WO2018126397A1

WO2018126397A1 - Plastic spring with diamond shape

Info

Publication number: WO2018126397A1
Application number: PCT/CN2017/070285
Authority: WO
Inventors: Vincent JACQUART; Jinseok Kim; Stéphane Leroux
Original assignee: L'oreal
Priority date: 2017-01-05
Filing date: 2017-01-05
Publication date: 2018-07-12

Abstract

Provided a resilient member (100), the process of manufacturing the resilient member, a push button and a cosmetic device. The resilient member (100) comprises a plurality of spring cells (C) that are arranged in parallel around a longitudinal axis (X) of the resilient member, forming a spring stage (N), and the resilient member includes a plurality of spring stages (N-1, N, N+1) that are superposed along the longitudinal axis; a spring stage (N) comprises a top zig-zag ring (120) and a bottom zig-zag ring (110), the top and bottom zig-zag rings are in contact at a plurality of contact points (P) distributed around the longitudinal axis (X), a spring cell (C) being defined between two adjacent contact points (P) of the spring stage (N); the top zig-zag ring of a spring stage forms the bottom zig-zag ring of the spring stage arranged directly above, and the bottom zig-zag ring of the spring stage forms the top zig-zag ring of the spring stage arranged directly below; the top zig-zag ring (120) and the bottom zig-zag ring (110) comprise at least a linear portion adjacent to the contact point (P).

Description

Plastic spring with diamond shape

Field of the invention

The present invention relates to a resilient member, especially a spring to be used in the cosmetic field device, such as in an applicator and/or device comprising said spring.

The cosmetic product is preferably a liquid, a cream, an emulsion, a gel or a foam. It may alternatively be a powder or a cast composition. The cosmetic product is for example a coloring product for the eyelids, the lips or the skin of the face, or a care product.

More generally, a “cosmetic product” is a product defined in Regulation EC 1223/2009 of the European Parliament and of the Council, dated 30 November 2009, on cosmetic products.

Background of the invention

For applying cosmetic products, it is known to use applicators and/or devices provided with a spring.

Plastic springs are well known.

For example, US 6 932 246 and WO2015/105 716 disclose plastic springs in cosmetic pump systems.

FR 2 956 649 also disclose a resilient member, particularly a spring, made of a synthetic material, such as polyoxymethylene (POM) , by injection molding. The resilient member comprises a plurality of spring cells that are arranged in parallel around a longitudinal axis of said resilient member, forming a spring stage. It includes a plurality of spring stages that are superposed along said longitudinal axis, a spring stage comprising a top undulation ring having multiple undulations, and a bottom undulation ring having multiple undulations. The top and bottom undulations are arranged relative to each other in such a manner that said top and bottom undulation rings are in contact at a plurality of contact points distributed around said longitudinal axis, a spring cell being defined between two adjacent contact points of said spring stage.

Nevertheless, the resilient member according to FR 2 956 649 is not completely easy to unmold.

Moreover, after compression, the height of the resilient member according to FR 2 956 649 can be reduced of a small percentage only. Consequently, it is thus particularly suited to short deformation strokes that are characteristic of pumps or valves used in the pharmaceutical industry. On the opposite, it is not so adapted to be included in a system that delivers higher cosmetic doses or to produce a deformation of an applicator member.

There is a need to benefit from a resilient member adapted to the delivery of cosmetic doses.

There is a need to benefit from a resilient member easy to unmold.

There is a need to benefit from a resilient member offering new opportunities in the aesthetically and ergonomic fields.

There is also a need for a new gesture for applying a cosmetic product.

Object and summary of the invention

The invention aims to meet some or all of these needs and relates, according to one of its aspects, to a resilient member, particularly a spring, comprising a plurality of spring cells that are arranged in parallel around a longitudinal axis X of said resilient member, forming a spring stage, and said resilient member includes a plurality of spring stages that are superposed along said longitudinal axis, a spring stage comprises a top zig-zag ring and a bottom zig-zag ring, said top and bottom zig-zag rings are in contact at a plurality of contact points distributed around said longitudinal axis X, a spring cell being defined between two adjacent contact points of said spring stage, the top zig-zag ring of a spring stage forms the bottom zig-zag ring of the spring stage arranged directly above, and the bottom zig-zag ring of said spring stage forms the top zig-zag ring of the spring stage arranged directly below, characterized in that the top zig-zag ring and the bottom zig-zag ring comprise at least a linear portion adjacent to the contact point.

Thanks to the linear portion of the zig-zag rings adjacent to the contact point, the height of the resilient member according to the invention can be notably reduced. Because the portions adjacent to the contact point are linear, each binding part can be easily crushed under the effect of the compressive force. The contact points come close one to each other, which results in decreasing notably the height of the spring compared to the unstressed state.

In the resilient member according to the invention, application of an axial force causes progressive contact between linear portions of adjacent rings. This sliding results in storing potential energy due to tensile and compressive stresses in the respective rings. Due to the location of the linear portions next to the contact point, distribution of the tensile and compressive stresses is close to uniform in the cross sections of the rings, resulting in a uniform behavior of the spring along the X-axis.

After application of a maximal axial force, contact between linear portions of adjacent rings is entire. Fast no void can be observed between the adjacent linear portions. This leads to a maximal reduction of the resilient member’s height.

As a matter of course, the resilient member according to the invention is particularly useful for cosmetic compact devices or applicators.

The invention also relates to a process of manufacturing a resilient member as described above comprising a step of injection and/or molding of a synthetic material, preferably the molding is carried out in a casting mold with drawers.

The linear portions of the zig-zag rings adjacent to the contact point promote the unmolding, which results in a high production efficiency.

The invention also relates to push button comprising a resilient member as described above.

With the linear portions of the zig-zag rings adjacent to the contact point, the stroke of the resilient member is high.

The invention also relates to a cosmetic device comprising a reservoir of cosmetic product and a resilient member.

Main definition

A “transversal cross-section” is a cross section perpendicular to the longitudinal axis (X) of the container.

An “undulation” is a curve recalling the motion which occurs on the surface of the water under the influence of wind and which propagates in the form of a wave. An undulation has no linear portion.

A “zigzag ring” is an arrangement of alternating peaks and valleys. Each peak or valley joins consecutive linear and/or curved portions of the ring.

As the zigzag ring according to the invention comprises linear portion, it cannot be an undulation.

A “binding part” joins the top of a peak to the ground of a valley.

Preferred embodiments

According to further advantageous aspects of the invention, the resilient member comprises one or several of the following features taken in isolation or in any technically possible combination:

- All portions of the top zig-zag ring adjacent to a contact point and all portions of the bottom zig-zag ring adjacent to a contact point are linear. The sliding between linear portions of adjacent rings is easier.

- The top zig-zag ring forms a broken line forming alternately protruding and re-entrant angles and the bottom zig-zag ring forms a broken line forming alternately protruding and re-entrant angles. The shear stress distribution across the cross section is more uniform.

- The contact points of a spring stage are offset relative to the contact points of the spring stages that are directly above and directly below, a contact point of the spring stage being arranged half way between two contact points of the spring stage that is directly above, and half way between two contact points of the spring stage that is directly below. The resilient member is well suited for high cycling rates, as fatigue failure commonly occurs due to poor effort distribution.

Brief description of the drawings

The invention can be better understood on reading the following description of non-limiting embodiments thereof, and on examining the accompanying drawings, schematic and partial, in which:

- figure 1 is a perspective inclined view showing an first example of the resilient member according to the invention,

- figures 2 is a perspective view showing an second example of the resilient member according to the invention,

- figures 3 is a front view of the resilient member of figure 1,

- figure 4 is a view of figure 1 after rotation of 45°,

- figure 5 is an axial cut of the resilient member of figure 3,

- figure 6 is a front view of a cosmetic device comprising the resilient member of figure 1,

- figure 7 is a front view of a cosmetic device comprising the resilient member of figure 2,

- figure 8 is a perspective view of a molding device with four drawers for manufacturing the resilient member according to figure 1 or 2,

- figure 9 is a perspective view of a molding device with eight drawers in closed position of the drawers,

- figure 10 is a perspective view of a molding device with eight drawers in partially open position of the drawers,

- figures 11 and 12 are perspective views of a resilient member obtained with the molding device of figure 8,

- figures 13 and 14 are perspective views of a resilient member obtained with the molding device of figures 9 and 10.

Detailed description of the drawings

Figures 1 to 5 show the particular structure of the resilient member according to the invention.

The resilient member 100 represented on the figures has a diamond shape on eight directions, which makes elastic pushing force and returning force. The stroke will be managing pushing force with number of diamond shape and angled diamond shape between 100° and 160°. The stroke will be managing returning force with diamond thickness e and wall thickness w. Preferably, the diamond thickness e is between 0, 4 mm and 2 mm and the wall thickness w is between 0, 6 mm and 30 mm.

The resilient member comprises a plurality of spring cells C that are arranged in parallel around the longitudinal axis X of the resilient member 100. The plurality of parallel spring cells C form a spring stage N. In the invention, the resilient member 100 includes a plurality of spring stages among which N-2, N-1, N, N+1, N+2 and N+3. Naturally, some other number of spring stages may be used. The spring stages are superposed one on another along said longitudinal axis X.

With reference more particularly to the spring stage N, said spring stage comprises a top zig-zag ring 110 having multiple binding parts, and a bottom zig-zag ring 120 also having multiple binding parts. The top and bottom zig-zag rings 110, 120 are arranged in such a manner that they touch at a plurality of contact points P distributed around said longitudinal axis X. Thus, a trough of the top zig-zag ring comes into contact with a crest of the bottom zig-zag ring so as to form a contact point P. In this way, a spring cell C is formed between two adjacent contact points P, and a plurality of spring cells C are thus distributed around the periphery of the spring stage N.

Thanks to the diamond shape of the resilient member, it will be easy to push from top direction and it makes returning force after removing finger.

The structure of the figures has diamond shape with eight directions. It will be molded in a mold comprising four directions of opening for de-mold. Moreover, it will be easy to push from top direction and it makes returning force after removing finger.

As can be seen, the top zig-zag ring of the spring stage N forms the bottom zig-zag ring of the spring stage N+1 arranged directly above, and the bottom zig-zag ring of the spring stage N forms the top zig-zag ring of the spring stage N-1 arranged directly below. In other words, each spring stage has the same number of spring cells C and contact points P. In particular, the contact points of the spring stage N are offset relative to the contact points of the spring stages N+1, N-1 that are directly above and directly below, with a contact point of the spring stage N that is arranged half way between two contact points of the spring stage N+1 that is directly above, and half way between two contact points of the spring stage N-1 that is directly below. In other words, the contact points of one spring stage form the crests of the spring cells of the spring stages that are directly above and below, and vice versa.

Preferably, the top and bottom axial ends of the resilient member 100 comprise

flat rings

130, 140. Thus, the first spring stages starting from the top and from the bottom of the resilient member 100 are not complete spring stages since their spring cells C are not formed by two zig-zag rings but by only one zig-zag ring associated with a flat ring.

The top flat ring 130 is extending downwardly from the upper wall portion 42. The top flat ring 130 is higher on figure 2 than on figure 1. This height can be chosen according to the final use of the resilient member, depending on the needed stability.

Advantageously, the height h of the top flat ring is between 0, 1 mm and 30mm.

The resilient member 100 can comprise fixing means on a part of a device, for example a tip 200, such that a duct or a flow conduit is concentrically received within the tip 200 for example.

The top and bottom zig-zag rings 110, 120 have zigzag wave profiles 8 with substantially rectilinear sides 6 and 7 located on both sides of a contact point P.

Preferably, the rectilinear sides 6 and 7 are inclined relative to the X axis of an angle α between 30° and 70° at the uncompressed state of the resilient member, and preferably of 50° to 60°.

Preferably, the rectilinear sides 6 and 7 are inclined relative to the X axis of an angle α between 80° and 90° at the compressed state of the resilient member, and preferably of 85° to 90°.

Preferably, the rectilinear sides 6 and 7 have a length l between 3 mm and 15 mm, and preferably between 5 mm and 10 mm.

The wave thus comprises a series of wave peaks, upper and lower, with the same shape.

The manufacture of the wave profiles 8 is thereby achieved quickly, economically and reliably.

Alternatively, only the ends of the straight portions 6 and 7 are rectilinear. They can be bounded through a central arc, in order to modify the hardness of the resilient member for some specific applications.

An applicator assembly for a cosmetic product, comprising a reservoir 2 containing the product and an applicator member 5 that can be actuated in translation from the outside through a push button comprising the resilient member of figure 1 is shown figure 6 an comprising the resilient member of figure 2 is shown figure 7.

The resilient member can be manufactured by injection and/or molding of a synthetic material.

Preferably, the synthetic material is chosen in the group comprising polypropylene (PP) , polyamide (PA) , polyurethane (PU) , a polyacrylonitrile (PAN) , polyethylene (PE, PEHD, LDPE) , polyoxymethylene (POM) , buthylene polyterephtalate (BPT) , styrene butadiene acrylonitrile (ABS) , polystyrene (PS) , ethylen polyterephtalate (PET, PETG) .

More preferably, the synthetic material is a polyketone material, especially a polyketone marketed under trade mark Schulaketon

by A. Schulman.

Generally, the resilient member 100 with diamond shape according to the invention is made using an eight slide or four slide mould structure, and the best mould structure will be eight slide mould.

Figure 8 shows a molding device 200 with four drawers for manufacturing the resilient member 100 according to the invention. This molding device consists of:

- a central hub 29 having the essentially the shape of a cylinder of longitudinal axis Y,

- four movable drawers 21, 22 and 23 (and another one that is not represented or completely pulled ) that are mobile relative to the central hub 29. Each drawer can be shifted in translation along a direction perpendicular to the Y axis between an open position and a closed position,

- a molding cavity 200 built between the drawers and the fixed central hub. The synthetic material is molded into this molding cavity 200 to elaborate the resilient member.

- one or more injection nozzles arriving into a mold cavity. The nozzles are positioned to optimize the flow of synthetic material into the mold cavity and thereby obtain a rate of rejection of relatively low molded bodies.

The synthetic material is cooled and allowed to harden. Then, the drawers are all pulled and removed. The resilient member 100 can be unmolded.

Indeed, access to optimum injection point in the cavity requires in some cases to use a cold runner.

On figure 8, the mold will be open with four directions A, B, C, D and these four directions can be demold in diamond shape.

The opening of one drawer lets appear a part of the resilient member 100 showing two spring stages N and N+1. Opening of each drawer let appear another piece of the resilient member, up to achievement the of a diamond shape resilient member after opening of the drawers in the four directions.

Depending on the number of drawers, the resulting resilient member can have a different shape. On figure 11 and 12, the resilient member is molded in the molding device of figure 8.

Figure 9 and 10 shows a molding device 200 with eight

drawers

21, 22, 23, 24, 25, 26, 27 and 28. On figure 10, the drawer 24 is removed. The principle of operation of this molding device is the same than the one of the molding device of figure 8.

For the eight slides mould (molding device 200) , the rotation structure of the central hub 29 comprises a gear member. The gear can be changed from rotation force to sliding force (8 directions) as it is one time rotated on the molding device 200.

Power from a driving source is transmitted via a transmission unit, which is a gear, to a screw rod unit, so as to drive the mould holder to move. When the mould is actuated to close, a clamping unit 32 engages to a gear wheel member of the screw rod unit 31. Typically, such an injection-moulding machine has two types of clamping devices 32, a toggle type and a direct pressure type. Generally, the screw rod unit 31 shares the same axis of rotation Y as the gear wheel member.

The sections called slides (drawers) move into a cavity perpendicular to the draw direction, to form overhanging part features. When the mould is opened, the slides are pulled away from the central hub by using stationary “protusion” 33 on the stationary mould half. These protusions 33 enter a slot 34 in the slides and cause the slides to move backward when the mould opens. The resilient member 100 is then ejected and the mould closes. The closing action of the mould causes the slides to move forward along the protusions 33.

Since molten material is supplied into the mold cavity under a high pressure, it is necessary to apply a sufficient clamping force to tightly close the mold to avoid flashing.

A molding device marketed by the company - “Shanghai Derkwei Kubota Mould Co., Ltd” under the trade name “Rotating of 8 slide mould”

is preferably used according to the invention.

A fully electronic injection-molding machine can also be used according to the invention.

Opening of each drawer let appear another piece of the resilient member, up to achievement the of a diamond shape resilient member after opening of the drawers in the eight directions.

On figure 13 and 14, the resilient member is molded in the molding device of figure 9 and 10.

This structure of the resilient member 200 according to the invention having a plurality of levels of multiple cells in parallel is particularly advantageous. Firstly, it enables resilient members to be made that are compact.

In addition, the elastic deformation is distributed in substantially homogeneous or uniform manner over all of each cell, and this favors the life span of the spring and the consistency of its performance over time, eliminating any localized zones that are greatly stressed on each actuation. This is further reinforced by the completely flat top and bottom rings that distribute the axial deformation force over all of the cells of the spring in homogeneous manner.

The present invention is not limited to the shown embodiments. In particular, the applicator and the device could be different without departing from the scope of the invention. In particular, changes can occur on the thickness of the rings, their round or rectangular or other section, their material, the size of the spring cells, depending on the type of device in which the resilient member is used.

Claims

Resilient member (100) comprising a plurality of spring cells (C) that are arranged in parallel around a longitudinal axis (X) of said resilient member, forming a spring stage (N) , and said resilient member includes a plurality of spring stages (N-1, N, N+1) that are superposed along said longitudinal axis, a spring stage (N) comprises a top zig-zag ring (120) and a bottom zig-zag ring (110) , said top and bottom zig-zag rings are in contact at a plurality of contact points (P) distributed around said longitudinal axis (X) , a spring cell (C) being defined between two adjacent contact points (P) of said spring stage (N), the top zig-zag ring of a spring stage forms the bottom zig-zag ring of the spring stage arranged directly above, and the bottom zig-zag ring of said spring stage forms the top zig-zag ring of the spring stage arranged directly below, characterized in that the top zig-zag ring (120) and the bottom zig-zag ring (110) comprise at least a linear portion adjacent to the contact point (P) .
Resilient member according to claim 1, characterized in that all portions of the top zig-zag ring (120) adjacent to a contact point (P) and all portions of the bottom zig-zag ring (110) adjacent to a contact point (P) are linear.
Resilient member according to any of the preceding claim, characterized in that the top zig-zag ring (120) forms a broken line forming alternately protruding and re-entrant angles and the bottom zig-zag ring (110) forms a broken line forming alternately protruding and re-entrant angles.
Resilient member according to any of the preceding claim, characterized in that the contact points (P) of a spring stage (N) are offset relative to the contact points (P) of the spring stages that are directly above (N+1) and directly below (N-1) , a contact point (P) of the spring stage being arranged half way between two contact points (P) of the spring stage that is directly above, and half way between two contact points (P) of the spring stage that is directly below.
Process of manufacturing a resilient member according to any of the preceding claim, characterized in that it comprises a step of injection and/or molding of a synthetic material in a casting mold having a slide mold structure, the slide mold structure being an eight slide mold structure or a four slides mold structure.
Push button, characterize in that it comprises a resilient member according to anyone of the preceding claims 1 to 4.
Cosmetic device (101) comprising a reservoir of cosmetic product, said device being characterized in that it comprises a resilient member according to anyone of the preceding claims 1 to 4.