Grain iron

Abstract

The invention relates to a die (1) for machining the retaining arms (2) of jewelry pieces (4). The die (1) comprises a cylindrical shank (11) and a head (12). The head (12) comprises a cylindrical section (13) and a transition section (14). The shank (11) and the head (12) are arranged along a common central axis (X - X). The outer diameter (11a) of the shank (11) is larger than the outer diameter (13a) of the cylindrical section (13). Furthermore, the cylindrical section (13) is arranged at a first end (15) of the die (1), with the transition section (14) being located between the cylindrical section (13) and the shank (11). The head (12) at the first end (15) has a recess (16) on its end face.

Description

[0001] The invention relates to a graining tool for machining the holding arms of jewelry pieces, and to an arrangement with a rotary tool and a graining tool.

[0002] In jewelry making, gemstones, especially diamonds, are held in a prong setting, for example around a ring, using wire-like prongs made of precious metal. The prongs encircle the gemstone at regular intervals, for example in a three-, four-, or six-prong setting, so that light can enter the gemstone, particularly from the sides or underside, and achieve an attractive light reflection, especially with diamonds. To avoid obstructing the light and to allow for a delicate appearance, the prongs sometimes have very fine structures. After the stone is inserted, the individual prongs must be bent over to secure it. This has traditionally been done with a set tool, which has a thin point with a depression whose diameter is adapted to the shape of the prongs.Existing prong cutters, such as those described in DE 10 2013 01 1607 A1, have a conical tip. This does not allow for resharpening of the tip, as this would change its diameter and thus prevent precise machining of the prongs. Furthermore, the conical tip restricts the view of the workpiece and handling. After the prongs are bent, they are often reground in a further step, for which a hollow drill is used, for example. This machining process results in increased material consumption.

[0003] It is therefore an object of the present invention to provide a graining tool and an arrangement with a rotary tool for machining the retaining arms of jewelry pieces, which, with its simple design and easy, cost-effective manufacturing, offers simplified handling and improved service life. Furthermore, it should enable simplified and faster reworking of the retaining arms.

[0004] This problem is solved with a grain iron having the features of claim 1 and an arrangement having the features of claim 13. The dependent claims describe preferred embodiments of the invention.

[0005] The beading tool according to the invention with the features of claim 1 has the advantage that the beading tool can be reground. This improves the service life of the beading tool and saves costs for new beading tools. Furthermore, a permanently sharp beading tool increases the processing quality of the holding arms of the piece of jewelry. The beading tool according to the invention has a cylindrical shaft and a head, which are arranged along a common central axis. The beading tool can be clamped into a tool via the cylindrical shaft and operated in a rotating manner. The head of the beading tool comprises a cylindrical section, which is arranged at a first end of the beading tool, and a transition section, which is arranged between the cylindrical section and the shaft. The cylindrical section has a smaller outer diameter than the shaft of the beading tool.Furthermore, the head has a concave depression at its first end. This first end thus forms the tip of the apex, which can be used to machine holding arms. The cylindrical section allows the concave depression at the tip of the apex to be resharpened without changing the diameter of the cylindrical section at the first end.

[0006] Preferably, the transition section has a concave surface. This concave surface is preferably tangential to the cylindrical section and curves away from the central axis. This results in a narrow head at the first end of the apex, facilitating easy machining and improved visibility of the workpiece. The increasing curvature towards the cylindrical shaft further contributes to the apex's good mechanical properties.

[0007] The recess is also preferably conical. A conical recess, with its defined flanks, enables precise machining of the retaining arms.

[0008] Particularly preferably, the tip of the conical recess is rounded. This allows for smooth machining of the holding arms due to the smooth transition to the conical recess.

[0009] More preferably, the opening angle of the conical recess is between 100 and 130°, in particular between 115° and 125°. The opening angle of the conical recess is particularly preferably 120°.

[0010] The chamfer is preferably designed to be clamped into a rotary tool. The geometry according to the invention enables simultaneous use of the chamfer for reshaping the holding arms and for polishing the holding arms by rapidly rotating the chamfer around the central axis of the chamfer by the rotary tool. Thus, the tip of the holding arm can be rounded and / or polished without machining, thereby reducing material loss in the material being machined. Since the material is often a precious metal, this can significantly reduce manufacturing costs and contribute to sustainable material use. The operation of the chamfer in a rotary tool is only possible due to the cylindrical section and the option of regrinding the tip without changing the diameter of the tip, since tool wear of the rotating chamfer is increased.The rotating grain iron also allows the prongs to be machined with reduced effort.

[0011] Preferably, the cylindrical section has a length between 0.4 mm and 0.7 mm. In particular, the length of the cylindrical section is 0.5 mm. This length allows for multiple regrinding of the tip without the mechanical properties of the abrasive being impaired due to an excessively long cylindrical section.

[0012] Preferably, the head has a length of 3.2 mm and 6.7 mm. The length of the head increases with decreasing diameter of the cylindrical section. This allows for a smooth transition between the cylindrical shaft and the cylindrical section of the head.

[0013] Preferably, the length of the apex hammer is 40 mm to 50 mm. This relatively short length minimizes the wrist movement required by the jeweler when working on the holding arms. Consequently, a length of 40 mm to 50 mm allows for comfortable and joint-friendly handling of the apex hammer.

[0014] The shank of the graining tool preferably has an outer diameter between 2 mm and 2.6 mm. In particular, the outer diameter of the shank is 2.35 mm, so that it can be arranged in a 104-HP holder of a rotary tool.

[0015] The ratio of the outer diameter of the cylindrical section to the outer diameter of the shaft is preferably between 0.16 and 0.6. Thus, the cylindrical section with the recess in the area according to the invention enables the machining of very fine wire-shaped retaining arms up to larger retaining arms.

[0016] The ratio of the outer diameter of the cylindrical section to the diameter of the recess is preferably between 1.03 and 1.2. The diameter of the recess is defined in a plane on the end face at the first end of the apex. Due to the ratio according to the invention, the apex has a thin edge region at the tip between the cylindrical section and the recess. This thin edge region enables precise machining of the retaining arms.

[0017] The grain iron is preferably made of hard metal or stainless steel.

[0018] Furthermore, an arrangement for processing the retaining arms of jewelry pieces is claimed according to claim 13. The arrangement comprises a die, as previously described, and a rotary tool. The shank of the die is arranged in a tool holder of the rotary tool. The arrangement according to the invention thus enables both the forming and polishing of retaining arms of jewelry pieces by rapidly rotating the die around its central axis.

[0019] Further details, advantages, and features of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawings. It shows: Fig. 1 schematically a grain iron for machining holding arms according to the state of the art, Fig. 2 schematically a grain iron for machining holding arms according to a preferred embodiment of the invention, Fig. 3a schematic side view of the grain iron according to the preferred embodiment, and Fig. 4 A schematic detailed sectional view of the tip of the grain iron according to the preferred embodiment.

[0020] Fig. 1 shows a beading iron 1 according to the prior art, which is used to reshape the holding arms 2 of a piece of jewelry 4. By reshaping the holding arms 2, stones 3 or other objects can be fixed to the piece of jewelry 4. In Figure 1 Figure 1 shows a section of a piece of jewelry 4, which displays four cut gemstones 3 in a setting. Four retaining arms 2 are arranged around each gemstone 3, which in their initial state allow the gemstones 3 to be inserted into the piece of jewelry 4. After insertion, the retaining arms 2 can be reshaped towards the gemstones 3 using the die 1 to fix the gemstones 3 in place. The retaining arms 2 can be, as shown in Figure 1 and Figure 2The retaining arms may have the shape of a polyhedron or, for example, be wire-shaped. The retaining arms preferably consist of the base material of the jewelry piece 4, which is in particular a precious metal such as silver, gold, or platinum. The diameter of the tip of the die 1 is preferably adapted to the size and shape of the retaining arms 2. After the forming process with the die 1, the retaining arms 2 can be post-processed in a single operation, e.g., rounded and polished.

[0021] The grain iron 1 according to the state of the art has a conical head, which widens constantly from a tip to a shaft. Due to the fact that the tip widens directly, it covers Figure 1 the view of two retaining arms 2. Furthermore, according to the state of the art, it is not possible to resharpen the grain iron 1 if its tip is worn.

[0022] In the following, a grain iron 1 according to a preferred embodiment of the invention is described with reference to the Figs. 2 to 4 described in detail.

[0023] Fig. 2 The piece of jewelry shows 4 of Figure 1 with four stones 3, each surrounded by four holding arms 2. Instead of the grain iron 1 according to the state of the art, Figure 2 a head 12 of the grain iron 1 according to the invention is shown.

[0024] In contrast to the prior art graining tool 1, which has a conical head 12, the head 12 of the graining tool according to the invention comprises a cylindrical section 13 and a transition section 14. Thus, the head 12 of the graining tool 1 can be narrower in the region of a first end 15, thereby improving the view of the jewelry piece 4 to be machined. The cylindrical section 13 allows the graining tool 1 to be resharpened when it becomes dull.

[0025] The lateral surface of the transition section 14 is concavely curved in the direction of a central axis X - X. The lateral surface of the transition section 14 lies tangentially against the lateral surface of the cylindrical section 13, so that the cylindrical section 13 transitions smoothly into the transition section 14.

[0026] Figure 3 shows a schematic side view of the entire graining iron 1 according to the preferred embodiment. A cylindrical shaft 11 adjoins the head 12 of the graining iron 1. The shaft 11 and the head 12 are arranged along a common central axis X - X. The shaft 11 of the graining iron 1 is Figure 3 Abbreviated version.

[0027] The outer diameter 13a of the cylindrical section 13 is preferably 0.1 to 0.6 times smaller than the outer diameter 11a of the shank 11. In the illustrated embodiment, the length 13b of the cylindrical section is 0.5 mm. The shank 11 of the abrasive bar 1 is preferably designed as a 104-HP shank with an outer diameter 11a of 2.35 mm, so that the abrasive bar 1 can be clamped in a rotary tool. The shank is preferably turned and has an average surface roughness Rz of 4.

[0028] Clamping the beveling iron 1 into a rotary tool enables regular use of the beveling iron 1 for reshaping the holding arms 2 with the rotary tool as a handpiece. In addition, the inventive shape of the beveling iron 1 enables subsequent rounding and / or polishing of the holding arms 2 by causing the beveling iron 1 to rotate around its central axis X-X by the rotary tool. This is possible with reduced force when using a rotating beveling iron.

[0029] The grain iron 1 is preferably made of a tool steel for cold work, such as DIN / EN-1.2516, which is characterized by high wear resistance and hardness. The tool steel is preferably hardened and annealed and has a Vickers hardness of 810+30 HV. Alternatively, the grain iron 1 can be made of hard metal.

[0030] The die 1 preferably has a length 1b of 40 mm to 50 mm. Due to the comparatively short length 1b, the distance the jeweler has to travel with their wrist when shaping the holding arms 2 can be minimized, resulting in a more comfortable and joint-friendly workflow.

[0031] The head 12 of the grain iron 1 preferably has a length 12b between 3.2 mm and 6.7 mm and is preferably dependent on the outer diameter 13a of the cylindrical section 13. The smaller the outer diameter 13a of the cylindrical section 13, the longer the length 12b of the head 12.

[0032] Figure 4 shows an enlarged cross-sectional view of the grain iron 1 from Figure 3 in the area of ​​the first end 15. A recess 16 is provided at the end face of the cylindrical section 13 at the first end 15.

[0033] The recess 16 is conical, with one apex 18 of the conical recess 16 being rounded. The apex 18 of the recess 16 is preferably located on the center line X - X. The apex 18 transitions continuously into the conical recess 16.

[0034] The opening angle 16c between the opposing areas of the conical recess 16 is preferably 120°.

[0035] A narrow, annular edge region 17 is preferably present between a maximum diameter 16a of the recess 16 and the outer diameter 13a of the cylindrical section 13. The width of the edge region 17 is defined by the ratio between the diameter 16a of the recess 16 and the outer diameter 13a of the cylindrical section 13. The outer diameter 13a of the cylindrical section 13 is preferably 1.03 to 0.2 times larger than the maximum diameter 16a of the recess 16, so that the resulting narrow edge region 17 enables precise machining of the holding arms 2 without slipping.

[0036] In addition to the above written description of the invention, reference is hereby explicitly made to the graphic representation of the invention in the figures for its supplementary disclosure. List of reference symbols

[0037] 1Beading iron 1bLength of the beading iron 2Holding arm 3Stone 4Jewel 11Cylindrical shaft 11aOuter diameter of the shaft 12Head 12bLength of the head 13Cylindrical section 13aOuter diameter of the cylindrical section 13bLength of the cylindrical section 14Transition section 15First end 16Recess 16aDiameter of the recess 16cOpening angle 17Edge area 18Tip of a recess X - XCentral axis

Claims

1. Beading iron (1) for machining holding arms (2) of pieces of jewelry (4), comprising: • a cylindrical shaft (11) and • a head (12) which comprises a cylindrical section (13) and a transition section (14), • wherein the shaft (11) and the head (12) are arranged along a common central axis (X - X), • wherein the outer diameter (11a) of the shaft (11) is larger than the outer diameter (13a) of the cylindrical section (13). • wherein the cylindrical section (13) is arranged at a first end (15) of the beading iron (1), • wherein the transition section (14) is arranged between the cylindrical section (13) and the shaft (11), and • wherein the head (12) has a recess (16) on the front side at the first end (15).

2. Grain iron (1) according to claim 1, wherein the transition section (14) has a concave outer surface.

3. Grain iron (1) according to one of the preceding claims, wherein the recess (16) is conical.

4. Grain iron (1) according to claim 3, wherein a tip (18) of the conical recess (16) is rounded.

5. Grain iron (1) according to claim 3 or 4, wherein the opening angle (16c) of the conical recess (16) is between 100° and 130°, in particular between 115° and 125°, furthermore the opening angle (16c) is in particular approximately 120°.

6. Grain iron (1) according to one of the preceding claims, wherein the grain iron (1) is designed to be clamped in a rotary tool.

7. Grain iron (1) according to one of the preceding claims, wherein the cylindrical portion (13) has a length (13b) between 0.4 mm and 0.7 mm, in particular 0.5 mm.

8. Grain iron (1) according to one of the preceding claims, wherein the head (12) has a length (12b) between 3.2 mm and 6.7 mm.

9. Grain iron (1) according to one of the preceding claims, wherein the grain iron (1) has a length (1b) between 40 mm and 50 mm.

10. Grain iron (1) according to one of the preceding claims, wherein the shaft (11) has an outer diameter (11a) between 2 mm and 2.5 mm, in particular of 2.35 mm.

11. Grain iron (1) according to one of the preceding claims, wherein the ratio of an outer diameter (13a) of the cylindrical portion (13) to the outer diameter (11a) of the shaft (11) is between 0.16 and 0.

6.

12. Grain iron (1) according to one of the preceding claims, wherein the ratio of the outer diameter (13a) of the cylindrical portion (13) to a diameter (16a) of the recess (16) is between 1.03 and 1.

2.

13. Grain iron (1) according to one of the preceding claims, characterized in that it is made of hard metal.

14. Arrangement for machining holding arms (2) of jewelry pieces (4), comprising: • a grain iron (1) according to one of the preceding claims, and • a rotary tool, • wherein a shaft (11) of the grain iron (1) is arranged in a tool holder of the rotary tool.

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