Cutting tool, particularly a boring bar, as well as a process for machining a number of bores

Patent metadata

Field	Value
Publication number	US-9789547-B2
Application number	US-201414895852-A
Country	US
Kind code	B2
Filing date	Jun 3, 2014
Priority date	Jun 4, 2013
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

To make it possible for bores (16) that are in line with one another to be efficiently worked by means of a boring bar (2), the boring bar has a main body (10) with an axis of rotation (R) and a number of cutting elements (12, 12A) at intervals from one another in the axial direction (4) and also guiding elements (14) for guiding the main body (10) in a guiding bore (16A). The guiding elements (14) are kept at a distance from the axis of rotation (R) equivalent to a guide radius (r1). The main body (10) is divided into a functional region (19) and an eccentric region (10), wherein the cutting elements (12, 12A) and the guiding elements (14) are arranged such that they are distributed around the main body (10) over an angular range (a) of less than 180°. Furthermore, the circumferential side (22) of the main body (10) can be passed eccentrically through a respective bore (16, 16A) of which the unworked tube radius (r2) is less than the guide radius (r1).

First claim

The invention claimed is:

1. A cutting tool, particularly a boring bar for machining bores spaced apart from one another by a predetermined spacing (a) in the axial direction, comprising a basic body extending in the axial direction having a rotational axis (R) and having at least one cutting element, as well as a number of guide elements for guiding the basic body in a guide bore, wherein the guide elements are spaced apart by a guide radius (r 1 ) with respect to the rotational axis (R),
wherein the basic body is subdivided into a function area and an eccentric area, when viewed in cross-section, and the cutting elements as well as the guide elements are distributed around the basic body arranged over an angle range (α) of less than 180°, and in that the peripheral side of the basic body has a reduced distance (d) with respect to the rotational axis (R) in comparison to the guide radius (r 1 ) in the eccentric area; and
wherein the peripheral side of the basic body extends along a curved line in the eccentric area, the center point of which is arranged on a retraction axis (E), which is displaced into the function area opposite the rotational axis (R).

2. The cutting tool according to Claim 1 , wherein the peripheral side in the function area extends around the rotational axis (R) along a circular arc having a first circular radius (k 1 ), and in the eccentric area ( 20 ) extends around the retraction axis (E) along a circular arc having a second circular radius (k 2 ).

3. The cutting tool according to claim 1 , wherein the guide elements are spaced apart from the at least one cutting element in the axial direction.

4. The cutting tool according to claim 1 , wherein the guide elements are arranged at an axial position equivalent to the at least one cutting element at a guide/working position.

5. The cutting tool according to claim 4 , wherein the cutting element of the guide/working position is arranged in a leading position in the axial direction compared to other cutting edges with respect to the predetermined spacing, so that, to form the guide bore, when machining the bores, the bore at the guide/working position is machined first.

6. The cutting tool according to claim 5 , wherein the guide elements extend over an axial length ( 1 ) which is measured such that it supports the basic body in the guide bore while the other bores are being machined.

7. The cutting tool according to claim 4 , wherein the guide/working position is formed in a middle area of the basic body.

8. The cutting tool according to claim 1 , wherein the basic body has a base body as well as at least one balancing element, which is designed to at least partially balance an imbalance that would otherwise exist.

9. The cutting tool according to claim 8 , wherein the balancing element is flush with the base body around the periphery.

10. The cutting tool according to claim 8 , wherein the balancing element is formed as a circular segment when viewed in cross-section, particularly within the eccentric area.

11. The cutting tool according to claim 8 , wherein the balancing element is formed from a denser material than the base body.

12. The cutting tool according to claim 8 , wherein a residual imbalance is intentionally set such that during operation a resulting force is generated in the direction of the guide area.

13. The cutting tool according to claim 12 , wherein the residual imbalance is developed only at an axial position at which a guide element is arranged.

14. The cutting tool according to claim 8 , wherein the arrangement of the at least one balancing element simultaneously creates an energy absorption element designed to dampen vibrational energy.

15. The cutting tool according to claim 8 , wherein the balancing element is bonded to the base body.

16. The cutting tool according to claim 1 , wherein in the axial direction, the base body is subdivided into at least two parts, which can be reversibly connected to one another, and each of the parts has at least one cutting element or guide element.

17. A process comprising:
machining a number of bores spaced apart by a predetermined spacing (a) with the assistance of a cutting tool according to claim 1 .

18. The process according to claim 17 , wherein the process comprises, prior to machining the number of bores:
first, operating the cutting tool eccentrically in the axial direction through the bores;
then, radially offsetting the cutting tool in the direction of the rotational axis (R), and in that the machining of the bores starts afterwards,
wherein the basic body is supported in a guide bore with the guide elements.

19. The process according to claim 17 , wherein a two-step machining process occurs, wherein, in a first machining step, one of the bores for forming a guide bore is machined with the assistance of the boring bar, then the boring bar is further advanced in the axial direction and further bores are then machined, and simultaneously the basic body is supported in the guide bore via the guide elements.

20. The process according to claim 17 , wherein the bores are bored out from an unworked radius (r 2 ) to an end radius (r 3 ), wherein the unworked radius (r 2 ) is less than the guide radius (r 1 ).

21. The process according to claim 17 , wherein each of the bores has an unworked radius (r 2 ), and wherein the unworked radii (r 2 ) of all bores are equal.

22. The process according to claim 17 , wherein all bores of the workpiece are machined in a single retraction of the cutting tool.

23. A cutting tool, particularly a boring bar for machining bores spaced apart from one another by a predetermined spacing (a) in the axial direction, comprising a basic body extending in the axial direction having a rotational axis (R) and having at least one cutting element, as well as a number of guide elements for guiding the basic body in a guide bore, wherein the guide elements are spaced apart by a guide radius (r 1 ) with respect to the rotational axis (R),
wherein the basic body is subdivided into a function area and an eccentric area, when viewed in cross-section, and the cutting elements as well as the guide elements are distributed around the basic body arranged over an angle range (α) of less than 180°, and in that the peripheral side of the basic body has a reduced distance (d) with respect to the rotational axis (R) in comparison to the guide radius (r 1 ) in the eccentric area;
wherein the basic body has a base body as well as at least one balancing element, which is designed to at least partially balance an imbalance that would otherwise exist; and
wherein a residual imbalance is intentionally set such that during operation a resulting force is generated in the direction of the guide area.

24. A process comprising:
machining a number of bores spaced apart by a predetermined spacing (a) with the assistance of a cutting tool, the cutting tool comprising a basic body extending in the axial direction having a rotational axis (R) and having at least one cutting element, as well as a number of guide elements for guiding the basic body in a guide bore, wherein the guide elements are spaced apart by a guide radius (r 1 ) with respect to the rotational axis (R),
wherein the basic body is subdivided into a function area and an eccentric area, when viewed in cross-section, and the cutting elements as well as the guide elements are distributed around the basic body arranged over an angle range (α) of less than 18

Assignees

• Kennametal Inc

Inventors

• Hacker Michael
• Kunschir Sebastian

Classifications

• B23B2229/04

  Guiding pads · CPC title

• B23B2265/12

  Eccentric · CPC title

• B23B29/03

  Boring heads · CPC title

• B23B27/002

  with vibration damping means · CPC title

• Y10T408/03

  Processes · CPC title