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JP-2026075603-A - Manufacturing method of Kobako Shin

JP2026075603AJP 2026075603 AJP2026075603 AJP 2026075603AJP-2026075603-A

Abstract

[Problem] To provide a method for manufacturing a barrel arsenal used in watchmaking. [Solution] The mainspring barrel 1 is arranged to pivot around a pivot D and includes a core 3 having a support surface 30 for the inner coil of the mainspring, from which a hook 2 protrudes to engage with an eyelet in the inner coil, the hook includes an end face that functions as a support for the eyelet when the mainspring is wound, and the core includes a relief 4 upstream of the hook in the winding direction of the mainspring for holding the end of the mainspring. The method is, - The process of preparing the rod material, - A process of forming at least one cylindrical portion including a vertical surface and a horizontal surface by tracing and turning a rod material. - The process includes machining a cylindrical portion by performing several translational reciprocating motions in the true pivot direction to simultaneously form the core, including the hook, support surface, and relief, using a broaching tool. [Selection Diagram] Figure 1

Inventors

  • モレル、 ドリアン
  • ハフェリ、 フレデリック

Assignees

  • ニヴァロックス－ファー ソシエテ アノニム

Dates

Publication Date
20260508
Application Date
20251007
Priority Date
20241022

Claims (8)

  1. A method for manufacturing a barrel arbor (1) used in watchmaking, wherein the barrel arbor (1) is arranged to pivot around a pivot (D), and the barrel arbor (1) includes a core (3) having a support surface (30) for the inner coil of a mainspring, from which a hook (2) protrudes to engage with an eyelet in the inner coil, and the core (3) also has a relief (4) upstream of the hook (2) in the winding direction (S) of the mainspring for holding the end of the mainspring. The aforementioned method, - The process of preparing the rod material, - A step of tracing and turning the aforementioned rod material to form at least one cylindrical portion (13) including a vertical surface and a horizontal surface, A method characterized by comprising the step of machining the cylindrical portion (13) by performing several translational reciprocating motions in the direction of the true pivot (D) in order to simultaneously form the core including the hook (2), the support surface (30), and the relief (4) using a broaching tool.
  2. A method for manufacturing a barrel arsenal (1) used in watchmaking, as described in claim 1, characterized in that the reciprocating motion is performed with a cutting depth of 0.2 mm.
  3. A method for manufacturing a barrel arbor (1) used in watchmaking, as described in claim 1, characterized in that the support surface (30) of the mainspring includes a sector (33) having a helical cross-section and a sector (34) having a cylindrical cross-section.
  4. A method for manufacturing a barrel arsenal (1) used in watchmaking, as described in claim 1, characterized in that the relief (4) has a curved surface.
  5. A method for manufacturing a barrel truss (1) used in watchmaking according to claim 1, characterized in that the material of the truss is selected from metal or a metal alloy.
  6. A method for manufacturing a barrel arbor (1) used in watchmaking, as described in claim 1, characterized in that the vertical surface (20) for forming the hook (2) and the curved support surface (30) are machined simultaneously using the same broaching tool.
  7. A method for manufacturing a barrel truss (1) used in watchmaking, as described in claim 1, characterized in that the broaching tool is a forming tool having a punched shape identical to the desired shape of the barrel truss.
  8. A barrel truss obtained by the method described in claim 1.

Description

This invention relates to a method for manufacturing a barrel arbor used in watchmaking. The barrel arbor pivots around a pivot axis and includes a hook that engages with the inner coil of the barrel spring in a single winding direction. Furthermore, it includes a curved spring support surface in a first portion of the periphery near the hook and downstream of the hook in the winding direction, which supports the inner coil. In a mechanical watch movement, the barrel is the prime mover that supplies the energy necessary to power the various components. The barrel includes a drum, a cover that closes the drum, a barrel arbor on which the drum and cover pivot freely, and a mainspring incorporated into the drum. The outer coil of the mainspring is held by the drum wall. The barrel arbor includes a portion known as the core, which has a hook to which the inner coil of the mainspring is attached. The barrel arbor is rotatably fixed to a ratchet, and via this ratchet, it can be rotated by a winding stem (manual winding) or an oscillating mass (automatic winding) on the movement to wind the mainspring and store energy. The mainspring barrel arbor of a watch is a small component subjected to considerable stress and requires special care in its manufacture. Its geometric shape, particularly the presence of a hook, generally makes machining it quite costly. The hook requires machining around its entire circumference to ensure it securely engages with the mainspring and, on the other hand, to allow sufficient play in the eyelet on the mainspring. The barrel truss is usually machined through several milling operations. However, with commonly used milling cutters, the cutter radius is too large, making some angles difficult to manufacture. Therefore, one objective of the present invention is to provide a simpler method for manufacturing a kōbako shin (a type of Japanese confectionery box), requiring fewer steps. For this purpose, the present invention relates to a method for manufacturing a barrel arbor used in watchmaking. The barrel arbor comprises a core positioned to pivot around a pivot and including a support surface for the inner coil of a mainspring, from which a hook protrudes to engage with an eyelet in the inner coil, and the core also includes a countersink upstream of the hook in the winding direction of the mainspring for holding the end of the mainspring. According to the present invention, this method is - The process of preparing the bar material, - A step of profile turning the aforementioned rod material to form at least one cylindrical portion including a vertical plane and a horizontal plane, The process includes machining the cylindrical portion by performing several translational reciprocating motions in the direction of the true pivot in order to simultaneously form the core, including the hook, the support surface, and the relief, using a broaching tool. According to other advantageous modifications of the present invention, The aforementioned reciprocating motion is performed with a cutting depth (passes) of 0.2 mm. - The support surface of the mainspring includes a sector having a helical cross-section and a sector having a cylindrical cross-section. - The relief has a curved surface, The aforementioned true material is selected from metals or metal alloys. - The vertical surface for forming the hook and the curved support surface are machined simultaneously using the same broaching tool. The broaching tool is a forming tool having a punched shape identical to the desired shape of the barrel truing post. This invention also relates to a barrel truss obtained using the method according to the present invention. Other features and advantages of the present invention will become apparent from the following detailed description with reference to the accompanying drawings. This is a perspective view of the barrel according to the present invention.Figure 1 is a cross-sectional view along the P-plane of the barrel's true axis.Figures 3 to 5 show the steps in the manufacturing method of the Koubako Shin.Figures 3 to 5 show the steps in the manufacturing method of the Koubako Shin.Figures 3 to 5 show the steps in the manufacturing method of the Koubako Shin.Figures 6a and 6b are schematic diagrams of cutting tools used to machine the barrel arbor.This is a schematic diagram of the machining tools positioned at the mainspring barrel shaft that is scheduled for machining. This invention relates to the manufacture of a barrel arbor 1 used in watchmaking. The barrel arbor includes a hook 2 for engaging with the inner coil of the barrel mainspring in a single winding direction S. Referring to Figures 1 and 2, the barrel trunnion 1 according to the present invention includes at least one pivot 10 for pivoting around axis D in a bearing within the watch movement, a rectangular cross-section portion 14 to which a ratchet wheel can be attached, two cylindrical portions 11 and 12 for pivoting the barrel drum an