HK1163266B - Method for making a micromechanical part - Google Patents

Description

Method for manufacturing micromechanical component

Technical Field

The present invention relates to a method of manufacturing micromechanical parts, and more particularly to such a method for assembling micro-machined and/or electroformed portions.

Background

It is advantageous for the horology industry to manufacture parts or parts by means of micromachining processes, such as photolithography (photolitohraphie) followed by deep reactive ion etching, or electrodeposition processes, such as photolithography followed by electroplating growth (capillary). In fact, these processes allow to achieve a manufacturing with improved precision compared to the conventional techniques.

However, it is difficult to form a part from multiple parts. Thus, in the case of electroformed parts, laser welding between the two parts and, for example, the shaft, has the potential to deform the parts, thereby losing the very good precision afforded by the electrodeposition process. Furthermore, regardless of the process, it is difficult to obtain assembly accuracy between the two parts and, for example, the pivot shaft.

Disclosure of Invention

The aim of the present invention is to remedy all or part of the above-mentioned drawbacks by proposing a method for manufacturing a micromechanical part, comprising for example at least three parts, whose assembly precision does not alter the precision of the process.

To this end, the invention relates to a method for manufacturing a multilayer micromechanical part, comprising the following steps:

a) forming at least two plates each comprising a frame connected by at least one material bridge to a portion of the part, each portion comprising an aperture;

said method is characterized in that it further comprises the steps of:

b) stacking the at least two plates on a support to stack at least two of the portions;

c) securing a pin in the hole of each of the at least two portions of the stack to form a part;

d) releasing the formed part from each plate.

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Advantageously according to the invention, the portions can be manufactured according to any process (micro-machining, electro-forming, electro-erosion, stamping) without the need to operate them before their final assembly, but only by means of the frame and the pins. Furthermore, the references of the supports are used to produce the final part more precisely, while preserving the precision of the processes (micro-machining, electroforming, electroerosion, stamping) used to realize each part in step a).

According to other advantageous features of the invention:

-for each plate, step b) comprises a step e) in which the plate is guided by means of alignment means so as to be reliably oriented with respect to the support, and a step f) in which the plate is slid on at least one shaft fixed to the support until resting against a shoulder of said shaft so as to be reliably placed with respect to the support;

-each of said alignment means comprises at least one inclined ring mounted in an extension of said at least one shaft of the support and intended to cooperate with a recess formed in each of said at least two plates in step a);

the guiding of step e) is achieved with at least two alignment means to improve reliability;

-each recess is formed in the frame of the at least two plates, or corresponds to a space between the frame and the portion of each of the at least two plates;

-each at least one material bridge comprises a section narrowing at the end connected to said portion of the piece, allowing to create a weakened area capable of facilitating step d);

-forming a plurality of portions on each plate to form a plurality of parts in step c);

-the pin is extended at each of its ends by a shank (tigeron) comprising a pivot to form a pivot axis;

-the pin coaxially comprises a ring for acting as a stop to limit the entry of the pin in the hole;

-the coaxial ring comprises teeth to form a gear;

at least one of the plates is formed in step a) by means of an electrodeposition and/or micromachining process;

at least one sub-portion may be mounted on at least one of said portions laterally with respect to said plate before, during or after step b).

Drawings

Further characteristics and advantages will become apparent from the following description, given by way of illustration and not of limitation, with reference to the accompanying drawings. In these drawings:

figure 1 is a schematic view of two plates according to the invention;

figures 2 to 4 are schematic views of successive steps of the method according to the invention;

fig. 5 to 7 are schematic views of micromechanical parts that can be realized according to the method of the invention;

fig. 8 is a block diagram of a method according to the invention.

Detailed Description

As shown in fig. 8, the invention relates to a method 1 for manufacturing a micromechanical part 31, 41, 51. The method 1 is used for fixedly assembling at least two different parts 19, 21 by stacking by means of pins 29. The method 1 comprises the following steps: step 3 of manufacturing the portions 19, 21 of the final part 31, 41, 51; a step 5 of stacking the plates 11, 13 including the portions; a step 7 of fixing the portion; then there is a step 9 of releasing the parts 31, 41, 51 thus formed from the plates 11, 13.

Advantageously according to the invention, the first step 3 of manufacturing the portions 19, 21 of the parts 31, 41, 51 can be carried out by means of a micro-machining and/or electro-deposition process. Micromachining processes, i.e. processes with machining accuracies approximately equal to or less than micrometers, may include, for example, photolithography to form a protective mask on a plate of micromachinable material, followed by etching of the unprotected parts of the plate, for example by deep reactive ion etching. The micromachinable material may thus for example be composed of a material based on silicon, crystalline silicon oxide or crystalline aluminum oxide. Of course, other materials may be used.

The electrodeposition process may include, for example, photolithography for forming a mold in which an electroplating growth is performed. The plating growth material may thus for example be composed of a metallic material such as pure nickel or nickel-phosphorus. Of course, other materials may be used.

The manufacturing step 3 comprises at least two different forming stages 2, 4. Each stage 2, 4 of the micromachining and/or electrodeposition process is used to form the plates 11, 13, respectively, as shown in fig. 1. Each plate 11, 13 comprises a frame 15, 17 connected by at least one material bridge 12, 14 to a portion 19, 21 for making a final part 31, 41, 51. As can be seen in fig. 1, each portion 19, 21 preferably comprises a through hole 16, 18.

It will therefore be appreciated that the final parts 31, 41, 51 may be realized by the same process, or by a plurality of different processes. Of course, processes other than micromachining and/or electrodeposition may be used that allow the plates 11, 13, etc. to be manufactured, such as electroerosion or stamping.

According to the invention, the method 1 comprises a second step 5 for stacking the plates 11, 13 on a support 23. In the example shown in fig. 2 to 4, the support 23 comprises at least one shaft 22, the shaft 22 being intended to cooperate with an associated recess 20, 26 formed in the plates 13, 11 to be stacked. The combination of the shaft 22-recess 20, 26 allows to precisely position the plates 13, 11 with respect to the support 23.

Preferably according to the invention, each shaft 22 comprises a shoulder 24, the shoulders 24 serving to secure the distancing of the plates 13, 11 with respect to the support 23. Preferably, the support 23 further comprises alignment means 25, the alignment means 25 allowing a secure orientation of the plates 13, 11 with respect to the support 23. In the example shown in figures 2 to 4, the alignment means 25 comprise a beveled ring mounted on an extension of each shaft 22 and intended to cooperate with recesses 20, 26 formed in the plates 13, 11.

According to a first stage 6 of the second step 5 shown in fig. 2, the first plate 13 is mounted on a support 23. In a first time, the plate 13 is brought close to the support 23 along the direction a. In a second time, the plate 13, shown by a dashed line, encounters the alignment means 25 to be guided in the direction B. By means of the alignment means 25 and the recesses 20, the plate 13 is reliably oriented such that the recesses 20 are placed on the plumb line of each axis 22 of the support 23. In a third time, the plate 13 is made to slide on its shaft 22 by means of its recess 20 along the direction a until the plate 13 comes into contact with the shoulder 24 of each shaft 22 in a fourth time, as shown in fig. 2. It can thus be understood that the plate 13 is placed very precisely with respect to the support 23.

According to a second stage 8 of the second step 5, as shown in fig. 3, the second plate 11 is mounted on a support 23, stacked with respect to the first plate 13. In a first time, the plate 11 is brought close to the support 23 along the direction a'. In a second time, the plate 11, shown by a dashed line, encounters the alignment means 25 to be guided in the direction B'. By means of the alignment means 25 and the recesses 26, the plate 11 is reliably oriented such that the recesses 26 are placed on the plumb line of each axis 22 of the support 23. In a third time, the plate 11 is made to slide on its shaft 22 by means of its recess 26 in the direction a' until the plate 11 comes into contact with the upper part of the first plate 13 in a fourth time, as shown in fig. 3.

It will thus be appreciated that the plates 11 and 13 are placed very precisely with respect to the support 23 and, incidentally, with respect to each other. It will also be noted that the portion 21 of the plate 13 is located below the portion 19 of the plate 11 and is in contact with this portion 19. Finally, it can also be seen in the example shown in fig. 3 that the holes 16 and 18 are substantially aligned with each other in the vertical direction.

Of course, the first step 3 and the second step 5 are not limited to manufacturing and then stacking the two only plates 11 and 13. In fact, the method 1 advantageously allows to manufacture more or less than two plates in step 3, to manufacture in step 5 the parts 31, 41, 51 from more or less than two portions stacked on the support 23. It will also be appreciated that more or fewer stages 2, 4 are required in step 3, and more or fewer stages 6, 8 are required in step 5.

According to the invention, the method 1 comprises a third step 7 for fixing the stacked portions 19, 21 to form the micromechanical part 31, 41, 51. Preferably according to the invention, the fixing step 7 is carried out by means of the fitting of a pin 29 in the holes 16, 18 of each portion 19, 21. To this end, the support 23 preferably also comprises a post 27, the post 27 comprising a hollow upper portion 28 which allows to avoid any relative displacement between the portions 29, 21 and their plates 11, 13 when the pins 29 are introduced in their respective holes 16, 18. In fact, such a relative displacement would cause a risk of breakage of the material bridges 12, 14 which is undesirable in this third step 7 of method 1.

Depending on the nature of the material used for manufacturing the plates 11, 13, etc., a number of embodiments of the third step 7 may be considered. Thus, according to the invention, preferred embodiments are press-fitting (passage), welding and gluing. Of course, if one of the plates 11, 13, etc. is made of a material that includes no or little plastic deformation region, it becomes difficult to achieve press fitting.

In a first embodiment relating to press fitting, in the example shown in fig. 4, in a first time of the third step 7, the pins 29 are brought close to the respective holes 16, 18 stacked in the direction C. During the second time, the pin 29 is pressed hard into the holes 16 and then 18 of the plates 11 and 13. Advantageously, the force of the press fitting can be adjusted by using an automatic device. Each part 19 and 21 thus becomes fixed on the pin 29 and forms the final part 31, 41, 51.

In a second embodiment related to welding, in the example shown in fig. 4, the pin 29 is coated with solder in the first time of the third step 7. In a second time, the pin 29 is brought close to each hole 16, 18 stacked in the direction C. In a third time, the pins 29 are introduced into the holes 16 and then 18 of the plates 11 and 13. Advantageously, the accuracy of the direction C can be improved by using automatic means. In a fourth time, the solder is solidified, for example by means of a heat treatment. Thus, each portion 19 and 21 becomes fixed on the pin 29 and forms the final part 31, 41, 51.

In a third embodiment relating to gluing, in the example shown in fig. 4, in the first time of the third step 7, the pins 29 are coated with an adhesive material, for example of the polymer glue type. In a second time, the pin 29 is brought close to each hole 16, 18 stacked in the direction C. In a third time, the pins 29 are introduced into the holes 16 and then 18 of the plates 11 and 13. Advantageously, the accuracy of the direction C can be improved by using automatic means. In a fourth time, the binder material is activated, for example, by heating. Thus, each portion 19 and 21 becomes fixed on the pin 29 and forms the final part 31, 41, 51.

According to the invention, method 1 comprises a fourth step 9 for releasing the formed micromechanical parts 31, 41, 51 from the respective plates 19, 21, etc. stacked in second step 5. Step 9 is preferably achieved by applying a force capable of breaking the material bridges 12, 14.

It is preferred for all embodiments of the third step 7 that a pin 29 is fixedly mounted projecting from at least one of the stacked plates to be able to serve as a holding means, i.e. without the need to manipulate the parts 19, 21, etc. of each plate 11, 13, etc. Advantageously, the method 1 thus allows achieving a high surface quality of each portion. It will also be appreciated that the hollow upper portion 28 of the post 27 mounted on the support 23 allows the pin 29 to pass under the plate 13 and/or limit its extent of penetration into the holes 16, 18 etc.

According to a first variant of the invention, the pin 29 comprises a ring 30, the ring 30 forming a stop at said projection to limit the entry of the pin 29 in the hole of said portion. The ring 30 thus allows an improved manufacturing quality. Furthermore, the ring 30, which may be integral with the pin 29, may also advantageously comprise teeth capable of forming a gear as described below.

According to a second variant of the invention, the pin can also be extended at each of its ends, in addition to the ring 30, by a shank comprising a pivot to form a pivot axis. Advantageously according to the invention, it is therefore understood that in the third step 7 it is possible to fix a plurality of elements in the holes of the stacked portions, wherein said elements can be changed by a simple pin 29 to a pivot shaft equipped with at least one gear.

It will be appreciated from reading method 1 that a plurality of identical or different portions 19, 21, etc. may be formed on each plate 11, 13, etc. in order to mass-produce identical or different final parts 31, 41, 51. It will also be understood that, after third step 7, plates 11, 13, etc. may be supplied directly to a production line for example for producing a timepiece movement, before carrying out fourth step 9. This has the advantage that only the frames 15, 17 etc. of the plates 11, 13 etc. of many final parts are operated simultaneously without the risk of damaging the stacked parts 19, 21 etc. as a result of the operation.

Advantageously, the method 1 thus allows to improve the manufacturing accuracy, to be able to flexibly manufacture high-quality composite parts (i.e. comprising a plurality of different materials) without the need to operate parts of the final part with a high degree of simplicity and a plurality of plates. It will thus be appreciated that the method 1 can be fully automated, for example by means of a multi-station production line.

With reference to fig. 5 to 7, an example of the manufacture of a micromechanical part according to method 1 is shown. In the example shown in fig. 5, a timepiece wheel set 31 is seen, the wheel set 31 comprising a pivot 33, a gear 35 and a toothed wheel 37. The method 1 may allow, for example, that the gear 35 is part of a plate obtained by an electrodeposition process, while the wheel 37 is based on a plate obtained by a micromachining process.

In the example shown in fig. 6, a timepiece wheel set 41 is seen, the wheel set 41 comprising a pivot axis 43, a gear wheel 45 and two toothed wheels 47, 49. The method 1 may allow, for example, that the gear 45 is part of a plate obtained by an electrodeposition process, while the wheels 47, 49 are based on a plate obtained by a micromachining process.

Advantageously, according to the first variant described above, the gears 35, 45 may also be integral with the shafts 33, 43, respectively, and thus form an integral body capable of fixing the final parts 31, 41 in the third step 7 of the method 1.

It is therefore understood that a plurality of micromechanical parts to be manufactured may be considered depending on the materials used, the embodiments used and/or the variants selected. Thus, as an example, as shown in fig. 7, it is also possible to consider manufacturing a timepiece pallet 51 comprising a pivot shaft 53, an upper arm 55, a body 57, and a fork pin 55 'and possibly a pin 53'.

The method 1 may allow, for example, pallet 51 to be obtained by means of a silicon-based part only. Such pallet 51 can be obtained from two plates, made by a micro-machining process in step 3, stacked on support 23 in step 5, the upper arm 55 and the fork pin 55 'being fixed on body 57 by gluing in step 7 by means of shaft 53 and pin 53', respectively, from which plate pallet 51 is released by exerting a force on shaft 53 in final step 9.

Of course, the invention is not limited to the examples shown, but may have various variations and modifications that may occur to those skilled in the art. In particular, as illustrated in fig. 8 with double lines, an intermediate stage 10 for depositing adhesive material between each plate 11, 13, etc. and/or ring 30 stacked may be considered in step 5. Such adhesive material allows to locally improve the fixation between at least two elements of the final part, if necessary. The adhesive material may be deposited by a screen printing process that allows the adhesive material to be deposited in a precise thickness and area.

Furthermore, in order to provide a breaking point in step 9, it may be required that each material bridge 12, 14 comprises a section that narrows at the end connected to its associated portion 19, 21, as shown in fig. 1.

There may also be more or fewer shaft 22-recess 20, 26 combinations. Furthermore, these recesses 20, 26 may be replaced by recesses already present between the portions 19, 21 of the plates 11, 13 and the frames 15, 17.

Finally, all components according to the above description are mounted substantially in a vertical position in each step only for the sake of convenience in understanding the invention. In fact, the component mounting direction is not limited to direction A, A' or C. In fact, for example in the case of the manufacture of pallet 51, it is possible to consider mounting pallet stones from the perforated side of frames 15, 17, etc. of plates 11, 13, etc. for forming portion 57 and/or upper arm 55 before, during and after step 5. In fact, the positioning of the pallet stone is of great importance, the mounting on the support 23 in stages 6, 8, etc. of step 5 can be used to mount the pallet stone very precisely along a direction substantially perpendicular to the directions A, A', C. More generally, it is understood that at least one sub-portion may be mounted on at least one of said portions laterally with respect to the plate before, during or after step 5.

Claims (14)

1. A method (1) of manufacturing a micromechanical part (31, 41, 51), comprising the steps of:

a) -forming (3) at least two plates (11, 13) each comprising a frame (15, 17) connected by at least one material bridge (12, 14) to a portion (19, 21) of the piece, said portion (19, 21) comprising a hole (16, 18);

the manufacturing method is characterized by further comprising the steps of:

b) stacking (5) said at least two plates on a support (23) to stack at least two of said portions;

c) -fixing (7) a pin (29) in a hole (16, 18) of each of said at least two parts of the stack, to form a piece (31, 41, 51) with a single pin projecting from at least one of the plates of the stack so as to be able to act as gripping means;

d) -releasing (9) the formed part (31, 41, 51) from the at least two plates (11, 13).

2. Method (1) according to claim 1, wherein step b) comprises, for each plate (11, 13), the steps of:

e) guiding (B) the plate by means of an alignment device (25) in order to reliably orient the plate with respect to the support (23);

f) the plate is slid on at least one shaft (22) fixed to the support (23) until it abuts against a shoulder (24) of the shaft, so that the plate is securely placed relative to the support (23).

3. Method (1) according to claim 2, wherein each of said alignment means comprises at least one inclined ring mounted in the extension of said at least one shaft of said support (23) and intended to cooperate with a recess (20, 26) formed in each of said at least two plates in step a).

4. The method (1) according to claim 2, wherein the guiding in step e) is performed with at least two alignment means (25) to improve reliability.

5. A method (1) according to claim 3, wherein each recess (20, 26) is formed in the frame (15, 17) of the at least two plates.

6. A method (1) according to claim 3, wherein each recess corresponds to a space between said portion (19, 21) of each of said at least two plates and the frame (15, 17).

7. Method (1) according to claim 1, characterized in that each at least one material bridge (12, 14) comprises a section that narrows at the end connected to said portion of the piece, allowing to create a weak area that can facilitate step d).

8. Method (1) according to claim 1, characterized in that a plurality of portions (19, 21) are formed on each plate (11, 13) to form a plurality of parts (31, 41, 51) in step c).

9. A method (1) according to claim 1, wherein the pin (29) is extended at each of its ends by a shank comprising a pivot to form a pivot axis.

10. Method (1) according to claim 1, characterized in that the pin (29) comprises coaxially a ring (30) intended to act as a stop to limit the entry of the pin in the hole.

11. The method (1) according to claim 10, wherein said coaxial rings (30) comprise teeth to form a gear.

12. The method (1) according to claim 1, wherein at least one of the plates is formed in step a) by means of an electrodeposition process.

13. Method (1) according to claim 1, characterized in that at least one of the plates is formed in step a) by means of a micro-machining process.

14. The method (1) according to claim 1, wherein at least one sub-portion is mounted on at least one of said portions laterally with respect to the plate before, during or after step b).