JPH063499B2 - Rotary polygon mirror and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rotating polygon mirror as an optical deflector used in an optical system such as a laser printer and a method for manufacturing the same.

2. Description of the Related Art Conventionally, in a laser printer, a laser beam emitted from a laser oscillator passes through a reflection mirror, a modulator, a beam expander, etc., and is then shaken by a rotary polygon mirror attached to a motor to form a photosensitive member by a converging lens. It is designed to be irradiated in the axial direction of.

By the way, the manufacturing method of the rotary polygon mirror attached to the motor is as follows.

That is, first, the material of a round bar made of aluminum alloy is cut, then both end faces are ground and then polished, and then
A rotary polygon mirror material is obtained by milling to form a desired multifaceted shape and forming a smooth surface to be a mirror surface portion, further performing drilling and spot facing, and then performing strain relief annealing. By subjecting the smooth surface, which is the mirror surface portion of this rotary polygon mirror material, to ultra-precision cutting, a rotary polygon mirror as a finished product can be obtained.

Therefore, the mirror surface characteristics such as the reflectance and scattered light intensity of the mirror surface of the rotating polygon mirror depend on the crystal grain size in the crystal structure, and the crystal of the smooth surface of the rotating polygon mirror material before the ultra-precision cutting process is performed. It is desirable that the particle size be subdivided and uniform. This is because if the crystal grain size is subdivided and made uniform, the mirror surface characteristics after ultra-precision cutting are improved, but in the past, as described above, the crystal grain size in the raw material of the round bar was improved. However, there is a problem that the mirror surface characteristics are not yet sufficient for the rotary polygon mirror made of aluminum alloy.

The present invention has been made in view of the problems existing in the above-mentioned prior art, and it is possible to subdivide and uniformize the crystal grain size of the mirror surface portion and improve the mirror surface characteristics such as reflectance and scattered light intensity. It is an object of the present invention to provide a rotating polygon mirror and a manufacturing method thereof.

In order to achieve the above object, the invention according to claim 1 is
Along with compressing the entire circumference on the outer periphery of the rotary polygon mirror that is attached to the motor to form a polyhedral shape by plastic working, the mirror surface portion of the rotary polygon mirror is formed as a desired polyhedral shape by shearing, and thereafter, The mirror surface portion is annealed to subdivide and uniformize the crystal grain size of the mirror surface portion to obtain a rotary polygon mirror material.

Embodiment One embodiment of the present invention will be described below with reference to the drawings.

First, as shown in FIGS. 1 to 3, the rotary polygon mirror 1
The entire peripheral portion on the outer periphery of the base material is compressed by plastic working to form the stepped portion 2 narrower than the base material. The stepped portion 2 is annealed later, and the crystal grain size of the base material of the rotary polygon mirror is recrystallized and subdivided and made uniform through the processes of compression and annealing. In this case, it is known that the recrystallized grain size becomes finer as the working degree of compression processing becomes higher. That is, by compressing and forming a stepped shape, it is possible to select the optimum processing degree for obtaining the mirror surface characteristics of the mirror surface portion of the rotary polygon mirror.

Further, the mirror surface portion 3 of the rotary polygon mirror 1 is formed by shearing, but the shearing surface at the time of press punching causes a plastic flow of the crystal structure due to the shearing stress at the time of punching and the crystal grain size becomes fine. . That is, since the sheared surface of this shearing phenomenon is applied to the mirror surface portion of the rotary polygon mirror, the mirror surface characteristics of the mirror surface portion are also improved from this surface.

If a corner R or a chamfer is provided at the end of the mirror surface portion 3 of the rotary polygon mirror 1, burrs that occur during ultra-precision cutting can be suppressed, but this corner R is formed during the process of press punching. This phenomenon can be utilized as it is (see FIG. 3).

Next, the processing steps will be described with reference to FIGS. 4 to 6. The basic configuration of this processing step is composed of the first step to the third step. In the first step, the motor shaft assembly reference hole 4, the crushing material relief pilot hole 5 in the counterbore portion of the motor assembly screw, and the compression material relief slit 6 in the stepped portion are simultaneously machined. Next, in the second step, compression molding of the stepped portion 2, crush molding of the spot facing portion 7, and surface chamfering of the motor shaft assembly reference hole 4 are simultaneously processed. Further, in the third step, the desired chamfered shape 8 having the mirror surface portion 3, the mounting hole 9 for the motor mounting screw, and the back chamfering of the motor shaft mounting reference hole 4 are simultaneously machined. As a result, a rotary polygon mirror material is obtained.

Next, a processing method when the above steps are taken will be described.

In the first step, a general press punching method may be used as long as a simple hole shape is obtained. In the second step, the forging method is preferable because there are compression molding of the stepped portion and crush molding of the spot facing portion. Further, in the third step, a punching method in which hydrostatic pressure is applied is suitable for obtaining the surface roughness of the mirror surface portion, the perpendicularity of the sheared portion, and the material hardness.

Further, as the production method, these single-shot flow-through production methods and progressive production methods in consideration of operating efficiency can be considered. In the case of the progressive production method, it is necessary to consider a facility having the required functions of the first step to the third step (composite processing for simultaneously processing the first step to the third step). Currently conceivable equipments include forging press, opposed die press, fine blanking press, etc., but considering the restrictions such as processing speed and processing area, fine blanking press is most suitable for the conditions.

As described above, in this embodiment, the plastic working is applied to all the workings when forming the rotary polygon mirror material. Next, referring to FIG. The plastic working mold will be described.

In FIG. 7, 10 is an upper mold and 11 is a lower mold, but the basic mold structure is a fine blanking fixed punch type progressive feed type. Since the die has to be crushed and forged and punched at the same time, the die floating method is adopted and the floating die 12 is provided in order to keep the timing. In addition, a hydrostatic pressure generating mechanism is provided to obtain a clear sheared surface. In the figure, 13 indicates a hydrostatic pressure generation ring. Further, a vanish punch 14 is provided on the third stage for the purpose of correcting the deformation when the reference hole for assembling the motor shaft is crushed, and the chamfering function is also provided on the punch.

Effect As described above, according to the present invention, a rotary polygon mirror material in which the crystal grain size is subdivided and made uniform can be obtained, so that the mirror surface characteristics can be improved. Further, it is possible to shorten the processing time in the ultra-precision cutting processing in the post process. Further, since the plastic cutting is used instead of the conventional cutting, the cost of the rotary polygon mirror can be reduced.

As in the present embodiment, if the processing for obtaining the rotary polygon mirror material is all plastic processing, the cost reduction of the rotary polygon mirror can be more remarkable due to the drastic reduction of the processing time. .

[Brief description of drawings]

1 is a plan view of a rotary polygon mirror according to the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, FIG. 3 is a detailed view of a portion III of FIG. 2, and FIGS. FIG. 6 shows an embodiment according to the present invention. FIG. 4 is a bottom view of the raw material in the first step, and FIG.
FIG. 7 is a bottom view of the material of the second step, FIG. 6 is a bottom view of the material of the third step, and FIG. 7 is an explanatory view of the mold according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Rotating polygonal mirror, 2 ... Stepped part, 3 ... Mirror surface part, 4 ... Motor shaft assembly reference hole, 7 ... Motor assembly screw counterbore part, 8 ... Polyhedral shape, 9 ... Motor assembly screw Mounting holes, 10… upper mold, 11… lower mold, 12… floating die, 13… hydrostatic pressure generation ring.

Claims (3)

[Claims] 1. A method of manufacturing a rotary polygon mirror having a polygonal shape and attached to a motor, comprising: compressing a peripheral whole circumference on an outer periphery of the rotary polygonal mirror by plastic working and performing a desired polygonal shape by shearing. Forming a mirror surface portion of the rotary polygon mirror as a shape, and thereafter subjecting the mirror surface portion to annealing treatment to subdivide and homogenize the crystal grain size of the mirror surface portion to obtain a rotary polygon mirror material; Method for manufacturing rotating polygon mirror. 2. The method for manufacturing a rotary polygon mirror according to claim 1, wherein at least the motor shaft assembly reference hole, the spot facing portion of the motor assembly screw, and the mounting hole are formed by plastic working. 3. A rotary polygonal mirror having a polygonal shape and attached to a motor, wherein the rotary polygonal mirror has its entire periphery in the vicinity thereof compressed by plastic working and has a desired polygonal shape by shearing. A rotary polygon mirror, characterized in that the crystal grain size of the mirror surface portion is subdivided and uniformized by annealing.