HOB CUTTER ARRANGEMENT

Abstract

A hob cutter arrangement includes a tool body which has a continuous axial bore, conical bore sections forming both ends of the axial bore, an end shank body at each end of the tool body, and a conical section inserted into the conical bore section. Each end shank body has a radial flange which can be placed against an end face of the tool body and a shaft section on the side of the flange opposite the conical section for clamping in a machine tool. An axle connects the end shank bodies and clamps them together. The end shank bodies are provided with blind holes opening towards the axle and provided with threads to the axle. Elastic elements are clamped between a central section of the axle and a front side of the end shank body on both sides of the axle.

Claims

1. A hob cutter arrangement with a tool body is at least partially formed from a cutting material, and which has a continuous axial bore, conical bore sections forming both ends of the axial bore, an end shank body, respectively, at each end of the tool body, adapted for coupling with a hobbing machine, and which has a conical section inserted fittingly into the conical bore section, and which has a radial flange which can be placed against the end face of the tool body when the section is seated in the bore section, and which end shank body has a shaft section on the side of the flange opposite the conical section for clamping in a machine tool, with an axle connecting the end shank bodies, which is adapted to clamp the end shank bodies together and bias the conical sections into the bore sections, and which is provided with at least partly threaded end sections, wherein at least one of the end shank bodies are provided with axial blind holes for insertion of the end sections of the axle and which are provided with complementary threads to the axle, and that elastic elements are clamped between the axle and the front side of the end shank body on both sides of the axle.

2. A hob cutter arrangement with a tool body which is at least partially formed from a cutting material, and which has a continuous axial bore, conical bore sections forming both ends of the axial bore, an end shank body, respectively, at each end of the tool body, adapted for coupling with a hobbing machine, and which has a conical section inserted fittingly into the conical bore section, and which has a radial flange which can be placed against the end face of the tool body when the section is seated in the bore section, and which end shank body has a shaft section on the side of the flange opposite the conical section for clamping in a machine tool, with an axle connecting the end shank bodies, which is adapted to clamp the end shank bodies together and bias the conical sections into the bore sections, and which is provided with at least partly threaded end sections, wherein at least one of the end shank bodies are provided with axial blind holes for insertion of the end sections of the axle.

3. The hob cutter arrangement according to claim 2, wherein the axle has a central section with an outer diameter smaller than the inner diameter of the central section of the tool body.

4. The hob cutter arrangement according to claim 2, wherein at least one circumferential coupling arrangement between the axle and the tool body is located in the central section.

5. The hob cutter arrangement according to claim 4, wherein the coupling arrangement includes a positive connection with a longitudinal groove in the inner surface of the tool body and a longitudinal ridge on the surface of the axle.

6. The hob cutter arrangement according to claim 5, wherein the longitudinal ridge is formed by an insert piece received in a longitudinal groove of the axle.

7. The hob cutter arrangement according to claim 6, wherein the axle has sections with smaller diameter than the central section and adjacent to the central section, with pressure springs fit onto said sections for acting onto the end shank pieces.

8. The hob cutter arrangement according to claim 7, wherein each end shank piece is provided with at least one locking screw cooperating with a non-threaded portion of the end section of the axle.

9. The hob cutter arrangement according to claim 8, wherein a clamping ring is inserted between the flange of the end shank body and the end of the tool body on each side of the tool body.

10. A hob cutter comprising: a tool body having a continuous axial bore, conical bore sections forming both ends of the axial bore, an end shank body, respectively, at each end of the tool body, and which has a conical section inserted fittingly into the conical bore section, and which has a radial flange which can be placed against the end face of the tool body when the section is seated in the bore section, and which end shank body has a shaft section on the side of the flange opposite the conical section for clamping in a machine tool, with an axle connecting the end shank bodies, which is adapted to clamp the end shank bodies together and bias the conical sections into the bore sections, and which is provided with at least partly threaded end sections, wherein at least one of the end shank bodies are provided with axial blind holes for insertion of the end sections of the axle.

11. The hob cutter according to claim 10, wherein the axle has a central section with an outer diameter smaller than an inner diameter of a central section of the tool body.

12. The hob cutter according to claim 10, wherein at least one circumferential coupling arrangement is located between the axle and the tool body.

13. The hob cutter according to claim 12, wherein the coupling arrangement includes a longitudinal groove in an inner surface of the tool body.

14. The hob cutter according to claim 13, further comprising a longitudinal ridge formed by an insert piece received in the longitudinal groove of the axle.

15. The hob cutter arrangement according to claim 14, wherein the axle has sections with a smaller diameter than a central section and adjacent to the central section, pressure springs fit onto said sections.

16. The hob cutter according to claim 10, wherein each end shank piece is provided with at least one locking screw that cooperates with a non-threaded portion of the end section of the axle.

17. The hob cutter arrangement according to claim 10, further comprising a clamping ring inserted between the flange of the end shank body and the end of the tool body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The disclosure will be explained in greater detail below with reference to an embodiment shown in the drawings.

[0022] FIG. 1 shows a single-piece hobbing cutter according to the prior art,

[0023] FIG. 2 shows an explosion view of an exemplary embodiment of a hob cutter arrangement according the disclosure,

[0024] FIG. 3 shows an axial front view of the hob cutter arrangement of FIG. 2,

[0025] FIG. 4 shows a side view of another embodiment of an end shank piece for a hobbing cutter, for instance for the embodiment of the hob cutter arrangement of FIG. 2,

[0026] FIG. 5 shows a longitudinal section of the hob cutter arrangement according to FIG. 2,

[0027] FIG. 6 shows a cross section along line VI-VI in FIG. 5, seen in the direction of the arrows,

[0028] FIG. 7 shows a cross section along line VII-VII in FIG. 5, seen in the direction of the arrows, and

[0029] FIG. 8 shows a cross section along line VIII-VIII in FIG. 5, seen in the direction of the arrows.

DETAILED DESCRIPTION

[0030] While this disclosure may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the disclosure. This description is an exemplification of the principles of the disclosure and is not intended to limit the disclosure to the particular embodiment illustrated.

[0031] The prior art hob cutters, as depicted in FIG. 1, consist mainly of a cutting part 1.1 of solid carbide, with cutting part—machine interfaces 1.2, 1.3. One interface 1.2 is coupled to the drive side of the machine and the other interface 1.3 is used as a guide element.

[0032] The main element of the hybrid hob cutter according to the present disclosure, a preferred embodiment shown in FIGS. 2 to 8, is a tool body 2.1 made from carbide cutting material. End shank pieces 2.2 and 2.3 as the tool body—machine interfaces are made of hardened steel. Thus, each of these elements is made from the most suitable material for the respective purpose. One end shank piece 2.2 is coupled to the drive side of the machine and can be for instance designed with at least one flat at the outer end opposite the tool body side. The other end shank piece 2.3 is used as a guide element and could also show at least one flat, preferably two flats 2.22. The shaft sections of the end shank pieces 2.2 and 2.3 are shaped depending on the machine the hob cutter arrangement is used for.

[0033] Further, the tool body 2.1 has a cutting portion 2.5 on which the cutting teeth are provided and an axial bore 2.6, the inner surface of which bore 2.6 can remain unworked and raw but could also be grinded. In a preferred embodiment, at least one axial groove 2.12 is provided in the bore 2.6 (for coupling with the axle by an insert piece 2.11, see FIGS. 6 to 8).

[0034] The two end sections 2.7 of the bore 2.6 in the tool body 2.1 are tapered, preferably with an angle between 5 and 25°, most preferably with an angle of 14°, as can be seen best in FIG. 5. These ranges allow for the best combination of centering properties and fixation by the end shank pieces 2.2 and 2.3 and their corresponding cones 2.25 (as explained below).

[0035] The two bearing faces 2.8 of the tool body 2.1 are rectified perpendicular to the axis of the tool body 2.1 and the two tapered end sections 2.7. Test collars 2.9 are provided adjacent to the cutting portion 2.5 of the tool body 2.1.

[0036] A hardened steel pin is provided as the axle 2.10 of the hob cutting arrangement with at least partly threaded sections 2.13 at both ends. Preferred is an embodiment with end sections 2.13 threaded preferably over their whole length. Further, at least one axial groove 2.24 (seen better in FIGS. 6 and 7) is provided on the outer surface of the axle 2.10, for coupling with the tool body 2.1 by an insert piece 2.11, which engages with both grooves 2.12 and 2.24 and thereby couples the axle 2.10 with the tool body 2.1. The insert piece 2.11 is secured and fixed in the groove 2.24 by a screw 2.27. Rotation of the axle 2.10 also rotates the tool body 2.1, even without contact of the inner surface of the tool body 2.1 and the outer surface of the axle 2.10, as the largest outer diameter is preferably smaller than the minimum inner diameter of the tool body 2.1, and can be at maximum corresponding to the minimum inner diameter of the tool body 2.1, to allow for easy assembling the tool body 2.1 and the steel pin as the axle 2.10 by inserting the steel pin in the axial bore 2.6.

[0037] The end shank piece 2.2 is built for coupling the hob cutter arrangement with the drive section of the hob cutting machine. One end of the end shank piece 2.2 has a centering cone 2.25 with a complementary angle to those of the tapered section 2.7 of the bore 2.6 of the tool body 2.1. The angle of the conical section lies preferably between 5 and 25° and is most preferred being 14°. The conical section 2.25 is further provided with a blind hole 2.14 with a section with an inner thread designed, opening towards the axle 2.10 and located to be connected to the threaded end section 2.13 of the axle 2.10. Thus, this is allowing an adjusting and clamping action of the tool body 2.1 by adjusting the distance of the end shank pieces 2.2 and 2.3 on the axle 2.10 by screwing them onto the end sections 2.13 or screwing them in the other direction.

[0038] The end shank piece 2.3 on the opposite side is structured in the same way as end shank piece 2.2, with respect to its inner side for coupling with the tool body 2.1 and the threaded end section 2.13 of the axle 2.10. The portion of the end shank piece 2.3 opposite the cone 2.25 is adapted to the function of this end shank piece 2.3 as a guide piece in the hobbing machine.

[0039] Before assembling, the end shank pieces 2.2 and 2.3 are completely machined between their outer end points thanks to two center holes 2.15 (see FIG. 3) and 2.16, so as to result in an outer geometry of the arrangement having a theoretical runout of Zero, and to guarantee on optimum concentricity. The tightening of the tool body 2.1 and its end shank pieces 2.2, 2.3 is made by screwing. It is a cone-to-face clamping. Centering is ensured by the conical surfaces 2.7 of the bore 2.6 and the cone sections 2.25 of the end shank pieces 2.2 and 2.3.

[0040] Between the front surfaces 2.19 of the end shank pieces 2.2, 2.3 and the front surface 2.8 of the tool body 2.1 deformable washers 2.17 are inserted, which ensure an optimal tightening and coupling of the tool body 2.1 and the end shank pieces 2.2, 2.3 by deformation. The assembly is secured by at least one screw, preferably by three countersunk screws 2.18 with brass end caps. The latter end caps are provided with a threaded front part, for engaging the threaded end section 2.13 of the axle 2.10. The screws 2.18 are distributed evenly around the circumference of the end shank pieces 2.2, 2.3.

[0041] The assembly is kept in tension by means of springs 2.20 previously mounted on the axle 2.10, preferably on both sides adjacent to its center section 2.26 with the greatest diameter. The springs 2.20 are—in this embodiment—clamped between the front sides of the center section 2.26 of the axle and the foremost front sides of the cone sections 2.25 of the end shank pieces 2.2 and 2.3 (as can be seen better in FIG. 5). The springs 2.20 or any other elastic elements with the same characteristics are acting onto the end shank pieces 2.2, 2.3, biasing them with a force acting away from the center section 2.26 of the axle 2.10, and they are located on sections of the axle with a little smaller diameter, adjacent to the center section 2.26, with the threaded sections 2.13 with again smaller diameter, adjacent to the section of the axle 2.10 with the springs 2.20.

[0042] The end shank piece 2.2, 2.3 can take different forms depending on the machine. For example, the end shank piece 2.2 on the drive side can be an HSK cone 2.4 as shown in FIG. 4, with a cylindrical section for coupling with the machine and a cone section 2.25 built similar to the above-explained end shank piece 2.2. Other variants are for instance a SK cone (not depicted), a simple short or long cone (not depicted), a single or stepped cylinder with one or two drive flats 2.21 (see FIG. 2, right side), or a cone or cylinder (not depicted). On the guide side of the hob cutter arrangement, the end shank piece 2.3 on the guide side can be a simple or stepped cylinder with or without a flat 2.22 (see FIG. 2, left side), a simple short or long cone (not depicted), or a cone or cylinder (not depicted).

[0043] The above examples and disclosure are intended to be illustrative and not exhaustive. These examples and description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto.

LIST OF REFERENCE SIGNS

[0044] 1.1 prior art tool body [0045] 1.2 prior art drive side tool body—machine interface [0046] 1.3 prior art guide side tool body—machine interface [0047] 1.4 flat [0048] 2.1 tool body [0049] 2.2 drive side end shank piece [0050] 2.3 guide side end shank piece [0051] 2.4 HSK cone [0052] 2.5 cutting portion [0053] 2.6 axial bore [0054] 2.7 bore end section [0055] 2.8 bearing face [0056] 2.9 test collar [0057] 2.10 axle [0058] 2.11 insert piece [0059] 2.12 axial groove tool body [0060] 2.13 threaded section [0061] 2.14 blind hole [0062] 2.15 drive side center hole [0063] 2.16 guide side center hole [0064] 2.17 deformable washer [0065] 2.18 locking screw [0066] 2.19 front face of end shank piece [0067] 2.20 spring [0068] 2.21 drive side flat [0069] 2.22 guide side flat [0070] 2.23 end cap of locking screw [0071] 2.24 axial groove axle [0072] 2.25 centering cone [0073] 2.26 center section of axle [0074] 2.27 screw for insert piece