtained by a tensile test of the material, and within the slope range where the material returns to its original length when the load is removed. means.

In addition, brass plate, which is considered to be the most suitable material for lenticular lens molds, has the best flatness after turning and the lens shape can be finely adjusted if the plate thickness and the diameter of the cylindrical roll meet the following conditions. It has been found that a lenticular lens mold free of oxidation can be obtained.

D1500≧t (D - cylindrical roll diameter mm, t: shape material thickness mm) Furthermore, in order to improve adhesion when a thin-walled shape material is wound around a cylindrical roll, it is also possible to apply tension in the circumferential direction to the shape material. It has become clear that a good lenticular lens mold can be obtained if the stress generated in the circumferential cross section is within the elastic limit.

The method of the present invention does not cause minute deformation of the lens shape and can manufacture molds with extremely good surface precision required for lens molds, so it is suitable for use in low pitch lenticular lens molds, especially those with zero pitch and edges. Ideal for manufacturing molds of 5mm or less.

When actually using the lenticular lens mold manufactured as described above to create a lenticular lens sheet, for example, a lenticular lens sheet used for projection lenses and lenses, the mold material thickness may be used as is. However, if a reinforcing plate or the like is attached and used, handling becomes easier.

[Function] As described above, in the lenticular lens mold manufactured according to the present invention, the amount of distortion during cylindricalization of the mold material is within the elastic range, so the mold material after turning recovers to a flat plate shape due to elasticity. Because no plastic working is added,
The lens is highly accurate, with no minute changes in the shape of the lens.

[Example] Example 1 A lenticular lens mold in which a brass plate was used as the mold material, the mold material was wound around a cylindrical roll according to the relationship between the mold material thickness and the diameter of the cylindrical roll as shown below, and the mold material was removed from the cylindrical roll after turning. The flatness was good, and no minute changes in the shape of the precision lens occurred.

Shape material thickness: 0.7 mm Cylindrical roll diameter: 350 mm Example 2 The shape material of Example 1 was made to have a thickness of 0-5 mm, and after being wound around a cylindrical roll, a strain gauge was attached to the surface of the shape material, and the elastic limit of the shape material used was Tension was applied in the circumferential direction to a certain strain amount of 0.15%, and turning was performed. After processing, the lenticular lens mold removed from the cylindrical roll had good flatness, and no minute changes in the precision lens shape were observed.

[Effects of the Invention] As described above, the lenticular lens mold manufactured by the present invention does not require bending or stretching due to plastic processing of the mold material during turning, has excellent flatness, and has excellent lens shape accuracy. You can get something great.

Claims (1)

[Claims] 1. Wrap a thin profile material made of a non-ferrous metal plate material around a cylindrical roll so that the amount of surface distortion is within the elastic limit of the profile material,
A method for manufacturing a flat mold for a lenticular lens, characterized by performing turning processing.