Mandrel Shock Absorbing Means for Cross-Threading Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing installation tools for nut inserts in blind applications often cause cross-threading and damage due to improper alignment and impact of the mandrel tip on the insert threads, resulting in deformation and binding issues.
Innovation Solution
The improved installation tool features a mandrel with shock absorbing means that allows for axial movement upon contact with the insert threads, preventing impact damage and cross-threading, and includes a chamfered or rounded tip for proper alignment, along with a hydraulic piston system for controlled linear force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the mandrel is made rigid with no give, then the installation tool can apply sufficient linear force to deform the insert sleeve, but the mandrel tip impacts the insert threads causing cross-threading and damage
Solution Approach 1:
The mandrel is designed with a resilient tip portion that can be compressed axially, providing beforehand cushioning against impact damage. This resilient portion acts as a buffer that absorbs impact energy when the mandrel tip contacts the insert threads, preventing cross-threading and thread damage while maintaining sufficient force transmission for sleeve deformation.
Solution Approach 2:
The mandrel structure is changed from a completely rigid configuration to one with a resilient tip portion that can compress axially. This parameter change allows the mandrel to have both rigidity for force transmission and compliance for impact absorption, resolving the contradiction between applying sufficient linear force and preventing impact damage to the threads.
2Manufacturing precision
If the mandrel threads are engaged forcefully to ensure proper alignment, then threading accuracy improves, but cross-threading occurs due to improper initial alignment
Solution Approach 1:
The resilient tip portion provides beforehand cushioning that allows the mandrel to be inserted into the insert without causing impact damage to the threads. This cushioning effect enables proper thread engagement even when initial alignment is not perfect, as the resilient tip can compress to accommodate minor misalignments and guide the threads into proper engagement.
Solution Approach 2:
The resilient tip portion acts as an intermediary between the rigid mandrel body and the insert threads. It mediates the interaction by providing a compliant interface that can absorb impact energy and facilitate proper thread alignment, reducing cross-threading while ensuring accurate thread engagement.
3Object-affected harmful factors
If the mandrel is designed to be compressible axially, then impact damage is prevented, but the ability to apply sufficient linear force for sleeve deformation is reduced
Solution Approach 1:
The mandrel is designed with non-uniform structural properties: the tip portion is resilient and compressible to prevent impact damage, while the body portion remains rigid to transmit sufficient linear force for sleeve deformation. This local quality differentiation allows the mandrel to simultaneously provide impact absorption and force transmission capabilities.
Solution Approach 2:
The mandrel structure is modified by changing the material or geometric parameters of the tip portion to make it resilient and compressible, while maintaining the rigid properties of the body portion. This localized parameter change enables the mandrel to compress axially for impact protection while still transmitting sufficient force through the rigid body for effective sleeve deformation.
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 tool effectively reduces cross-threading and damage to the insert threads by allowing the mandrel to 'give' upon contact, ensuring proper alignment and preventing thread deformation, thus ensuring successful installation without damaging the insert or the tool.
Implementation Method 1
the resilient tip portion can be compressed axially a predetermined distance to absorb impact energy
Implementation Method 2
The linear force applied to the mandrel by partially pulling the mandrel into the tool body with reciprocation means causes the sleeve of the insert to plastically deform
Data Source
AI summary
An insert installation apparatus comprises a housing having a body section and a nose piece. The nosepiece comprises a forward end and a rearward end, where the rearward end of the nose piece is attached to the body section. The apparatus comprises a rotary power source and reciprocating means which are employed to set a threaded insert in a work piece. The rotary power source has an extension member which connects the rotary power source to the first end of a drive shaft which is received by the extension member. The second end of the drive shaft is operationally coupled to a partially threaded mandrel which extends out of the forward end of the nose piece. The apparatus further comprises mandrel shock absorbing means which allow the mandrel to reciprocate with respect to the nose piece from a first position to a second position, where the mandrel shock absorbing means operates independently from the reciprocating means which usually employed to set the threaded insert. The mandrel shock absorbing means allows the threaded shaft to “give” if the tip of the mandrel impacts the crests of the threads of the insert as the tip is inserted into the opening of the insert. While a small spring or other biasing means are used to bias the threaded shaft forward the threaded shaft may be partially pushed back into the nose piece upon contact with the threads of the insert, thus preventing impact damage to the root thread of the insert and preventing cross-threading.