# US 5,127,776 A · Tap with relief

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- Number: US 5,127,776 A
- Document ID: US5127776A
- Status: Granted
- Kind: A
- Application number: 07/750,753
- Filed: 1991-08-22
- Granted: 1992-07-07
- Earliest claimed: 1990-01-19
- Assignees: Emuge-Werk Richard Glimpel Fabrik fur Prazisionswerkzeuge vormals Moschkau & Glimpel
- Inventors: Helmut Glimpel
- Web page: https://patentgrep.com/patent/US5127776A

## CPC

- B23G 5/06: Taps (chucks therefor B23B31/00)
- B23G 2210/12: Threads having a large diameter
- Y10T 408/90467: and relieved cutting edge
- Y10T 408/9048: Extending outwardly from tool-axis
- B23G: THREAD CUTTING; WORKING OF SCREWS, BOLT HEADS, OR NUTS, IN CONJUNCTION THEREWITH (making helical grooves by turning B23B5/48, by milling B23C3/32, by forging, pressing, or hammering B21K1/56, by grinding B24B19/02; arrangements for copying or controlling B23Q; thread-forming by corrugating tubes B21D15/04, by rolling B21H3/02)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

There is a tap whose thread portion 2 forms a cutting section 5 and a guiding section 6 and is provided on a plurality of adjacent thread teeth of the cutting section 5 with a relief 8. It is desirable that a further machining measure be provided for the tap whereby favorable compromises can be obtained with respect to guidance and friction. This is achieved in that the relief 8 of the adjacent cutting-section 5 thread teeth--seen in a longitudinal direction--have a clearance angle which varies increasingly or decreasingly. Varying the relief enables the requirements with respect to avoiding incorrect tapping and avoiding friction-generated cold welding to be met and matched up in an improved manner.

## Claims

### Claim 1

A tap having a threaded portion including a toothed cutting portion and a guiding portion, and being essentially cylindrical, the threaded portion having reliefs at several adjacent thread teeth of the cutting portion, the reliefs having clearance angles based upon a cutting portion thread tooth with a maximum flank diameter, the reliefs of adjacent cutting portion thread teeth, viewed in a longitudinal direction, having clearance angles that increase from front to rear, the reliefs of adjacent guiding portion teeth, viewed in a longitudinal direction, having clearance angles that decrease from front to rear.

### Claim 2 (depends on 1)

A tap according to claim 1, wherein the relief clearance angles vary along the entire length of the cutting portion.

### Claim 3 (depends on 1, 2)

A tap according to claim 1 or 2, wherein the relief clearance angles vary from 5 minutes to 2.degree..