JPH03214117A - Manufacture of rotary polygon mirror - Google Patents

Abstract

PURPOSE:To form the rotary polygon mirror which has high durability and surface accuracy and is made of synthetic resin by providing a ring-shaped gate in the hole part of the rotary polygon mirror which has mirror surfaces on the surfaces of a polygon body having the hole part in the center, and cutting a runner part in a metallic mold and taking the rotary polygon mirror out. CONSTITUTION:The molten resin which is pressed in the metallic mold for molding from the nozzle of a molder is charged in the runner 32 through a spool 31 and pressed and then injected radially in the cavity part 10A of the rotary polygon mirror 10 after passing through the thin ring-shaped gate 33. Then the gate 33 is sheared and separated to seal the cavity part 10A, and then compression molding is carried. In the metallic mold, the runner part 32 is cut to take the rotary polygon mirror 10 out. Consequently, the rotary polygon mirror which has the high surface accuracy as compared with a rotary polygon mirror made of a metallic material, glass, etc., and is made of the synthetic resin is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a rotating polygon mirror used in an optical device having a laser scanning system.

[Background of the invention]

A rotating polygon mirror included in an optical device having a laser scanning system is generally a regular polygonal prism member such as a regular octagon whose side surfaces are reflective mirrors, and is used to change the traveling direction of a laser beam, for example. It is used for purposes such as scanning the light receiving surface.

Traditionally, aluminum alloy or optical glass is used as the material for such rotating polygon mirrors, and after forming them into regular polygons by cutting or grinding, the former is processed with a carbide cutting tool, while the latter is polished. The method used was to form a reflective mirror surface through processing.

When grinding glass materials, a huge number of machining operations are required to obtain the flatness accuracy, and compared to metal cutting, it is several times smaller than metal cutting.
The cost is more than 0 times higher, and even in metal cutting, the curvature of the machining mark due to the cutting tool or the A of the material itself.
Slight dripping due to difficulties in processing such as scattering during light scanning due to holes in the l1 material, material cost rather than the ratio of processed and molded products,
The cost was higher than the processing cost.

[Problem that the invention seeks to solve]

Rotating polygon mirrors made of metal or glass are heavy, so the drive system and control system are complicated and expensive to rotate at high speeds, and the rotating polygon itself also forms a highly accurate reflective mirror surface. In order to do so, there is a problem to be solved in that the manufacturing process described above requires a great deal of labor and time and increases manufacturing costs.

Under these circumstances, attempts are being made to mold rotating polygon mirrors using synthetic resin materials instead of metal materials or glass, but injection molding of resin materials does not allow for the complicated shape of rotating polygon mirrors. Therefore, the molding pressure of the resin material becomes uneven, which tends to cause warping and sink marks due to internal stress, and as a result, it is extremely difficult to obtain a reflective mirror surface with sufficient mechanical strength and high surface precision.

Furthermore, in the case of resin molding, the runner part of the resin injected product in the mold is integrally connected, so it takes time to separate the runner part when taking it out from the mold, and the resin does not enter the runner part. There is also the problem that the so-called injection pressure molding method, which involves clamping the mold after the resin pressure λ, cannot be used because of the risk of backflow.

As a result of solving these problems and improving the present invention, by improving the structure of the gate of the mold, it has achieved durability comparable to that of conventional metal or glass molds. The object of the present invention is to provide a method for manufacturing a rotating polygon mirror that can automatically take out a synthetic resin rotating polygon mirror with high surface accuracy with its runner section separated.

[Means for solving problems]

The above object is to provide a ring-shaped gate in the hole of a rotating polygon mirror whose surface is a mirror surface of a polygon with a hole in the center;
This is achieved by a method for manufacturing a rotating polygon mirror, characterized in that the rotating polygon mirror is removed by cutting a runner portion inside a mold.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1-3.

Figure 1 shows the shape of a rotating polygon mirror according to the present invention, Figure 2 shows the type of gate for injection molding the rotating polygon mirror, and Figure 3 shows the structure of a mold for injection molding. It is something that

The rotating polygon mirror 10 is a regular polygonal member with eight flat surfaces on its outer circumferential surface, and is made of thermoplastic or thermoplastic material that is injection-molded radially around a hole 11 into which a driving rotation shaft is inserted. It is a plate-shaped molded member made of curable resin.

For example, polycarbonate resin is preferably used as the resin material forming the rotating polygon mirror 10 because it has excellent mechanical strength and has good transferability after molding, so that a high-quality finished surface can be obtained. A metal coating of aluminum is vaporized on each of the flat parts to form mirror-finished parts 1 on 8 sides.
2 is formed, and the surface thereof is further coated with 5i02 or the like as a protective film.

The rotary polygon mirror 10 is attached to a driving rotating shaft by fitting the hole 11 and rotates integrally, and converts the traveling direction of the laser beam irradiated to each mirror surface W12 and sequentially receives the laser beam. It is designed to scan over a surface.

Each of the mirror surface parts 12 requires a surface precision of 0.2 μm or more, so it is necessary to be very careful when cutting the runner part from the rotating polygon mirror 10 after molding, and also to avoid It was considered desirable to use injection compression molding to obtain a good finish, but with the conventional gate structure, it was impossible to separate the runner part within the mold, so it was necessary to keep the cavity part in a sealed state. Therefore, it was not possible to realize compression molding by clamping the mold.

Therefore, in the present invention, we propose a disk gate type that injects resin radially from the inside of the hole 11 into the cavity of the mold, thereby separating the runner part of the rotating polygon mirror 10 within the mold. This enables molding by injection compression.

FIG. 2(A) shows the setting side of the above-mentioned disk gate with respect to the rotating polygon mirror IO using a dashed-dotted line, and FIG. 2(B) is a sectional view taken along the arrow BB.

Molten resin is press-fitted into the mold from the nozzle of the molding machine, passes through the sprue 31, fills the runner 32, is pressurized, and then passes through the thin ring-shaped gate 33 to the rotating polygon mirror 1.
0 radially injected into the cavity 10A 77.

Thereafter, the gate 33 is sheared and separated to bring the cavity 10A into a sealed state, thereby enabling compression molding by clamping the mold.

The specific structure and coloring effect of the mold used in such injection compression molding will be explained with reference to FIG.

The mold includes a fixed side mold plate IA and a mounting plate I that supports this.
The movable mold 2 consists of a fixed side mold 1 consisting of a movable side mold plate 2A, a receiving plate 2B, a mounting plate 2C supporting these, etc. During molding, the center line XX As shown in the upper part of , the movable template 2A is connected to the fixed template IA.
The first stage of mold clamping maintains a distance of 0.3m LlL from 0.2 to It is operated by switching to the fA2 stage of mold clamping.

That is, the sprue bush 3 provided on the stationary mold l
A nozzle (not shown) of a molding machine is pressed into contact with the molding machine. ! :Applicable,
The Blue Bushico 3 slides in the direction G within the stationary template IA and stops at the position shown.

Next, the movable mold 2 is moved to the left and the molten resin is press-fitted while it is set at the first stage position. In this case, the movable member 4 built in the movable template 2A slides to the left under the force of the compression spring 5, and abuts the abutment surface 4A bored on the left end surface against the end surface of the sprue bush 3. and held in the position shown.

As shown in FIG. 2(A), the abutment surfaces 4A are provided at four equal intervals, and the gaps between the abutment surfaces 4A form the gates 33 of the disk gate described above.

In this state, molten resin is press-fitted, and the resin passes through the sprue 31 and the runner 32 and is injected radially from the gate 33 into the cavity portion 10A.

After the injection path T, the pressure contact of the nozzle is released and the movable member 4 further slides to the left under the bias of the compression spring 5, whereby the gate 33 is sheared and separated, and at the same time the movable side template IA of the movable member 4 As a result, the cavity portion 10A is brought into a sealed state, and the integration of the movable mold 2
The shift to the left causes the process to proceed to the second stage, and as a result compression molding of the rotary polygon mirror 10 within the cavity portion 10A is realized.

C Effects of the Invention] According to the present invention, it is possible to place a rotating polygon mirror inside a mold and separate its runner part, thereby making it possible to separate the runner part from a mold made of metal or glass by adopting the injection compression molding method. A method for manufacturing a rotating polygon mirror made of synthetic resin with high surface accuracy that is not inferior even under the conditions of the present invention has now been realized.

As a result, it has become possible to provide a rotating polygon mirror which is extremely useful in practice and whose weight has been reduced so as not to place any burden on the drive system or control system, and which has also become mass-produced, reducing the manufacturing cost by KL.

[Brief explanation of drawings]

FIG. 1 is a plan view and a side view of a rotating polygon mirror according to the present invention. FIG. 2 is an explanatory diagram showing the configuration of a disk gate for the rotating polygon mirror. FIG. 3 is a sectional view of an injection compression mold. 1... Fixed side mold 2... Movable side mold 3...
・Sprue-bush 4A... Abutting surface 1 (IA... Cavity part 12... Mirror surface part 32... Runner 4... Movable member 10... Rotating polygon mirror 11... Hole part 31 ...Sprue 33...Gate

Claims (2)

[Claims] (1) A ring-shaped gate is provided in the hole of a rotating polygon mirror whose surface is a mirror surface of a polygon with a hole in the center, and the rotating polygon mirror is taken out by cutting the runner part inside the mold. A method for manufacturing a rotating polygon mirror, characterized in that: (2) The method for manufacturing a rotating polygon mirror according to claim 1, wherein the rotating polygon mirror is resin-molded by injection compression molding.