COMPOSITE MILLING CUTTER

Description

BACKGROUND OF THE INVENTION 1. Technical Field

[0001] The present invention relates to a chamfer mill, and more particularly to an assembled chamfer mill provided with an extension shaft having an appropriate length according to the thickness of a workpiece, so as to adjust the distance between two chamfer bits connected to opposing two ends of the extension shaft. The assembled chamfer mill is especially suitable for simultaneously chamfering the edges of a workpiece in the form of a thin plate.2. Description of Related Art

[0002] In general, after the surface of a workpiece is machined, the edges of the workpiece are chamfered or deburred successively to avoid sharp edges or burrs occurred to affect the assembly accuracy and size of the workpiece. A conventional chamfer mill generally uses a single chamber bit for directly cutting or milling a workpiece by 45 degrees or rounding the corners of the workpiece. However, for a thin workpiece, the workpiece is generally chamfered and deburred manually with a grinder.

[0003] Taiwan Patent TWM443594U discloses a chamfer cutter, comprising a round blade disc, three blade holders and three blades. The blade holders each have a front taper portion. The front taper portion has an upper slope and a lower slope intersecting the upper slope. The blades each have a front taper cutting portion. The front taper cutting portion has an upper cutting slope and a lower cutting slope intersecting the upper cutting slope. The upper cutting slope and the lower cutting slope correspond to the upper slope and the lower slope, respectively. The chamfer cutter is used to cut the top and bottom edges of a workpiece to form upper and lower chamfers without turning the workpiece.

[0004] The above-mentioned chamfer cutter may include two chamfer cutters arranged one on top of another and connected to a rotating member. The distance between the blades of the two chamfer cutters is the thickness of a workpiece for chamfering the upper and lower edges of the workpiece simultaneously. But, its disadvantage is that the two chamfer cutters need to be arranged one on top of another. The thickness of the chamfer is also limited by the thickness of the chamfer cutters, being a fixed size. It is not suitable for chamfering the upper and lower edges of a thin workpiece or a workpiece with a changing thickness.

[0005] EP3539701A1 discloses an example of an assembled chamfer cutter according to the preamble of claim 1.SUMMARY OF THE INVENTION

[0006] In view of the shortcomings of the prior art, the primary objective of the present invention is to provide an assembled chamfer mill.

[0007] The assembled chamfer mill of the present invention comprises the features of claim 1, which include a tool holder, a plurality of chamfer bits, at least one extension shaft, and a screw bolt. The chamfer bit is insertedly connected to one end of the tool holder. One end of the extension shaft is insertedly connected to the chamfer bit so that the extension shaft locks the chamfer bit to the tool holder. The other end of the extension shaft is connected with the other chamfer bit locked by the screw bolt. Thus, the two ends of the extension shaft are connected with at least two chamfer bits. The chamfer bit has upper blades and lower blades for chamfering the edges of a workpiece simultaneously.

[0008] The length of the shaft body of the extension shaft of the present invention may be set in various sizes. Depending on the thickness and shape of the workpiece, the extension shaft having an appropriate length is selected to control the distance between the two chamfer bits, or another extension shaft is provided to connect a further chamber bit for chamfering the edges of the workpiece simultaneously.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is an exploded view of the assembled chamfer mill of the present invention; FIG. 2 is a cross-sectional view of the assembled chamfer mill of the present invention; FIG. 3 is a cross-sectional view of the assembled chamfer mill coupled with two chamfer bits for chamfering a thick workpiece according to an embodiment of the present invention; FIG. 4 is a schematic view of the assembled chamfer mill coupled with a short extension shaft and two chamfer bits for chamfering a thin workpiece according to an embodiment of the present invention; FIG. 5 is a schematic view of the assembled chamfer mill coupled with three chamfer bits for chamfering a workpiece according to an embodiment of the present invention; FIG. 6 is a schematic view of the assembled chamfer mill coupled with a single chamfer bit; FIG. 7 is a cross-sectional view of the chamfer bit wherein the upper blade and the lower blade of the chamfer bit are concavely curved surfaces; FIG. 8 is a cross-sectional view of the chamfer bit wherein the upper blade the lower blade of the chamfer bit are sloping surfaces; and FIG. 9 is a cross-sectional view of the chamfer bit wherein an arc-shaped groove is formed between the upper blade and the lower blade of the chamfer bit. DETAILED DESCRIPTION OF THE INVENTION

[0010] Referring to FIG. 1 and FIG. 2, an assembled chamfer mill 1 of the present invention comprises a tool holder 10, a plurality of chamfer bits 20, an extension shaft 30, and a screw bolt 40.

[0011] The tool holder 10 has its one end recessed with a tool holder inner taper hole 11 functioning as a joint surface and a tool holder inner screw hole 12 extending inwardly from the tool holder inner taper hole 11.

[0012] The chamfer bits 20 are disposed at both ends of an extension shaft 30 and locked to the tool holder 10. Each chamfer bit 20 has opposing two ends formed with a cylindrical hole 23 and a chamfer bit inner taper hole 24 communicating with the cylindrical hole 23. One end of the chamfer bit 20 has a taper top 21. The taper top 21 and the cylindrical hole 23 are located at the same end of the chamfer bit 20. The taper top 21 functions as a joint surface. The taper top 21 is fitted with the tool holder inner taper hole 11, so that the cylindrical hole 23 and the chamfer bit inner taper hole 24 communicate with the tool holder inner taper hole 11 and the tool holder inner screw hole 12. A plurality of upper blades 221 and a plurality of lower blades 222 are arranged annularly on the periphery of the chamfer bit 20. The upper blades 221 and the lower blades 222 of the chamfer bit 20 are arranged at an equal angle (as shown in FIG. 4). The cylindrical hole 23 functions as a guide, and the chamfer bit inner taper hole 24 functions as a joint surface.

[0013] The extension shaft 30 includes a shaft body 31. The length of the shaft body 31 is set according to the thickness of a workpiece to be machined. One end of the shaft body 31 is sequentially extended with an extension shaft taper rod 34, a guide post 33 and a screw rod 32. The other end of the extension shaft 30 is recessed with an extension shaft inner taper hole 35 and an extension shaft inner screw hole 36 extending inwardly from the extension shaft inner taper hole 35. The extension shaft taper rod 34, the guide post 33 and the screw rod 32 of the extension shaft 30 are inserted into the chamfer bit inner taper hole 24 and the cylindrical hole 23, so that the screw rod 32 is locked into the tool holder inner screw hole 12 of the tool holder 10, the guide post 33 is fitted with the cylindrical hole 23 of the chamfer bit 20, and the extension shaft taper rod 34 is fitted with the chamfer bit inner taper hole 24. The other chamfer bit 20 is connected to the extension shaft 30, so that the taper top 21 of the other chamfer bit 20 is fitted with the extension shaft inner taper hole 35, and the cylindrical hole 23 and the chamfer bit inner taper hole 24 of the other chamfer bit 20 communicate with the extension shaft inner taper hole 35 and the extension shaft inner screw hole 36.

[0014] The screw bolt 40 has opposing two ends provided with a screw thread 41 and a screw bolt taper rod 42. The screw bolt 40 is inserted into the chamfer bit inner taper hole 24 and the cylindrical hole 23 of the other chamfer bit 20, so that the screw thread 41 is engaged with the extension shaft inner screw hole 36, and the screw bolt taper rod 42 is fitted with the extension shaft inner taper hole 35, thereby being correspondingly fitted with the chamfer bit inner taper hole 24 of the other chamfer bit 20. Thus, the other chamfer bit 20 is locked to the extension shaft 30.

[0015] As shown in FIG. 2, the tool holder 10 of the present invention is connected with two chamfer bits 20 in series, and the two chamfer bits 20 are separated by the extension shaft 30. The shaft body 31 of the extension shaft 30 is configured to control the distance between the two chamfer bits 20 to match the thickness of the workpiece to be machined. As shown in the embodiment of FIG. 3, the shaft body 31 having an appropriate length of the extension shaft 30 is selected for use, in cooperation with the thickness t of the workpiece 5. As shown in FIG. 4, if the workpiece 5 has a small thickness t, the extension shaft 30 having a shorter length of the shaft body 31 is selected for assembly, so as to form an assembled chamfer mill 1 with a shorter interval for chamfering operations.

[0016] As shown in FIG. 5, the number of chamfer bits 20 of the assembled chamfer mill 1 of the present invention can be appropriately adjusted according to the diversity of the workpiece 5 to be machined. The workpiece 5 in an I-like shape, as shown in FIG. 5, has three edges to be chamfered. The present invention may be assembled with three chamfer bits 20 and two extension shafts 30 having an appropriate length, so that three edges of the workpiece 5 can be chamfered at one time.

[0017] In addition to this arrangement that the tool holder 10 of the present invention is in cooperation with plural chamfer bits 20 through the extension shaft 30 for chamfering, as shown in FIG. 6, which shows an assembled chamfer mill not according to the invention, the tool holder 10 may be in cooperation with a single chamfer bit 20 locked by the screw bolt 40 to form the chamber mill for performing the chamfering operation of a single edge.

[0018] Please refer to FIG. 1 and FIGS. 7-9. In the chamfer bit 20 of the assembled chamfer mill of the present invention, the upper blades 221 of the chamfer bit 20 are connected to the taper top 21. The upper blades 221 and the lower blades 222 of the chamfer bit 20 are gradually reduced outwardly. As shown in FIG. 7, the upper blades 221 and the lower blades 222 of the chamfer bit 20 are concavely curved surfaces. As shown in FIG. 8, the upper blades 221 and the lower blades 222 of the chamfer bit 20 are sloping surfaces. As shown in FIG. 9, an arc-shaped groove is formed between each of the upper blades 221 and a corresponding one of the lower blades 222 of the chamfer bit 20.

[0019] Although particular embodiments of the present invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the scope of the present invention. Accordingly, the present invention is not to be limited except as by the appended claims.

Claims

1. An assembled chamfer mill (1), configured to chamfer a workpiece (5), comprising: a tool holder (10), having its one end recessed with a tool holder inner taper hole (11) and a tool holder inner screw hole (12) extending inwardly from the tool holder inner taper hole (11); a chamfer bit (20), having opposing two ends formed with a cylindrical hole (23) and a chamfer bit inner taper hole (24) communicating with the cylindrical hole (23), one end of the chamfer bit (20) having a taper top (21), a plurality of upper blades (221) and a plurality of lower blades (222) being arranged annularly on the chamfer bit (20); the chamfer bit (20) being connected to the tool holder (10), the taper top (21) being fitted with the tool holder inner taper hole (11) so that the cylindrical hole (23) and the chamfer bit inner taper hole (24) communicate with the tool holder inner taper hole (11) and the tool holder inner screw hole (12); a screw bolt (40), having opposing two ends provided with a screw thread (41) and a screw bolt taper rod (42), the screw bolt (40) being inserted into the chamfer bit inner taper hole (24) and the cylindrical hole (23) of the chamfer bit (20) so that the screw thread (41) is engaged with the tool holder inner screw hole (12) of the tool holder (10) and the screw bolt taper rod (42) is fitted with the chamfer bit inner taper hole (24), thereby locking the chamfer bit (20); characterized in that the assembled chamfer mill (1) further comprises an extension shaft (30) and another chamfer bit (20), wherein the extension shaft (30) includes a shaft body (31), the shaft body (31) has a length that is set according to a thickness of the workpiece (5), one end of the shaft body (31) is sequentially extended with an extension shaft taper rod (34), a guide post (33) and a screw rod (32), another end of the extension shaft (30) is recessed with an extension shaft inner taper hole (35) and an extension shaft inner screw hole (36) extending inwardly from the extension shaft inner taper hole (35); after the screw bolt (40) is removed from the chamfer bit (20) and the tool holder (10), the extension shaft taper rod (34), the guide post (33) and the screw rod (32) of the extension shaft (30) are inserted into the chamfer bit inner taper hole (24) and the cylindrical hole (23) of the chamfer bit (20), so that the screw rod (32) is locked into the tool holder inner screw hole (12) of the tool holder (10), the guide post (33) is fitted with the cylindrical hole (23) of the chamfer bit (20), and the extension shaft taper rod (34) is fitted with the chamfer bit inner taper hole (24); the another chamfer bit (20) is connected to the extension shaft (30), so that the taper top (21) of the another chamfer bit (20) is fitted with the extension shaft inner taper hole (35), and the cylindrical hole (23) and the chamfer bit inner taper hole (24) of the another chamfer bit (20) communicate with the extension shaft inner taper hole (35) and the extension shaft inner screw hole (36), the screw bolt (40) is inserted into the chamfer bit inner taper hole (24) and the cylindrical hole (23) of the another chamfer bit (20), so that the screw thread (41) is engaged with the extension shaft inner screw hole (36), and the screw bolt taper rod (42) is fitted with the extension shaft inner taper hole (35), thereby being correspondingly fitted with the chamfer bit inner taper hole (24) of the another chamfer bit (20), thereby locking the another chamfer bit (20) to the extension shaft (30).

2. The assembled chamfer mill (1) as claimed in claim 1, wherein the extension shaft (30) is plural with different lengths.

3. The assembled chamfer mill (1) as claimed in claim 1, wherein after the screw bolt (40) is removed from the another chamfer bit (20) and the extension shaft (30), at least another extension shaft (30) and the another chamfer bit (20) are assembled with the tool holder (10) in sequence, and then the another extension shaft (30) and the another chamfer bit (20) are locked by the screw bolt (40).

4. The assembled chamfer mill (1) as claimed in claim 1, wherein the upper blades (221) of the chamfer bit (20) are connected to the taper top (21).

5. The assembled chamfer mill (1) as claimed in claim 1, wherein the upper blades (221) and the lower blades (222) of the chamfer bit (20) are arranged at an equal angle.

6. The assembled chamfer mill (1) as claimed in claim 5, wherein the upper blades (221) and the lower blades (222) of the chamfer bit (20) are gradually reduced outwardly.

7. The assembled chamfer mill (1) as claimed in claim 6, wherein the upper blades (221) and the lower blades (222) of the chamfer bit (20) are sloping surfaces or concavely curved surfaces.

8. The assembled chamfer mill (1) as claimed in claim 7, wherein the upper blades (221) and the lower blades (222) of the chamfer bit (20) are arranged in a same or different configuration.

9. The assembled chamfer mill (1) as claimed in claim 6, wherein an arc-shaped groove is formed between each of the upper blades (221) and a corresponding one of the lower blades (222) of the chamfer bit (20).