Patent Application
20150224813
The present invention concerns a writing instrument comprising a body extending longitudinally along a central axis and a clip extending substantially parallel to the central axis and fixed to at least one portion of the body up to a free end.
There are known in the prior art writing instruments formed of a body which extends longitudinally along a central axis C between a front end and a rear end. The front end comprises an opening through which a writing tip, which is not visible as it is retracted, can extend. At the rear end, the writing instrument has a push button which actuates a tip protraction/retraction mechanism. The body may be made in two parts: a conical nose and a barrel to which the conical nose is fixed.
This writing instrument is also provided with a clip used to enable the user to clip the writing instrument to a shirt pocket for example. This clip consists of an arm provided, at a first end, with a free protruding portion that must be in contact with the body of the writing instrument and, at a second end, attachment means for securing said clip to the body of the writing instrument. These attachment means may be a snap fit system, i.e. the snap fit system is inserted in an orifice in the body to secure said clip. The attachment means may also take the form of an open ring encircling the body of the writing instrument.
A first drawback is that this type of writing instrument is unattractive and fragile. Indeed, the fact that the clip is an additional part leads to risks of said clip being pulled off during handling.
Moreover, a drawback of this configuration is that it requires a manufacturing method wherein the body and the clip are each made separately. A supplementary assembly step is then provided to fit each writing instrument with a clip.
Further, the material forming the clip is any metal. Each material is characterized by its Young's modulus E or modulus of elasticity (generally expressed in GPa), characterizing its resistance to deformation. Further, each material is also characterized by its elastic limit ae (generally expressed in GPa) which represents the stress beyond which the material deforms plastically. Thus, it is possible, for a given thickness, to compare materials, by establishing the ratio of the elastic limit to the Young's modulus σe/E, for each material, said ratio being representative of the elastic deformation of each material. Thus, the higher the ratio, the higher the elastic deformation of the material. However, crystalline materials such as those used in the prior art, for example, the alloy Cu—Be, which has a Young's modulus E equal to 130 GPa and a typical elastic limit σe value of 1 GPa, give a low σe/E ratio, namely of around 0.007. These crystalline alloy parts consequently have limited elastic deformation. In the case of a writing instrument clip, it is noted that the user tends to handle the clip frequently and the clip is eventually deformed or breaks.
Similarly, the use of precious crystalline metals to manufacture such a clip cannot be envisaged given the insufficient mechanical characteristics of these metals. Indeed, these precious metals have, in particular, a low elastic limit, of around 0.5 GPa for alloys of Au, Pt, Pd and Ag, compared to around 1 GPa for the crystalline alloys conventionally used. Given the modulus of elasticity of these precious metals, which is around 120 GPa, a ratio σe/E of around 0.004 is achieved. However, a high ratio σe/E is necessary to produce such a clip, as explained above. Consequently, those skilled in the art are not inclined to use these precious metals to produce such a clip.
Another drawback of existing writing instruments is the spring which is placed in the lower portion of the body and which provides the return force to protract/retract the writing tip. Indeed, this spring is a separate part which sometimes escapes from the body of the writing instrument when the writing tip is replaced, which eliminates a basic function of the writing instrument.
The invention concerns a protective element for a writing tip of a writing instrument which overcomes the aforementioned drawbacks of the prior art by proposing a writing instrument made in one piece and of at least partially amorphous material.
To this end, the present invention concerns a protective element for a writing tip of a writing instrument comprising a cap extending longitudinally along a central axis and arranged to be fitted onto the body of said instrument, and a clip extending substantially parallel to the central axis from a first end fixed to the cap to a free end, characterized in that the clip and said cap are in one piece and are made of at least partially amorphous metal alloy.
In a first advantageous embodiment, the metal alloy includes at least one precious element from the list including gold, platinum, palladium, rhenium, ruthenium, rhodium, silver, iridium or osmium.
In a second advantageous embodiment, said clip and said cap are made of totally amorphous material.
In a third advantageous embodiment, said material is free of cobalt, of beryllium or of nickel.
In another advantageous embodiment, said cap further includes complementary members directly inlaid in said body during a casting or hot forming operation.
The invention also concerns a method of making a protective element for a writing tip of a writing instrument, which is characterized in that the cap is achieved by the following steps:
The method of making a protective element for a writing tip of a writing instrument is also characterized in that the cap is achieved by the following steps:
d) exerting pressure on the preform with the aid of the dies for a predetermined time in order to replicate the shape thereof on each of the surfaces of the preform,
Advantageously, the dies or the mould include surface states in order to replicate them directly during the casting or hot forming operation.
Surprisingly, precious materials in amorphous form have a high ratio σe/E making it possible to produce components such as the clip or the spring according to the present invention.
A first advantage of the present invention is that it has more advantageous elastic characteristics. In fact, in the case of an amorphous material, the ratio σe/E is increased by raising the elastic limit σe. Thus, the stress beyond which the material does not return to its initial shape increases. This improvement in the ratio σe/E thus permits greater deformation. This allows the dimensions of the clip to be optimised according to whether it is desired to increase the measurement range of the clip or to reduce the size of said clip for an equivalent measurement range. Similarly for the spring, the return force can be adjusted by modifying the dimensions of said spring.
Another advantage of these amorphous materials is that they offer new shaping possibilities for developing parts in complicated shapes with greater precision. Indeed, amorphous metals have the particular characteristic of softening while remaining amorphous within a given temperature range [Tg-Tx] peculiar to each alloy (where Tx is the crystallisation temperature and Tg is the vitreous transition temperature). It is therefore possible to shape these metals under relatively low stress and at a low temperature. This means that fine geometries can be very accurately reproduced since the viscosity of the alloy is greatly decreased and the latter thus adopts all the details of the mould.
The objects, advantages and features of the protective element for the writing instrument according to the present invention will appear more clearly in the following detailed description of at least one embodiment of the invention, given solely by way of non-limiting example and illustrated by the annexed drawings, in which:
a shows a schematic, radial cross-section of a writing instrument according to the present invention; and
This writing instrument is also provided with a resilient element 10 such as a clip 8 used to enable the user to clip the writing instrument, for example, to a shirt pocket. This clip 8 consists of an arm 81 provided at a first end 82 with a protruding element 83 that must be in contact with the body of the writing instrument. This clip is fixed, via a second end 84, to the body 2 of the writing instrument.
In a variant, body 2 can be made in two parts, a conical nose 9 and a barrel to which the conical nose is fixed. It may also be made in three parts, a first portion to which the clip is fixed, a second portion used for gripping said instrument and a third portion which is the conical nose fixed to the second portion. These three portions thus form said body 2.
Advantageously according to the invention, at least the first portion of body 2 and clip 8 are in one piece and are made of a totally amorphous or partially amorphous material. In particular, metallic glasses are used, i.e. amorphous metal alloys. This configuration wherein at least the first portion of body 2 and clip 8 are in one piece provides a more solid appearance of better quality.
Indeed, the advantage of these amorphous metal alloys, in terms of deformation, arises from the fact that, during manufacture, the atoms forming the amorphous material do not arrange themselves in a particular structure as is the case of crystalline materials. Thus, even if the Young's modulus E of a crystalline metal and that of an amorphous metal are identical, the elastic limit σe is different. Indeed, the amorphous material differs in that it has a higher elastic limit σea than that of crystalline material in a ratio substantially equal to two. This enables amorphous materials to undergo greater stress before reaching elastic limit σe, the stress thus withstood being four to eight times greater than that withstood by an equivalent crystalline material.
First, this configuration makes it possible to improve the reliability of clip 8 on the writing instrument. Indeed, the elastic limit σea is higher, which makes the plastic domain more remote and therefore reduces the risk of plastically deforming clip 8 when the user handles the writing instrument.
Further, advantageously, it is noted that, with a clip 8 made of amorphous material, it is possible, for the same stress, to optimise the dimensions of the clip in order to withstand the same stresses. Indeed, the dimensions of clip 8, such as the thickness, modify its deformation. Advantageously, if the elastic limit increases, then the stress that can be applied to clip 8 without any plastic deformation, increases. It then becomes possible to maintain the same stress resistance while reducing its thickness. Clip 8 consequently becomes thinner and thus less visible which may be an advantage in terms of aesthetics.
Further, amorphous materials or amorphous metal alloys have the characteristic of being harder than their crystalline equivalents. Consequently, the body 2 made of such materials will be harder and therefore more resistant.
The following can be cited as examples of amorphous materials that may be used: Zr41Ti14Cu12Ni10Be23, which has a Young's modulus E value of 105 GPa and elastic limit of σe=1.9 GPa, and which has a ratio σe/E=0.018, and Pt57.5Cu14.7Ni5.3P22.3, which has a Young's modulus E value of 98 GPA and elastic limit of σe=1.4 GPa, with a ratio σe/E=0.014. It will be understood that the alloys cited in the following Patents: U.S. Pat. No. 5,288,344; U.S. Pat. No.5,618,359 and U.S. Pat. No. 7,368,022 are incorporated by reference in this Patent Application.
Of course, there are other features which may be advantageous such as the allergenic aspect of the alloy. Indeed, it may be noted that whether the materials are crystalline or amorphous they often use alloys comprising allergens. For example, these types of alloys include cobalt, beryllium or nickel. Thus, variants of the invention may be made with alloys that do not contain these allergens. It may also provided that allergens are present but do not cause an allergic reaction.
According to another variant of the invention, it may be provided that the at least first portion of body 2 and clip 8 are made of noble material. Indeed, in the crystalline state, noble materials such as gold or platinum are too soft to produce a flexible and robust clip 8. However, once they take the form of metallic glass, i.e. an amorphous state, these precious metals then enjoy characteristics such that it becomes possible to use them while providing a valuable, attractive appearance. Preferably, platinum 850 (Pt850) and gold 750 (Au 750) are the precious metals that will be used to make the assembly formed by said at least first portion of body 2 and clip 8. Of course, other precious metals could be used, such as palladium, rhenium, ruthenium, rhodium, silver, iridium and osmium. It will be understood that the alloys cited in the following Patents: WO 2006/045106 and WO 2004/059019 are incorporated by reference in this Patent Application.
It may also be noted that amorphous metal alloys are easy to shape. Indeed, amorphous metals have the specific characteristic of softening while remaining amorphous within a given temperature range (Tx-Tg) specific to each alloy. It is therefore possible to shape these metals under relatively low stress and at a low temperature.
This method, precisely described in US Patent No 2003/0047248 incorporated by reference in this Patent Application, consists in hot forming an amorphous preform. The preform is obtained by melting the metallic elements forming the amorphous alloy in a furnace. The melting is carried out in a controlled atmosphere in order to obtain the lowest possible oxygen contamination of the alloy. Once these elements have melted, they are cast in semi-finished product form, then rapidly cooled to preserve the amorphous state. Once the preform is made, hot forming is performed in order to obtain a finished part. This hot forming is achieved by pressing within a temperature range of between Tg and Tx for a determined period of time in order to preserve a totally or partially amorphous structure or state. This is performed in order to preserve the characteristic elastic properties of amorphous metals. The various final shaping steps are then:
This shaping method can very accurately reproduce fine geometries since the viscosity of the alloy is greatly decreased, and the alloy therefore adopts all the details of the mould. The advantage of this method is that there is no solidification shrinkage which allows a more precise component to be obtained, achieved at a higher temperature than by injection. Further, this makes it possible to produce at least a first portion of body 2 and the clip in the same single step. Moreover, the fact that at least the first portion of body 2 and clip 8 are in one piece reduces the risk of clip 8 being pulled off.
Of course, other types of shaping are possible such as injection shaping. This method, described precisely in U.S. Pat. No. 5,711,363 incorporated by reference in the present Application, consists in moulding the alloy obtained by melting metallic elements in a furnace, in the form of any component, such as a bar, which may be either in a crystalline or amorphous state. Then, this alloy component of any shape is melted again and injected into a mould having the shape of the final component. Once the mould has been filled, it is rapidly cooled to a temperature below Tg to prevent crystallisation of the alloy and thus to obtain the assembly formed of the at least first portion of body 2 and clip 8 in amorphous or semi-amorphous metal.
Thus, it is possible to shape the assembly formed of the at least first portion of body 2 and clip 8 in the desired geometry.
A variant consists in creating decorations directly during manufacture of the assembly formed by the at least first portion of body 2 and clip 8. To achieve this, the decorations of writing instrument 1 such as “Côtes de Geneve”, circular graining, satin finishing or engine-turning are achieved directly in the negative pattern cavities of said mould or of said dies used respectively for casting and hot forming. Thus, in addition to the aforecited advantages, this variant also avoids the use of the heavy equipment currently used to produce these decorations in series. It is clear that the method therefore makes it possible to produce a decorated writing instrument more rapidly and, incidentally, more cheaply.
Advantageously, it may be provided that complementary members, such as pearl inserts or precious stones are inlaid in the writing instrument. It could be provided that the complementary member is placed straight into the mould or onto the dies and inlaid during casting or hot forming steps. This complementary member thus forms an integral part of the writing instrument and is not an additional part.
In a second embodiment seen in
Advantageously, clip 80 and said cap 20 are in one piece and are made of at least partially amorphous metal alloy. Naturally, all the variants described for the first embodiment are also possible for the second embodiment.
In the case of a writing instrument with a push button and retractable lead tip or ballpoint, it will also be noted that body 2 may further include a return spring 11 for the writing tip-cartridge assembly as seen in
It will be clear that various alterations and/or improvements and/or combinations evident to those skilled in the art may be made to the various embodiments of the invention set out above without departing from the scope of the invention defined by the annexed claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 12184917.8 | Sep 2012 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/068926 | 9/12/2013 | WO | 00 |
