JPH03226250A - Balance regulating structure for rotary body - Google Patents

Abstract

PURPOSE:To make working of boring, tapping or grooving for the regulation of dynamic balance unnecessary by providing a magnet with a block for correcting the balance on the circumference thereof. CONSTITUTION:The magnets 8 of a rotary body are provided with an arbitrary number of blocks 12 for correcting the balance of the rotary body on the circumference thereof with equal circumferential intervals having an arbitrary angle theta. The block 12 is provided with a plurality of block pieces 12a, partitioned by grooves 12b. The block pieces 12a can be broken at any arbitrary place and can be removed. According to this constitution, the rotary body can be balanced by a method wherein the balance of the rotary body is measured and the block pieces 12a of the block 12 in a direction, in which the balance is to be regulated, are removed in accordance with the amount of unbalance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a structure for adjusting the balance of a rotating body such as a scanner motor to which a rotating polygon mirror used in an optical scanning system of a laser printer, digital copying machine, etc. is attached.

[Prior Art] In recent precision instruments, vibrations due to imbalance of rotating bodies have become a problem, and it has become necessary to correct the balance with fairly high precision. Particularly in polygon scanner motors used in laser printers and the like, as the speed of printers increases, motors that can be used at even higher rpm are also required.

A rotating body that rotates at such a high speed requires fairly high-precision balance correction.

Conventionally, methods for adjusting the dynamic balance of rotating bodies,
As for the structure, 1) one that removes weight by drilling a hole in the rotating body, 2) one that adds weight by filling the pre-drilled hole or groove with adhesive (Utility Model Publication No. 65 of 1983). 3) It is known to provide tapped holes in the rotating body and adjust the weight using adjustment screws or solid adhesive (Japanese Patent Application Laid-Open No. 174243/1999).

In addition, as a preliminary step to adjusting the balance using the above method and structure, draw a reference line on the rotating body with a marker, set the rotating body on the measuring table of the rotating body unbalance measuring device, and check the unbalance. The unbalance measurement work involved reading the amount and angular position.

[Problem to be solved by the invention]

In the above-mentioned prior art, in the case of 1), it takes a lot of effort and cost to make the hole, and there is also a problem that the mirror surface of the attached rotating polygon mirror gets dirty due to the debris generated when making the hole.

In the case of 2), there is a drawback that the cost increases due to the machining of holes and grooves.

Furthermore, in the case of 3), there is also a drawback that the cost is increased due to the tapped holes and screw parts.

Further, the above-mentioned unbalance measurement work has a problem in that the target balance amount cannot be obtained unless it is repeated 4.5 times in order to correct the balance with high precision, resulting in poor work efficiency.

An object of the present invention is to provide a structure for adjusting the balance of a rotating body, which can reduce processing costs and material costs, and can also reduce unbalance measurement work.

[Means to solve the problem]

The above purpose is to provide a balance adjustment structure for a rotating body fixed to a rotating shaft. This is achieved by a first means of forming a block of a plurality of individually removable block pieces at intervals.

This can also be achieved by a second means in which the block is arranged on a plane substantially perpendicular to the rotational center of gravity position.

This can also be achieved by providing a reference line for balance measurement and adjustment on the rotating body, and providing each of the blocks with a code indicating an angle with respect to the reference line.

Also, when the mass at the above block position is mm (mg), mg #2
pm), r; block position radius (tm).

Furthermore, when the difference between the height of the center of gravity of the rotating body and the height of the block position is defined as Lu(w), Lu≦4775 (M
G L / N VQ ) [L; Bearing span (IIll
), vo; initial unbalance amount (mg·n)).

[Effect]

According to the first means, balance adjustment can be performed by removing block pieces of blocks in the direction to be adjusted according to the amount of adjustment.

According to the second method, by arranging the block on a plane substantially perpendicular to the center of gravity of the rotating shaft, when the rotating body is rotated after correction, a moment that tends to overturn the shaft acts on the rotating shaft. Never.

Further, according to the third means, in advance, a rotating body (including all rotating units; therefore, in addition to a motor component unit such as a yoke and a disc-shaped magnet attached to the yoke, a rotating polygon mirror attached to the motor) A reference line is provided (drawn) on the rotor (also a rotating body component),
Moreover, since each block is provided with a code indicating the angle with respect to the reference line, it is possible to accurately measure the unbalance amount in a short time without using a balance correction jig.

Further, according to the fourth means, since the mass of the block piece is determined by the above formula, the correction work is minimized and always falls within the allowable range.

Furthermore, according to the fifth means, since the relationship between the position of the block and the height of the center of gravity of rotation is determined by the above formula, it is possible to design the scanner motor according to its level. Also, there is no need to make corrections on two sides, just one.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an embodiment of a scanner motor according to the present invention, in which 1 is a housing, and 2 is a housing 1.
A disk-shaped iron substrate (stator yoke) is fixed to the iron substrate 2, and 3 is a coil fixed to the upper surface of the iron substrate 2 at a predetermined angle r.The iron substrate 2 and the coil 3 constitute the stator of the motor. Ru.

On the other hand, a rotary shaft 5 is fitted into the housing 1 via two bearings 4, and a flange 6 is fixed to the upper portion of the rotary shaft 5. A rotor yoke 7 is fixed to the lower surface of the flange 6a at the lower end of the flange 6, and a magnet portion 8a for the motor that faces the coil 3 with a gap therebetween is fixed to the lower surface of the rotor yoke 7.
A disc-shaped magnet 8, which is integrally formed with a magnet part 8b for a frequency oscillator (FG), is fixed.

A rotary polygon mirror 9 is fitted onto the flange 6 and placed on the upper surface of the flange 6a, and is held down by a washer holder 10 and a uniform washer 1).

Due to the magnetic repulsion between the coil 3 and the magnet part 8a, the magnet 8 and the yoke 7, flange 6, rotating polygon mirror 9, etc. that are fixed to the magnet 8, together with the rotating shaft 5, are moved against the housing 1 and the iron substrate 2. They rotate at ultra-high speed and each form a rotating body.

In this embodiment, blocks 12 for balance correction are provided at regular intervals at arbitrary angles on the circumference of the magnet 8 of this rotating body.

FIG. 2 is a perspective view of the magnet 8 having blocks 12, which are provided in any number at equal intervals in the circumferential direction at any angle θ as described above.

FIG. 3 is an enlarged perspective view of the block 12, which includes a plurality of block pieces 1 partitioned by grooves 12b.
It has 2a. This block piece 12a can be folded and removed from any desired position. However, it is strong enough not to break due to the centrifugal force generated during rotation of the magnet 8 that constitutes the rotating body.

The mass m of this block piece is given by the following formula.

[G: Balance class, M: Mass of rotating body (g), N: Rotation speed (rpm), r: Block position radius (Dragon)]

Block mass greatly affects balance grade and machining time. In other words, by reducing the mass m, more precise balance can be achieved (balance grade improved). However, the removal work is inefficient and leads to increased costs. The reverse is also a problem. Although the processing time can be shortened by increasing the block mass ml and taking it roughly, there may be cases where it does not fall within the allowable balance.

Therefore, by using the above-mentioned formula, it can be efficiently determined.

According to JIS B-0905, balance grade G is described as follows.

[ε: eccentricity of rotating body (μm), N: number of rotations (rpm)
) Also, the amount of eccentricity ε (μm) is expressed as follows, which is summarized together with the formula below.

V.

ε = □ 9550CM N (V+: unbalance amount (mg·ta), M: rotating body mass (g)) From this equation, the unbalance amount v1 of the rotating body whose balance class is G is determined.

To reduce the number of operations as much as possible by removing block pieces from an initial unbalance amount v0 to bring the unbalance amount within v1.

■ As shown in Figure 6. Karashi ■ To come within 1 ○
The mark is the most efficient. This is because the width 2v+ of the removal step and the tolerance range are made the same.

From the above results, the block mass m is as follows.

m1lxr-2×v r [r; block position radius] Furthermore, the position (height) of the block piece falls within the following range. According to JIS B-0905, if the residual even imbalance v after surface correction satisfies the following formula, there is no need for two-surface correction.

2 (2π/60) N (L; bearing span) On the other hand, if the initial unbalance is Vo (mg・n), and the height difference between the block piece and the center of gravity of rotation is (n), then
The even imbalance vt, (mg/dragon) due to correction is: ■L-v0×Lu.

Therefore, it can be seen that if this VL is set to be less than or equal to the right side of the above equation, only one-sided correction is required.

From the above relationship. The range of is as follows.

N　v　.

With the above configuration, the balance of the rotating body can be balanced by measuring the balance of the rotating body and removing the block pieces 12a of the block 12 in the direction to be adjusted according to the amount of unbalance. Here, depending on the amount of unbalance, one block 1
Of course, not only block 2 but also adjacent block 12 can be removed and correction can be made by combining vectors.

Further, the block 12 is arranged on a plane substantially perpendicular to the height of the center of gravity of the rotating body, which is indicated by reference numeral G in FIG.

By doing this, a moment is not generated due to adjustment, and it is possible to improve the balance by correcting one side. If the block 12 is not located at the height of the center of gravity, a moment will occur and two-sided correction will be required, resulting in high costs.

FIG. 4 is a vertical cross-sectional view of a main part showing another example of the structure of the magnet 8. The magnet 8 shown in FIG. 1 had a groove between the magnet parts 8a and 8b in order to reduce the amount of material. In this configuration, in order to simplify integral molding of the magnet parts 8a and 8b, the grooves are eliminated and magnetization is performed to form the magnet parts 8a and 8b on the lower plane, respectively.

Next, a method for measuring an unbalance amount according to the present invention will be explained.

FIG. 5 is a plan view of the scanner motor, and in this embodiment, a reference line 13 for balance measurement and correction is provided on the upper surface of the rotating body polygon mirror 9 constituting the rotating body by printing, punching, sealing, etc. There is.

On the other hand, each block 12 equally divided at an arbitrary angle in the circumferential direction
Similarly to the reference line 13, a code (in this case, a number) 14 indicating a reference display based on the reference line 13 is provided.

With such a configuration, it is possible to perform the unbalance amount measurement work without setting a rotating body (in this case, the magnet 8) in the balance correction jig.

〔Effect of the invention〕

As explained above, according to the invention as claimed in claim 1, since the balance correction block is provided on the circumference of the magnet, holes, taps, grooves, etc. are prepared in advance in order to adjust the dynamic balance 8 times around the magnet. Processing is not required, and parts and materials such as adjustment adhesives (Dream Weight, etc.) are not required, making it possible to reduce processing costs, material costs, etc.

Further, according to the second aspect of the invention, no moment is generated to tilt the shaft due to the adjustment work, and the balance can be easily improved.

Furthermore, according to the third aspect of the invention, a reference line is provided on the rotating body, and an angle is displayed on the block based on the reference line, so there is no need to set the rotating body on the balance correction jig. , it is possible to measure the unbalance amount accurately and in a short time.

Furthermore, according to the fourth aspect of the invention, since the mass of the block side is determined by the formula described in the claim, the correction work (removal work of the block side) is minimized and always falls within the allowable range.

Therefore, it is possible to reduce costs by increasing work efficiency.

Furthermore, according to the invention set forth in claim 5, since the relationship between the position of the block and the height of the center of gravity of rotation is determined by the equation set forth in the claim, the following effects can be obtained.

1) It is possible to design according to the level of the scanner motor (high-precision, high-speed rotation, popular use), and since Lu can be large especially for low-speed rotation, the blocks can be arranged according to the surrounding layout. can.

2) Since there is no need to revise two sides and only one side is required, costs can be reduced by shortening the work time.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of a scanner motor according to the present invention, and FIG. 2 is a perspective view of a magnet having a block.
Fig. 3 is an enlarged perspective view of the block, Fig. 4 is a vertical cross-sectional view of main parts showing another example of the structure of the magnet, Fig. 5 is a plan view of the scanner motor according to the present invention, and Fig. 6 is the number of operations and imbalance. FIG. 2 is a characteristic diagram showing the relationship between quantities. 5... Rotating shaft, 8... Magnet, 8a, 8b...
- Magnet part, 9... Rotating polygon mirror, 12... Block, 12a... Block piece, 12b... Groove, G.
...The center of gravity of magnet 8. No.! Fig. 2 Fig. 5 Fig. 6 Fig. Step allowable range number of operations (removal)

Claims (5)

[Claims] (1) In a balance adjustment structure for a rotating body fixed to a rotating shaft, at equal intervals on the circumference of a disc-shaped magnet consisting of a motor magnet part and a frequency oscillator magnet part that constitute the rotating body, A structure for adjusting the balance of a rotating body, characterized in that a block is formed from a plurality of individually removable block pieces. (2) A balance adjusting structure for a rotating body according to claim 1, wherein the block is arranged on a plane substantially perpendicular to the center of gravity of the rotation. (3) In claim 1, the rotating body is provided with a reference line for balance measurement and adjustment, and each of the blocks is provided with a code indicating an angle based on the reference line. Balance adjustment structure for a rotating body. (4) In claim 1, when the mass of one block is m_B (mg), m_B≒2×(9550GM/Nr) [G: balance grade, M: rotating body mass (g), N; A balance adjustment structure for a rotating body, characterized in that the following relationship holds true: rotation speed (rpm), r; block position radius (mm). (5) In claim 1, when the difference between the height of the center of gravity of the rotating body and the height of the block position is Lu (mm), Lu≦4775 (MGL/Nv_0) [L: bearing span (mm), v_0; Initial unbalance amount (
A balance adjustment structure for a rotating body, characterized in that the following holds true: