Tapered Thread Rolls for API 11B Sucker Rod Precision

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Solution Overview

Problem

Current methods for forming tapered threads on sucker rods, such as those used in oil well pumping systems, are inefficient and lack precision, particularly in creating the required angled connections specified by standards like API 11B.

Innovation Solution

A thread rolling tool equipped with a set of tapered thread rolls, which includes a cylindrical body with annular rings angled greater than zero degrees, is used in a rotary machine to form threads on a workpiece, ensuring accurate and precise formation of tapered threads by synchronizing feed rate and spindle speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional thread-cutting methods are used to form tapered threads on sucker rods, then the threading process can be performed with standard equipment, but the manufacturing precision and strength of the threaded connection are insufficient to meet API 11B standards

Engineering Contradiction:

Improvethread angle precisionVSAvoidthread rolling tool complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The thread rolling tool employs annular rings with angles greater than zero degrees that dynamically engage with the workpiece during rotation, allowing the thread geometry to be formed through controlled plastic deformation rather than static cutting. This dynamic forming process enables precise tapered thread geometry while using standardized equipment.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the fundamental parameter of thread formation from material removal (cutting) to material displacement (rolling). By using annular rings with specific angles greater than zero degrees, the process transforms the workpiece material plastically to form the tapered thread profile, achieving superior precision and strength.

Inventive Principle:

Principle #35Parameter changes

2Strength

If conventional thread-cutting methods are used, then the equipment is simpler, but the strength and reliability of the threaded connection are insufficient

Engineering Contradiction:

Improvethreaded connection strengthVSAvoidthreading process complexity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The thread rolling process performs preliminary plastic deformation of the material before final threading, work-hardening the material in the thread root area. This preliminary action increases the strength and fatigue resistance of the threaded connection while maintaining ease of manufacture through a single-pass rolling operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces the mechanical cutting system with a rolling system that uses friction and plastic deformation to form threads. This substitution eliminates the weaknesses associated with cutting (stress concentrations, material removal) and leverages the strengths of rolling (material consolidation, work hardening) to produce stronger connections.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Strength

If thread rolling is used to form threads, then the threaded connection strength is improved, but achieving precise tapered thread geometry is more difficult

Engineering Contradiction:

Improvethreaded connection strengthVSAvoidtapered thread geometry precision

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The annular rings are designed with specific local qualities - angles greater than zero degrees - that are optimized for forming tapered threads. Each ring's geometry is tailored to the specific tapered thread requirements, enabling precise geometry control while maintaining the strength benefits of rolling.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The use of annular rings with curved surfaces and angles greater than zero degrees allows the tool to conform to and form the tapered cylindrical geometry of the sucker rod. The curved contact surfaces enable precise tapered thread formation through rotational rolling motion.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution enables the precise and efficient formation of threads that meet API 11B standards, resulting in stronger and more reliable connections compared to conventional cutting methods.

Implementation Method 1

a first thread roll may comprise a first cylindrical body and a first set of annular rings... the first set of annular rings may protrude from the circumferential surface of the first body... adapted to form threads in a workpiece

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentUS8726711B2Apparatuses and methods for rolling angled threads

Publication Date: 2014.05.20 KENNAMETAL INC

AI summary

In various embodiments, a tapered thread roll, a set of tapered thread rolls, a thread rolling tool, and a thread rolling method are provided for rolling angled or tapered threads onto a workpiece to create a threaded workpiece. In at least one embodiment, the threaded workpiece may comprise a polished rod or a polished rod precursor as specified by the American Petroleum Institute for use in an oil-field sucker-type pump, for example.