Clamping bolt and cutting assembly with clamping bolt
The clamping bolt's innovative design with protective projections, recesses, and reinforcing ribs enhances its durability and chip evacuation, addressing the durability issues of conventional clamping bolts.
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- KENNAMETAL INC
- Filing Date
- 2024-11-21
- Publication Date
- 2026-05-21
AI Technical Summary
Clamping bolts for cutting tools experience reduced service life due to high operational loads, which limits their durability.
The clamping bolt design includes a head section with protective projections and recesses, a clamping section with a reinforcing rib, and a transition section with a non-circular cross-section, enhancing stability and chip evacuation while distributing loads effectively.
The enhanced design results in a clamping bolt that is more resistant to wear and damage, improving its service life and operational efficiency.
Smart Images
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Abstract
Description
[0001] The invention relates to a clamping bolt for fastening a cutting insert to a cutting tool, comprising a head section at a first longitudinal end of the clamping bolt, a clamping section arranged at a second longitudinal end of the clamping bolt opposite the first longitudinal end and having a clamping surface as an engagement surface for a fastening element, and a transition section connecting the head section to the clamping section. The invention further relates to a cutting assembly comprising a cutting tool and a cutting insert fastened to the cutting tool by means of such a clamping bolt.
[0002] Such clamping bolts and cutting assemblies are known.
[0003] The clamping bolts fix the cutting inserts to the cutting tool and are subjected to high loads during operation of the cutting tool, which limits their service life.
[0004] The object of the invention is to provide a clamping bolt that is particularly resistant and thus has a long service life. A further object of the invention is to provide a cutting assembly with such a clamping bolt.
[0005] The problem is solved by a clamping bolt for fastening a cutting insert to a cutting tool, comprising a head section at a first longitudinal end of the clamping bolt, a clamping section arranged at a second longitudinal end of the clamping bolt opposite the first longitudinal end and having a clamping surface as an engagement surface for a fastening element, and a transition section connecting the head section to the clamping section. The clamping bolt has at least one of the following features: the head section has a protective contour on an axial end face at the first longitudinal end, wherein the protective contour has several projections and / or several recesses; the clamping section has a recess with a reinforcing structure that includes a rib; the transition section has a non-circular cross-section perpendicular to the longitudinal extent of the transition section.
[0006] It was recognized according to the invention that certain sections of the clamping bolt are subject to particularly high loads and that the clamping bolt can be designed to be particularly robust and resistant by having at least one of these sections have the corresponding feature.
[0007] Due to the protrusions, the head section has more material at the end face, which is typically exposed during operation, making it more stable and resistant to passing chips. The recesses reduce the frictional surface for passing chips, thus reducing wear. Furthermore, coolant can be retained or collected in the recesses during operation, improving chip evacuation. Therefore, the protective contour improves chip evacuation and protects the clamping bolt from damage.
[0008] The rib of the reinforcement structure distributes loads favorably at the clamping section, resulting in a particularly high strength of the clamping section.
[0009] By having a non-circular cross-section, the transition section can have a particularly large cross-sectional area and thus be designed to be particularly stable.
[0010] According to one aspect, the protective contour is not part of a screw head drive. Therefore, no recess in the sense of a slot for a screwdriver or an Allen key is provided.
[0011] Furthermore, according to another aspect, the clamping bolt does not have a screw head drive.
[0012] In one embodiment, the projections of the protective contour are arranged in an edge area, thereby effectively reinforcing this outer area, which is exposed to particularly high loads.
[0013] Additionally or alternatively, the recesses of the protective contour can be arranged in a central area of the front surface and in this way particularly effectively reduce friction with passing chips at the head section.
[0014] Furthermore, the projections and / or recesses of the protective contour can be arranged rotationally symmetrically about an axis perpendicular to the end face. This design significantly promotes effective chip flow and reduces the risk of chips becoming jammed against the protective contour.
[0015] In another embodiment, the transition section has an oval or elliptical cross-section perpendicular to the longitudinal extent of the transition section, which makes the transition section particularly stable.
[0016] The transition section can have an elliptical cross-section with semi-axes a and b, wherein the length of a is at least 120% of the length of b. Compared to a conventional clamping bolt, which has a circular cross-section with radius b, the transition section of the clamping bolt according to the invention has a significantly larger cross-sectional area and is therefore considerably more stable.
[0017] According to one aspect, the transition section is curved, and the central longitudinal axis of the head section runs at an angle greater than 0° to the central longitudinal axis of the clamping section. In accordance with the invention, the longitudinal extent of the transition section in this case runs along the curve of the transition section. Due to the curved transition section, the head section has a different orientation than the clamping section. This allows the clamping bolt and the associated fastening element to be arranged particularly advantageously in the cutting tool, for example, in a manner that facilitates the assembly of the cutting insert and / or the manufacture of the cutting tool.
[0018] The angle can be greater than 5°.
[0019] Furthermore, the rib can be designed to have a longitudinal extension that runs parallel to the longitudinal extension of the clamping section. This design has the advantage that the loads are distributed particularly effectively across the longitudinal extension of the clamping section by the rib.
[0020] According to one embodiment, the rib tapers longitudinally towards the clamping surface. That is, its height decreases. In this way, the rib can extend over a particularly large longitudinal section without blocking the area through which the fastening element extends to the clamping surface when a cutting insert is attached to the cutting tool by means of the clamping bolt and the fastening element.
[0021] Additionally or alternatively, the rib can taper longitudinally towards one end facing the clamping surface to form a corresponding recess for the fastening element.
[0022] In another embodiment, the head section and the clamping section each have a rotationally symmetrical section where they adjoin the transition section. This makes the clamping bolt particularly material-efficient.
[0023] According to the invention, to solve the above-mentioned problem, a cutting assembly is also provided with a cutting tool and a cutting insert which is attached to the cutting tool by means of a clamping bolt according to the invention with the aforementioned advantages.
[0024] Further advantages and features will become apparent from the following description and the accompanying drawings. These show: - Fig. 1 in a schematic sectional view a cutting assembly according to the invention with a clamping bolt according to the invention, - Fig. 2 in a side view of the clamping bolts made of Fig. 1, - Fig. 3 in a top view of the clamping bolts made of Fig. 1, - Fig. 4 in a detailed view a head section of the clamping bolt made of Fig. 3, - Fig. 5 a transition section of the clamping bolt in a sectional view along the plane N - N in Fig. 2, and - Fig. 6 in a perspective view of the clamping bolts made of Fig. 1.
[0025] The detailed description below, in conjunction with the accompanying drawings, in which identical numbers refer to identical elements, is intended to describe various embodiments of the disclosed subject matter and is not meant to represent the only embodiments. Each embodiment described in this disclosure serves only as an example or illustration and should not be construed as preferable or advantageous over other embodiments.
[0026] All features disclosed below with reference to the exemplary embodiments and / or the accompanying figures can be combined alone or in any subcombination with features of the aspects of the present disclosure, including features of preferred embodiments, provided that the resulting combination of features is meaningful to a person skilled in the art.
[0027] Fig. Figure 1 shows a cutting assembly 10 with a cutting tool 12, a cutting insert 14 and a clamping bolt 20 in an assembled state.
[0028] The cutting tool 12, for example, is a milling tool such as a milling cutter.
[0029] The cutting insert 14 is arranged in a pocket 22 of the cutting tool 12 and is attached to the cutting tool 12 by means of the clamping bolt 20 and a fastening element 24.
[0030] The clamping bolt 20 extends along its longitudinal extent 26 from a first longitudinal end 28 to an opposite second longitudinal end 30.
[0031] The longitudinal extent 26 is formed by a curve with continuous curvature, which extends through all the centers of the cross-sections of the clamping bolt 20 from the first longitudinal end 28 to the second longitudinal end 30. The cross-sections are each perpendicular to the longitudinal extent 26.
[0032] Furthermore, the clamping bolt 20 has a head section 32, which is arranged at the first longitudinal end 28, a clamping section 34, which is arranged at the second longitudinal end 30, and a transition section 36, which connects the head section 32 with the clamping section 34.
[0033] In the illustrated embodiment, the fastening element 24 is a screw which is screwed to the cutting tool 12.
[0034] In principle, the fastening element 24 can be designed as desired and can be connected to the cutting tool 12 in any adjustable way.
[0035] In the assembled state, the head section 32 is arranged in a through hole 38 of the cutting insert 14, while the clamping section 34 extends into a receptacle 40 in the cutting tool 12.
[0036] The fastening element 24 engages with an axial end 42 on a clamping surface 44 of the clamping section 34 on the clamping bolt 20 and pre-tensions it.
[0037] In this way, the cutting insert 14 is clamped in the pocket 22 by means of the clamping bolt 20 and thus fixed to the cutting tool 12.
[0038] In this context, the head section 32 has an axial end face 46 at the first longitudinal end 28, which forms part of the outer surface 48 of the cutting assembly 10.
[0039] In the operation of the cutting assembly 10, i.e., when a workpiece is machined using the cutting assembly 10, the outer surface 48 forms a side of the cutting assembly 10 over which chips can flow.
[0040] The same applies to cooling lubricant if it is used in the operation of the cutting assembly 10.
[0041] Based on the Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. Section 6 below explains the design of the clamping bolt 20 in more detail.
[0042] The head section 32 has twelve projections 50 on the axial end face 46 (see Fig. 4) and seven recesses 52, which together form a protective contour 54 of the head section 32.
[0043] In an alternative embodiment, the protective contour 54 can have any number of projections 50 and / or recesses 52, but at least two projections 50 or at least two recesses 52.
[0044] The protrusions 50, for example, are formed by rounded elevations.
[0045] The depressions 52, for example, are round, trough-shaped depressions.
[0046] In principle, the projections 50 and the recesses 52 can each be designed as desired.
[0047] In the illustrated embodiment, the projections 50 are arranged in an outer, annular edge region 56 of the axial end face 46, while the recesses 52 are arranged in the central region 58 of the axial end face 46.
[0048] In the present case, the projections 50 and the recesses 52 are each arranged rotationally symmetrically about an axis 60, which is perpendicular to the axial end face 46.
[0049] In the present embodiment, the axis 60 coincides with the central longitudinal axis 62 of the head section 32.
[0050] In an alternative embodiment, the projections 50 and the recess 52 can each be arranged arbitrarily on the axial end face 46, for example each rotationally symmetric about an arbitrary axis.
[0051] The clamping section 34 has a lateral recess 64 (see Fig. 2), which adjoins the clamping surface 44 and has a reinforcing structure 66 in the form of a rib 68.
[0052] The rib 68 extends longitudinally L from an end 70 facing the transition section 36 to an end 72 facing the clamping surface 44. This means that the longitudinal extent of the rib 68 runs parallel to the longitudinal extent 26 of the clamping section 34.
[0053] In the illustrated embodiment, the radial height of the rib 68, measured relative to the central longitudinal axis 74 of the clamping section 34, decreases continuously in the longitudinal direction L from a radial height H at the end 70 facing the transition section 36 to a radial height h at the end 72 facing the clamping surface 44. In other words, the rib 68 tapers towards the clamping surface 44 in the longitudinal direction L (see Fig. 6).
[0054] Furthermore, the width (see Fig. 3) The rib 68 tapers continuously in the longitudinal direction L from a width D at the end 70 facing the transition section 36 to a width d at the end 72 facing the clamping surface 44. In other words, the rib 68 tapers in the longitudinal direction L towards the clamping surface 44.
[0055] In principle, rib 68 can be designed in any way.
[0056] Furthermore, in an alternative embodiment, the reinforcement structure 66 can be designed arbitrarily, as long as it has a rib 68.
[0057] The transition section 36 has, in a section perpendicular to the longitudinal extent 26, an elliptical cross-section 76 (see Fig. 5) with a major semi-axis a and a minor semi-axis b.
[0058] The major semi-axis a has a length M that is 125% of the length m of the minor semi-axis b.
[0059] Thus, the cross-sectional area (A=πab) of the elliptical cross-section 76 is correspondingly 25% larger than the area of a circle (A=πb). 2 ) with radius b.
[0060] In principle, the length L of the major semi-axis a can be any multiple of the length m of the minor semi-axis b, for example at least 1.2.
[0061] In an alternative embodiment, the transition section 36 can have any non-circular cross-section 76 perpendicular to the longitudinal extent 26, for example an oval one.
[0062] Furthermore, the transition section 36 is bent in the illustrated embodiment (see Fig. 2), whereby the central longitudinal axis 62 of the head section 32 runs at an angle α of 30° to the central longitudinal axis 74 of the clamping section 34.
[0063] Basically, the angle α can have any value greater than 0°, for example greater than 5°.
[0064] Alternatively, the angle α can be 0° and the transition section 36 can be straight, i.e., not curved.
[0065] In this context, the transition section 36 borders on a section 78 of the head section 32 on the one hand and a section 80 of the clamping section 34 on the other, which are each rotationally symmetrical to the central longitudinal axis 62, 72 of the head section 32 and the clamping section 34 respectively.
[0066] In this way, a clamping bolt 20 and a cutting assembly 10 with a clamping bolt 20 is provided, which is designed to be particularly robust and has a long service life.
Claims
[1] Clamping bolt (20) for fastening a cutting insert (14) to a cutting tool (12), comprising a head section (32) at a first longitudinal end (28) of the clamping bolt (20), a clamping section (34) arranged at a second longitudinal end (30) of the clamping bolt (20) opposite the first longitudinal end (28) and having a clamping surface (44) as an engagement surface for a fastening element (24), and a transition section (36) connecting the head section (32) to the clamping section (34), wherein the clamping bolt (20) has at least one of the following features: the head section (32) has a protective contour (54) on an axial end face (46) at the first longitudinal end (28), wherein the protective contour (54) has several projections (50) and / or several recesses (52); the clamping section (34) has a recess (64) with a reinforcing structure (66) which has a rib (68); the transition section (36) has a non-circular cross-section (76) perpendicular to the longitudinal extent (26) of the transition section (36). [2] Clamping bolt (20) according to claim 1, wherein the projections (50) of the protective contour (54) are arranged in an edge region (56) and / or the recesses (52) of the protective contour (54) are arranged in a central region (58) of the end face (46). [3] Clamping bolt (20) according to claim 1 or 2, wherein the projections (50) of the protective contour (54) and / or the recesses (52) of the protective contour (54) are arranged rotationally symmetric to an axis (60) which is perpendicular to the end face (46). [4] Clamping bolt (20) according to one of the preceding claims, wherein the transition section (36) has an oval or elliptical cross-section (76) perpendicular to the longitudinal extent (26) of the transition section (36). [5] Clamping bolt (20) according to claim 4, wherein the transition section (36) has an elliptical cross-section (76) with semi-axes a and b, wherein the length of a is at least 120% of the length of b. [6] Clamping bolt (20) according to one of the preceding claims, wherein the transition section (36) is bent and the central longitudinal axis (62) of the head section (32) extends at an angle (α) greater than 0° to the central longitudinal axis (74) of the clamping section (34). [7] Clamping bolt (20) according to one of the preceding claims, wherein the rib (68) has a longitudinal extent which runs parallel to the longitudinal extent (26) of the clamping section (34). [8] Clamping bolt (20) according to one of the preceding claims, wherein the rib (68) extends in the longitudinal direction (L) towards the clamping surface (44). [9] Clamping bolt (20) according to one of the preceding claims, wherein the rib (68) tapers in the longitudinal direction (L) towards an end (72) facing the clamping surface (44). [10] Clamping bolt (20) according to one of the preceding claims, wherein the head section (32) and the clamping section (34) each have a rotationally symmetric section (78, 80) via which they adjoin the transition section (36). [11] Cutting assembly (10) comprising a cutting tool (12) and a cutting insert (14) which is attached to the cutting tool (12) by means of a clamping bolt (20) according to one of the preceding claims.