WO2024225307A1

WO2024225307A1 - Balancer and method for adjusting rotation balance

Info

Publication number: WO2024225307A1
Application number: PCT/JP2024/016041
Authority: WO
Inventors: 重幸山添
Original assignee: 株式会社かいわ
Priority date: 2023-04-24
Filing date: 2024-04-24
Publication date: 2024-10-31

Abstract

Provided are: a balancer capable of adjusting the rotation balance of a rotating body at high precision; and a method for adjusting the rotation balance. A balancer 10 has a weight-holding body 21, weights 22, a keep plate 23, cap screws 24, and mounting parts 25. The weight-holding body 21 has a doughnut plate shape and is secured in a state in which a main shaft 12 passes through a through-hole 27. A groove 31 is formed in an adjustment surface 21a, which is one end surface of the weight-holding body 21. Three weights 22 are disposed in the groove 31. Each weight 22 is secured by being pressed by a circumferential section 23a of the keep plate 23, which is attached to the weight-holding body 21 by the cap screws 24. The weights 22 can be slid and moved by loosening the cap screws 24 in the vicinity of the weights 22.

Description

Balancer and rotation balance adjustment method

The present invention relates to a balancer that adjusts the rotational balance of a rotating body and a method for adjusting the rotational balance.

For example, if there is an imbalance in the mass distribution around the rotating axis of a rotating body such as the main shaft (spindle) or tool holder of a machine tool such as a machining center, vibrations will occur in the thrust and radial directions of the rotating body, reducing the machining accuracy and accelerating the deterioration of the spindle bearings. For this reason, a balancer is used to adjust the rotational balance, i.e. to correct the imbalance in the mass distribution of the rotating body.

A method is known in which multiple screw holes are provided at regular intervals on the end surface of the spindle in the direction of rotation, and the position of the screw hole into which the set screw that acts as a weight is inserted and screwed, and the weight (mass) of the set screw are changed to adjust the rotation balance (see, for example, Patent Document 1). Also, a method is known in which multiple screw holes are provided at regular intervals on the circumferential surface of the tool holder in the direction of rotation, and the rotation balance is adjusted in a similar manner to the above (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 6-126588 JP 2001-138162 A

However, with the above-mentioned rotational balance adjustment method, the positions and number of screw holes into which the set screws that act as weights are attached are predetermined, so there is a limit to how much the imbalance in the mass distribution of the rotating body can be corrected, and vibrations of the rotating body cannot be sufficiently suppressed. In addition, the length of the set screws inserted into the rotating body changes depending on the weight, which causes changes in the mass distribution of the entire rotating body including the set screws, making it difficult to accurately correct the state.

The present invention aims to provide a balancer and a method for adjusting rotational balance that can adjust the rotational balance of a rotating body with high precision.

The balancer of the present invention is a balancer for adjusting the rotational balance of a rotating body, and is provided with a plurality of end surface weights, a doughnut-shaped weight holder to which the plurality of end surface weights are attached and which rotates coaxially integrally with the rotating body, a first groove formed on the end surface of the weight holder and formed in an annular shape along the direction of rotation of the weight holder, within which the plurality of end surface weights can slide freely, and a fixing portion for fixing the plurality of end surface weights at any position within the first groove, and is provided on a spindle as the rotating body, or on a tool holder which can be detachably attached to the spindle.

The balancer of the present invention is a balancer for adjusting the rotational balance of a rotating body, and is provided with: a plurality of end surface weights; a doughnut plate-shaped weight holder to which the plurality of end surface weights are attached and which rotates coaxially integrally with the rotating body; a first groove formed on the end surface of the weight holder and formed in an annular shape along the direction of rotation of the weight holder, within which the plurality of end surface weights can slide freely; and a doughnut plate-shaped pressing plate whose outer diameter is larger than and smaller than the inner diameter of the first groove, and the pressing plate is disposed coaxially with the weight holder on the end surface of the weight holder, and presses and fixes a portion of each of the plurality of end surface weights inside the first groove with its peripheral portion.

The method for adjusting the rotational balance of the present invention uses a balancer that adjusts the rotational balance of a rotating body by changing the angular position of a plurality of weights arranged on a weight holder that rotates coaxially with the rotating body, using a spindle or a tool holder that can be detachably attached to the spindle as the rotating body, and measures the unbalance state of the rotating body when the rotating body is rotated with the plurality of weights arranged at equal intervals in the rotation direction of the weight holder, and the unbalance state of the rotating body when the rotating body is rotated with the position of one of the plurality of weights shifted from the equally spaced arrangement state, and determines an angular position that corrects the unbalance using each unbalance state of the rotating body, and a second measurement step that measures the unbalance state of the rotating body by arranging the plurality of weights at an angular position that corrects the rotational unbalance of the rotating body obtained based on the unbalance state of the rotating body measured in the immediately preceding measurement step, and repeats the second measurement step after the first measurement step until the unbalance state reaches a predetermined allowable state.

The balancer of the present invention adjusts the rotational balance of the rotor by fixing multiple end surface weights in a first groove formed in the end surface of a doughnut-shaped weight holder that rotates coaxially with the rotor, making it possible to adjust the rotational balance of the rotor with high precision.

In the balancer of the present invention, multiple end weights are placed in a first groove formed in the weight holder, and the multiple end weights are fixed by pressing the peripheral portion with a pressing plate whose outer diameter is larger than the inner diameter of the first groove but smaller than the outer diameter. This prevents the end weights from falling off and allows the end weights to be fixed while being exposed so that they can move.

According to the method for adjusting rotational balance of the present invention, when adjusting the rotational balance of a rotating body with a balancer using multiple end surface weights, the unbalance state of the rotating body is measured in a state where the multiple weights are arranged at equal intervals in the rotational direction of the weight holder and in a state where the position of one of the multiple weights is shifted, and an angular position for correcting the unbalance is determined. Thereafter, this is repeated with a second measurement step in which the multiple weights are arranged at an angular position based on the unbalance state measured in the immediately preceding measurement step and the unbalance state is measured until the unbalance state reaches a predetermined allowable state, thereby making it possible to adjust the rotational balance of the rotating body with high precision.

FIG. 2 is a perspective view from below showing a balancer attached to a spindle of the vertical machining center according to the first embodiment. FIG. 4 is an exploded perspective view of the balancer, seen from below. FIG. 2 is a perspective view from below showing the balancer in an assembled state. 11 is a cross-sectional view of a main portion showing a state in which a weight protrudes from a mounting surface portion. FIG. 13 is a perspective view showing a fall-off prevention plate provided on the upper surface of the weight holder. FIG. FIG. 13 is a perspective view from below showing an example in which a balancer is attached to a tool holder. FIG. 11 is a perspective view showing an example in which a balancer is attached to a spindle of a lathe. FIG. 11 is a perspective view showing a balancer according to a second embodiment. 4 is a cross-sectional view of a main portion showing the cross-sectional shape of a groove provided on the peripheral surface of a weight holder and a weight placed in the groove. FIG. FIG. 13 is a cross-sectional view of a main portion showing an example in which the weight holder is made up of two members. 13 is a cross-sectional view of a main portion showing an example in which two grooves are provided on the adjustment surface of the weight holder. FIG. 13 is a cross-sectional view of a main portion showing an example in which grooves are provided on both sides of a weight holder as adjustment surfaces. FIG.

[First embodiment]
1, a balancer 10 according to this embodiment is attached to a main shaft (spindle) 12 as a rotating body, and adjusts the rotational balance of the main shaft 12, i.e., corrects imbalance (unbalanced mass distribution) around a rotation axis Z. The balancer 10 is suitable for precisely adjusting the rotational balance of a rotating body such as the main shaft 12 that rotates at a high speed of, for example, 10,000 rpm (10,000 revolutions per minute) or more.

The spindle 12 is that of a machine tool, such as a vertical machining center, protrudes downward from the spindle head 14, and rotates around the rotation axis Z. In addition to the spindle 12, the spindle head 14 is equipped with a bearing that rotatably supports the spindle 12, a drive mechanism that rotates the spindle 12, a clamping mechanism that clamps the tool holder 15, and the like. The balancer 10 is attached to the end of the spindle 12 protruding from the spindle head 14 (the lower end in this example) so as to rotate together with the spindle 12, and corrects any imbalance in the spindle 12.

In this example, the balancer 10 is fixed to the exposed portion of the spindle 12 protruding from the spindle head 14, but it may also be provided on the spindle rotor of the spindle 12 housed in the spindle head 14. Also, in this example, a configuration is described in which the spindle 12 rotates around a vertical rotation axis Z, but the rotation axis Z may also be horizontal.

A tool holder 15 with a tool such as a drill or end mill (not shown) attached thereto is replaceably attached to the spindle 12. The tool holder 15 has a tool fixed to the end opposite the shank 15a. A fitting hole 12a is provided inside the spindle 12, and the fitting hole 12a opens to the lower end surface of the spindle 12. The tool holder 15 is fixed to the spindle 12 by fitting the shank 15a provided at the upper part of the tool holder 15 into the fitting hole 12a and clamping it. This causes the tool to rotate integrally with the spindle 12.

Figure 2 shows the components that make up the balancer 10 disassembled, and Figure 3 shows the components assembled. The balancer 10 is composed of weight holders 21, weights 22, pressure plates 23, pressure screws (bolts) 24, mounting parts 25, etc. Except for the arrangement of the weights 22, the balancer 10 is formed in a shape that is rotationally symmetrical about the central axis (rotation axis Z) of the weight holder 21, which is three-fold symmetrical in this example. In this example, there are the same number of weights 22, pressure screws 24, and mounting parts 25, all of which are three.

The weight holder 21 is a donut-shaped plate with a circular through-hole 27 that penetrates the thickness of the disk-shaped member in the center. The inner diameter of the through-hole 27 is the same as or slightly larger than the outer diameter of the main shaft 12, and the balancer 10 is fixed coaxially to the main shaft 12 that passes through the through-hole 27, and rotates coaxially with the main shaft 12.

The through hole 27 is formed with a plurality of notches 28 that extend radially outward from the through hole 27 and are cut out in a circumferential direction. The notches 28 are formed at equal intervals in the rotation direction of the spindle 12, i.e., the rotation direction (circumferential direction) of the weight holder 21. When the notches 28 are provided at equal intervals, they do not have to be strictly equal, but it is preferable to make them as precisely equal as possible in order not to significantly disrupt the rotation balance of the spindle 12 by the balancer 10. In this example, three notches 28 are formed at intervals of 120° around the rotation axis Z. The mounting parts 25 are fitted into each of the notches 28. Each mounting part 25 is composed of

mounting pieces

25a, 25b that, when assembled, form a block shape that is approximately the same shape as the notch 28, and a set screw 25c. In this example, the set screw 25c is a hexagon socket set screw (hollow set, set screw).

Attachment piece 25a is roughly U-shaped along three sides of cutout 28, and has a recess that opens toward through-hole 27. Attachment piece 25b has the same shape as the recess of attachment piece 25a, and is fitted into the recess so as to be movable in the radial direction of weight holder 21 relative to attachment piece 25a. A screw hole 29 that divides attachment piece 25a and attachment piece 25b is formed at the boundary between

attachment pieces

25a and 25b along the circumferential direction of weight holder 21. When

attachment pieces

25a and 25b are assembled without any gaps, the diameter of screw hole 29 becomes smaller than the diameter of set screw 25c from a specified depth, and gradually decreases as the depth increases.

The mounting

pieces

25a and 25b are fitted into the notch 28 with the spindle 12 passing through the through hole 27. When fixing the weight holder 21 to the spindle 12, the set screw 25c is screwed into the threaded hole 29 while widening the threaded hole 29 deeper than a predetermined depth, i.e., while sliding the mounting piece 25a outward and the mounting piece 25b toward the spindle 12 in the radial direction of the weight holder 21. As a result, the mounting piece 25b presses against the outer circumferential surface of the spindle 12 in the radial direction of the weight holder 21, and the mounting piece 25a presses against the inner surface of the notch 28 facing the outer circumferential surface of the spindle 12, fixing the weight holder 21 to the spindle 12.

The lower surface, which is one end surface of the weight holder 21, serves as an adjustment surface 21a in which a groove 31 is formed. On this adjustment surface 21a, a groove 31 is formed in an annular shape along the rotational direction of the weight holder 21 at a position on the outer periphery side of the cutout portion 28, and a scale 33 is engraved on the portion outside this groove 31. The portion inside the groove 31 of the adjustment surface 21a serves as an attachment surface portion 34 for attaching the pressure plate 23.

In this example, the groove 31 as the first groove has a flat bottom surface, and the center side surface on the rotation axis Z side and the outer periphery side surface on the outer periphery side of the weight holder 21 are shaped to rise vertically from the bottom surface. The scale 33 indicates the rotation center of the weight holder 21, i.e., the position around the rotation axis Z (hereinafter referred to as the angular position), as an angle centered on the rotation axis Z, and has scale lines engraved in increments of 1°, for example. The weights 22 can be fixed at a predetermined angular position based on this scale 33. The scale 33 has numbers engraved near the scale lines for arranging the weights 22 at equal intervals, that is, the angular positions of each angle (hereinafter referred to as the reference angle) when arranging the weights at equal intervals when correcting the imbalance by opening angle calculation (opening angle calculation balancing), that is, the multiple weights 22 are arranged at equal intervals. In this example, numbers indicating 0°, 120°, and 240° are engraved near the scale lines that are equal intervals (120° intervals) when three weights 22 are used. Note that in Figures 2 and 3, only the number "0" for the reference angle "0°" is shown. When placing the weights 22 at equal intervals, they do not have to be spaced exactly at equal intervals.

In this example, the balancer 10 is provided with three weights 22 as end weights. Each weight 22 is disposed in a groove 31. The weight 22 has a rectangular cross-sectional shape along the radial direction of the weight holder 21, and both the upper surface 22a that contacts the bottom surface of the groove 31 and the lower surface 22b (see FIG. 4) are flat. In addition, the weight 22 has an arc-like shape in a plan view that follows the groove 31. The inner circumferential surface of the weight 22 has approximately the same radius of curvature as the center side surface of the groove 31, and the outer circumferential surface of the weight 22 has approximately the same radius of curvature as the outer circumferential side surface of the groove 31. As a result, the weight 22 can slide freely in the rotational direction within the groove 31 without moving in the radial direction of the weight holder 21. The three weights 22 have the same shape and weight (mass).

A center line 22c is engraved on the underside 22b of the weight 22, passing through the circumferential center of the weight holder 21 and extending in the radial direction. By aligning the center line 22c with the scale markings of the scale 33, the weight 22 can be fixed at a specified angular position.

The pressure plate 23 is a doughnut plate with a circular opening 23a in the center of the disk. In this example, the pressure plate 23 is a fixing part that holds down and fixes each weight 22, and prevents them from falling out of the notch 28. The outer diameter of the pressure plate 23 is larger than the inner diameter of the groove 31 (the radius of curvature of the side surface on the center side, the outer diameter of the mounting surface portion 34) and smaller than the outer diameter of the groove 31 (the radius of curvature of the side surface on the outer periphery). By pressing down a part of the weight 22 with such a pressure plate 23, the outer periphery of the weight 22 is exposed without being covered by the pressure plate 23, and the exposed part of the weight 22 can be pushed and slid, for example, making it easy to adjust the angular position of the weight 22.

The inner diameter of the pressure plate 23 (diameter of the opening 23a) is the same as or slightly larger than the inner diameter of the through hole 27. As a result, when the weight holder 21 and the pressure plate 23 are assembled coaxially, the peripheral portion 23b of the pressure plate 23 presses and fixes each weight 22 arranged in the groove 31. Furthermore, if the mounting portion 25 falls out of the cutout portion 28, the mounting portion 25 will be scattered by centrifugal force, but by covering the mounting portion 25 with the pressure plate 23 on the adjustment surface 21a side, the mounting portion 25 is prevented from falling out of the cutout portion 28. Note that, in this example, the weight holder 21 is provided close to the spindle head 14 on the upper surface side of the weight holder 21, so that the spindle head 14 prevents the mounting portion 25 from falling out.

The mounting surface portion 34 has a plurality of screw holes 35 formed at equal intervals in the rotational direction of the weight holder 21. The intervals between the plurality of screw holes 35 do not have to be strictly equal. The screw holes 35 are provided near the groove 31. In this example, the mounting surface portion 34 is divided into a first surface area 34a surrounding the periphery of the through hole 27 and a donut-shaped second surface area 34b outside the first surface area 34a, and the first surface area 34a protrudes slightly downward from the second surface area 34b. The screw holes 35 are formed in the second surface area 34b, and the first surface area 34a is located closer to the center than the position where the pressure screw 24 screwed into the screw hole 35 presses the pressure plate 23, as described below.

Through holes 23c are formed in the pressure plate 23 at positions corresponding to the screw holes 35. The same number of screw holes 35 and through holes 23c are provided as the pressure screws 24. In this example, three screw holes 35 and through holes 23c are provided at intervals of 120° in the rotational direction of the weight holder 21, and the screw holes 35 are provided on the extensions of the 0°, 120°, and 240° graduation lines of the scale 33. The pressure plate 23 is coaxially assembled to the weight holder 21 by screwing the three pressure screws 24, which serve as first screws and pass through the through holes 23c, into the screw holes 35.

In the following explanation, when it is necessary to distinguish between the three pressure screws 24, the one on the extension of the 0° scale line of the scale 33 will be referred to as the first pressure screw 24, the one on the extension of the 120° scale line will be referred to as the second pressure screw 24, and the one on the extension of the 240° scale line will be referred to as the third pressure screw 24. Similarly, when it is necessary to distinguish between the three weights 22, the one whose angular position is fixed at 0° in the initial measurement described below will be referred to as the first weight 22, the one whose angular position is fixed at 120° will be referred to as the second weight 22, and the one whose angular position is fixed at 240° will be referred to as the third weight 22.

The pressure plate 23 also has through holes 23c formed at positions corresponding to the screw holes 29 of each mounting portion 25. The set screws 25c can be tightened or loosened, or inserted or removed from the screw holes 29, through the through holes 23c. Therefore, with the weight 22 and pressure plate 23 fixed to the weight holder 21, the balancer 10 can be attached to and detached from the spindle 12.

In FIG. 4, as described above, the mounting surface portion 34 is divided into a first surface area 34a and a second surface area 34b, and the first surface area 34a protrudes further in the direction of the rotation axis Z (downward) than the second surface area 34b. The pressure plate 23 is attached to the weight holder 21 by screwing the pressure screw 24 through the through hole 23c into the screw hole 35, so that the area of the pressure plate 23 on the second surface area 34b side is pressed by the pressure screw 24, and the area of the pressure plate 23 on the center side is in close contact with the first surface area 34a.

The weight 22 has a thickness (length in the direction of the rotation axis Z) greater than the depth of the groove 31, and protrudes in the direction of the rotation axis Z (downward) beyond the second surface region 34b of the mounting surface portion 34 that contacts the groove 31. That is, the weight 22 has a thickness such that the lower surface 22b protrudes in the direction of the rotation axis Z from the second surface region 34b as a protruding surface. As described above, by making the outer diameter of the pressure plate 23 greater than the inner diameter of the groove 31, the peripheral portion 23b of the pressure plate 23 protrudes from the mounting surface portion 34 (second surface region 34b) toward the groove 31. This allows the peripheral portion 23b to come into contact with the lower surface 22b of the weight 22 with a gap formed between the pressure plate 23 and the second surface region 34b when the pressure screw 24 is not tightened.

With the above configuration, by tightening the pressure screws 24, the peripheral portion of the pressure plate 23 around the pressure screw 24 bends slightly, and the peripheral portion 23b in the vicinity strongly presses against the underside 22b of the weight 22, fixing the weight 22 so that it does not slide within the groove 31. Also, by slightly loosening one of the pressure screws 24 from the state in which the weight 22 in the vicinity is fixed, the pressing force of the peripheral portion 23b on the weight 22 can be weakened, allowing the weight 22 to slide within the groove 31. Therefore, by loosening only one of the three pressure screws 24, only the weight 22 in the vicinity of the pressure screw 24 can be moved, while the other weights 22 remain fixed. This makes it easy to adjust the angular position of the weight 22.

The length of protrusion of the weight 22 from the second surface region 34b may be slight, for example, about 0.1 mm. The length of protrusion of the first surface region 34a from the second surface region 34b may also be slight, for example, approximately the same as the length of protrusion of the weight 22 from the second surface region 34b. Note that in FIG. 4, the protrusion of the first surface region 34a and the weight 22 from the second surface region 34b is exaggerated. Also, in FIG. 4, a gap is depicted between the pressure plate 23 and the mounting surface portion 34, but the pressure plate 23 and the second surface region 34b may come into contact with each other by tightening the pressure screw 24. The same applies to FIG. 11 and FIG. 12.

In this example, the mounting surface portion 34 is divided into the first surface area 34a and the second surface area 34b of different heights and has a step as described above, but the mounting surface portion 34 may be a flat surface. In this case, a gap is formed between the mounting surface portion 34 and the pressing plate 23 when the pressing plate 23 comes into contact with each weight 22. Alternatively, the mounting surface portion 34 may be a flat surface and a step may be provided on the surface of the pressing plate 23 on the mounting surface portion 34 side, so that the step brings the pressing plate 23 into close contact with the first surface area 34a of the mounting surface portion 34, and a gap may be formed between the portion of the pressing plate 23 on the outer periphery side of the position of the pressing screw 24 and the second surface area 34b of the mounting surface portion 34.

In the following explanation, the state in which the pressure screw 24 is tightened to fix the nearby weight 22 is referred to as "full tightening," and the state in which the pressure screw 24 is tightened or in this state after being loosened from this full tightening so that the nearby weight 22 can slide is referred to as "pre-tightening."

In this example, the balancer 10 fixes the weight 22 with the pressing plate 23, but the configuration of the fixing part for fixing the weight 22 is not limited to this. For example, similar to the mounting part 25 described above, the weight 22 may be formed of two members and a set screw may be screwed into a screw hole provided in the two members to expand the weight 22 in its width direction (radial direction of the weight holder 21) within the groove 31. In this case, the weight 22 is fixed by pressing the center side and the outer circumferential side of the groove 31 in opposite directions. On the other hand, the configuration in which the weight 22 is fixed with the pressing plate 23 as in this example does not require the weight 22 to be divided or to have a screw hole, and the weight 22 can be miniaturized, which is advantageous in terms of adjusting with higher accuracy using a weight 22 with a small weight. Furthermore, since centrifugal force increases in proportion to the square of the speed, it is particularly useful to be able to use a miniaturized weight 22 in the main shaft 12 that rotates at high speed, etc., since it is necessary to correct minute deviations in mass distribution.

Next, the adjustment of the rotational balance of the spindle 12 using the balancer 10 will be described. This adjustment of the rotational balance of the spindle 12 is performed with the tool holder 15 not attached to the spindle 12. In this example, the imbalance is corrected by calculating the opening angle using three weights 22. Note that a balance measuring machine, such as a device called a field balancer, is used for the measurement, i.e., detection of the vibration value (vibration magnitude) and vibration phase of the spindle 12, and calculation of the setting position of the weights 22 including the opening angle calculation based on the vibration detection results.

First, the balancer 10 with the three weights 22 placed in the grooves 31 is fixed to the spindle 12. It is also set up so that measurements can be taken with a balance measuring machine. The balance measuring machine is set up by attaching a vibration sensor (vibration pickup) to the spindle head 14 to detect the vibration of the spindle 12, and then attaching a reflective sticker to the spindle 12 to detect the rotation speed of the spindle 12 and use it as a reference position for the vibration phase, and placing a sensor to detect the reflective sticker close to the spindle 12.

Furthermore, the three weights 22 are slid to angular positions at equal intervals (120° intervals) and fixed, and the angular position and weight of each weight 22 are input to the balance measuring machine. When fixing each weight 22, for example, with the three pressure screws 24 temporarily fastened, the weights 22 are slid to the vicinity of the 0°, 120°, and 240° graduation lines of the scale 33, and then two of them, for example the second pressure screw 24 and the third pressure screw 24, are tightened to fully tighten. After this, the weights 22 placed near the 0° angular position are finely adjusted to the 0° angular position, and then the first pressure screw 24 is fully tightened to fix the weights 22. Next, the second pressure screw 24 is temporarily tightened, and the weights 22 placed near the 120° angular position are finely adjusted to the 120° angular position, and then the second pressure screw 24 is fully tightened to fix the weights 22. Similarly, the third press screw 24 is temporarily tightened, and the weight 22 placed near the 240° angular position is finely adjusted to the 240° angular position, and then the third press screw 24 is fully tightened to fix the weight 22. In this case, the angular positions input to the balance measuring machine are 0°, 120°, and 240°. Note that the angular positions of each weight 22 may be specified by the balance measuring machine.

After each weight 22 is fixed, the main shaft 12 is rotated at a predetermined rotational speed to perform an initial measurement. Through this initial measurement, the imbalance state (vibration value and vibration phase) of the main shaft 12 to which the balancer 10 is attached is obtained by the balance measuring machine as the measurement result of the initial measurement. The measurement results including this initial measurement can be displayed, for example, on the balance measuring machine.

Following the initial measurement, a trial measurement is performed. For this trial measurement, one weight 22 is shifted to the trial measurement angle position and fixed according to the instructions from the balance measuring machine. For example, the first weight 22 is fixed at an angle position of 10°. Note that the weight 22 to be shifted and fixed can be selected arbitrarily, and the trial measurement angle position can also be set arbitrarily within a predetermined range. In this case, the angular position of the shifted weight 22 is input into the balance measuring machine.

After fixing the first weight 22 at the trial measurement angle position (10° in this example), the main shaft 12 is rotated at a predetermined rotation speed, and the unbalanced state of the main shaft 12 is obtained as the trial measurement result by the balance measuring machine. When the trial measurement result is obtained, the balance measuring machine performs a calculation based on the initial measurement result and the angular position of each weight 22, the trial measurement result and the angular position of each weight 22, and the weight of each weight 22, and determines the angular position of each weight 22 to cancel out the vibration measured in the initial measurement, and displays that angular position.

After the trial measurement, the angular position of each weight 22 is adjusted according to the new angular position of each weight 22 displayed on the balance measuring machine during measurement. After this, a first residual measurement is performed with the balance measuring machine. In this residual measurement, the main shaft 12 is rotated at a predetermined rotation speed and the unbalance state of the main shaft 12 is obtained as a measurement result. Then, it is determined whether the unbalance state obtained by this residual measurement is within a predetermined allowable range, i.e., whether the vibration value of the main shaft 12 is below the target vibration value.

Furthermore, after the first residual measurement, the balance measuring machine performs a calculation based on the measurement results of the initial measurement and the angular position of each weight 22, the measurement results of the first residual measurement and the angular position of each weight 22, and the weight of each weight 22, to determine the angular position of each weight 22 to cancel out the vibrations measured in the initial measurement, and displays each of these angular positions.

For example, if the vibration value obtained in the first residual measurement is greater than the target vibration value, each weight 22 is slid and fixed to the angular position of each weight 22 displayed on the balance measuring machine after the first residual measurement as described above, and then a second residual measurement is performed. For the second residual measurement, the unbalanced state of the spindle 12 is obtained and displayed as a measurement result, as in the first residual measurement. Furthermore, the balance measuring machine performs a calculation based on the measurement result of the initial measurement and the angular position of each weight 22, the measurement result of the second residual measurement and the angular position of each weight 22, and the weight of each weight 22, and the angular position of each weight 22 is obtained to cancel out the vibration measured in the initial measurement, and the angular position is displayed.

In the same manner, the angular position of each weight 22 is slid to the angular position displayed after the previous residual measurement and a residual measurement is performed, until the measured vibration value becomes equal to or less than the target vibration value. Note that for each residual measurement, the balance measuring machine performs a calculation based on the result of that residual measurement, the result of the initial measurement, and the weight of each weight 22, and determines and displays the angular position of each weight 22 that cancels out the vibration measured in the initial measurement. Then, when the measured vibration value becomes equal to or less than the target vibration value, the adjustment of the rotational balance of the spindle 12 is completed.

As described above, the angular position of each weight 22 is adjusted based on the measurement results. In this adjustment, the weights 22 are slid one by one to adjust the angular position, as in the case of the initial position adjustment. That is, for one weight 22 whose angular position is to be adjusted, the pressure screw 24 in its vicinity is loosened and temporarily tightened, the weight 22 is slid to a new angular position, and the temporarily tightened pressure screw 24 is fully tightened. In a similar procedure, each weight 22 whose angular position is to be adjusted is moved to a new angular position and fixed. When adjusted in this manner, the two weights 22 other than the weight 22 to be moved are fixed, so while one weight 22 is being moved, the other weight 22 does not move, and the position of each weight 22 can be easily and accurately adjusted. Also, since a part of the weight 22 is exposed and not hidden by the pressure plate 23, the weight 22 can be easily slid.

In addition, by correcting the unbalance of the main shaft 12 as described above, the rotational balance of the main shaft 12 is adjusted with high precision, and by using the balancer 10, the radial and thrust vibrations of the main shaft 12 are reduced. In addition, each weight 22 can be slid within the groove 31 and fixed at any position, so the rotational balance of the main shaft 12 can be adjusted with even higher precision.

Generally, the vibration sensor of a balance measuring machine has high sensitivity to vibrations in one direction (sensitive axis) and low sensitivity to vibrations in the direction perpendicular to that (lateral sensitivity), but by attaching the vibration sensor to an appropriate position on the spindle head 14 and adjusting it as described above, the balancer 10 can reduce both radial and thrust vibrations of the spindle 12.

On the other hand, for example, sequentially correcting the imbalance by detecting the radial vibration of the main shaft 12 and calculating the opening angle, and then correcting the imbalance by detecting the thrust vibration, or repeating them alternately, is also useful for further reducing the radial vibration and the thrust vibration.

When detecting vibrations in the radial direction, the vibration sensor is attached to the surface of the spindle head 14 perpendicular to the radial direction of the spindle 12, for example, so that its sensitive axis coincides with the radial direction of the spindle 12. When detecting vibrations in the thrust direction, the vibration sensor is attached to the surface of the spindle head 14 perpendicular to the rotation axis Z, for example, so that its sensitive axis coincides with the thrust direction of the spindle 12 (the direction of the rotation axis Z). It is also possible to use two vibration sensors, one attached to detect vibrations in the radial direction and the other attached to detect vibrations in the thrust direction, and connected to a balance measuring machine, and to select each of them one by one with the balance measuring machine to perform balance adjustment in each direction.

The unbalance state of the spindle 12 may be intentionally changed using one test weight to measure the unbalance state, and based on the measurement result, three weights 22 may be arranged to correct the unbalance by calculating the opening angle. In this case, first, as a first preliminary measurement, the spindle 12 is rotated with the three weights 22 removed from the balancer 10 to measure the unbalance state. Next, a second preliminary measurement is performed using one weight 22 as a test weight. The weight 22 as a test weight is fixed, for example, at an angle position of 0°. The remaining two weights 22 are removed from the balancer 10. After fixing the weight 22 at an angle position of 0°, the spindle 12 is rotated to obtain the unbalance state of the spindle 12 as the measurement result of the second preliminary measurement. By inputting the weight and angular position (0°) of the weight 22 used as the test weight into the balance measuring machine, the angular position of the weight 22 for correcting the unbalance obtained by the calculation of the balance measuring machine is obtained and displayed. Here, the angular position of the weight 22 for correcting the imbalance is the angular position of the weight 22 for canceling the vibration measured in the first advance measurement, which is calculated by a calculation based on the measurement results of the first advance measurement, the measurement results of the second advance measurement, and the angular position and weight of the weight 22. Note that in the second advance measurement, the weight 22 may be fixed at an angular position of 120° or 240° instead of the angular position of 0°.

Next, the imbalance is corrected by calculating the opening angle. To do this, the three pressure screws 24 are loosened more than when provisionally tightened to create a gap between the pressure plate 23 and the weight holder 21, and the other two weights 22 are inserted into the groove 31 through the gap, and their respective angular positions are adjusted before being fixed. At this time, the weight 22 selected as the test weight among the three weights 22 is slid and fixed to the angular position obtained based on the measurement results of the second preliminary measurement. The remaining two weights 22 are positioned and fixed so that the three, including the weight 22 selected as the test weight, are equally spaced in the rotational direction of the weight holder 21 (120° in this example).

For example, if the angular position of the weights 22 obtained by performing the second preliminary measurement is 5°, the test weight 22 is fixed at an angular position of 5°, and the other two weights 22 are fixed at angular positions of 125° and 245°, respectively. By fixing each weight 22 in this way, the imbalance of the main shaft 12 is corrected in advance.

The angular position of each weight 22 is input into the balance measuring machine; in the above example, 5°, 125°, and 245°, and the weight of each weight 22 is also input. After this, initial measurements and trial measurements are carried out in the same manner as above, and adjustments to the angular position of each weight 22 and residual measurements are repeated until the measured vibration value is below the target vibration value. This allows the rotational balance of the spindle 12 to be quickly adjusted so that the vibration is below the target vibration value.

In the above, the balancer 10 is fixed to the spindle 12 with the adjustment surface 21a facing downward (toward the side opposite the spindle head 14), but when a gap can be secured between the balancer 10 and the spindle head 14 for adjusting the position of the weight 22, the balancer 10 may be fixed to the spindle 12 with the adjustment surface 21a facing upward (toward the spindle head 14 side). When the adjustment surface 21a faces upward in this way, or when the gap between the surface of the weight holder 21 opposite the adjustment surface 21a and the spindle head 14 becomes large, it is preferable to provide a drop prevention plate 41 on the surface opposite the adjustment surface 21a, in this example, the upper surface 21b, as shown in FIG. 5. The drop prevention plate 41 is fixed to the upper surface 21b with a screw 42 so as to closely contact and cover the mounting portion 25 exposed on the upper surface 21b side. This prevents the mounting portion 25 from coming off the cutout portion 28 toward the upper surface 21b side. The fall prevention plate 41, like the pressure plate 23, is a doughnut-shaped plate with a circular opening 41a in the center of the plate through which the main shaft 12 passes.

In the above, the spindle 12 is used as a rotating body, and the balancer 10 is provided on the rotating body, but the rotating body to which the balancer 10 is attached is not limited to this. FIG. 6 shows an example in which the balancer 10 is provided on a tool holder 15 as a rotating body. The balancer 10 is fixed to the end 15b of the tool holder 15 opposite the shank 15a. The configuration of the balancer 10 attached to the tool holder 15 can be the same as that attached to the spindle 12. It is preferable to provide a fall prevention plate 41 for the balancer 10 provided on the tool holder 15, as shown in FIG. 5. In this example, the balancer 10 is fixed to the tool holder 15 with the adjustment surface 21a facing downward (toward the opposite side to the shank 15a), but the balancer 10 may be fixed to the tool holder 15 with the adjustment surface 21a facing upward (toward the shank 15a side). When the balancer 10 is provided on the tool holder 15, the tool holder 15 is attached to the spindle 12 and rotated, and the rotational balance is adjusted in the same manner as in the case of the spindle 12 described above.

Figure 7 shows an example in which the balancer 10 is attached to the spindle 45 of a lathe, which has a chuck 47 attached to its end for gripping a workpiece. The lathe in this example is a horizontal type, and the spindle 45 protrudes horizontally from the headstock 46. Therefore, in this example, the balancer 10 rotates integrally with the spindle 45, which rotates around a horizontal axis of rotation. The lathe may also be a vertical type.

The balancer 10 can be attached to a rotating grinding wheel attached to a rotating shaft as a rotating body, and the rotational balance of the grinding wheel can be adjusted by attaching the balancer 10 to the grinding wheel as a flange. Furthermore, the balancer 10 can be used with the rotating parts of machining centers, grinding machines, milling machines, motors, and engines as rotating bodies.

In the above, the rotational balance is adjusted using three weights 22 as the multiple weights 22, but the number of weights 22 is not limited as long as it is two or more. When correcting the imbalance by calculating the opening angle, at the beginning of the measurement, multiple weights 22 can be fixed to the weight holder 21 at equal intervals along the rotational direction as described above.

In the above example, the balancer 10 is attached to the spindle 12 as a rotating body by the mounting portion 25, but the method of attaching the balancer to the rotating body is not limited to this. For example, a female thread may be formed on the inner circumferential surface of the through hole 27 of the weight holder 21, and a male thread may be formed on the circumferential surface of a rotating body such as the spindle 12 or tool holder 15, and the weight holder 21 may be screwed onto the rotating body for attachment. Also, although the balancer is constructed as a separate member from the rotating body such as the spindle or tool holder and attached to the rotating body, the weight holder of the balancer may be formed integrally with the rotating body. In this case, for example, the end surface of the spindle or tool holder may be used as the adjustment surface.

[Second embodiment]
The balancer of the second embodiment has weights for adjusting the rotation balance arranged on the peripheral surface as well as the end surface of the weight holder. The balancer of the second embodiment is similar to that of the first embodiment except for the following description, and the same reference numerals are used to designate substantially the same members, and detailed description thereof will be omitted.

The balancer 50 shown in FIG. 8 is attached to a rotating body such as a spindle or a tool holder. The balancer 50 is composed of a weight holder 51,

weights

22 and 52, a pressure plate 23, a pressure screw 24, and an attachment part 25. The balancer 50 is fixed coaxially to the rotating body passed through the through hole 27 by the attachment part 25, and rotates coaxially with the rotating body.

The weight holder 51 is a doughnut plate with a circular through hole 27 that penetrates the center of the disk-shaped member in the thickness direction. A groove 31 is formed as a first groove on the adjustment surface 51a, which is one end surface of the weight holder 51, and each weight 22 arranged in the groove 31 is fixed by a pressing plate 23. A groove 54 is formed as a second groove in the rotation direction (circumferential direction) of the weight holder 51 on the peripheral surface 51c of the weight holder 51. A plurality of weights 52, three weights 52 in this example, are arranged and fixed in the groove 54 as peripheral weights. In FIG. 8, only two weights 52 are shown. The weight holder 51 may be formed integrally with the rotating body, and in this case, a groove 54 may be formed on the peripheral surface of the rotating body. The number of weights 52 may be more than one (two or more), and may be different from the number of weights 22. In addition, when the end surface of the rotating body is the adjustment surface 51a, a groove 54 may be provided on the peripheral surface of the rotating body.

As shown in FIG. 9, the groove 54 is a dovetail groove. That is, the groove 54 has a cross-sectional shape in which its width (length in the thickness direction of the weight holder 51) gradually increases toward the bottom of the groove 54. The weight 52 is composed of a pair of weight members 52a divided into two in the width direction, and a set screw 52b. Each of the pair of weight members 52a is large enough to be inserted into the groove 54 from its opening, and is inserted into the groove 54 and then assembled together within the groove 54. The cross-sectional shape of the pair of weight members 52a when assembled together is approximately the same as the cross-sectional shape of the groove 54, but is narrower than the groove 54. A screw hole 57 is formed at the boundary where the pair of weight members 52a are assembled, dividing each of the pair of weight members 52a into two.

When the pair of weight members 52a are assembled without any gaps, the diameter of the screw hole 57 becomes smaller than the diameter of the set screw 52b from a predetermined depth, and gradually decreases as the depth increases. When fixing the weight 52 in the groove 54, the set screw 52b is screwed deeper than the predetermined depth into the screw hole 57 formed by assembling the pair of weight members 52a in the groove 54. As a result, the pair of weight members 52a press against the opposing inner surfaces of the groove 54, fixing the weight 52. The set screw 52b can be loosened to move the weight 52 in the groove 54.

A scale 58 is engraved on the peripheral surface 51c near the opening of the groove 54, similar to the scale 33, to indicate the angular position of the weight holder 51 around the center of rotation in degrees. One of the weight members 52a of the weight 52 is engraved with a center line 52c extending in the thickness direction of the weight holder 51 (the direction of the rotation axis Z) at the circumferential center of the weight holder 51. By aligning the center line 52c with the scale line of the scale 58, the weight 52 can be positioned and fixed at a predetermined angular position. By fixing the weight 52 in the groove 54, which is a dovetail groove, the weight 52 is less likely to slip out of the groove 54 and fly away. In this example, three weights 52 are used, but two weights 52 may be used as in the weight 22.

When the balancer 50 is used, three weights 22 are fixed in the groove 31, and three weights 52 are fixed in the groove 54 at equal intervals, for example at angular positions of 0°, 120°, and 240°, respectively. After this, the three weights 22 are used to correct the imbalance of the rotor by opening angle calculation to reduce the vibration of the rotor, and three more weights 52 are used to correct the imbalance of the rotor by opening angle calculation to further reduce the vibration of the rotor. In this way, by adjusting both the weights 22 arranged on the end face of the weight holder 51 and the weights 52 arranged on the circumferential surface, the balance of both thrust and radial is adjusted as in the first embodiment.

In addition, the imbalance may be corrected using three weights 52, and then the imbalance may be corrected using three weights 22. The imbalance correction using three weights 22 and the imbalance correction by opening angle calculation using three weights 52 may be repeated alternately. Also, the imbalance correction by opening angle calculation performed by detecting the vibration in the radial direction of the rotor and the imbalance correction by opening angle calculation performed by detecting the vibration in the thrust direction may be used in combination. For example, the imbalance correction using three weights 22 and the imbalance correction by opening angle calculation using three weights 52 are performed by detecting the vibration in the radial direction of the rotor, and then the imbalance correction using three weights 22 and the imbalance correction by opening angle calculation using three weights 52 are performed by detecting the vibration in the thrust direction of the rotor.

FIG. 10 shows an example in which the weight holder 51 is composed of a first member 61 and a second member 62, and the groove 54, which becomes the second groove, is formed so as to divide it in the direction of the rotation axis Z. The weight holder 51 is divided into two in its thickness direction (the direction of the rotation axis Z), and is composed of a first member 61 on the adjustment surface 51a side and a second member 62 on the upper surface 51b side. In this example, the second member 62 is assembled to the first member 61 by threading a screw 64 passed through a through hole 63 formed in the second member 62 into a screw hole 65 formed in the first member 61. A plurality of through holes 63 and a plurality of screw holes 65 are provided at equal intervals in the rotation direction of the weight holder 51, and the first member 61 and the second member 62 are assembled by threading a plurality of screws 64 into them.

In this example, the groove 54 has a T-shaped cross section along the radial direction of the weight holder 51. That is, the groove 54 has the same width (length in the direction of the rotation axis Z) as the opening exposed on the peripheral surface 51c up to a certain depth, and has a certain width larger than the opening between the certain depth and the bottom surface. In this way, the groove 54 has a cross section along the radial direction of the weight holder 51 that has a portion wider than the opening width. This groove 54 is formed by combining the portions formed by dividing the groove 54 into the first member 61 and the second member 62. That is, the groove 54 is divided by a plane perpendicular to the rotation axis Z, one portion of which is formed in the first member 61 and the other portion is formed in the second member 62. More specifically, in this example, the groove 54 is divided so that the opening and the bottom surface are divided into two in the direction of the rotation axis Z.

In this example, each weight 52 is a single member, and its cross-sectional shape is the same as the cross-sectional shape of the groove 54, that is, a T-shape. Each weight 52 is placed in the groove 54 by inserting it between the first member 61 and the second member 62 that form the groove 54 and assembling the first member 61 and the second member 62. The weight 52 is pressed and fixed by the opposing inner surfaces of the first member 61 and the second member 62 that form the inner wall surface of the groove 54 by tightening the screw 64. When the angular position of the weight 52 is to be adjusted, the screw 64 near the weight 52 whose angular position is to be adjusted is loosened. This weakens the pressing force of the first member 61 and the second member 62 on the weight 52, and the weight 52 can slide within the groove 54.

By configuring as described above, weight 52 can be configured as a single member while being shaped so that weight 52 does not fall out of groove 54 and scatter, and weight 52 can be fixed within groove 54. As with the case where weight 52 is held down by pressing plate 23, weight 52 can be made smaller, which is advantageous for high-precision adjustment.

In each of the above embodiments, the weight is placed and fixed in one groove on the adjustment surface (end surface) of the weight holder, but multiple grooves may be provided on the adjustment surface and the rotational balance of the rotating body may be adjusted by moving the weights placed in each groove. In the example shown in FIG. 11, groove 31 and groove 71 are formed on adjustment surface 21a of weight holder 21. Groove 71 is formed outside groove 31, and three weights 72, for example, are placed in groove 71. For example, it is desirable to determine the masses of

weights

22, 72 so that the moment of inertia of weight 22 is smaller than that of weight 72. The number of

weights

22, 72 may be multiple (two or more), and the number of weights 22 and weights 72 may be different.

The weight 72 is composed of a pair of weight members 72a and a set screw 72b. The cross-sectional shape of the pair of weight members 72a when combined is almost the same as the cross-sectional shape of the groove 71, but is narrower than the groove 71. The weight 72 is fixed in the groove 71 by screwing the set screw 72b to a predetermined depth or more into a screw hole 73 formed at the boundary part where the pair of weight members 72a are combined. When the pair of weight members 72a are combined without any gaps, the diameter of the screw hole 73 becomes smaller than the diameter of the set screw 73b from a predetermined depth, and the diameter of the screw hole 73 is gradually reduced as it becomes deeper from that depth. As a result, by screwing the set screw 72b into the screw hole 73 deeper than a predetermined depth, the pair of weight members 72a press the opposing inner surfaces of the groove 71, and the weight 72 is fixed. By loosening the set screw 72b, the weight 72 can be slid within the groove 71. The weight 22 in the groove 31 is pressed and fixed by the pressing plate 23.

In this configuration, for example, three weights 22 are fixed in groove 31, and three weights 72 are fixed in groove 71, each equally spaced apart in the rotational direction of weight holder 21. The angular positions of the three weights 22 and the three weights 72 may differ from each other. First, for example, the three weights 72, each of which has a larger moment of inertia than weight 22, are used to correct the imbalance through an opening angle calculation, thereby reducing the vibration of the rotating body. After this, the three weights 22 are used to correct the imbalance through an opening angle calculation, thereby further reducing the vibration of the rotating body. Note that the correction of the imbalance through an opening angle calculation using weights 72 and the correction of the imbalance through an opening angle calculation using weights 22 may be repeated.

FIG. 12 shows an example in which the upper and lower end faces of the weight holder 75 are each used as an adjustment surface 75a, a groove 31 is provided on each adjustment surface 75a, and weights 22 are placed in each groove 31. In this example, the rotational balance of the rotating body is adjusted by moving the weights 22 placed in the grooves 31 of each adjustment surface 75a. The number of weights 22 on each adjustment surface 75a may differ from each other.

10, 50

Balancer

12, 45 Spindle 15

Tool holder

21, 51, 75

Weight holder

21a, 51a,

75a Adjustment surface

22, 52, 72 Weight 23 Pressing plate 23b Periphery 24

Pressing screw

31, 54, 71 Groove 34 Mounting surface

Claims

In balancers that adjust the rotation balance of rotating bodies,
A plurality of end weights;
a doughnut-shaped weight holder to which the plurality of end surface weights are attached and which rotates coaxially integrally with the rotor;
a first groove formed on an end surface of the weight holder, the first groove being formed in an annular shape along a rotation direction of the weight holder, the first groove being capable of allowing the end surface weights to slide freely therein;
a fixing portion that fixes the plurality of end weights at any position within the first groove;
Equipped with
The balancer is provided on a spindle as the rotating body or on a tool holder that is detachably attached to the spindle.
The balancer according to claim 1, wherein the fixing portion is in the shape of a donut plate with an outer diameter larger than the inner diameter of the first groove and smaller than the outer diameter, and is provided with a pressing plate that is arranged coaxially with the weight holder on the end face of the weight holder and presses and fixes with its peripheral portion a portion of each of the multiple end surface weights that are arranged inside the first groove so as to be movable in the rotational direction.
the end surface weights each have a thickness that protrudes in a direction of a rotation axis of the weight holder from a mounting surface portion of the end surface that is located on the inner side of the first groove,
a plurality of screw holes formed in the mounting surface portion along the rotation direction;
a plurality of through holes formed in the pressing plate along the rotation direction in correspondence with the plurality of screw holes,
3. The balancer according to claim 2, wherein the fixing portion has a plurality of first screws that screw into the plurality of screw holes through the plurality of through holes, respectively, and press the pressing plate toward the mounting surface portion, so that the peripheral portion presses against protruding surfaces of the plurality of end-face weights that protrude beyond the mounting surface portion, thereby fixing the pressing plate to the weight holder.
the plurality of screw holes and the plurality of through holes are provided at equal intervals along the rotation direction in the same number as the plurality of end surface weights,
The balancer according to claim 3 , wherein the plurality of screws include first screws, the number of which is equal to the number of the end surface weights, that press and fix the retainer plate.
a second groove formed in an annular shape along the rotation direction on a peripheral surface of the weight holder;
A plurality of peripheral weights fixed inside the second groove;
A balancer according to any one of claims 1 to 4, comprising:
The second groove has a portion whose cross-sectional shape along a radial direction of the weight holder is wider than an opening width,
The plurality of peripheral weights have a cross-sectional shape along a radial direction of the weight holder that is the same as the cross-sectional shape of the second groove,
6. The balancer according to claim 5, wherein the weight holder has a first member in which one of the second grooves divided in the direction of the rotation axis of the weight holder is formed, and a second member in which the other of the second grooves is formed and which is assembled to the first member.
In balancers that adjust the rotation balance of rotating bodies,
A plurality of end weights;
a doughnut-shaped weight holder to which the plurality of end surface weights are attached and which rotates coaxially integrally with the rotor;
a first groove formed on an end surface of the weight holder, the first groove being formed in an annular shape along a rotation direction of the weight holder, the first groove being capable of allowing the end surface weights to slide freely therein;
a presser plate having a doughnut shape, the outer diameter of which is larger than the inner diameter of the first groove and smaller than the outer diameter of the first groove;
The pressing plate is
a balancer that is disposed coaxially with the weight holder on the end surface of the weight holder and that presses and fixes a portion of each of the plurality of end surface weights inside the first groove by means of a peripheral portion thereof;
A balancer is used to adjust the rotational balance of a rotating body by changing the angular positions of a plurality of weights arranged on a weight holder that rotates coaxially with a rotating body, the weight holder being a rotating body that is a spindle or a tool holder that is detachably attached to the spindle, around the rotation axis of the rotating body,
a first measurement step of measuring an unbalance state of the rotating body when the rotating body is rotated in a state in which the plurality of weights are arranged at equal intervals in the rotational direction of the weight holder, and measuring an unbalance state of the rotating body when the rotating body is rotated with a position of one of the plurality of weights shifted from the state in which the weights are arranged at equal intervals, and determining an angular position for correcting the unbalance using each unbalance state of the rotating body;
a second measuring step of measuring an unbalance state of the rotating body by disposing the plurality of weights at angular positions that correct an unbalance state of the rotating body obtained based on the unbalance state of the rotating body measured in the immediately preceding measuring step,
After the first measuring step, the second measuring step is repeated until the unbalance state reaches a predetermined allowable state.
How to adjust the rotation balance.