METHOD FOR THE PRODUCTION OF A REAMER

Abstract

A method for the production of a reamer, such as a burr for milling a patient's acetabular cavity, including a substantially hemispherical, hollow cutting body with a perforated wall. The method includes a step of forming at least one tooth by stamping the wall, during which an area of the thinned portion of the wall, adjacent to a hole, is pressed between a punch and an anvil.

Claims

1-8. (canceled)

9. A method for producing a reamer, such as a milling cutter intended to mill the acetabular cavity of a patient, comprising a substantially hemispherical hollow cutter body with a perforated wall, said method comprising a step in which at least one tooth is formed by stamping the wall by means of a punch plastically deforming a portion of the wall extending radially from and away from a hole formed in the wall, wherein, in the stamping of the tooth, a zone of the deformed portion of the wall, adjacent to the hole, is thinned and pressed by the punch against an anvil.

10. The production method as claimed in claim 9, wherein: the punch comprises a free end with a set pressing surface, in the step of forming of the tooth, a generatrix (I-I) of the pressing surface is oblique relative to a plane (P1) defined by the orifice of the hole.

11. The production method as claimed in claim 10, wherein: the anvil comprises a set pressing surface whose generatrix (II-II) is oblique relative to the plane (P1) defined by the orifice of the hole, in the forming of the tooth, the angle (A2) between the generatrix (II-II) of the pressing surface of the anvil and the plane (P1) defined by the orifice of the hole is smaller than the angle (A1) between the generatrix (I-I) of the pressing surface of the punch and the plane (P1) defined by the orifice of the hole, preferably by approximately 2 degrees.

12. The production method as claimed in claim 9, wherein, until the step of forming of the tooth, the cutter body takes the form of a perforated flat metal blank.

13. The production method as claimed in claim 12, wherein the flat metal blank has a thickness (E) of between approximately 0.4 mm and approximately 1 mm.

14. The production method as claimed in claim 12, wherein, after the forming of the tooth, the flat blank is cut to obtain a plurality of perforated and toothed petals extending radially from a central zone from which the petals extend to a free end, and separated from one another by radial lateral spaces.

15. The production method as claimed in claim 14, wherein, after the cutting of the flat blank to form the petals: the flat blank is shaped as a hemisphere, the free ends of the petals are added and fixed onto an at least partially circular base body.

16. The production method as claimed in claim 9, wherein the cutter body is made of stainless steel, preferably of 304L or 316L grade stainless steel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Other objects, features and advantages of the present invention will emerge from the following description of particular embodiments, given in relation to the attached figures, in which:

[0040] FIG. 1 is a perspective view of an exemplary embodiment of a reamer according to the invention;

[0041] FIG. 2 is a perspective view of a follow-on tool workstation;

[0042] FIG. 3 is a front view of a punch;

[0043] FIG. 4 is a side view of the punch of FIG. 3;

[0044] FIG. 5 is a perspective view of the punch of FIG. 3;

[0045] FIGS. 6 to 8 are perspective and cross-sectional views of the second workstation on which a flat metal blank is stamped to form a tooth;

[0046] FIG. 9 is a detailed and side view of FIG. 8;

[0047] FIG. 10 is a perspective and cross-sectional view of the workstation of FIG. 2 after the stamping of the metal blank to form a tooth;

[0048] FIG. 11 is a perspective view of the metal blank after stamping to form a tooth;

[0049] FIG. 12 is a schematic and perspective view illustrating a method for producing the reamer of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0050] FIG. 1 illustrates a reamer 1 which is a milling cutter intended to mill the acetabular cavity of a patient. The reamer 1 comprises a substantially hemispherical hollow cutter body 2 with perforated wall 3. A plurality of teeth 4 have been formed by deformation of the wall 3. Their forming is more particularly done by stamping in a follow-on tool, as will be explained hereinbelow using FIGS. 2 to 12.

[0051] In said stamping, use is made of a punch 5 as illustrated in FIGS. 3 to 5. The punch 5 comprises a free end 5a with set pressing surface 5b whose cross section is in the form of a circular arc of radius R (FIG. 3). The punch 5 is intended to be driven by a two-way translational movement in the axial direction III-III illustrated by the double arrow 5 while a wall 3 to be deformed is located in the plane P1 illustrated in FIG. 6. Thus, in the step of forming of a tooth 4, the generatrix I-I of the pressing surface 5b is oblique relative to the plane P1 (FIG. 9).

[0052] In said stamping, users simultaneously made of an anvil 7 as illustrated in FIG. 2. The anvil 7 comprises a set pressing surface 7a that also has a cross section in the form of a circular arc of radius slightly greater than the radius R. As is more particularly visible in FIG. 6, the generatrix II-II of the pressing surface 7a of the anvil 7 is oblique relative to the plane P1 in which the face of the wall 3 which is not in contact with the anvil 7 is located. More specifically, the plane P1 is defined by the orifice 9 of the hole 10 formed in the wall 3.

[0053] The pressing surfaces 5b and 7a can have a cross section of different form. It is for example possible to envisage a cross section composed of the succession of three circular arcs of different radii, in particular with the first and third radii equal and smaller than the second radius. The pressing surface 5b then has a vertex (while the pressing surface 7a has a bottom) that is a little flattened.

[0054] In the detailed view of FIG. 9 more specifically illustrating the cooperation between the punch 5 and the anvil 7 in the forming of a tooth 4, it can be seen that the angle A2 between the generatrix II-II of the pressing surface 7a of the anvil 7 and the plane P1 is smaller than the angle A1 between the generatrix I-I of the pressing surface 5b of the punch 5 and the plane P1. This difference is approximately 2 degrees.

[0055] In the production of the reamer 1 of FIG. 1, until the step of forming of the tooth 4, the cutter body 2 takes the form of a flat metal blank 11 partially illustrated in FIG. 6. This flat metal blank 11 is provided with a hole 10 with orifice 3. This hole 10 is preferably produced on a preceding workstation of the follow-on tool, and on which the blank 11 is cut by punching. The hole 10 defines the plane P1, which coincides here with the plane of the top face 11a of the flat metal blank 11.

[0056] The flat metal blank 11 has a thickness E of between approximately 0.4 mm and approximately 1 mm. The flat metal blank 11 is made of 304L or 316L grade stainless steel.

[0057] In FIG. 6, the blank 11 rests bearing on the anvil 7 by a face 11b. A portion 8 of wall 3 extends radially from and away from the hole 9 formed in the wall 3, and is situated to correspond with the pressing surface 7a of the anvil 7.

[0058] In a subsequent step, illustrated in FIG. 7, the punch 5 is displaced toward the anvil 7 (as illustrated by the arrow 12) in an axial direction III-III substantially at right angles to the plane P1.

[0059] In this displacement, the punch 5 plastically deforms the portion 8 of wall 3 as illustrated in FIG. 8. Through the principle of conservation of material, a zone 8a of the deformed portion 8 of wall 3, adjacent to the hole 10, undergoes a thinning by virtue of its protruding displacement relative to the face 11b of the flat blank 11.

[0060] At the end of a certain travel of the punch 5, the zone 8a of deformed portion 8 of wall 3, adjacent to the hole 10, is pressed by the punch 5 against the anvil 7 (FIG. 9).

[0061] The stamping and the subsequent pressing between the punch 5 and the anvil 7 of the zone 8a of the deformed portion 8 of wall 3 provide a stretching and a thinning of the wall 3 to form the tooth 4. This thinning gives cutting capabilities to the free edge 4a of the duly formed tooth 4. By suitably controlling the pressing force, a thinning is achieved that is well controlled and repeatable for cutting characteristics that are substantially identical for all the teeth 4.

[0062] The pinching between the punch 5 and the anvil 7 provides a kind of local cold working of the tooth 4 (or fiber orientation of the material) which gives it an increased structural strength and a better durability over time during the use of the reamer 1.

[0063] Here, all of the portion 8 of wall 3 is pinched between the pressing surface 5b of the punch 5 and the pressing surface 7a of the anvil 7. It would however be possible to pinch only a part of the portion 8, said part extending from the hole 10 to at least form the free edge 4a of the tooth 4 by giving if cutting properties and a structural strength that are satisfactory.

[0064] It can be seen in FIG. 9 that, by virtue of the difference between the angles A1 and A2, the thickness of the portion 8 forming the tooth 4 increases progressively away from the free edge 4a of the tooth 4.

[0065] The punch 5 is then displaced away from the anvil 7 by a movement that is the reverse of that illustrated by the arrow 12 in FIG. 7. The blank 11 is then in the configuration illustrated in FIG. 10, and is then removed from the anvil 7 by means of ejectors.

[0066] FIG. 11 partially illustrates the blank 11 provided with the tooth 4 which forms a protuberance on the face 11b.

[0067] Once all the teeth 4 are formed in the flat metal blank 11, the latter is cut to obtain a plurality of perforated and toothed petals 13a to 13h extending radially from a central zone 14 from which the petals 13a to 13h extend to a free edge 130a to 130h. The petals 13a to 13h are separated from, one another by radial lateral, spaces (step a) in FIG. 12).

[0068] Next, in a step b), the flat blank 11 is shaped as a hemisphere. Then, in a step c), the free ends 130a to 130h of the petals 13a to 13h are added and fixed onto an at least partially circular base body 15. The blank 11 is then kept in substantially hemispherical dome form to form a cutter body 2 capable of milling the acetabular cavity of a patient.

[0069] The present invention is not limited to the embodiments which have been explicitly described, but it includes the miscellaneous variants and generalizations thereof contained in the scope of the claims hereinbelow.