Spindle Lock Mechanism for High-Torque Screwdriver Anvil

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional impact screwdrivers are inefficient for further tightening screws beyond the torque set by the compression spring, requiring a separate manually operable screwdriver, which complicates the process and reduces efficiency.

Innovation Solution

A spindle lock device that includes an engaging ring and an anvil with a flat relief surface, allowing the screwdriver body case to be rotated to apply additional torque without motor assistance, locking the anvil relative to the body case to increase tightening and loosening capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a compression spring is used to bias the hammer for tightening screws, then the screw tightening force can be controlled, but the tightening force cannot exceed the spring's biasing force

Engineering Contradiction:

Improvescrew tightening forceVSAvoidtightening force range

Core Design Contradiction:

ForceVSAdaptability or versatility

Solution Approach 1:

The hammer is made rotatably supported on the drive shaft instead of being fixed, allowing it to dynamically adjust its position. When the anvil contacts the screw, the hammer can rotate to maintain contact, enabling continuous torque application beyond spring compression limits

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The anvil is separated into a spindle portion and an impact receiving portion that can rotate relative to each other. This segmentation allows the impact portion to engage the hammer while the spindle portion transmits torque to the screw, enabling both impact and continuous tightening functions

Inventive Principle:

Principle #1Segmentation

2Reliability

If the motor is stopped after initial tightening, then the screw can be tightened by set torque, but further tightening requires a separate manual screwdriver

Engineering Contradiction:

Improvetightening torque controlVSAvoidnumber of tools required

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The impact screwdriver is designed to perform multiple functions: initial impact tightening by the motor, and further continuous tightening by manual rotation of the body case. The anvil's rotational capability allows it to function in both impact mode and direct drive mode, eliminating the need for a separate manual screwdriver

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Instead of requiring the motor to provide all tightening force, the invention inverts the approach by allowing the user to manually rotate the body case for further tightening. The anvil rotates with the body case to directly drive the screw, converting the limitation of motor stoppage into a feature that enables both automated and manual tightening phases

Inventive Principle:

Principle #13The other way round (Inversion)

3Power

If the hammer moves away from the anvil under external torque, then impact is applied to rotate the spindle, but the anvil cannot be locked against rotation for high torque application

Engineering Contradiction:

Improveimpact powerVSAvoidhigh torque tightening

Core Design Contradiction:

PowerVSEase of operation

Solution Approach 1:

The engaging member acts as an intermediary between the engaging ring and the anvil. When the anvil needs to be locked, the engaging member engages with the relief surface to prevent rotation. When impact is needed, the engaging member disengages, allowing the hammer to strike the anvil freely. This intermediary mechanism enables both impact and locked torque transmission modes

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Enables further screw tightening or loosening without a separate manual screwdriver, improving operability and efficiency by allowing higher torque application than the impact device alone, and facilitating screw loosening with enhanced ease.

Implementation Method 1

The engaging member can wedge between the engaging ring and an end portion in the circumferential direction of the relief surface of the anvil, so that the anvil is locked with respect to rotation relative to the body case.

Methodology Applied

Scientific EffectWedge: Wedge

Implementation Method 2

the screw tightening force is set by a compression spring that biases the hammer in the axial direction of the spindle

Methodology Applied

Scientific EffectSpring: Spring

Implementation Method 3

The hammer can move toward and away from the anvil in order to intermittently apply impacts on the anvil for rotating the spindle

Methodology Applied

Scientific EffectImpact force: Impact Force

Data Source

PatentUS8651198B2Spindle lock devices for screwdrivers

Publication Date: 2014.02.18 MAKITA CORP

AI summary

A spindle lock device includes an engaging ring fixed in position relative to a body case of an impact screwdriver. A flat relief surface is definable on an outer circumference of the anvil that can be disposed inside of the engaging ring. An engaging member can be disposed between the engaging ring and the flat surface of the anvil. The engaging member can wedge between the engaging ring and an end portion in the circumferential direction of the relief surface of the anvil, so that the anvil is locked with respect to rotation relative to the body case.