GB2113975A

GB2113975A - Watch band

Info

Publication number: GB2113975A
Application number: GB08302551A
Authority: GB
Inventors: Tsunetoshi Sekiguchi; Toshio Murata; Kouichi Nakajima; Yoshihiro Itou
Original assignee: Citizen Watch Co Ltd
Current assignee: Citizen Watch Co Ltd
Priority date: 1982-01-29
Filing date: 1983-01-31
Publication date: 1983-08-17
Also published as: GB8302551D0; HK15586A; DE3302789A1; GB2113975B; DE3302789C2

Abstract

This invention relates to a watch band and a method of manufacture thereof. In one aspect of the invention there is provided a watch band comprising a band body 12 composed of a flexible material and a resin net 14 composed of a synthetic resin. The flexible material is capable of being injection molded. The resin net 14 is inserted and affixed in the interior of the band body 12, when the band body 12 is formed. In a further aspect of the invention, there is provided a method of forming a watch band 12 comprising the steps of closing upper and lower molds to clamp a resin net 14 in such a manner as to form a rugged form, and injection molding a flexible material between the upper and lower molds to form a band body 12. <IMAGE>

Description

SPECIFICATION Watch band This invention relates to a watch band, containing a reinforcing net, which can be used under harsh conditions experienced in diving, skiing, mountain climbing, etc, and to a method of forming the band.

Conventional watch bands are broadly classified into metal bands and leather bands.

Metal bands have excellent durability but do not fit well to one's wrist. The metal bands are also high in price because of numerous manufacturing steps and need to use materials which exhibit excellent corrosion resistance.

Leather bands, on the other hand, fit to one's wrist better than metal bands and are comparatively simple to manufacture. However, they have poor durability, therefore, they are apt to tear after years of use. Further, since they cannot be used in water, they are not suitable for use as watches for divers.

Recently, watch bands made of synthetic resin elastomers or rubber have come into use in place of these conventional watch bands. Watch bands comprising a synthetic resin elastomer or the like fit better to one's wrist and are superior to leather bands in terms of water resistance. Such bands therefore have been widely used in, for example, underwater applications and make it possible to provide new designs. For these reasons, such watch bands are becoming more widespread.

Nevertheless, with long use, even watch bands consisting of a synthetic resin develop cracks around the locking holes in which the locking element of a clasp is inserted, and at portions of the band that tend to strike hard objects. In particular, when a band of this type is attached to a diver's watch, the band is inevitably used in undersea applications and under other harsh conditions and therefore sustains damage quite early, with the danger that flaws and cracks will spread and cause the band to break. If the band should break in this manner underwater, the watch may fall off the diver's wrist. If this occurs, the diver will be unable to confirm the elapsed diving time and to estimate the amount of air remaining in his tank. Another hazard resulting from the inability to check elapsed diving time is that the diver's life may be threatened by diving sickness.

In accordance with the present invention there is provided a watch band comprising: a band body comprising a flexible material capable of being injection molded; and a resin net comprising a synthetic resin and inserted and affixed in the interior of the band body.

The present invention also provides a method of forming a watch band, comprising the steps of: closing an upper mold having a plurality of pressing pins and a lower mold having a plurality of pressing pins to clamp a resin net by the pressing pins of the upper and lower mold in such a manner as to form a rugged form; and injection molding a flexible material between the upper and lower molds to form a band body.

Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: Fig. 1 is a plan view illustrating a watch band according to .he prior art; Fig. 2 is a plan view, partially cut away, illustrating a watch band according to the first embodiment of the present invention; Fig. 3 is a sectional view taken on the line Ill-Ill of Fig. 2; Fig. 4 is a plan view of a resin net used in the band shown in Figs. 2 and 3; Fig. 5 is a plan view, partially cut away, illustrating a modification of the watch band shown in Figs. 2 and 3; Fig. 6 is a sectional view taken on the line VI-VI of Fig. 5; Fig. 7 is a plan view illustrating a watch band according to the second embodiment of the present invention:: Fig. 8 is a plan view illustrating a resin net used in the watch band of Fig. 7; Fig. 9 is a sectional view of the watch band shown in Fig. 7, taken on the line IX-IX; Fig. 10 is a sectional view showing conditions when the watch band of Fig. 7 is formed; and Fig. 11 is an enlarged view of a principal portion shown in Fig. 10.

Fig. 1 shows a conventional watch band 10 made of a synthetic resin elastomer. This conventional watch band 10 has a number of locking holes 1 Oa into which the locking member of a clasp is inserted when the band 10 is affixed to the wrist. Since the locking hole 1 Oa is constantly acted by a force applied by the locking member, a crack 1 Ob forms around the locking hole 1 Oa when the band 10 is worn for an increasing number of years. In addition, the sides 1 Oc of the band 10 become flawed because the band 10 is often twisted and struck against hard objects.

In particular, in watches for divers, flexible bands made of synthetic resins or the like are often employed. These watches are used under harsh conditions or underseas, therefore, the band 10 sustains damage quite early. If the band continues to be used in such conditions the crack 1 Ob may spread and cause the band to break to pieces.

Figs. 2 and 3 show the first embodiment of the present invention, in which Fig. 2 is a plan view, partially cut away, and Fig. 3 is a sectional view of Fig. 2 taken on the line Ill-Ill. The watch band of this embodiment comprises a band body 12 and a resin net 14. The band body 12 is made of a flexible material consisting of a synthetic resin such as a polyurethane or vinylchloride, and is formed by injection molding. The band body 12 has locking holes 1 2a into which the locking member of a clasp provided at the other band (not shown) is inserted when the band body 12 is affixed to one's wrist. The resin net 14 is insert molded in the band body 12 and at the portion peripheral to the locking holes 12a of the band body 12.

Fig. 4 is a plan view illustrating the resin net 14 shown in Figs. 2 and 3. In Fig. 4, lines 14a of the resin net 14 are formed crosswise, and each of the lines 14a is aligned in the longitudinal direction of the band body 12 and at right angles thereto. The width of the resin net 14 is less than that of the band body 12, and the net 14 is subjected to trimming work so as not to protrude from the outside of the band body 12.

The resin net 14 includes holes 14b provided at the portion corresponding to the locking holes 12a of the band body 12. Each of the holes 14b has the diameter that is equal to or slightly larger than that of the locking hole 12a. Alternatively, instead of providing the hole 14b from the begining, the hole 14b can be formed in the net by fusing the net 14 by means of a heated rod after the insert molding step. As for the material used to fabricate the net 14, it has been confirmed by experiment that a mesh size of 20 mesh is preferred in view of a favorable insert molding property.

Figs. 5 and 6 show a modification of the watch band shown in Figs. 2 and 3, in which Fig. 5 is a plan view, partially cut away, and Fig. 6 is a sectional view of Fig. 5 taken on the line VI-VI.

Like elements corresponding to those of Figs, 2 and 3 are indicated by like numerals. In Fig. 5, the alignment of the lines of the resin net 14 are inclined at an angle of 450 with respect to the band body 12. This improves the stretching and contraction of the resin net 14 or the band body 12.

As described hereinabove, in the embodiment and the modification, the net made of resin is inserted and affixed in the interior of the band body comprising a synthetic resin elastomer, rubber or the like. With the passage of time, therefore, cracks little form about the locking holes and at the sides of the band body.

Fig. 7 is a plan view illustrating the second embodiment of a watch band according to the present invention. The watch band of this embodiment comprises a band body 16 and a resin net 18. The band body 16 comprises a flexible material capable of being injection molded, such as polyurethane, vinyl chloride or other synthetic resins, rubber and the like. The resin net 18 comprises, e.g. nylon, teflon or viiiylon. The band body 16, which is one of a pair or bands forming a single watch band, has locking holes 16a into which the locking member of a clasp provided at the other band is inserted.The band body 16 is provided with side holes 16b arrayed longitudinally of the band body 16 in the same manner as the locking holes 1 6a. The side holes 16b are necessary when inserting and affixing the resin net 18 within the band body 16, as will be described in further detail below. The resin net 18 is insert molded at the portion peripheral to the locking holes 16a. In the present embodiment, the resin net 18 has holes only at positions corresponding to the locking holes 16a and side holes 16b.

An accordion portion 1 6c is provided, when required, at the left end of the band body 1 6 as shown in Fig. 7 for the purpose of assisting the mechanical stretching and bending of the band body 16. The resin net 18 is made by knitting a fine resin thread into a mesh-like pattern which is formed into required shape and incorporated in the interior of the band 1 6. The resin net 1 8 has pilot holes 18a, 18b provided in the ends thereof in advance, as shown in Fig. 8. The pilot holes 18a, 18b are used to position the resin net 18 when inserting and affixing the resin net 18 in the interior of the band body 16.

Fig. 9 is a sectional view of the watch band taken on the line lX-lX of Fig. 7. The resin net 18 accommodated within the band has a rugged form in profile as will be apparent from the drawing. In other words, the portion of the resin net 18 in the vicinity of the locking holes 16a of the band body 16 is situated approximately in the center of the band body 16 viewed in cross-section, while the portion of the resin net 18 in the vicinity of the side holes 16b is situated slightly higher than the central portion of the band body 1 6, viewed in cross-section. The reason is that when the resin net 18 is insert molded in the interior of the band body 16 in the injection molding of the band body 16, the resin net 18 settles down, owing to the heat given in molding the band body 16, until the band hardens.It has been confirmed by experiment that such settling of the resin net 18 causes the net to be exposed from the bottom side of the band body 16. Accordingly, in order to prevent the resin net 18 for settling in this manner, the net 18 is inserted and affixed in such a manner as to form a rugged form. The rugged form of the resin net 1 8 is formed through such a making process as will be described next.

Fig. 10 is a sectional view illustrating conditions when molding the watch band shown in Fig. 7, and Fig. 11 is an enlarged view illustrating a principal portion of Fig.10. Numeral 20 denotes an upper mold having pressing pins 20a, 20b secured by force-fitting or bonding at the positions of the locking holes 1 6a and side holes 16b, respectively. Numeral 22 denotes a lower mold having pressing pins 22a, 22b secured by force-fitting or bonding at positions corresponding to the pressing pins 20a, 20b of the upper mold 20, respectively. A watch band according to the present invention is made through the following process using the upper mold 20 and lower mold 22: (a) The pilot holes 18a, 18b of the resin net 18 are engaged with the pressing pins at the extreme ends of the upper mold 20 or lower mold 22 to position the resin net, and the upper and lower molds 20, 22 are closed to clamp the resin net 18 between the pressing pins 20a, 22a and 20b, 22b in such fashion as to forcibly form a rugged form.

(b) A flexible material for forming the band 1 6 is injection molded from a gate 24. In the case of using urethane rubber for the flexible material, the molding temperature is about 180 C. When the temperature drops to 700C following the injection molding step, the band 16 is extracted from the mold and air-cooled.

(c) Following the injection molding of the band body 16, an end mill or a heated rod is passed through the locking holes 16a and side holes 16b to form through-holes.

This step will not be necessary if the resin net 18 is provided beforehand with holes corresponding to the locking holes 16a and side holes 16b, or if the resin net 18 is exposed from the side holes 16b.

In step (a), the resin net 18 is held in the manner shown in Fig. t when it is clamped between the pressing pins boa, 22a and 20b, 22b.

The pressing pin 20a of the upper mold 20 and the pressing pin 22a of the lower mold 22 abut against each other at the center of the band in the thickness direction thereof, namely at in the position of half the clearance A between the upper mold 20 and lower mold 22. More specifically, the pressing pins 20a,22a are so set that they protrude from the inner faces 20c, 22c of the respective upper and lower molds 20, 22 by a distance equivalent to A/2. Further, the pressing pin 20b of the upper mold 20 is so set as to be shorter than the pressing pin 20a, while the pressing pin 22b of the lower mold 22 is set to be longer than the pressing pin 22a. The position at which the pressing pins 20b, 22b meet, therefore, is higher than the midway point of the band 16 when viewed in section.Consequently, even if the resin net 18 clamped between the pressing pins 20a, 22a and 20b, 22b begins to settle after it is insert molded, the band body 16 hardens by the time the net 18 reaches the midway point of the band body 16, whereby the settling of the resin net 18 is halted. It has been confirmed by experiment that the portions, or areas peripheral thereto, pressed by the pressing pins 20a, 20b, 22a, 22b of the resin net 18 little settle when the band body 16 is injection molded, but that other portions, specifically portions not pressed by the pins, do settle after the injection molding step.

In the second embodiment the portion of the resin net 18 within the band closest to the bottom side of the band body 16 is pressed by the pressing pins 20a, 22a, while the other portions of the net 18 are positioned higher than the approximate center of the band body 16 when viewed in section. In consequence, the resin net 18 will not be exposed from the bottom side of the band body 16 even if the resin band settles during injection molding.

As described hereinabove, the watch band of the present invention is inserted and affixed in the interior of the band comprising, e.g. a synthetic ' resin, so that the periphery of the locking holes and the like can be reinforced. In addition even if the band should, say, tear, the watch will not fall off the wearer's wrist as long as the resin net is not cut. This makes it possible to enhance the durability and safety of a watch band consisting of a synthetic resin.

Claims

1. A watch band comprising: a band body composed of a flexible material capable of being injection molded; and a resin net composed of a synthetic resin and inserted and affixed in the interior of said band body.

2. A watch band according to claim 1, in which said band body is one of a pair of bands forming said watch band, and has locking holes into which locking member of a clasp provided at the other tand is inserted, and in which said resin net is inserted at the portion peripheral to the locking holes of said band body.

3. A watch band according to claim 1, in which said resin net is inserted and affixed in the interior of said band body in such a manner as to form a rugged form.

4. A watch band according to claim 3, in which said resin net has a lowermost surface positioned at substantially a central portion of said band body when viewed in section.

5, A watch band according to claim 3, in which said band body has side holes formed when said resin net is positioned in the interior of said band body in the operation of inserting and affixing said resin net.

6. A method of forming a watch band, comprising the steps of: closing an upper mold having a plurality of pressing pins and a lower mold having a plurality of pressing pins to clamp a resin net by the pressing pins of said upper and lower molds in such a manner as to form a rugged form: and injection molding a flexible material between said upper and lower molds to form a band body.

7. A method of forming a watch band according to claim 6, and further comprising the step of engaging pilot holes provided beforehand in said resin net, with the pressing pins of said upper or lower mold to position said resin net before the step of closing said upper and lower molds.

8. A method of forming a watch band according to claim 6, and further comprising the step of cooling said band body after said injection molding step.

9. A method of forming a watch band according to claim 6, in which some of the pressing pins of said upper mold and some of the pressing pins of said lower mold clamp said resin net at substantially the center of said band body when viewed in section, and the other pressing pins of the upper and lower molds clamp said resin net at a position higher than the center of said band body when viewed in section.

10. A watch band substantially as hereinbefore described with reference to Figures 2 to 11 of the accompanying drawings.

11. A method of forming a watch band, substantially as hereinbefore described with reference to the accompanying drawings.