Band coupling structure and method of manufacturing piece member therefor

A coupling structure of a watch band in which a coupling member such as a coupling pin or a hair pin does not sup from a coupling hole even if a user practices strenuous sports or a rotation and a twist are always applied to the coupling portion due to use for years, and a method of manufacturing a piece member for the band coupling structure. In a coupling structure of a band comprising a plurality of piece members, a projection protruded in a central direction of a coupling hole from an internal wall of the coupling hole is formed on an outer end of the coupling hole in the piece member positioned on an outside in a transverse direction, and a coupling member is inserted in the coupling hole provided in the transverse direction of the piece member and is engaged with the projection, thereby coupling the piece members to each other.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a coupling structure of a band comprising a plurality of piece members such as a band of a wrist watch and to a method of manufacturing the piece member for the coupling structure.

2. Description of the Prior Art

A conventional watch band structure comprises a plurality of piece members that are coupled to each other in a longitudinal direction which can be bent freely in conformity with the shape of a user's arm (see Japanese Laid-Open Utility Model Publications Nos. Sho 50(1975)-50071 and Sho 51(1976)-121368).

In a coupling structure100of a watch band, for example, depicted inFIGS. 15 and 16, coupling holes108and110are formed on coupling ends104and104on the outside in a transverse direction which are formed on one of the ends of an almost U-shaped piece member102and a coupling projection106in a central part which is formed on the other end respectively. The coupling projection106of one of the piece members102is positioned between the coupling ends104and104of the other piece member102. Then, an adjust pin112energized in a diameter increasing direction, such as a hair pin is inserted as a coupling member in such a state that the coupling holes108and110of the coupling end104and the coupling projection106are coincident with each other. Thus, the piece members102are coupled to each other in the longitudinal direction in such a manner that the adjust pin112does not slip from the coupling holes108and110.

In the case in which the adjust pin energized in the diameter increasing direction, such as the hair pin is used as the coupling member, a coupling pin is removable and the length of a band can be adjusted. In the case in which the coupling pin is used, it is pressed into the coupling hole and is thus fixed unremovably.

In such a coupling structure, however, in the case in which a user practices strenuous sports or a rotation and a twist are always applied to the coupling portion due to use for years, for example, there is a possibility that the coupling member such as the coupling pin112might slip from the coupling holes108and110.

Depending on processing precision of the coupling holes108and110or processing precision of the coupling member such as the coupling pin112, moreover, there is a possibility that the coupling member such as the coupling pin112might slip from the coupling holes108and110.

Furthermore, there is a possibility that the coupling member itself, such as the coupling pin112, might corrode or might repetitively receive a stress to be broken or to lose elastic force thereof and might thus slip off.

In the case in which the coupling member is thus broken or slips off, the band slips from the user's arm, which is not preferable.

In consideration of the circumstances, it is an object of the present invention to provide a band coupling structure in which a coupling member such as a coupling pin or a hair pin does not slip from a coupling hole even if a user practices strenuous sports or a rotation and a twist are always applied to a coupling portion due to use for years, and to provide a method of manufacturing a piece member for the band coupling structure therefor.

Moreover, it is another object of the present invention to provide a band coupling structure in which a spew or the like is not generated around the coupling hole of a piece member and a finished face such as a mirror finished surface, a hairline, a matte finished surface or a concavo-convex pattern is applied thereto, and external quality is enhanced and a high-class impression is given, and to provide a method of manufacturing the piece member for the band coupling structure therefor.

SUMMARY OF THE INVENTION

The present invention has been made in order to solve the problems and to achieve the objects in the prior art described above, and provides a coupling structure of a band comprising a plurality of piece members,

wherein a projection protruded in a central direction of a coupling hole from an internal wall of the coupling hole is formed on an outer end of the coupling hole in the piece member positioned on an outside in a transverse direction, and

a coupling member is inserted in the coupling hole provided in the transverse direction of the piece member and is engaged with the projection, thereby coupling the piece members to each other.

Moreover, the present invention provides a method of manufacturing a piece member to be used for a coupling structure of a band comprising a plurality of piece members,

wherein a punch member is pressed against an outer end of a coupling hole in the piece member positioned on an outside in a transverse direction, thereby forming a projection protruded in a central direction of the coupling hole from an internal wall of the coupling hole.

With such a structure, the projection protruded in the central direction of the coupling hole from the internal wall of the coupling hole is formed on the outer end of the coupling hole of the piece member which is positioned on the outside in the transverse direction. When the coupling member is inserted and attached into the coupling hole, therefore, the coupling member is engaged with the projection. Consequently, it is possible to reliably prevent the coupling member from slipping out of the coupling hole. In addition, a spew generated by forming the coupling hole is absorbed by the formation of the projection. Consequently, external quality can be enhanced.

In the present invention, moreover, a projection protruded in the central direction of the coupling hole from the internal wall of the coupling hole may be formed on an inner end of the coupling hole in the piece member positioned on the outside in the transverse direction.

With such a structure, the coupling member is also engaged with the projection formed on the inner end of the coupling hole in the piece member which is positioned on the outside in the transverse direction. Consequently, it is possible to more reliably prevent the coupling member from slipping out of the coupling hole. In addition, a spew generated by forming the coupling hole is absorbed by the formation of the projection. Therefore, the movements of the piece members in the coupling portion are not inhibited.

In the present invention, furthermore, the projection protruded in the central direction of the coupling hole from the internal wall of the coupling hole may be formed on an outer end of the coupling hole in the piece member positioned on an inside in the transverse direction.

With such a structure, the coupling member is also engaged with the projection formed on the outer end of the coupling hole in the piece member which is positioned on the inside in the transverse direction. Consequently, it is possible to more reliably prevent the coupling member from slipping out of the coupling hole. In addition, a spew generated by forming the coupling hole is absorbed by the formation of the projection. Therefore, the movements of the piece members in the coupling portion are not inhibited.

In this case, it is possible to provide both the projection formed on the inner end of the coupling hole in the piece member which is positioned on the outside in the transverse direction and the projection formed on the outer end of the coupling hole in the piece member which is positioned on the inside in the transverse direction. Consequently, it is possible to more enhance the effect of preventing the coupling member from slipping off.

In the present invention, moreover, the projection may be formed over a whole periphery of the internal wall of the coupling hole or may be partially formed on the internal wall of the coupling hole. In the case in which the projection is formed over the whole periphery of the internal wall of the coupling hole, the coupling member can sufficiently resist the force for slipping outward from the coupling hole and the coupling member can be reliably prevented from slipping out of the coupling hole.

In the present invention, furthermore, the projection may be formed on the outer ends at both sides of the coupling hole or may be formed on the outer end at either side of the coupling hole. In the case in which the projection is formed on the outer end at either side of the coupling hole, it can correspond to the case in which the coupling hole is a so-called blind hole.

Moreover, the band coupling structure according to the present invention is characterized in that the projection has an outside wall surface formed to have a taper surface inclined toward an inner central part of the coupling hole.

Furthermore, the method of manufacturing a piece member according to the present invention is characterized in that a tip portion of the punch member is cone-shaped so that the projection has an outside wall surface formed to have a taper surface inclined toward an inner central part of the coupling hole.

Thus, the projection has an outside wall surface formed to have the taper surface inclined toward the inner central part of the coupling hole. Therefore, the coupling member can sufficiently resist the force for slipping outward from the coupling hole, and furthermore, the inclined taper surface is chamfered so that the external quality can be enhanced decoratively.

Furthermore, the band coupling structure is characterized in that the projection has an outside wall surface formed to take a curved shape.

The method of manufacturing a piece member according to the present invention is characterized in that a tip portion of the punch member is cone-shaped so that the projection has an outside wall surface formed to take a curved shape.

With such a structure, the projection has an outside wall surface formed to take a curved shape. Therefore, the coupling member can sufficiently resist the force for slipping outward from the coupling hole, and furthermore, the outside wall surface of the projection formed to take the curved shape is finely chamfered so that the external quality can be enhanced decoratively.

Moreover, the band coupling structure according to the present invention is characterized in that the projection has an outside wall surface formed to be perpendicular to the coupling hole.

The method of manufacturing a piece member according to the present invention is characterized in that a tip portion of the punch member includes a fitting portion for fitting in the coupling hole and a flat portion therearound so that the projection has an outside wall surface formed to be perpendicular to the coupling hole.

Thus, the projection has an outside wall surface formed to be perpendicular to the coupling hole. Consequently, the coupling member can sufficiently resist the force for slipping outward from the coupling hole, and furthermore, the outside wall surface of the projection which is formed flatly is finely chamfered so that the external quality can be enhanced decoratively.

In the present invention, moreover, a crossing angle α formed by the taper surface of the projection is set to range from 90° to 130°, is preferably at least one selected from 90°, 100°, 110°, 120° and 130°, and is more preferably set to 110°.

More specifically, if the crossing angle α formed by the taper surface of the projection is smaller than 90°, the projection is not formed on the internal wall of the coupling hole and the coupling member might slip off, and furthermore, a bulged portion is formed on the outside in the transverse direction of the coupling hole, resulting in a deterioration in the external quality.

To the contrary, if the crossing angle α formed by the taper surface of the projection is greater than 130°, very great force is required for forming the projection so that a workability is deteriorated and the size of a processing apparatus is increased. In addition, it is hard to carry out a centering work for causing the center of a punch member to be coincident with the center of the coupling hole. Consequently, the projection is not uniformly formed around the internal wall of the coupling hole so that the coupling member might slip off and the external quality is deteriorated.

In the present invention, moreover, it is preferable that the projection should be formed by pressing a punch member against the outer end of the coupling hole positioned on the outside in the transverse direction of the piece member by force having an impact load of 5 kgf to 14 kgf. Preferably, the punch member is pressed by at least one force having an impact load selected from 5 kgf, 6 kgf, 7 kgf, 8 kgf, 9 kgf, 10 kgf, 11 kgf, 12 kgf, 13 kgf and 14 kgf, and more preferably, the punch member is pressed by force having an impact load of approximately 8 kgf.

More specifically, if the pressing force of the punch member has a smaller impact load than 5 kgf, it is too small so that the projection is not formed on the internal wall of the coupling hole and the coupling member might slip off. To the contrary, if the pressing force of the punch member has a greater impact load than 14 kgf, the area of the outside wall portion of the projection is increased so that the external quality is deteriorated, and furthermore, a workability becomes poor and the size of a processing apparatus is increased.

Moreover, the present invention is characterized in that the projection is formed by pressing a punch member against the outer end of the coupling hole positioned on the outside in the transverse direction of the piece member by force having an impact load of approximately 8 kgf at a crossing angle α formed by the taper surface of the projection of approximately 110°.

Thus, the coupling member can sufficiently resist the force for slipping outward from the coupling hole, and the taper surface is finely chamfered and the external quality can be greatly enhanced decoratively.

Furthermore, the present invention is characterized in that a surface of a tip portion of the punch member has at least one finished face selected from a mirror finished surface, a hairline, a matte finished surface and a concavo-convex pattern, and the finished face of the surface of the tip portion of the punch member is thereby transferred onto the outside wall surface of the projection so that the outside wall surface of the projection has at least one finished face selected from the mirror finished surface, the hairline, the matte finished surface and the concavo-convex pattern.

Thus, the surface of the tip portion of the punch member has at least one finished face selected from the mirror finished surface, the hairline, the matte finished surface and the concavo-convex pattern. Such a punch member is simply pressed against the outer end of the coupling hole so that the finished face of the surface of the tip portion of the punch member can easily be transferred onto the outside wall surface of the projection. Accordingly, the outside wall surface of the projection can be formed to have at least one finished face selected from the mirror finished surface, the hairline, the matte finished surface and the concavo-convex pattern. Therefore, the taper surface can be finely chamfered. Thus, it is possible to provide a coupling structure of a band in which external quality can be enhanced decoratively and a high-class impression can be given.

In the band coupling structure according to the present invention, moreover, the coupling member is a coupling pin or an adjust pin.

In this case, it is preferable that the coupling pin should be at least one selected from a press-in pin, a hair pin and a pin and split pipe.

Furthermore, it is preferable that the adjust pin should be at least one selected from a hair pin and a pin and split pipe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment (example) of the present invention will be described below with reference to the drawings.

FIG. 1is a sectional view showing a band coupling portion according to a first embodiment of a band coupling structure in accordance with the present invention,FIG. 2is a partially enlarged view ofFIG. 1,FIG. 3is an end view in a direction of A inFIG. 2,FIG. 4is a further enlarged sectional view ofFIG. 2,FIG. 5is a schematic view for explaining the function of the band coupling structure according to the present invention illustrated inFIG. 1, andFIG. 6is a schematic view for explaining a method of manufacturing a piece member of the band coupling structure according to the present invention illustrated in FIG.1.

As shown inFIG. 1, a band coupling structure10according to the present invention is constituted by rotatably coupling almost U-shaped piece members12to each other.

The piece member12comprises coupling ends14and14on the outside in a transverse direction which are formed to be protruded from one of ends, and a coupling projection16in a central part which is formed to be protruded from the other end. The coupling end14and the coupling projection16are provided with coupling holes18and20, respectively.

The coupling projection16of one of the piece members12is positioned between the coupling ends14and14of the other piece member12, and an adjust pin22energized in a diameter increasing direction, for example, a hair pin is inserted as a coupling member in such a state that the coupling holes18and20of the coupling end14and the coupling projection16are coincident with each other. Thus, the piece members12are coupled to each other in a longitudinal direction such that the adjust pin22does not slip from the coupling holes18and20.

In this case, in the band coupling structure10according to the present invention as shown inFIGS. 2 and 4, in order to prevent the adjust pin22to be the coupling member from slipping out of the coupling holes18and20, for example, when a user practices strenuous sports or a rotation and a twist are always applied due to use for years, a projection26protruded in the central direction of the coupling hole18from an internal wall24of the coupling hole18is formed. This projection is formed on the outer end of the coupling hole18in the piece member12positioned on the outside in a transverse direction.

Consequently, the adjust pin22to be the coupling member is inserted in the coupling hole18provided in the transverse direction of the piece member12and is thus engaged with the projection26, so that the piece members12are rotatably coupled to each other.

By such a structure, when the adjust pin22to be the coupling member is inserted and attached into the coupling hole18as shown inFIG. 5, a bulged portion22aof the adjust pin22abuts on the projection26so that the adjust pin22is engaged with the projection26, for example. Therefore, the adjust pin22can be reliably prevented from slipping out of the coupling hole18. In addition, a spew generated by forming the coupling hole18is absorbed by the formation of the projection26. Consequently, external quality can be enhanced.

In this case, the projection26has an outside wall surface28formed to be a taper surface30which is included toward the inner central part of the coupling hole18as shown in FIG.4. Thus, the projection26has the outside wall surface28formed to be the taper surface30which is inclined toward the inner central part of the coupling hole18. Therefore, the adjust pin22to be the coupling member can sufficiently resist the force for slipping outward from the coupling hole18, and furthermore, the tapered surface30which is inclined is chamfered so that the external quality can be enhanced decoratively.

Moreover, a crossing angle α formed by the taper surface30of the projection26is set to range from 90° to 130°, is preferably at least one selected from 90°, 100°, 110°, 120° and 130°, and is more preferably approximately 110°.

More specifically, if the crossing angle α formed by the taper surface30of the projection26is smaller than 90°, the projection26is not formed on the internal wall24of the coupling hole18and the adjust pin22to be the coupling member might slip off, and furthermore, a bulged portion32is formed on the outside in the transverse direction of the coupling hole18as shown in FIG.7(A), resulting in a deterioration in the external quality.

To the contrary, if the crossing angle α formed by the taper surface30of the projection26is greater than 130°, very great force is required for forming the projection26so that a workability is deteriorated and the size of a processing apparatus is increased. In addition, it is hard to carry out a centering work for causing the center of a punch member to be coincident with the center of the coupling hole18. Consequently, the projection26is not uniformly formed around the internal wall24of the coupling hole18so that the adjust pin22to be the coupling member might slip off and the external quality is deteriorated.

In order to form the projection26as shown inFIG. 6, it is preferable that a punch member40which is constituted to be perpendicularly movable by a driving mechanism (not shown), should be pressed against the outer end of the coupling hole18of the piece member12positioned on the outside in the transverse direction. As a result, the projection26protruded in the central direction of the coupling hole18from the internal wall24of the coupling hole18can be formed.

Moreover, the projection26may be formed after the piece member12is assembled by the coupling member or when the piece member12itself is to be fabricated.

In this case, the surface of a tip portion42of the punch member40is cone-shaped. It is preferable that an angle β formed by a cone-shaped slant surface44should correspond to the crossing angle α formed by the taper surface30of the projection26provided by pressing the tip portion42of the punch member40. More specifically, the angle β formed by the cone-shaped slant surface44ranges from 90° to 130°, is preferably at least one selected from 90°, 100°, 110°, 120° and 130°, and is more preferably approximately 110°.

For the pressing force to press the punch member40against the outer end of the coupling hole18of the piece member12positioned on the outside in the transverse direction, moreover, pressing is carried out by force having an impact load ranging from 5 kgf to 14 kgf, preferably at least one force having an impact load selected from 5 kgf, 6 kgf, 7 kgf, 8 kgf, 9 kgf, 10 kgf, 11 kgf, 12 kgf, 13 kgf and 14 kgf, and more preferably force having an impact load of approximately 8 kgf.

More specifically, if the pressing force of the punch member40has a smaller impact load than 5 kgf, it is too small so that the projection26is not formed on the internal wall24of the coupling hole18and the coupling member might slip off. To the contrary, if the pressing force of the punch member40has a greater impact load than 14 kgf, the area of the outside wall portion of the projection26is increased so that the external quality is deteriorated, and furthermore, a workability becomes poor and the size of a processing apparatus is increased.

In this case, a punch apparatus comprising the punch member40is not particularly restricted but a well-known punch apparatus can be employed.

In other words, the punch apparatus comprising the punch member40serves to carry out pressing at a static load or pressing at an impact load, which is not particularly restricted. For example, it is possible to employ an autopunch for carrying out pressing at an impact load.

Moreover, the pressing force applied at the impact load is approximately 20 times as much as the pressing force applied at the static load based on a conversion. For example, if the autopunch is used and the impact load is 5 kgf, a static load of approximately 100 kgf is obtained based on the conversion.

Accordingly, it is suitable that the punch member40should be pressed against the outer end of the coupling hole18of the piece member12positioned on the outside in the transverse direction by force having an impact load of approximately 8 kgf at a crossing angle α of approximately 110° which is formed by the taper surface30of the projection26. Thus, the coupling member can sufficiently resist the force for slipping outward from the coupling hole, and the taper surface30is finely chamfered and the external quality can also be greatly enhanced decoratively.

As shown inFIG. 4, moreover, a projection distance L of the projection26is 10 μm to 100 μm, preferably 30 μm to 70 μm, and more preferably 40 μm to 50 μm depending on the diameter of the coupling hole18. If the projection distance L is smaller than 10 μm, the coupling pin or the adjust pin22to be the coupling member cannot be engaged so that the coupling member might slip from the coupling hole18. To the contrary, if the projection distance L is greater than 100 μm, it is hard to carry out a work for removing the coupling member from the coupling hole18in the case of the adjust pin22.

Furthermore, the projection26may be formed over the whole periphery of the internal wall24of the coupling hole18as shown inFIG. 3or may be partially formed over the internal wall24of the coupling hole18as shown in FIG.7(B). In the case in which the projection26is formed over the whole periphery of the internal wall of the coupling hole, the coupling member can sufficiently resist the force for slipping outward from the coupling hole and the coupling member can be reliably prevented from slipping out of the coupling hole.

Moreover, the projection26may be formed on the outer ends at both sides of the coupling hole18or may be formed on the outer end at either side of the coupling hole18. The projection26formed on the outer end at either side of the coupling hole18can correspond to the case in which the coupling hole18is a so-called blind hole. The coupling hole of a watch band has a general diameter of 800 μmφ to 1300 μmφ every 100 μm.

Furthermore, the surface of the tip portion42of the punch member40may have at least one finished face selected from a mirror finished surface, a hairline, a matte finished surface (honing) and a concavo-convex pattern. Consequently, the finished face of the surface of the tip portion42of the punch member40is transferred onto the outside wall surface28of the projection26so that the outside wall surface28of the projection26has at least one finished face selected from the mirror finished surface, the hairline, the matte finished surface (honing) and the concavo-convex pattern.

Thus, the punch member40including the surface of the tip portion42having at least one finished face selected from the mirror finished surface, the hairline, the matte finished surface and the concavo-convex pattern is simply pressed against the outer end of the coupling hole18, so that the finished face of the surface of the tip portion42of the punch member40can be easily transferred onto the outside wall surface28of the projection26.

Accordingly, the outside wall surface28of the projection26can be formed to have at least one finished face selected from the mirror finished surface, the hairline, the matte finished surface (honing) and the concave-convex pattern. Consequently, it is possible to provide a band coupling structure in which the taper surface30is finely chamfered, external quality is decoratively enhanced and a high-class impression is given.

A processing method of finishing the surface of the tip portion42of the punch member40to have the mirror finished surface, the hairline, the matte finished surface (honing) or the concavo-convex pattern is not particularly restricted but a well-known processing method can be employed, for example, brushing is carried out for the hairline.

While the adjust pin22energized in the diameter increasing direction, such as a hair pin is used as the coupling member in the present embodiment, the adjust pin22can further be constituted by a pin50and a split pipe52as shown in FIG.8and can also have such a structure that the split pipe52is previously attached to the coupling hole20of the coupling projection16in the central part of the piece member12and the pin50is attached and fixed into the split pipe52.

In the case in which the adjust pin is thus used for the coupling member, the coupling pin is removable and the length of the band can be adjusted.

Furthermore, a coupling pin to be pressed into a coupling hole and fixed unremovably may be used for the coupling member. It is preferable that such a coupling pin should be at least one selected from a press-in pin, a hair pin, and a pin and split pipe.

FIG. 9is a sectional view showing a band coupling portion according to a second embodiment of the band coupling structure in accordance with the present invention, andFIGS. 10 and 11are schematic views for explaining a method of manufacturing a piece member thereof.

Since the band coupling structure according to the present embodiment is basically the same as the band coupling structure according to the first embodiment described above, the same components have the same reference numerals and detailed description thereof will be omitted.

In a band coupling structure10according to the embodiment, an outside wall surface28of a projection26for preventing an adjust pin22to be a coupling member from slipping out of coupling holes18and20is formed to take a curved shape30a. In this case, the curved shape is not particularly restricted but various shapes such as a circular arc, an elliptic arc, a parabola and a hyperbola can be employed.

With such a structure, the projection26has the outside wall surface28formed to take the curved shape30a. Therefore, the coupling member such as the adjust pin22can sufficiently resist the force for slipping outward from the coupling hole18, and the outside wall surface28of the projection26which is formed to take the curved shape30ais finely chamfered so that external quality is enhanced decoratively.

As a method of forming the outside wall surface28of the projection26to take the curved shape30a, the surface of a tip portion42of a punch member40preferably takes a curved shape42aas shown inFIG. 10or a ball portion42bis preferably provided in the tip portion42of the punch member40as shown in FIG.11.

FIG. 12is a sectional view showing a band coupling portion according to a third embodiment of the band coupling structure in accordance with the present invention, andFIG. 13is a schematic view for explaining a method of manufacturing a piece member thereof.

Since the band coupling structure according to the present embodiment is basically the same as the band coupling structure according to the first embodiment described above, the same components have the same reference numerals and detailed description thereof will be omitted.

In a band coupling structure10according to the present embodiment, an outside wall surface28of a projection26for preventing an adjust pin22to be a coupling member from slipping out of coupling holes18and20is formed to have a perpendicular portion30bto the coupling hole18.

With such a structure, the projection26is formed such that the outside wall surface28has a perpendicular portion26bto the coupling hole18. Therefore, the coupling member such as the adjust pin22can sufficiently resist the force for slipping outward from the coupling hole18. Furthermore, the outside wall surface28of the projection26formed to have a flat portion30bis finely chamfered so that external quality is enhanced decoratively.

As a method of forming the outside wall surface28of the projection26to have the perpendicular portion30bto the coupling hole18, it is preferable that a tip portion42of a punch member40should be provided with a fitting portion42cfor fitting in the coupling hole18and a flat portion42dtherearound as shown in FIG.13. It is preferable that the outside diameter of the fitting portion42cshould be set in consideration of the inside diameter of the coupling hole18according to the projection distance L of the projection26described above.

FIG. 14is a sectional view showing a band coupling portion according to another embodiment of the band coupling structure in accordance with the present invention.

Since the band coupling structure according to the present embodiment is basically the same as the band coupling structure according to the first embodiment described above, the same components have the same reference numerals and detailed description thereof will be omitted.

In a band coupling structure10according to the present embodiment, a projection26is provided on the outer end of a coupling hole18in a piece member which is positioned on the outside in a transverse direction in order to prevent an adjust pin22to be a coupling member from slipping out of coupling holes18and20. Furthermore, a projection26′ protruded in the central direction of the coupling hole from the internal wall of the coupling hole18is formed on the inner end of the coupling hole18in a piece member12which is positioned on the outside in the transverse direction.

With such a structure, the coupling member is also engaged with the projection26′ formed on the inner end of the coupling hole18in the piece member12which is positioned on the outside in the transverse direction. Consequently, it is possible to more reliably prevent the coupling member from slipping out of the coupling holes18and20. In addition, a spew generated by forming the coupling hole is absorbed by the formation of the projection26′. Therefore, the movements of the piece members in the coupling portion are not inhibited.

In the present embodiment, moreover, a projection26″ protruded in the central direction of the coupling hole from the internal wall of the coupling hole20is formed on the outer end of the coupling hole20in the piece member12which is positioned on the inside in the transverse direction.

With such a structure, the coupling member is also engaged with the projection26″ formed on the outer end of the coupling hole20in the piece member12which is positioned on the inside in the transverse direction. Consequently, it is possible to more reliably prevent the coupling member from slipping out of the coupling holes18and20. In addition, a spew generated by forming the coupling hole is absorbed by the formation of the projection26″. Therefore, the movements of the piece members in the coupling portion are not inhibited.

In this case, it is possible to provide both the projection26′ formed on the inner end of the coupling hole18in the piece member12which is positioned on the outside in the transverse direction and the projection26″ formed on the outer end of the coupling hole20in the piece member12which is positioned on the inside in the transverse direction or to provide one of them. Consequently, it is possible to more enhance the effect of preventing the coupling member from slipping off.

While the preferred embodiments of the present invention have been described above, the present invention is not restricted thereto. For example, while the band coupling structure according to the present invention has been applied to the band coupling structure of a watch in the embodiments described above, the band coupling structure can be used for the coupling structures of various bands such as a belt for a bag and a belt for trousers, and various changes can be thus made without departing from the scope of the present invention.

As shown inFIG. 6, the punch member40was pressed against the outer end of the coupling hole18positioned on the outside in the transverse direction of the piece member12by means of a punch device using a (Ti based) piece member formed of titanium (the coupling hole18having a diameter of 990 μmφ). As a result, the projection26protruded in the central direction of the coupling hole18from the internal wall24of the coupling hole18was formed.

The pressing was carried out by the pressing force of the punch member40having an impact load of 14 kgf, and the angle β formed by the slant surface44of the tip portion42of the punch member40was changed to 70°, 90°, 100°, 110°, 120°, 130° and 140°. Then, the hole diameter of the coupling hole18was measured after processing. A result is shown in the following Table 1.

As is apparent from the result of the Table 1, if the angle β formed by the cone-shaped slant surface44is 90° to 130°, the hole diameter is decreased by 17 to 20%. The projection26was formed well, particularly at 110°.

In the same manner as in the example 1, the projection26was formed. The angle β formed by the slant surface44of the tip portion42of the punch member40was set to 110° and a (SUS 304 based or 316 based) piece member formed of stainless (the coupling hole18having a diameter of 990 μmφ) was used in place of the (Ti based) piece member (the coupling hole18having a diameter of 990 μmφ) formed of titanium. Moreover, the pressing force of the punch member40was changed to have an impact load of 4 kgf, 5 kgf, 6 kgf, 7 kgf, 8 kgf, 9 kgf, 10 kgf, 11 kgf, 12 kgf, 13 kgf, 14 kgf and 15 kgf.

The hole diameter of the coupling hole18after the processing and the projection distance L were measured. A result is shown in the following Table 2.

As is apparent from the result of the Table 2, the pressing was carried out by the processing force of the punch member40having an impact load of 5 kgf to 14 kgf. Consequently, the projection26was formed well, particularly at an impact load of 8 kgf. There was no influence by the quality of the material of the piece member.

While the pressing force of the punch member40is indicated as the impact load in the Table 2, the pressing force indicated as the impact load is approximately 20 times as much as a static load based on a conversion. For example, in the case in which an autopunch is used and an impact load is set to 5 kgf, a static load of approximately 100 kgf was obtained based on the conversion.

A hair pin was inserted as a coupling member in the piece member and a band coupling structure was thus assembled, and the projection26was then formed in the same manner as in the example 1. The angle β formed by the slant surface44of the tip portion42of the punch member40was set to 110° and the pressing force of the punch member40was set to have an impact load of 8 kgf.

After the processing, antislipping force was measured. As a comparison, an antislipping force test was also executed for a band coupling structure assembled by using an unprocessed piece member. A result is shown in the following Table 3.

As is apparent from the result of the Table 3, the piece member fabricated according to the present invention had considerably great antislipping force and a more excellent effect of preventing the coupling member from slipping off as compared with the conventional unprocessed piece member.

TABLE 3Antislipping force mean value (kg/cm2)βPrior artInvention110°3.047.89

According to the present invention, the projection protruded in the central direction of the coupling hole from the internal wall of the coupling hole is formed on the outer end of the coupling hole of the piece member positioned on the outside in the transverse direction. Therefore, when the coupling member is inserted and attached into the coupling hole, the coupling member is engaged with the projection. Consequently, it is possible to reliably prevent the coupling member from slipping out of the coupling hole. In addition, a spew generated by forming the coupling hole is absorbed by the formation of the projection. Consequently, external quality can be enhanced.

In the present invention, moreover, the projection has an outside wall surface formed to have the taper surface inclined toward the inner central part of the coupling hole. Therefore, the coupling member can sufficiently resist the force for slipping outward from the coupling hole, and furthermore, the inclined taper surface is chamfered so that the external quality can be enhanced decoratively.

Furthermore, in the present invention, the projection has an outside wall surface formed to take a curved shape. Therefore, the coupling member can sufficiently resist the force for slipping outward from the coupling hole, and furthermore, the outside wall surface of the projection formed to take the curved shape is finely chamfered so that the external quality can be enhanced decoratively.

Moreover, in the present invention, the projection has an outside wall surface formed to be perpendicular to the coupling hole. Consequently, the coupling member can sufficiently resist the force for slipping outward from the coupling hole, and furthermore, the outside wall surface of the projection which is formed flatly is finely chamfered so that the external quality can be enhanced decoratively.

Furthermore, in the present invention, the surface of the tip portion of the punch member has at least one finished face selected from a mirror finished surface, a hairline, a matte finished surface and a concavo-convex pattern. Such a punch member is simply pressed against the outer end of the coupling hole so that the finished face of the surface of the tip portion of the punch member can easily be transferred onto the outside wall surface of the projection.

Accordingly, the outside wall surface of the projection can be formed to have at least one finished face selected from the mirror finished surface, the hairline, the matte finished surface and the concavo-convex pattern. Therefore, the taper surface can be finely chamfered. Thus, it is possible to provide a band coupling structure in which external quality can be enhanced decoratively and a high-class impression can be given Thus, the invention is very excellent because many functions and effects can be produced.