Friction-anchored metal bolt to plastic workpiece
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for connecting metal and plastic workpieces in multi-material structures face issues such as high stress concentrations, potential loosening due to creep or moisture, difficulty in estimating connection strength, long cycle times, and high energy consumption, as well as the need for surface pretreatment and complex processing.
Innovation Solution
A method involving a metal bolt being pressed into a plastic workpiece while rotating, causing the plastic to plasticize and deform, creating a form-fitting connection without the need for surface pretreatment, using easily controlled parameters like pressure and rotation speed, and optionally forming a friction-welded connection with a metal workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical connections (rivet or clinch) are used to connect metal and plastic, then the connection is strong, but high stress concentrations occur in the workpieces and later loosening can occur due to creep, moisture and relaxation
Solution Approach 1:
The invention changes the physical state of the plastic material through controlled heating and pressure application. The plastic workpiece is heated to a temperature where it becomes pliable and can be formed around the bolt, then cooled to lock in the deformed shape, creating a reliable mechanical interlock that avoids stress concentrations and loosening issues
Solution Approach 2:
The invention utilizes the phase transition of plastic material from solid state to a softened pliable state through heating, allowing the material to flow and form around the bolt. Upon cooling, the material returns to solid state, locking the bolt in place with a reliable connection that eliminates the loosening problems associated with traditional mechanical connections
2Strength
If adhesive connections are used to connect metal and plastic, then the connection is strong, but the cycle times are comparatively long due to curing time and surface pretreatment is necessary
Solution Approach 1:
The invention replaces the chemical bonding mechanism of adhesives with a mechanical interlocking system. By heating and forming the plastic around the bolt, a mechanical key-lock connection is created that provides equivalent or superior strength without requiring curing time or surface pretreatment, significantly reducing cycle time
Solution Approach 2:
The invention performs the connection-forming action during the same operation that positions the bolt, rather than requiring separate surface pretreatment and curing steps. The heating and forming process simultaneously prepares the plastic surface and creates the mechanical interlock, eliminating multiple sequential steps required by adhesive bonding
3Strength
If welding processes are used to connect metal and plastic, then the connection is strong, but surface pre-treatment is necessary and energy consumption is relatively high
Solution Approach 1:
The invention applies heating locally only to the specific area of the plastic workpiece where the connection is being formed, rather than heating the entire workpiece or using high-energy welding processes. This localized thermal treatment achieves the necessary material softening with minimal energy input while creating a strong mechanical interlock
4Reliability
If hybrid connection techniques are used, then the connection properties are improved, but complex pre-processing of metal parts is required which is very time-consuming
Solution Approach 1:
The invention extracts and eliminates the complex pre-processing steps required by hybrid connection techniques. By using a straightforward thermal forming process that directly creates the mechanical interlock without requiring collar formation, cavity creation, or other preliminary metal part modifications, the invention achieves reliable connections with minimal preparation time
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
This method provides a reliable, high-load-capacity connection with reduced stress concentration and no need for complex devices, ensuring a strong and resilient bond between metal and plastic workpieces, particularly in the axial direction, while minimizing cycle times and avoiding surface pretreatment.
Implementation Method 1
the screw being pressed into the body while rotating, so that the material of the body melts due to the frictional heat
Implementation Method 2
the first plastic workpiece being plasticized, such that the pin is positively anchored in the first plastic workpiece after the rotation is stopped
Implementation Method 3
the tip of the pin is deformed by bulging such that the diameter of the tip is greater than that of the section of the bolt that is pressed into the first plastic workpiece
Implementation Method 4
optionally forming a friction-welded connection with a metal workpiece
Data Source
Figure 1A~1D
Figure 2
Figure 3A~3C
AI summary
A metallic stud or bolt (1) is attached to a plastic component (2) by rotating it (3) and pressing (4) it into the plastic at the same time. The plastic melts due to friction and the stud is anchored by interlocking deformation. The surface of the stud can have surface serration and the tip (5) of the stud can deform to a larger diameter (D). The stud can be used to join two plastic components or to attach metal parts to plastic. The stud can have a head to be friction-welded to a metal part at the same time.