Device for connecting case body and lugs for a watch

Abstract

A method for attaching a horn on a middle of a watch, a horn / middle connection device and a horn / middle assembly, the horn comprising a first connector and the middle comprising a second connector having an undercut groove, the first connector interacting with the second connector in order to attach the horn on the middle. The method comprises: ○ placing the first connector of the horn in contact with the second connector of the middle, in such a way that one or more intermediate cavities are formed between the undercut groove and the first connector; ○ melting a part of the first connector of the horn in such a way as to create a molten material; ○ at least partially filling the one or more intermediate cavities by movement of the molten material; and ○ solidifying the molten material so as to rigidly connect the horn and the middle.

Description

TECHNICAL FIELD

[0001] In general, the invention relates to a method for fixing a horn to a case middle of a watch, a case middle-horn connection device. TECHNOLOGICAL BACKGROUND

[0002] Document CH 708815 relates to a covering element for a wristwatch case. The covering element is in the form of a separate cover plate fixed to the wristwatch case and which at least partially covers a connection area between a strand of a bracelet and the watch case.

[0003] Document EP 0466655 relates to a watch case and a device for attaching a bracelet to the watch case. The case middle has one or two recesses arranged to receive the end of each bracelet strand. The ends of the bracelet are held by attachment means, consisting of claws or hollows, corresponding to notches or protrusions arranged near the ends of the bracelet strands, and which are arranged on extensions of the case back or on intermediate parts secured to the case back or the case middle.

[0004] Document EP 0197416 relates to an assembly consisting of a watch case element and a bracelet comprising at least one strand. The bracelet strand is made of a first thermoplastic plastic material. The watch case element is made of a second thermoplastic plastic material having a melting temperature higher than the melting temperature of the first plastic material. The watch case element comprises a portion surrounding at least one end of the strand and being integral with this end.

[0005] Document CH668159A3 describes the attachment between a watch case and a bezel also carrying strap attachment lugs. The bezel is made of metal and has a housing. The case is made of plastic and has a connecting part in the form of a beveled step. The assembly is carried out as follows: the bezel is wedged onto the caseband until it presses on the bevelled step; the caseband is put into ultrasonic vibration using a sonotrode and, at the same time, the bezel is pushed downwards; the ultrasonic vibration of the caseband causes the bevelled step to melt, which deforms under the effect of the pressure exerted by the bezel; the melted material of the bevelled step will fill the bezel housing and, in its dried state, forms an annular protuberance for holding the bezel. GENERAL DESCRIPTION OF THE INVENTION

[0006] A first aspect of the invention relates to a method for attaching a fastener to at least one horn on a case middle of a watch case, the fastener comprising a first connector and the case middle comprising a second connector having an undercut groove, the first connector cooperating with the second connector to attach the fastener to the case middle, the method comprising: ∘ bringing the first connector of the attachment into contact with the second connector of the caseband so that one or more intermediate cavities are formed between the undercut groove and the first connector; ∘ melting a portion of the first connector of the attachment so as to create a molten material; ∘ filling, at least partially, the one or more intermediate cavities by displacement of the molten material; and o solidifying the molten material so as to make the attachment and the caseband integral.

[0007] By "undercut groove" is meant a groove whose shape prevents direct demolding of solid material filling it, even partially.

[0008] By "solidary" we mean that one element (e.g. the attachment to at least one horn) is irreversibly linked by contact to another element (e.g. the case).

[0009] Preferably, the fusion of the part of the first connector is carried out by ultrasound. By ultrasound is meant a longitudinal sound wave whose frequency is in a range from 16 to 10000 kHz, preferably in a range from 16 to 5000 kHz, more preferably in a range from 16 to 1000 kHz, most preferably in a range from 16 to 70 kHz.

[0010] According to one embodiment, the method comprises applying a compressive force between the attachment and the middle part brought into contact in order to fill, at least partially, the one or more intermediate cavities by displacement of the molten material.

[0011] According to one embodiment, the first connector comprises a tenon and the second connector comprises a mortise. The engagement of the first connector of the fastener with the second connector of the case may be guided by the tenon and the mortise.

[0012] According to a preferred embodiment, the first connector comprises two or more tenons and the second connector comprises two or more mortises. The engagement of the first connector of the fastener with the second connector of the case may be guided by the tenons and the mortises.

[0013] Preferably, the method comprises filling, at least partially, with the molten material, one or more buffer cavities present between the first connector and the second connector when they are in contact.

[0014] Asecond aspect of the invention relates to a caseband-lug connection device for a watch case comprising an attachment to at least one lug comprising a first connector and a caseband comprising a second connector having an undercut groove. The first connector is configured to cooperate with the second connector to fix the attachment to the caseband. The first connector and the second connector are configured to be brought into contact such that one or more intermediate cavities are formed between the undercut groove and the first connector. In addition, the one or more intermediate cavities are configured to allow the at least partial filling thereof by displacement of the molten material coming from a portion of the first connector. The attachment and the caseband are configured to be made integral by the solidification of the molten material.

[0015] According toone embodiment, the portion of the first connector is configured to be ultrasonically fused.

[0016] Preferably, the first connector, especially the part of the first connector, is (substantially) made of plastic. Optionally, the clip is made of plastic.

[0017] According to one embodiment, the first connector comprises a tenon and the second connector comprises a mortise, the mortise being configured to guide the tenon when the first connector of the fastener is brought into contact with the second connector of the case.

[0018] Preferably, the first connector comprises two or more tenons and the second connector comprises two or more mortises, the mortises being configured to guide the tenons when engaging the first connector of the fastener with the second connector of the case.

[0019] The device preferably comprises one or more buffer cavities between the first connector and the second connector when they are in contact.

[0020] According to one embodiment, the first connector comprises one or more projecting deflectors such that the movement of the molten material takes place substantially only towards the one or more intermediate cavities.

[0021] According to one embodiment, the attachment comprises four horns. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features and characteristics of the invention will emerge from the detailed description of certain advantageous embodiments presented below, by way of illustration, with reference to the appended drawings which show: Fig. 1 : a perspective view of a caseband-horn assembly according to one embodiment of the invention; Fig. 2 :a perspective view of a fastener according to one embodiment of the invention; Fig. 3 : a partial perspective cutaway view of a fastener according to one embodiment of the invention; Fig. 4 : a perspective view of a fastener as well as a section of the horn along the axis AA, according to one embodiment of the invention; Fig. 5 : a perspective view of a case middle according to one embodiment of the invention; Fig. 6 : a perspective view of a case middle and a section of the case middle along axis AA, according to one embodiment of the invention; Fig. 7 : a sectional view of a case and a fastener brought into contact according to an embodiment of the invention; and Fig. 8 : a sectional view of a solid case-horn assembly according to one embodiment of the invention.

[0023] The reader's attention is drawn to the fact that the drawings are not to scale. Furthermore, for reasons of clarity, the proportions between height, length and / or width may not be correctly represented. Last but not least, the spaces, recesses, between the connectors brought into contact may be larger or smaller than in an actual implementation of the invention. DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS OF THE INVENTION

[0024] With reference to the Fig. 1, a caseband 2 - attachment to at least one horn 4 (hereinafter caseband-horn assembly) according to an embodiment of the invention is described. Caseband 2 is an element of a watch case (partially shown) serving to protect the watch movement e.g. from dust, humidity, shocks, etc. It is the middle part of the watch case which receives the watch movement. According to the embodiment described, caseband 2 is circular. However, other shapes are suitable, such as e.g. a square shape, a rectangular shape, an ellipsoidal shape, etc. Caseband 2 defines a main plane P located halfway up it.

[0025] The attachment to at least one horn 4 makes it possible to attach a bracelet to the middle 2. In the embodiment illustrated in the Fig. 1, the attachment 4 comprises four horns 4a each provided with holes 6 aligned transversely to the longitudinal direction of a bracelet (not shown), the horns 4a being arranged to attach the bracelet using, for example, a bar passing through the holes 6. It is obvious that other means of fixing the bracelet to the attachment are suitable. Furthermore, the shape, length and width and number of horns 4a may vary depending on the type of watch.

[0026] THE Figs. 2-4illustrate the attachment 4 according to a preferred embodiment of the invention. The attachment 4 is generally curved and comprises a first connector 8 configured to cooperate with a second connector of the caseband in order to fix the attachment 4 on the caseband. The first connector 8 comprises a circular inner surface 10, perpendicular to the main plane P, configured to be in direct contact with the caseband. The first connector 8 comprises two tenons 12, a “V”-shaped portion 14 and two deflectors 16, all projecting from the circular inner surface 10 inwards (i.e. towards the caseband).

[0027] The tenons 12 are arranged symmetrically on either side of the attachment 4 and have a cylindrical shape, the base of the cylinder being perpendicular to the main plane P. According to other embodiments, the tenons 12 may have other shapes, e.g. a parallelepiped shape, a conical shape, etc.

[0028] The “V”-shaped portion 14 extends over a length L. The “V”-shaped portion 14 is arranged such that the two points of the “V” are radially the innermost. The two points of the “V” define two edges 18, of length L, collinear with the main plane P. The two edges 18 are included in the same plane perpendicular to the plane P. According to other embodiments, the edges 18 may have two different lengths and / or be included in two different planes.

[0029] The two deflectors 16 are arranged laterally on either side, symmetrically, of the “V”-shaped part 14, as shown in Figs. 2-4. Each deflector 16 comprises a flat inner abutment surface 20. The deflectors 16 protrude more than the “V”-shaped portion 14, in particular, the two abutment surfaces 20 protrude more than the two edges 18. The two abutment surfaces 20 are included in the same plane perpendicular to the plane P.

[0030] The fastener 4 further comprises several slots 22, 22', 22". The slot 22 creates a recess around the circumference of the circular inner surface 10. The slots 22', 22" are located at the base of the projecting "V"-shaped portion 14, thus creating two recesses on the circular inner surface 10.

[0031] The V-shaped portion 14 is made of plastic. The horn 4 may be made entirely of plastic. The horn 4 is preferably molded.

[0032] THE Figs. 5-6illustrate the middle part 2 according to a preferred embodiment of the invention. The middle part 2 comprises a second connector 24 configured to cooperate with the first connector of the attachment to fix the attachment on the middle part 2. In particular, the second connector 24 comprises a curved surface 26 radially set back with respect to the radially outer surface 27 of the middle part 2, configured to be placed in direct contact with the circular inner surface 10 of the attachment 4. The second connector 24 comprises an undercut groove 28, two mortises 30, and two hollow parts 32, all forming a depression with respect to the curved surface 26.

[0033] The mortises 30 are arranged symmetrically on either side of the second connector 24. The mortises 30 have a cylindrical shape, the base of the cylinder of which is perpendicular to the main plane P. According to other embodiments, the mortises 30 may have other shapes, e.g. parallelepiped, conical, etc.

[0034] The undercut groove 28 comprises a radially inner planar abutment surface 34. On the other hand, the undercut groove 28 comprises a recess 35 delimited by the radially inner abutment surface 34 and a first radially outer abutment surface 36 as well as a second radially outer abutment surface 38. The two abutment surfaces 36 and 38 are included in the same plane perpendicular to the plane P.

[0035] The two hollow parts 32 are arranged on either side, symmetrically, of the undercut groove 28, as shown in Figs. 5-6. Each hollow part 32 comprises a flat inner stop surface 40. The two stop surfaces 40 are included in the same plane, perpendicular to the plane P.

[0036] The second connector 24 is preferably machined. In addition, the second connector is preferably made of steel.

[0037] There Fig. 7 is a sectional view and illustrates the contact of the first connector of the attachment with the second connector 24 of the middle 2.

[0038] The two edges 18 of the “V”-shaped portion 14 are configured to be in direct contact with the radially inner planar abutment surface 34 of the undercut groove, when the middle part 2 is brought into contact with the attachment 4. In other words, the two edges 18 of the “V”-shaped portion 14 are in direct contact when the connectors are positioned one inside the other, at the end of their travel.

[0039] There“V”-shaped portion 14 partitions the recess 35 into two intermediate cavities 42 delimited by a surface of the “V”-shaped portion 14 as well as the radially inner planar abutment surface 34 and the second radially outer abutment surfaces 36 and 38.

[0040] In this position, the circular inner surface 10 of the horn and the curved surface 26 of the caseband are configured not to be in contact, thus leaving an intermediate space free of material. In the same way, the radially outer surface of the slot 22" is not in contact with the caseband, also leaving an intermediate space free of material.

[0041] Furthermore, and with reference to the Figs 1-7, the two deflectors 16, in particular the flat inner stop surfaces 20, are configured so as not to be in direct contact with the two hollow parts 32, in particular the inner stop surfaces 40, when the middle part is brought into full travel contact with the horn 4. More particularly, a space between the two deflectors 16 and the two hollow parts 32 persists when the two edges 18 are in contact with the radially inner flat stop surface 34 of the undercut groove 28.

[0042] It will be appreciated that the tenons and mortises facilitate the proper placement of the attachment 4 on the middle 2. Indeed, the contact is guided by the tenons and mortises.

[0043] The "V"-shaped portion 14 is then melted by ultrasound, so as to create a molten material. The molten material moves (flows) into the two intermediate cavities 42. As a result, the intermediate cavities 42 are filled, at least partially, by displacement of the molten material (see e.g. Fig. 8 where a portion 44 of an intermediate cavity remains free of material). Preferably, the intermediate cavities 42 are completely filled.

[0044] It will be appreciated that the tenons 12 of the attachment 4 housed in the mortises 30 of the middle 2 make it easier to hold the attachment 4 and the middle 2 in place during the fusion of the “V”-shaped part 14 by ultrasound.

[0045] On the other hand, compression is applied to the case-horn assembly. In this way, the molten material of the “V”-shaped portion 14 is forced to move into the intermediate cavities 42.

[0046] It will also be appreciated that the two deflectors 16 (see e.g. Fig. 3 ) prevent the movement of the molten material from occurring laterally but substantially only towards the intermediate cavities and / or the buffer cavities (see below).

[0047] The fusion of the “V”-shaped part 14 also allows the circular inner surface 10 of the attachment and the curved surface 26 of the caseband to be brought together and brought into contact.

[0048] The slots 22, 22', 22" arranged on the attachment 4 cooperate with the curved surface 26 to define several buffer cavities 46. The buffer cavities 46 can be filled, at least partially, with molten material coming from the parts of the attachment 4 and the middle 2. In this way, molten material, possibly in excess of the intermediate cavities, fills the buffer cavities 46. This makes it possible to prevent molten material from exiting towards the outside through the interface between the two connectors of the horn and the middle and thus being visible on the edges thereof. The aesthetic appearance is thus preserved.

[0049] The molten material is then solidified. The undercut cavity is now at least partially filled with solid material: the caseband-lug assembly is secured. Indeed, the removal of the attachment is now sterically prevented by the solid material having flowed from the “V”-shaped portion 14 into the intermediate cavities 42.

[0050] It should be noted that a case middle-horn assembly was discussed above. According to one embodiment, two horns can be fixed on the same case middle using the same method.

[0051] While particular embodiments have just been described in detail, those skilled in the art will appreciate that various modifications and alternatives thereto may be developed in light of the overall teaching provided by the present disclosure of the invention as defined in the claims. Accordingly, the specific arrangements and / or methods described herein are intended to be given solely by way of illustration, without the intention of limiting the scope of the invention.

Claims

1. A method for attaching an attachment piece with at least one horn (4) to a watch case middle (2), the attachment piece comprising a first connector (8) and the case middle comprising a second connector (24) having an undercut groove (28), the first connector cooperating with the second connector to attach the attachment piece to the case middle, and the method comprising: placing the first connector of the attachment piece in contact with the second connector of the case middle such that one or more intermediate cavities (42) are formed between the undercut groove and the first connector; melting one portion (14) of the first connector of the attachment piece so as to create a molten material; filling, at least partially, the one or more intermediate cavities by displacement of the molten material; and solidifying the molten material in order to make the attachment piece integral with the case middle.

2. The method according to claim 1, wherein the first connector portion is melted by ultrasound.

3. The method according to any of claims 1 to 2, comprising the compression of the attachment piece and of the case middle in order to fill, at least partially, the one or more intermediate cavities by displacement of molten material.

4. The method according to any of claims 2 to 3, wherein the first connector comprises a tenon (12) and the second connector comprises a mortise (30), the contact of the first connector of the attachment piece with the second connector of the case middle being guided by the tenon and the mortise.

5. The method according to claim 4, wherein the first connector comprises two or more tenons and the second connector comprises two or more mortises, the contact of the first connector of the attachment piece with the second connector of the case middle being guided by the tenons and the mortises.

6. The method according to any of claims 2 to 5, comprising the at least partial filling with molten material of one or more buffer cavities (46) present between the first connector and the second connector when said first and second connectors are in contact.

7. Case middle / horn connection device for a watch comprising: an attachment piece with at least one horn (4) comprising a first connector (8); and a case middle (2) comprising a second connector (24) having an undercut groove (28); wherein the first connector is configured to cooperate with the second connector in order to attach the attachment piece to the case middle; wherein the first connector and the second connector are configured to be placed in contact such that one or more intermediate cavities (42) are formed between the undercut groove and the first connector; wherein the one or more intermediate cavities are configured to allow the at least partial filling of said cavities by displacement of the molten material from one portion (14) of the first connector; and wherein the attachment piece and the case middle are configured to be made integral by solidification of the molten material.

8. Case middle / horn connection device according to claim 7, wherein the portion of the first connector is configured to be melted by ultrasound.

9. Case middle / horn connection device according to any of claims 7 to 8, wherein the first connector is made of plastic.

10. Case middle / horn connection device according to any of claims 7 to 9, wherein the first connector comprises a tenon (12) and the second connector comprises a mortise (30), the mortise being configured to guide the tenon when the first connector of the attachment piece is placed in contact with the second connector of the case middle.

11. Case middle / horn connection device according to claim 10, wherein the first connector comprises two or more tenons and the second connector comprises two or more mortises, the mortises being configured to guide the tenons when the first connector of the attachment piece is placed in contact with the second connector of the case middle.

12. Case middle / horn connection device according to any of claims 7 to 11, comprising one or more buffer cavities (46) between the first connector and the second connector when said connectors are in contact.

13. Case middle / horn connection device according to any of claims 7 to 12, wherein the first connector comprises one or more protruding deflectors (16) such that the displacement of molten material occurs substantially only towards the one or more intermediate cavities.

14. Case middle / horn connection device according to any of the preceding claims, characterized in that the attachment piece comprises four horns.

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