EP0854405B1 - Milling-machine for machining several elements from a bar - Google Patents

Abstract

The milling machine for machining several elements (48) from at least one bar (2d) consists of a clamping mechanism for the bars (8,10) and an advance feed (8,10) of the bars according to a primary direction (16) parallel to the longitudinal axis (14) of the bars. A front machining unit (24) is situated in the front zone of the milling machine and contains the primary mobile milling tools (28,30,32) arranged to machine the end of the bar. It also contains a lateral machining unit (40) situated in a lateral zone (42) and containing a secondary mobile milling tool (44) arranged to machine the bars in a lateral zone downstream of the ends of the bars. This operation effects an initial machining along the bars before they are advanced into the front zone for their terminal machining.

Description

The present invention relates to a milling machine (machine milling - cutting) machining from a bar several elements, including crowns and pushers for watchmaking or bracelet elements for watchmaking and jewelry.

According to current practice, when such elements are machined on a milling machine from a bar, the bar is first profiled on a drawing machine or rolling and then, once the bar is inserted on the milling machine, each element is machined at the end of one after the other.

In the case of crowns in particular, the toothing provided on the circular side surface of larger diameter of this crown is obtained initially by stretching of the bar on a specific machine before this bar is inserted into the milling machine for additional machining necessary for the manufacture of crowns. The initial stretch involves several disadvantages. First, it is an operation on a machine different from the milling machine used then for the final machining of the crowns. Then a such initial stretching generates losses due to particularly when lifting material. The bars do furthermore cannot exceed a certain length for guarantee sufficient quality of the surface finish of the teeth (for example about 1.5 meters for crowns Golden).

When machining on a 1.5 meter bar, there is at least 10% of waste, i.e. at least 15 cm of the bar cannot be machined on a conventional milling machine. On the other hand, on a bar 5 meters, only 30 centimeters are non-machinable so that the length limitation for the machined bar increases the cost of production; this being particularly expensive with noble materials like gold.

The initial stretching is therefore expensive in time and in material. In addition, the quality of the teeth is lower to that of milled teeth. According to practice, man of the trade may provide for machining at the end of a toothing, in particular by cutting; but this increases considerably the machining time and therefore the cost of manufactured items.

An object of the present invention is to provide a machine for manufacturing elements which can be machined on a bar for a relatively low cost all ensuring an excellent quality of these elements, and particular toothing for elements where such teeth are provided on a lateral surface, as in the case of crowns for watches.

• des moyens de serrage de ladite au moins une barre;
• des moyens d'avance de ladite au moins une barre selon une première direction parallèle à l'axe longitudinal de cette barre, et
• une unité d'usinage avant située dans une zone avant de ladite fraiseuse et comportant au moins une première fraise mobile agencée pour usiner en bout de barre.

To this end, the present invention relates to a milling machine arranged to receive at least one bar and to machine several elements from this bar, this milling machine comprising:

• means for clamping said at least one bar;
• means for advancing said at least one bar in a first direction parallel to the longitudinal axis of this bar, and
• a front machining unit located in a front zone of said milling machine and comprising at least a first mobile milling cutter arranged to machine at the end of the bar.

This milling machine is characterized in that it further includes a lateral machining unit located in a lateral zone of said milling machine and comprising at minus a second mobile cutter arranged to machine the said at least one bar in a region upstream of the end of it so as to allow at least an initial machining operation of said elements along said at least one bar before these elements are moved to said front area for machining terminal.

According to a particular feature of this invention, the second mobile cutter is designed to machine, on the bar inserted in the milling machine, a toothing, in particular the toothing of the lateral surface of a crowned. Therefore, at least part of the shape elements are machined in the lateral area upstream of the end of the bar where the terminal machining of elements is performed.

According to a preferred embodiment of the invention, the lateral machining unit and the front machining unit are controlled so that the terminal machining of a element at the end of the bar is at least partly simultaneous at the initial operation of another element then located in the aforementioned lateral area so that the operation above and initial machining are performed at least partially in masked time.

Thanks to the characteristics of the invention, the elements are fully machined on a single machine, know the milling machine according to the invention from a bar rough having for example a circular shape or rectangular. Then, all the operations being made by milling on the milling machine, it is possible to obtain very good machining quality. In addition, by the arrangement of the milling machine according to the invention, the man of the trade can place some strawberries and / or means of cutting and / or drilling means in the lateral zone to perform various initial machining operations and other milling cutters and / or cutting means and / or drilling in the front area for terminal machining of elements at the end of the bar.

By a suitable arrangement and control of the various milling cutters and / or cutting means and / or drilling it is possible to significantly reduce the total machining time per element, thereby reducing the cost of manufacturing the elements. We note in particular that in the side area it is possible to arrange the milling cutters and other means of machining along the bar different places so that operations parallel or simultaneous machining are carried out respectively on elements that are planned to be machined on the bar inserted in the milling machine according to the invention.

• la figure 1 est une vue schématique en perspective d'un mode de réalisation d'une fraiseuse selon l'invention;
• la figure 2 est une vue éclatée en perspective d'une partie de la fraiseuse représentée à la figure 1, et
• la figure 3 montre une coupe partielle de la fraiseuse représentée à la figure 1.

Other characteristics and advantages of the milling machine according to the invention will be described below in detail, with the aid of the following description made with the aid of the appended drawings, given by way of non-limiting example, in which:

• Figure 1 is a schematic perspective view of an embodiment of a milling machine according to the invention;
• FIG. 2 is an exploded perspective view of a part of the milling machine shown in FIG. 1, and
• FIG. 3 shows a partial section of the milling machine shown in FIG. 1.

With the aid of FIGS. 1 to 3, a description will be given below. embodiment of a milling machine according to the invention.

The milling machine according to the invention, represented by schematically in Figures 1 to 3, is arranged to receive four bars 2a, 2b, 2c and 2d from of which the milling machine machines several elements. In the present embodiment, it is planned to machine crowns, especially for watchmaking applications, as shown schematically in Figure 3. Note however that the present invention is not limited to the only machining of crowns, but can be used for machining various elements from at minus a bar. In addition, the number of bars that can to be machined in parallel on the milling machine is without importance for the present invention, this number possibly be any.

The milling machine includes a frame 4 on which are arranged positioning and clamping means 6 of bars 2a to 2d. These positioning and tightening means 6 include for each of the bars 2a to 2d a clamp fixed front 8 and movable rear clamp 10. The clamp front 8 and rear clamp 10 are respectively associated with means 12a and 12b for rotating the 2d bar (figure 3). The means of rotation 12a and 12b are digitally controlled so as to allow a precise rotational movement of the 2d bar around its longitudinal axis 14 so as to position angularly this 2d bar relative to this axis longitudinal 14 during various machining operations and in particular the machining of a toothing, as will be described below.

The movable gripper is arranged so that it can undergo a translational movement 16 parallel to the axis longitudinal 14 of bar 2d. Note that the four bars 2a to 2d are integral in the movements of translation planned. The mobile clamp 10 in association with the fixed clamp 8 define means for advancing the bars 2a to 2d in a direction parallel to the longitudinal axis 14 of each of these bars.

It will be noted that other support elements and / or stiffening of the bars, especially between the fixed clamp 8 and the movable clamp 10, can be arranged in a variant embodiment, these elements being formed by example by pebbles.

The positioning and clamping means 6 are arranged so as to be able to undergo in their entirety, relative to the frame 4, a translational movement horizontal 18 and a vertical translational movement 20. Those skilled in the art know the arrangement necessary for perform the translational movements 18 and 20, while as to carry out the translational movement 16 of the mobile clamp 10, and also for controlling these translational movements by an appropriate command, shown schematically in Figure 1 by the unit of command 22.

The milling machine also has a machining unit front 24 located in a front area 26 of the milling machine, this front machining unit 24 comprising at least one cutter 28 for machining at the end of the bar 2d. Note that it is provided in this mode of making three cutters 28, 30 and 32 to make a terminal machining at the end of each of the bars 2a to 2d.

The front machining unit 24 is located downstream of the fixed collet 8 relative to the advance movement of the 2d bar according to the direction defined by its axis longitudinal 14. The front machining unit 24 therefore makes it possible to machining at the end of the bar, element after element in a classic way. The front machining unit 24 is arranged so that it can undergo a movement of translation 34. Note that it is also possible to provide for strawberries 28, 30 and 32 a movement of vertical translation and / or also a movement of translation in the direction defined by the axes 14 of bars 2a to 2d, the latter movement of displacement which can move either the machining unit before 24 as a whole, one of the strawberries 28, 30 and 32 of this front machining unit.

In the context of the invention, the strawberries 28, 30 and 32 can also be formed by means of cutting or drilling means.

According to the invention, the milling machine further comprises a lateral machining unit 40 located in a lateral zone 42 of the milling machine relative to bars 2a to 2d introduced into this milling machine to be machined. The lateral machining unit 40 is arranged to machine laterally the bars 2a to 2d in a region located in upstream of the end of these bars. According to the invention, this lateral machining unit 40 comprises at least one cutter mobile 44 or 46 allowing at least one initial machining operation of the elements 48 along the bar 2d, respectively 2a, 2b and 2c, before these elements 48 are moved to the front area 26 to undergo terminal machining using the machining unit before 24.

In the present embodiment where it is provided to machine crowns, the lateral machining unit 40 has two cutters 44 and 46 for each of the bars 2a in 2d, the cutter 44 used to machine an external surface elements 48 with a toothed profile.

The initial machining operations of the elements 48 carried out by the lateral machining unit 40 are performed on the 2d bar (Figure 3) upstream of the clamp fixed clamping 8 and more particularly between this fixed clamp 8 and the movable clamp 10. As a result, the bar 2d stability in lateral machining area 42 is ensured during the initial machining operations.

In the present embodiment, the strawberries 44 and 46 are mounted on a mobile support 50. The support 50 is arranged so that it can undergo a movement of vertical translation 52 relative to the unit of positioning and tightening 6 of bars 2a to 2d, and also in order to be able to undergo a movement of rotation 54 relative to an axis 56 making it possible to move away strawberries 44 and 46 of bars 2a to 2d. In a variant embodiment, the rotational movement 54 can be replaced by an arrangement allowing movement of translation of strawberries 44 and 46 in one direction perpendicular to the longitudinal axis 14 of the bars 2a to 2d.

Note that in other embodiments, the different machining means that the machining unit includes lateral 40 are not necessarily integral in movement. This is particularly the case when the machining unit side has a drill for machining holes provided in the elements machined from the bars, as is the case in a second embodiment a milling machine according to the invention which will not be described here in detail since it is obvious that the present invention is not limited to the use of two cutters 44 and 46 in the lateral machining of bars 2a at 2d. So, in the case of a drill, the latter can be arranged to have a movement of independent translation in a perpendicular direction to the longitudinal axis 14 of the bars 2a to 2d.

The axis of rotation 56 around which can rotate the lateral machining unit 40 in the embodiment described here is perpendicular to the longitudinal axis 14 of bars 2a to 2d. However, it is also possible to design in another embodiment than axis 56 is parallel to the longitudinal axis 14.

The milling cutter 46 is arranged to machine recesses circular in bar 2d, these recesses having by example a tapered profile. Strawberry 44 is arranged for machining teeth on a lateral surface elements 48. To do this, the cutter 44 is likely to rotate around a perpendicular axis 58 to the longitudinal axis 14 of the bar 2d (Figure 3). Of more, as already mentioned, the cutter 44 is arranged so as to be able to undergo a translational movement vertical, i.e. parallel to the axis 58 of this strawberry 44.

The profit of the teeth of the cutter 44 is defined by the involute of the profile provided on elements 48, namely teeth. A person skilled in the art knows how to calculate the developing such a circular profile so as to define the profile of the teeth of the cutter 44 to obtain the desired teeth. When milling the teeth, the 2d bar rotation movement (figure 3) around its longitudinal axis 14 is synchronized with the movement of vertical translation of the cutter 44 in the direction of axis 58. This synchronization is such that the surface on which the teeth are machined rolls on the strawberry 44 without sliding. The value of the height of the strawberry 44 is at least equal to the value of the periphery of element 48 defined by the external surface on which the teeth are machined. So by a single movement of translation of the cutter 44 in the direction of the axis 58, the toothing of an element machined by the cutter 44 is fully machined.

It will be noted that the cutter 46 is placed in drawing before cutter 44, i.e. upstream of this cutter 44 relative to the displacement of the bars 2a to 2d in direction of the front machining unit 24. The cutter 46 serves to machine two end surfaces of the machined toothing subsequently by the cutter 44 on each of the elements 48. The initial machining, prior to the machining of the teeth, made by the cutter 46 provides a milling burr of the milling cutter 44 which is outside the hollow of the toothing itself, this burr being located then on the end surface of the teeth located on the side of this toothing where the cutter 44, turning around axis 58, comes out of the bar when machining the toothing. The burr being thus out of the hollows of the teeth, it is relatively easy to remove by a finishing operation, in particular carried out at the end of bar by the front machining unit 24.

It will be noted that, in the present mode of embodiment, the cutter 46 is offset vertically, that is to say along the direction of axes 56 and 58, relative to the cutter 44 so that the machining initial performed by the cutter 46 on an element 48 either after or after machining the teeth made by the cutter 44 on another element during a vertical translation movement of the support 50. This ensures perfect stability of the bars during each of the machining operations carried out by the cutters 44 and 46. This arrangement is necessary in the present case being given that the cutters 44 and 46 are mounted on a support common 50 and that the machining of the circular recess in the bar 2d by the cutter 46 is carried out with the cutter 46 in a fixed and determined vertical position, the bar rotating around its longitudinal axis 14 thanks to the rotation means 12a and 12b.

In an alternative embodiment, the cutter 46 and the cutter 44 are not arranged on a common support mobile 50, the cutter 46 being placed in a position fixed when the cutter 44 machining a toothing is moved vertically along its axis 58. In this variant, the machining of a circular recess by the cutter 46 and of a toothing by the cutter 44 along a bar are performed simultaneously in parallel.

An important advantage of the milling machine according to the invention stems from the fact that it is possible to perform some machining in masked time. In a variant preferred of the machining control, the front machining unit 24 and the lateral machining unit 40 are controlled from so that a terminal machining of an element 48 in end of bar is at least partly simultaneous with a initial machining operation by the cutter 44 and / or the cutter 46 on another element 48 then located in the area lateral machining 42, so that this operation initial machining and terminal machining at the end of the bar are performed at least partially in masked time on these two elements.

In a variant embodiment mentioned above, the machining of a circular recess by the cutter 46, the machining of a toothing by the cutter 44 on an element the along the bar and terminal machining using a strawberry 28 on another element at the end of the bar are performed at least partially simultaneously. From this done, the very high quality machining of the teeth on the outer surface of the crowns is made essentially in masked time, which decreases the time total milling of the machined elements and therefore the cost of manufacturing.

We will finally notice that the rotational movement 54 of the cutters 44 and 46 around the axis 56 makes it possible to return the strawberries 44 and 46 to an initial position after a machining operation of a toothing on one of the elements 48, so as to machine the teeth on the element following by operating a translational movement of the cutter 44 in the same direction, and this for machining all the teeth on the elements 48. However, it is possible to imagine machining a toothing with a vertical translation in one direction of the cutter 44 and the teeth on the next element by a translation in the same direction, but in an opposite direction, for the element next. In the latter case, the 2d bar will undergo alternately a rotation in one direction and in the other direction during the successive machining of the teeth on the elements 48. Thus, the rotational movement of the unit lateral machining 40 relative to axis 56 can be necessary when machining bars, or only useful for opening the lateral machining area and allowing easy access to strawberries 44 and 46, in particular for their set up and for their maintenance.

Claims (10)

1. Milling machine for receiving a least one bar (2d) and for machining several elements (48) from said bar, said milling machine including:

   means (8, 10) for clamping said at least one bar;

   means (8, 10) for feeding said at least one bar along a first direction (16) parallel to the longitudinal axis (14) of said bar; and

   a front machining unit (24) located in a front zone (26) of said milling machine and including at least a first mobile milling cutter (28, 30, 32) arranged to machine at the end of the bar;

   said milling machine being characterized in that it further includes a lateral machining unit (40) located in a lateral zone (42) of said milling machine and including at least a second mobile milling cutter (44) arranged to machine said at least one bar in said lateral zone located upstream of the end of the latter so as to enable at least one initial machining operation to be performed on said elements along said at least one bar before said elements are moved into said front zone to undergo final machining.
2. Milling machine according to claim 1, characterized in that said second milling cutter (44) is arranged to machine at least a part of the profile of the outer surface of said elements (48) machined from said bar (2d).
3. Milling machine according to claim 2, characterized in that said second milling cutter (44) is arranged to machine a toothing provided on an outer lateral surface of each of said elements (48) in association with a rotational movement of said at least one bar (2d) about its longitudinal axis (14), said second milling cutter rotating about a rotational axis (58) perpendicular to said longitudinal axis and undergoing a movement along said perpendicular axis which is synchronised with said rotational movement of the bar when said toothing is being machined.
4. Milling machine according to claim 3, characterized in that said lateral machining unit (40) further includes a third milling cutter (46) located upstream of said second milling cutter (44) and used to machine, before said toothing is machined, at least an end surface of the toothing located on the side of said toothing where the second milling cutter comes out of the bar when said toothing is machined relative to the rotation of said second milling cutter about its axis (58).
5. Milling machine according to claim 4, characterized in that said second and third milling cutters are mounted on a common mobile support (50).
6. Milling machine according to claims 1 or 2, characterized in that said lateral machining unit includes a drill enabling holes to be machined provided in said elements machined from said bar.
7. Milling machine according to any of the preceding claims, characterized in that said clamping and feeding means (8, 10) are jointly formed by a fixed front collet (8) and a mobile back collet (10), said front zone (26) where said final machining is performed being located downstream of said front collet (8), whereas said lateral zone (42) where said at least one initial machining operation is performed is located between said front collet (8) and said back collet (10).
8. Milling machine according to any of the preceding claims, characterized in that said lateral machining unit (40) is capable of undergoing a rotation about a rotational axis (56).
9. Milling machine according to any of the preceding claims, characterized in that said lateral machining unit (40) and said front machining unit (24) are controlled such that said final machining of an element (48) at the bar end is at least partly simultaneous with said initial machining operation of another element (48) then located in said lateral zone (42) so that said initial machining operation and said final machining are performed at least partially concurrently on these two elements.
10. Milling machine according to claim 9, characterized in that all the machining operations performed by said lateral machining unit (40) is performed at least partly simultaneously with final machining operations.

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