JP6150662B2 - Rotating shaft - Google Patents

Description

  The present invention relates to a rotating shaft body constituting a timepiece gear structure in a timepiece that notifies time using a pointer, and more particularly to a technique for reducing the weight and size of the rotating shaft body.

  As a typical timepiece gear structure, a watch wheel used for a rotation transmission system that transmits rotation from a rotation drive source to a pointer is known. An example of such a wheel is a fourth wheel to which a second hand is connected.

  In these number wheels, a large-diameter gear and a small-diameter gear are attached to the same shaft portion (rotating shaft body). For example, in the case of the fourth wheel, the small gear is connected to the large gear of the third gear, and the large gear is connected to the small gear of the escape wheel.

  As a structural example of such a wheel, a configuration in which a rotating shaft body and a small-diameter gear are integrally formed and a large-diameter gear is assembled thereto is widely known. For example, the configuration is as shown in FIG.

FIG. 6 is a cross-sectional view schematically showing a state where the shaft portion and the gear are cut along the rotation axis.
As shown in this figure, in the pinion member 50, the shaft portion 51 and the small-diameter gear 52 provided with the outer peripheral teeth 52a are integrally formed by cutting the shaft material. Further, the large-diameter gear 60 provided with the outer peripheral teeth 60a is formed by pressing or the like separately from this. Thereafter, the pinion member 50 is press-fitted into a shaft hole 60b formed at the center of the large-diameter gear 60, thereby forming an integrated wheel.

  In the conventional timepiece gear structure shown in FIG. 6, when the pinion member 50 is formed, a shaft member thicker than the outer diameter of the small diameter gear 52 is used to cut the small diameter gear 52 and the shaft portion 51 by cutting. Since it needs to be formed, it takes a long time for processing and a lot of material is wasted. For this reason, an improved technique has been proposed as a countermeasure (for example, see Patent Document 1).

The prior art shown in Patent Document 1 will be described with reference to FIG.
FIG. 7 shows a timepiece gear structure, which is a cross-sectional view schematically showing a state where a shaft portion and a gear are cut along a rotation axis, and is conventionally known as shown in FIG. It is the figure seen from the same direction as a structure.

  As shown in FIG. 7, the rotary shaft body 70 made of a single member is the same as the example of FIG. 6 in that the shaft member is formed as a single member by cutting, but the gear body 80 is press-fitted. Since the diameter is sufficient, there is no waste of material.

  Separately from this, the gear body 80 is integrally formed with a large-diameter gear portion 81 having outer peripheral teeth 81a and a small-diameter gear portion 82 having outer peripheral teeth 82a by press working or the like. Thereafter, the rotary shaft body 70 is press-fitted into a shaft hole 80 a formed at the center of the gear body 80, and the small-diameter gear portion 82 is brought into contact with a flange 71 provided on the rotary shaft body 70 to form an integral number wheel.

Next, an example in which the timepiece gear structure according to the prior art disclosed in Patent Document 1 is used as a train wheel structure for time display will be described.
FIG. 8 shows a part of the train wheel structure for time display, and schematically shows a state in which the shaft portion and the gear are cut along the rotation axis.

  The train wheel structure for time display of the timepiece shown in FIG. 8 is composed of a rotating shaft body 1 (corresponding to the rotating shaft body 70 in FIG. 7) and a gear body 9 (corresponding to the gear body 80 in FIG. 7). These constitute the fourth wheel 10.

  The gear body 9 is provided with a second hand pinion portion 9a (corresponding to the small diameter gear portion 82 in FIG. 7) and a second gear portion 9b (corresponding to the large diameter gear portion 81 in FIG. 7) formed coaxially therewith. It is integrally formed.

  The gear body 9 is press-fitted and fixed to the gear fitting portion 3 near one end of the rotating shaft body 1, and the second hand pinion portion 9 a side corresponds to the flange 2 of the rotating shaft body 1 (corresponding to the flange 71 in FIG. 7). ) And is positioned. A second hand fitting portion 5 to which the second hand 8 a is fitted is provided at the other end of the rotating shaft 1.

  The minute hand cylinder 77 to which the minute hand 8 b is attached is rotatably fitted to the rotary shaft body 1. The rotating shaft 1 and the minute hand cylinder 77 are separated from each other so that they can rotate smoothly. The hour hand cylinder 78 to which the hour hand 8c is attached is rotatably fitted to the minute hand pipe 77. The hour hand cylinder 78 is also separated from the minute hand cylinder 77 and rotates smoothly.

  The rotary shaft body 1 is provided with flange-shaped steady rests 16a and 16b. A convex shape toward the inner wall of the minute hand cylinder 77 so that the second hand 8a connected to the rotary shaft 1 does not tilt with respect to the timepiece dial 6 and so as not to cause rotational shake of the rotary shaft 1. have.

  In the example of FIG. 8, the steady rests 16 a and 16 b seem to be in contact with the minute hand cylinder 77, but are actually slightly separated and do not affect the rotation of the minute hand cylinder 77. For example, when rotational shake or tilt of the rotating shaft 1 occurs, the steady rests 16a and 16b and the inner wall of the minute hand cylinder 77 are in contact with each other to suppress rotational shake and tilt. In addition, although an example in which two steady rests are provided has been shown, it may of course be one.

  The symbol a is the minimum outer diameter portion of the shaft body 1, and the symbol P is the length of the rotating shaft body 1. As described above, the rotary shaft 1 fitted with the second hand 8a, the minute hand 8b, and the hour hand 8c has a length P that is considerably longer than the minimum outer diameter portion a.

Japanese Patent Laid-Open No. 9-33665 (page 2-3, FIGS. 1, 4)

  By the way, in recent years, with the diversification of watch exterior designs such as three-dimensional watch dials, functions added to watches, such as radio wave transmission and reception functions and compass, have become multifunctional. There exists a tendency for the length of a rotating shaft to become long. In the example shown in FIG. 8, the value of the length P of the rotating shaft 1 is required to exceed 10 mm.

  On the other hand, even in recent timepieces, there is a demand for reduction in size and weight as before, and the diameter of the rotating shaft 1 is also required to be as small as about 0.35 mm. In such a case, the value of the minimum outer diameter portion a is further reduced. For this reason, the shape of the rotating shaft 1 becomes a very long and narrow shape, and there is a limit problem of weight reduction in the conventional cutting process. In other words, if an attempt is made to reduce the weight of a long rotating shaft body, the material will be deformed or broken during cutting.

Further, if the diameter of the long rotating shaft is further reduced with the aim of reducing the weight, the strength is reduced even if the processing is successful, so it is very difficult to reduce the weight and maintain the strength.

  There is also a problem that the rotating shaft body 1 cannot have an optimum cross-sectional shape. For example, even when it is desired to make the shapes of the steady rests 16a and 16b, the fitting shape with the minute hand cylinder 77, and the like suitable, processing may not be possible. This is also a problem of a cutting apparatus that performs cutting, but if the diameter of the rotating shaft 1 is reduced or made finer in order to reduce the weight, it is not possible to process into an optimal shape.

  For such a problem, a rotating shaft body by synthetic resin (plastic) molding has also been proposed. However, the technique is insufficient in strength, and the shape of the runner portion is large with respect to the parts, and the waste of the material is insufficient.

  As described above, the rotating shaft body in the prior art is adapted to the diversification of the above-described exterior design, the multi-function of the watch function, the size and weight of the watch gear structure, and the low power consumption, and the maintenance of the strength. There was a problem that it was difficult to achieve both. In addition, the waste of materials cannot be improved sufficiently, and the manufacturing cost is also a problem.

  The present invention has been made in view of the above-described problems, and can cope with the diversification of the multi-function and exterior design of the watch, can reduce the waste of materials, and at the same time, achieves both a reduction in size and weight and a reduction in power consumption and strength. The purpose is to provide a shaft body.

  In order to achieve the above object, the rotating shaft body of the present invention employs the following configuration.

In the rotating shaft body constituting the timepiece gear structure, the rotating shaft body has a hollow structure inside the portion excluding at least a portion in contact with other components, and the hollow structure includes a plurality of gaps and a plurality of gaps. It characterized in that it has a beam.

  According to the above configuration, it is possible to realize a rotating shaft body that can reduce the waste of materials, reduce the size and weight, and reduce the power consumption without reducing the strength.

  Moreover, it is good for this rotating shaft body to be comprised integrally by the three-dimensional modeling method.

  According to the said structure, the hollow structure which cannot be performed by the conventionally known cutting process can be formed easily. In this way, waste of materials can be reduced, and an optimum cross-sectional shape with high dimensional accuracy can be easily formed.

  Moreover, this rotating shaft body is good to have a fitting part which fits the pointer for alerting | reporting time.

  According to such a configuration, the timepiece wheel train structure does not decrease in strength even if the length of the rotating shaft body is long or light, in response to the diversification of the exterior design of the watch and the multi-function of the watch function. Can be configured.

  By making the inside of the rotating shaft other than the portion in contact with the other components a hollow structure, it is possible to provide a rotating shaft that does not decrease in strength even if it is lightweight. As a result, it is possible to reduce the waste of materials in response to the multi-functionality of watches and the diversification of exterior designs.

It is sectional drawing which shows the rotating shaft body which comprises the gear structure for timepieces in the 1st Embodiment of this invention. It is a partial expanded sectional view of the A section in FIG. It is sectional drawing which shows the rotating shaft body which comprises the timepiece gear structure in the 2nd Embodiment of this invention. It is sectional drawing which shows the rotating shaft body which comprises the gear structure for timepieces in the 3rd Embodiment of this invention. It is a fragmentary sectional view which shows the other example of the space | gap shape inside the rotating shaft body which comprises the gearwheel structure for timepieces in embodiment of this invention. It is sectional drawing which shows the timepiece wheel for timepiece explaining the gearwheel structure for timepieces in a prior art. It is sectional drawing which shows the watch wheel for explaining the prior art shown in patent document 1. FIG. It is sectional drawing explaining the principal part of the train wheel structure for time displays using the prior art shown in patent document 1. FIG.

  The rotating shaft body has a non-contact region that is a region that does not come into contact with or directly mesh with other components such as other gears. A gap is provided inside the non-contact region of the rotating shaft body, and the rotating shaft body has a hollow structure due to the gap.

Since a strong force from an external component is not applied to the non-contact region, there is no problem in strength even if a gap is provided in such a portion.
That is, by having the gap, the weight can be reduced while maintaining the strength as the rotating shaft body. It is possible to reduce the power consumption of the watch by reducing the weight.

  Since such a rotating shaft body is formed by a three-dimensional modeling method, even a complicated shape can be easily formed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 and 2 are cross-sectional views for explaining the first embodiment, FIG. 3 is a cross-sectional view for explaining the second embodiment, and FIG. 4 is a cross-sectional view for explaining the third embodiment. FIG. 5 is a cross-sectional view illustrating the hollow structure of the rotating shaft body. These drawings are cross-sectional views schematically showing a state cut along the rotation axis. In addition, in embodiment described using FIGS. 1-4, the case where it has the two non-contact area | regions provided in the above-mentioned rotating shaft body is demonstrated to an example.

  The rotating shaft body in the embodiment of the present invention is characterized in that it has a void inside the portion other than the portion in contact with other components and has a hollow structure, and the other basic configuration is shown in FIG. This is similar to the conventional technique described above. Therefore, the same components as those in the conventional technology already described are denoted by the same reference numerals, and redundant description is omitted.

[First Embodiment: FIGS. 1 and 2]
1st Embodiment of a rotating shaft body is described in detail based on FIG. 1, FIG.
FIG. 1 is a cross-sectional view showing a main part of a rotating shaft body and a time display wheel train structure constituting a timepiece gear structure according to the first embodiment. FIG. 2 is an enlarged view of a part of the rotating shaft, and shows the state of the A part shown in FIG.

  As shown in FIG. 1, a rotary shaft body 11 having a circular cross-sectional shape and a gear body 9 made of a metal material are fitted to form a fourth wheel & pinion 20. The gear body 9 is provided with a second hand pinion portion 9a, which is a small-diameter gear, and a second gear portion 9b, which is a large-diameter gear formed coaxially therewith.

The gear body 9 is press-fitted and fixed to the gear fitting portion 3 in the vicinity of one end of the rotating shaft body 11, and the second hand pinion portion 9 a side of the gear body 9 is brought into contact with the flange 2 of the rotating shaft body 11. It is positioned. Therefore, this gear fitting part 3 becomes a part which contacts another component (gear body 9).

  A second hand fitting portion 5 to which the second hand 8 a is fitted is provided at the other end portion of the rotating shaft body 11. Therefore, the second hand fitting portion 5 is also a portion in contact with another component (second hand 8a).

  Further, the minute hand cylinder 77 to which the minute hand 8 b is attached is rotatably fitted to the rotary shaft body 11. Similar to the conventional technology already described, the rotary shaft 11 and the minute hand cylinder 77 are separated from each other, and the minute hand cylinder 77 rotates smoothly. The hour hand cylinder 78 to which the hour hand 8c is attached is rotatably fitted to the minute hand pipe 77. The hour hand cylinder 78 is also separated from the minute hand cylinder 77 and rotates smoothly.

  The rotating shaft body 11 is provided with steady rests 16a and 16b. In addition, although the example where two steady rests were provided was shown, of course, one place may be sufficient. Furthermore, although the cross section is a rectangular shape in the illustrated example, it may be a smooth shape without corners.

In the rotary shaft body 11, a region between the second hand fitting portion 5 and the steady rest 16a is defined as a first non-contact region 12, and a region between the steady rest 16b and the gear fitting portion 3 is defined as a second non-contact. Region 14 is designated.
The first non-contact region 12 and the second non-contact region 14 are each provided with a gap 15 which is a feature of the present application, and the rotary shaft 11 has a hollow structure.

  The gap 15 is provided in the first non-contact region 12 and the second non-contact region 14, and is not provided in the gear fitting portion 3 or the second hand fitting portion 5 to which force from other components is applied. For this reason, even if an excessive force is applied in the rotation axis direction or the rotation direction of the rotating shaft body 11, the breakage due to the provision of the gap 15 does not occur. For this reason, the intensity | strength as a rotating shaft body does not fall.

  That is, the rotating shaft body 11 can achieve weight reduction without sacrificing the strength as the rotating shaft body.

[Explanation of the gap of the rotating shaft: FIG. 2]
Next, the hollow structure of the rotating shaft body 11 shown in part A of FIG. 1 will be described with reference to FIG.
FIG. 2 is a partial enlarged cross-sectional view of a portion A in FIG. 1 and is a cross-sectional view showing the inside of the first non-contact region 12 of the rotating shaft body 11. As shown in FIG. 2, the hollow structure provided inside the first non-contact region 12 of the rotating shaft body 11 has a so-called truss structure by providing a plurality of gaps 15 having a triangular cross section. The truss structure is well known as a bracing structure in which beams are passed diagonally between columns or as a steel beam structure of a bridge over a river.

  If the space between the gaps 15 is expressed as a beam for the sake of convenience, there are a plurality of beams 17 a and 17 b inside the rotating shaft 11, and the gap 15 is between these beams.

  The beam 17 a is provided to be inclined so as to form a predetermined angle c with respect to the transverse sectional direction m of the rotating shaft 11. On the other hand, the beam 17 b is provided so as to be inclined so as to form a predetermined angle c in the direction opposite to the beam 17 a with respect to the transverse sectional direction m of the rotating shaft 11. These beams 17a and 17b are alternately and continuously provided in the direction of the rotation axis of the rotary shaft 11, thereby forming a truss structure.

  The internal structure of the rotating shaft 11 is not limited to the truss structure, and other structures can be used. Other examples will be described later.

[Description of Manufacturing Method of Rotating Shaft]
The described gear body 9 can be made of a metal material by pressing, as in a conventionally known technique. The rotating shaft body 11 can be formed by a known three-dimensional modeling method.

  The three-dimensional modeling method is a modeling method called a rapid prototyping method. A manufacturing method called additive manufacturing is known as a representative method. The additive manufacturing method divides the electronic three-dimensional information of a structure into two-dimensional information obtained by cutting a three-dimensional solid, and forms an actual material into a shape based on this information, and sequentially laminates these materials. It is a technology for manufacturing actual solids.

  In this embodiment, by using an inkjet method which is one of additive manufacturing methods, metal particles are ejected and laminated from an inkjet nozzle, and the inkjet nozzle is moved in a two-dimensional direction. A planar body was formed, and this operation was repeated to manufacture the rotating shaft body 11.

  As a result, the hollow structure having the gap 15 inside the first non-contact region 12 and the second non-contact region 14 other than the portion in contact with other components also has a complicated outer shape of the rotating shaft. However, it can be manufactured easily.

  The three-dimensional modeling method is a technology that has attracted particular attention recently, and is a well-known technology. However, the modeling by the inkjet method has also been proposed as a technology that can be equipped with a plurality of inkjet nozzles and can manufacture a plurality of structures at once. Therefore, the productivity is not inferior to the conventional manufacturing method of cutting one by one.

  The fourth wheel 20 can be manufactured by press-fitting the rotary shaft body 11 into the shaft hole of the gear body 9 manufactured by pressing a metal material from the second hand pinion portion 9a side. At the time of press-fitting, the second hand pinion portion 9 a abuts against the flange 2 of the rotating shaft body 11, and the gear body 9 is positioned on the rotating shaft body 11.

  As described above, by adopting a hollow structure having the gap 15 in a part of the inside of the rotary shaft body 11, it is possible to reduce the weight while maintaining a sufficient strength. Moreover, since the rotating shaft body 11 is manufactured by the three-dimensional modeling method, waste of the processed material can be reduced as compared with the conventional cutting process, and the material usage rate can be improved. Furthermore, it is possible to improve the straightness even with respect to the shaft body having a longer and narrower shape than the conventional case in response to the multi-function of the timepiece and the diversification of the exterior design. As a result, it is possible to reduce the diameter of the watch and reduce power consumption.

[Second Embodiment: FIG. 3]
A second embodiment of the rotating shaft will be described in detail with reference to FIG.
FIG. 3 is a cross-sectional view showing a rotating shaft body constituting the timepiece gear structure according to the second embodiment. In FIG. 3, configurations not necessary for the description are omitted.

  As shown in FIG. 3, the rotating shaft body in the present embodiment has a configuration in which the rotating shaft body 21 and the second hand pinion portion 19 a are integrally formed and the second hand gear 19 b is fixed by the fitting portion 13.

  Since the rotating shaft body 21 in this embodiment is formed by the three-dimensional modeling method so that the rotating shaft body 21 and the second hand kana part 19a are integrated, waste of a processing material can be reduced. For this reason, it is possible to improve the manufacturing efficiency and reduce the manufacturing cost.

[Third Embodiment: FIG. 4]
A third embodiment of the rotating shaft will be described in detail with reference to FIG.
FIG. 4 is a cross-sectional view showing a rotating shaft body constituting the timepiece gear structure according to the third embodiment. In FIG. 4, configurations that are not necessary for the description are omitted.

  As shown in FIG. 4, the rotating shaft body in the present embodiment has a configuration in which a rotating shaft body 31, a second hand pinion 29a, and a second hand gear 29b are integrally formed.

  Since the rotating shaft body 31 in this embodiment is formed by the three-dimensional modeling method so that the rotating shaft body 31, the second hand pinion portion 29a, and the second hand gear 29b are integrated, waste of processing material can be reduced. For this reason, it is possible to improve the manufacturing efficiency and reduce the manufacturing cost. The second hand gear 29b is considerably larger than the diameter of the rotating shaft 31, but can be easily formed by a three-dimensional modeling method.

[Description of Hollow Structure of Rotating Shaft: FIGS. 5 and 1]
Next, an example of the hollow structure of the rotating shaft will be described mainly with reference to FIG. In the description, the first non-contact region 12 of the rotating shaft body of the first embodiment shown in FIG. 1 will be described as an example. FIG. 5A to FIG. 5D show cross-sectional views of the rotating shaft body 11 cut along the rotating shaft.

The example shown in FIG. 5A is an example of a hollow structure in which no beam is provided in the gap in the non-contact region.
As shown in the figure, the first non-contact region 12 is provided with only one gap 41 and has a hollow structure without a beam. This example is a configuration suitable for reducing the weight of the rotating shaft body 11.

  If the length of the first non-contact region 12 is long (large), considering the strength of the rotating shaft 11, a small number of one or two beams similar to those of the first embodiment are provided. Any configuration may be used.

The example shown in FIGS. 5B and 5C is an example in which a gap 42 having a square cross section is provided in the first non-contact region 12.
As shown in FIG. 5B, a hollow structure is formed in which a plurality of beams 27 are formed in the gap 42 with a predetermined interval in a direction parallel to the transverse cross-sectional direction m of the rotating shaft 11.
Further, as shown in FIG. 5 (c), a plurality of beams 37 a are formed in the gap 43 with a predetermined interval in a direction parallel to the transverse cross-sectional direction m of the rotating shaft 11, and the rotating shaft of the rotating shaft 11 is formed. (Axial direction) A beam 37b is formed also in a direction parallel to n to form a hollow structure having a lattice beam structure.

  Incidentally, the gap 42 and the gap 43 shown in FIGS. 5B and 5C may be configured to penetrate adjacent gaps in a region smaller than the gap. In that case, the cross-section of the void has a shape similar to the alphabet “H” shape. Even such a shape can be easily formed by using a three-dimensional modeling method.

FIG. 5D shows an example of a hollow structure in which a spherical gap is provided in the first non-contact region 12.
As shown in the drawing, a special beam is not formed in the first non-contact region 12, and a hollow structure is formed in which a plurality of spherical voids 44 are regularly or irregularly arranged. Also in this example, since the gap 44 has the same effect as the beam, the strength can be maintained.

  In addition, as another example of the hollow structure of the rotating shaft 11, the example provided in the first non-contact region 12 has been described, but may be applied to the second non-contact region 14. Of course, it may be applied to both the first non-contact region 12 and the second non-contact region 14. And you may apply the shape of a space | gap in both non-contact area | regions.

  The embodiment described above is not limited to the configuration described. For example, the example of the gap shown in FIG. 5 may be applied to the second embodiment shown in FIG. 3 and the third embodiment shown in FIG.

  Further, in the embodiment described above, an example in which no gap is provided inside the rotary shaft body in the portions of the steady rests 16a and 16b is shown, but of course, a gap may be provided in this portion. For example, when the rotating shaft body is not likely to cause rotational shake due to a light second hand or the like, even if the rotating shaft body and the minute hand cylinder are in contact with each other, it is mild, and there is a gap inside the steady rests 16a and 16b. Even if it provides, there is no problem in strength.

In the present embodiment, the structure that rotates the second hand for time display has been described as an example of the rotating shaft body that constitutes the timepiece gear structure. However, the present invention is not limited to this. It can be applied to a winding stem (also called a winding core, which is an operating shaft).
In the present embodiment, the example in which the cross-sectional shape of the rotating shaft body has a circular shape has been described. However, the present invention is not limited to this. For example, the cross-sectional shape is a triangular shape or a quadrangular prism shape. It can also be applied to a rotating shaft body.

  Furthermore, in this embodiment, although the example which provided the non-contact area | region in two places in the rotating shaft was demonstrated, it is not limited to this, For example, you may provide one place or three places or more.

  In addition, although the production of the rotating shaft has been exemplified by the three-dimensional modeling method represented by the rapid prototyping method, it can be molded by a method different from this modeling method. For example, in recent years, there has been a proposal of a near net shape molding method capable of forming a void inside a shaped article in powder metallurgy. Since such a modeling method is also considered to be a three-dimensional modeling method in a broad sense, the rotating shaft body may be formed using such a technique.

  According to the present invention, it is possible to provide a rotating shaft body that does not decrease in strength even if it is lightweight. A timepiece having a multi-function or elaborate exterior design tends to have a deep dial direction and a long rotating shaft, and is suitable for such a timepiece.

DESCRIPTION OF SYMBOLS 1, 11, 21, 31 Rotating shaft body 2 Flange 3 Gear fitting part 5 Second hand fitting part 6 Dial 8a Second hand 8b Minute hand 8c Hour hand 9a Second hand Kana part 9b Second gear part 9 Gear body 10, 20 4th wheel 12 12th 1 non-contact area 13 fitting part 14 second non-contact area 15, 41, 42, 43, 44 gap 16a, 16b steady rest 17a, 17b, 27, 37a, 37b beam 77 minute hand cylinder 78 hour hand cylinder

Claims (3)

In the rotating shaft body constituting the timepiece gear structure,
The rotating shaft body has a hollow structure inside the portion excluding at least a portion in contact with other components ,
Said hollow structure, the rotation shaft member, characterized in that it has a plurality of voids and a plurality of beams.   The rotary shaft body according to claim 1, wherein the rotary shaft body is integrally formed by a three-dimensional modeling method.   The rotating shaft body according to claim 1 or 2, wherein the rotating shaft body has a fitting portion for fitting a pointer for notifying time.

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