FLEXIBLE COUPLING FOR ATTACHING A COLLET TO A DRAW BAR

• US 20170355024A1
• Filed: 06/09/2017
• Published: 12/14/2017
• Est. Priority Date: 06/14/2016
• Status: Active Grant

• Current Assignee: Schaublin SA (RBC Bearings Incorporated)
• Original Assignee: Roller Bearing Company of America Incorporated (RBC Bearings Incorporated)
• Inventors: Motschi, Ren
• Granted Patent: US 10,639,726 B2
• Time in Patent Office: Days
• CPC Class Codes: B23B 2231/2018 with a saw-tooth profile
• CPC Class Codes: B23B 2231/204 with saw tooth profiles
• CPC Class Codes: B23B 2231/2089 Slits of collets
• CPC Class Codes: B23B 2260/068 Flexible members
• CPC Class Codes: B23B 31/008 with arrangements for transmitting torque
• CPC Class Codes: B23B 31/08 holding tools yieldably
• CPC Class Codes: B23B 31/202 Details of the jaws
• CPC Class Codes: B23B 31/2073 Axially fixed cam, moving jaws B23B31/20125 takes precedence
• CPC Class Codes: B23B 31/265 by means of collets
• CPC Class Codes: B23B 31/36 with means for adjusting the chuck with respect to the working-spindle
• CPC Class Codes: Y10T 279/17529 Fixed cam and moving jaws

Abstract

A flexible coupling for attaching a collet to a draw bar includes a draw bar having a first longitudinal axis and a first coupling portion. The first coupling portion includes two or more legs spaced apart from one another with each of the legs having first coupling surface formed thereon. The flexible coupling includes a collet having a second longitudinal axis and a clamping portion proximate one end of the collet. The collet includes a second coupling portion proximate a second end of the collet. The second coupling portion has a second coupling surface formed thereon and configured in a shape complementary to the first coupling surface so that the first coupling surfaces moveably engage the second coupling surface such that the first longitudinal axis and the second longitudinal axis are coaxial when an axial force is applied to the draw bar and the collet.

Claims

1. A flexible coupling for attaching a collet to a draw bar, the flexible coupling comprising:

a draw bar having a first longitudinal axis and a first coupling portion proximate one end of the draw bar and a mounting portion proximate an opposite end of the draw bar, the mounting portion being configured to removably secure the draw bar to a pulling device of a machine tool, the first coupling portion comprising at least two legs spaced apart from one another, each of the at least two legs having a first coupling surface formed thereon;

a collet having a second longitudinal axis and a clamping portion proximate one end of the collet and a second coupling portion proximate a second end of the collet, the second coupling portion having a second coupling surface formed thereon, the second coupling surface being configured in a shape complementary to the first coupling surface so that the first coupling surfaces moveably engage the second coupling surface such that the first longitudinal axis and the second longitudinal axis are coaxial when an axial force is applied to the draw bar and the collet; and

a collet adaptor with a guiding surface and an angled surface being configured to contribute to the coaxial alignment of the collet.

2. The flexible coupling of claim 1, wherein the first coupling surface has a first threaded area formed thereon and the second coupling surface has a second threaded area formed thereon.

3. The flexible coupling of claim 2, wherein:

the first threaded area is an internal thread and the second threaded area is an external thread;

or

the first threaded area is an external thread and the second threaded area is an internal thread.

4. The flexible coupling of claim 2, wherein the first threaded area and the second threaded area are of a buttress thread configuration.

5. The flexible coupling of claim 4, wherein the buttress thread defines angled non-load bearing flanks.

6. The flexible coupling of claim 5, wherein the angled non-load bearing flanks of the first threaded area and the second threaded area frictionally engage one another as a result of the at least two legs being bent radially inward.

7. The flexible coupling of claim 1, wherein the at least two legs are spaced apart from one another by at least two slots.

8. The flexible coupling of claim 7, wherein the at least two slots are one of axially extending, radially extending, and angularly extending.

9. The flexible coupling of claim 1, wherein at least one surface of the draw bar, the collet and the collet adapter is plated to improve the performance of the system.

10. The flexible coupling of claim 1, wherein the collet adapter is one of a fixed type or an adjustable type.

11. A method for connecting a collet to a draw bar of a machine tool, the method comprising:

providing a machine tool having a spindle and a pulling device;

providing a collet adapter;

providing a flexible coupling comprising a draw bar having a first longitudinal axis and a first coupling portion proximate one end of the draw bar and a mounting portion proximate an opposite end of the draw bar, the first coupling portion comprising at least two legs spaced apart from one another, each of the at least two legs having a first coupling surface formed thereon, and a collet having a second longitudinal axis and a clamping portion proximate one end of the collet and a second coupling portion proximate a second end of the collet, the second coupling portion having a second coupling surface formed thereon, the second coupling surface being configured in a shape complementary to the first coupling surface;

securing the first coupling portion of the draw bar to the second coupling portion of the collet so that the first coupling surfaces moveably engage the second coupling surface;

positioning the collet in the collet adapter;

positioning the mounting portion of the draw bar in the machine tool;

securing the mounting portion to the pulling device;

securing the collet adapter to the spindle; and

applying a radial force, via the inwardly bent legs to the draw bar to concentrically seat the collet in the collet adapter such that the first longitudinal axis and the second longitudinal axis are coaxial.

12. The method according to claim 11, wherein the first coupling surface has a first threaded area formed thereon and the second coupling surface has a second threaded area formed thereon.

13. The method according to claim 12, wherein:

the first threaded area is an internal thread and the second threaded area is an external thread;

or

the first threaded area is an external thread and the second threaded area is an internal thread.

14. The method according to claim 12, wherein the first threaded area and the second threaded area are of a buttress thread configuration.

15. The method according to claim 14, wherein the buttress thread defines angled non-load bearing flanks.

16. The method according to claim 15, wherein the angled non-load bearing flanks of the first threaded area and the second threaded area frictionally engage one another as a result of the at least two legs being bent radially inward.

17. The method according to claim 11, wherein the at least two legs are spaced apart from one another by at least two slots.

18. The method according to claim 11, wherein the at least two slots are one of axially extending, radially extending, and angularly extending.