HK1247291B - Analogue display hand - Google Patents

Description

Analog display pointer

Technical Field

The present invention relates to the field of horology and in particular to the field of analog display members, such as timepiece hands.

The invention also relates to a timepiece and a method for producing a display hand.

Background Art

The manufacture of hands intended to be used as display members in timepieces is particularly complex, in particular when it comes to hands intended to be mounted in high-end timepieces where they must have a flawless surface, in particular provided with facets.

Typically, hands are made of brass, steel, gold, aluminum, or special alloys. These materials can be electroplated, coated with paint, oxidized, or, in the case of gold, left untreated. They are usually manufactured by machining or using stamping techniques.

A drawback of these display hands is that the material used has a high density, which means that in the event of an impact a high moment of inertia and large unbalanced forces occur, which lead to hand floating and hand slipping, respectively.

Furthermore, machining and stamping techniques involve high mechanical stress, which requires an operation of modifying the pointer shape to obtain a relatively flat pointer.

Another drawback is that current pointer manufacturing technology cannot produce all desired shapes.

Summary of the Invention

An object of the present invention is to overcome the various drawbacks of these known techniques.

More specifically, an object of the present invention is to provide a display hand having reduced weight and any desired form.

Another object of the present invention, at least in one particular embodiment, is to provide a display pointer that is simple and inexpensive to implement.

These aims, as well as others that will appear more clearly hereinafter, are achieved according to the invention by a display hand for mounting to a timepiece, comprising a body and a tube in which is provided an arbour hole arranged for fitting the display hand onto a drive arbour.

According to the invention, the body is made of composite material and the tube comprises, over the entire or partial periphery, a surface for connection to the body of the display hand, ensuring adhesion of the composite material to the tube.

Thus, according to the various functional and structural features described above, the object of the present invention is to make it possible to obtain a display hand that can be adapted to different sizes and/or different forms without regard to the weight of the hand.

According to other advantageous variants of the invention:

- the tube portion comprises a first portion with a diameter D1 and a second portion with a diameter D2, wherein D2 is greater than D1;

- the second portion comprises a connection surface for connection to the pointer body;

- the connecting surface is textured;

- the pointer body covers the second portion of the tube;

- the tube is made of a metal material such as brass or copper-beryllium alloy;

- the body is made of injection-molded carbon fiber reinforced plastic or injection-molded carbon fiber reinforced thermoplastic;

- the upper surface of the body comprises a relief pattern or facets;

- The upper surface of the body comprises a treated portion.

The invention also relates to a timepiece equipped with at least one display hand according to the invention.

The invention also relates to a method for manufacturing display hands intended to be mounted on a timepiece, each display hand comprising a body and a tube provided with a spindle hole arranged for fitting the display hand on a drive spindle, wherein the method comprises the following steps:

- placing the tube into a mold;

- injecting the composite material to form a sheet of composite material that is molded onto the tube;

- Micromachining the sheet to form the body of at least one hand.

Further advantageous variants of the method according to the invention:

- a micromachining step is carried out to produce simultaneously a plurality of display hands in the same composite material sheet;

-Micromachining steps include laser cutting, water jet cutting or CNC milling;

- the method comprises at least one step of depositing a coating on at least one surface of the body of each display hand;

The method comprises at least one step of micromachining the upper surface of the body in order to form thereon a relief pattern or facets.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become more apparent upon reference to the following description of specific embodiments of the present invention and the accompanying drawings, which are given by way of illustrative and non-limiting examples only, in which:

- Figure 1 is a top view of a display hand according to the invention.

- Figures 2a and 2b are respectively a top view and a cross-sectional view along line A-A of a display pointer according to the invention.

- Figure 3 is a plan view of a tube showing a hand according to the invention.

- Figures 4 to 7 are diagrams of a method for manufacturing a display hand according to the invention.

DETAILED DESCRIPTION

A display pointer according to the present invention will now be described below with joint reference to FIGS. 1 to 4 .

The display hand 1 is intended to be mounted to a timepiece; it comprises a body 10 and a tube 20 in which is provided an arbour hole 21 designed to fit the display hand 1 onto a drive arbour.

According to the embodiment described, body 10 comprises a circular head 11 in which tube 20 is housed to allow hand 1 to be fitted onto a drive spindle of a watch. The spindle hole 21 of tube 20 is arranged to be fitted onto the drive spindle, for example by means of a press-fit operation.

Tubular portion 20 applies a clamping force to the drive spindle, making it possible to retain pointer 1 axially on the drive spindle and to rotationally connect the two elements.

Body 10 also comprises a tip 12 forming the indicating section of hand 1 and connected to head 11 by an elongated portion 13. Tip 12 has here a triangular shape, but it may take any other shape suitable for indicating a determined angular position on a timepiece dial.

The body 10 of the pointer 1 may also include a weight 14 which is rectangular in shape and which is connected to the head 12 by extension of the elongated portion 13. Likewise, the weight 14 may take any form, for example it is conceivable that the weight takes the form of a logo.

According to the invention, body 10 is made of composite materials such as carbon fiber reinforced plastic, carbon fiber reinforced thermoplastic or carbon fiber reinforced polymer. These materials are very light and resistant, making it possible to reduce the moment of inertia of the pointer and obtain the desired pointer form and size.

The tube here takes the form of a cylinder provided with a spindle hole 21 for assembling the display pointer 1 onto a drive spindle. Tube 20 can be made of a metallic material such as brass, beryllium copper, aluminum, or gold, as these materials readily deform when the tube is pressed onto its spindle. In practice, tube 20 is typically pressed onto a spindle having a diameter slightly larger than the spindle hole; the elastic and plastic properties of the metallic material employed enable the tube 20 to be pressed onto the rotating spindle without damaging the pointer body 10, which is made of composite material.

According to the invention, tube 20 comprises, over the entire or partial periphery, a surface 24 for connection to body 10 of the pointer, in order to ensure adhesion of the composite material to tube 20. It is conceivable that surface 24 extends over the entire periphery of tube 20 or is geometrically arranged at certain angular positions.

3 , the tube comprises a first portion 22 of diameter D1 arranged to be pressed onto the spindle and a second portion 23 of diameter D2 (where D2 is greater than D1) arranged to receive and retain the pointer body 10. A tube having the same diameter throughout its height could also be used.

According to the invention, the connecting surface 24 may extend over the entire or partial height of the second portion 23. For example, the connecting surface 24 may occupy the entire height of the second portion of the tube 20 or only half the height.

According to a first embodiment of the invention, the connecting surface 24 may be textured to ensure better adhesion of the pointer body 10 to the tube 20. For example, as shown in FIG3 , a knurling operation may be performed on the second portion 23 of the tube so that the composite material penetrates the knurled ridges.

According to another embodiment of the invention, see FIGS. 2 a and 2 b , the connection surface 24 may take the form of a pinion or a gear, in which case the composite material is inserted between the teeth and ensures good retention of the body 10 on the tube 20 .

The connecting surface 24 can thus ensure a good radial connection between the tube 20 and the body 10 .

1 and 2 b , the body 10 of the pointer 1 can cover the second portion 23 of the tube 20 . The pointer has an overmolded portion with a diameter D3 below the second portion 23 , which provides good axial retention since the diameter D3 is smaller than the diameter D2 of the second portion 23 of the tube 20 .

According to one embodiment of the present invention, the upper surface of the body 10 of the pointer 1 may include a relief pattern or facets to decorate the pointer.

According to another embodiment of the present invention, the upper surface of the body 10 of the pointer 1 may be provided with a coating, such as a metal coating, which may be deposited by chemical vapor deposition or physical vapor deposition techniques.

4 to 7 illustrate several steps of a method for manufacturing a display hand 1 according to the technique of the present invention.

The invention also relates to a method for manufacturing display hands 1 intended to be mounted on a timepiece, each display hand comprising a body 10 and a tube 20 provided with an arbour hole 21 designed to assemble the display hand on a drive arbour. The method comprises the following steps:

- placing the tube 20 into the mould;

- injecting the composite material to form a sheet 30 of composite material that is molded onto the pipe 20 , the pipe being integral with the sheet 30 due to its connecting surface;

- Micromachining of sheet 30 to form the body of at least one hand 1 .

FIG4 shows a set of tube sections 20 before the method of the invention is carried out, ie before the tube sections are placed in a mould.

FIG. 5 shows a step of injecting a composite material into a mold including the pipe portion 20 to form a composite material sheet 30 on the pipe portion 20 .

6 shows a composite sheet 30 in which the pointer 1 is micromachined. The micromachining can be performed by means of laser cutting, water jet or plasma cutting or by means of CNC milling.

The final step in manufacturing the pointer 1 is to remove the pointer 1 from the composite material sheet 30 .

Advantageously, a set of multiple hands 1 is produced simultaneously in the same composite sheet 30 .

The method according to the invention may comprise at least one step during which a coating, for example a metallic coating, is deposited on the composite material sheet 30. This coating may be deposited by chemical vapor deposition or physical vapor deposition techniques.

This step may be carried out when the composite sheet 30 has been moulded onto the pipe.

According to the invention, the method comprises at least one step of micromachining the upper surface of the body to form a relief pattern or facets thereon. These patterns can be geometric or other patterns that create an aesthetically pleasing visual effect. Such geometric patterns can, for example, give the surface of the hands a guilloché effect.

This step can be carried out while the pointer 1 is still carried by the composite sheet 30 .

Specific dies for forming facets on the composite material sheet 30 when injecting the composite material sheet 30 into the tube portion 20 are also contemplated.

It is noteworthy that the method for manufacturing a hand 1 according to the invention makes it easy to produce hands 1 of various forms and appearances.

Advantageously, the method according to the present invention can be carried out simultaneously on a plurality of composite material sheets 30 , so as to produce hands having similar characteristics in a plurality of composite material sheets simultaneously.

As a result of the various aspects of the invention, a display hand is obtained which has a lower specific gravity than the materials used hitherto, which reduces the hand's moment of inertia and unbalanced forces. The invention also allows the hand to be obtained in various desired shapes.

The above description corresponds to a preferred embodiment and should not be considered as limiting, especially when it comes to describing the shapes of the various structural elements included in the pointer or the materials thereof. A person skilled in the art can easily select any other material having the mechanical properties required for implementing the present invention, for example, for the pointer body.

Since the invention is applicable to any type of portable device having a pointer, in particular hand-held or worn on the wrist, such a pointer may have many possible applications.

Description of Reference Numerals

1. Pointers

10.Ontology

11. Head

12. Tip

13. Slender part

14. Counterweight

20. Management Department

21. Spindle hole

22. The first part of the tube

23. The second part of the tube

24. Connecting Surfaces

30. Composite sheet

D1 Diameter of the first part

D2 Diameter of the second part

D3 lower diameter

Claims (12)

1. A display pointer (1) intended for mounting to a clock, the display pointer comprising a body (10) and a tube (20), the body comprising a head (11), a counterweight (14) extending from a first side of the head, and an elongated portion (13) extending from a second side of the head opposite to the first side, the head comprising a top side, a bottom side, and a through hole extending from the top side to the bottom side; the tube having a spindle hole (21) arranged for mounting the display pointer (1) to a drive spindle. The body (10) is characterized in that it is made of a composite material, and the tube (20) includes a connecting surface (24) on its entire or partly outer periphery for connecting to the body (10) for connecting to the display pointer (1) to ensure that the composite material adheres to the tube (20). The tube (20) includes a first portion (22) with a diameter of D1 and a second portion (23) with a diameter of D2, wherein D2 is greater than D1. The first portion (22) of the tube (20) is located below the bottom side of the through-hole of the head, and the second portion (23) of the tube (20) is arranged inside the head such that the diameter D2 of the second portion (23) of the tube (20) located inside the head is greater than the diameter of the through-hole located on the top side of the head and greater than the diameter of the through-hole located on the bottom side of the head. The connecting surface (24) extends over the entire or part of the height of the second portion (23), and the connecting surface (24) is textured. 2. The display pointer (1) according to claim 1, wherein the body (10) of the display pointer (1) covers the second portion (23) of the tube (20). 3. The display pointer (1) according to claim 1, wherein the tube (20) is made of a metallic material such as brass or a copper-beryllium alloy. 4. The display pointer (1) according to claim 1, wherein the body (10) is made of injection-molded carbon fiber reinforced plastic or injection-molded carbon fiber reinforced thermoplastic. 5. The display pointer (1) according to claim 1, wherein the upper surface of the body (10) includes an embossed pattern or facets. 6. The display pointer (1) according to claim 1, wherein the upper surface of the body (10) includes a processed portion. 7. A clock, characterized in that the clock includes at least one display hand (1) according to any one of the preceding claims. 8. A method for manufacturing a display pointer (1) according to any one of claims 1 to 6, the display pointer being intended for mounting to a clock, each display pointer comprising a body (10) and a tube (20) having a spindle hole (21) arranged for mounting the display pointer (1) to a drive spindle, characterized in that the manufacturing method comprises the following steps: - Place at least one tube (20) into the mold; - Injecting composite material to form a sheet (30) of composite material molded onto the at least one tube (20) such that the at least one tube (20) is integral with the sheet (30); - The sheet (30) is micromachined to form the body (10) of at least one display pointer (1). 9. The manufacturing method according to claim 8, wherein the micromachining step is performed by simultaneously producing multiple display pointers (1) in the same composite sheet (30). 10. The manufacturing method according to claim 8, wherein the micromachining step includes laser cutting, waterjet cutting, or CNC milling. 11. The manufacturing method according to claim 8, wherein the manufacturing method includes at least one step of depositing a coating on at least one surface of the body (10) of each display pointer (1). 12. The manufacturing method according to claim 8, wherein the manufacturing method includes at least one step of micromachining the upper surface of the body to form an embossed pattern or facets thereon.