Plastic Filter Head with Cold Extruded Threaded Insert
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Solution Overview
Problem
The production of plastic filter heads with metal threaded connector inserts is complex and expensive due to the need for precise manufacturing and sealing, which is not efficiently addressed by existing methods.
Innovation Solution
A method involving a cold extruded metal threaded connector insert is used, where the insert is placed in a plastic injection molding tool with a complementary receptacle and mandrel, allowing for compensation of dimensional tolerances and axial sealing, reducing manufacturing costs and improving sealing efficacy through radially extending plastic ribs and an anti-twist device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal threaded insert is pressed into plastic filter head, then sealing is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines the threading function and sealing function into a single integrated threaded insert component. The insert includes a threaded portion for filtering and a sealing portion with radial arms that terminate in a ring, eliminating the need for separate sealing components and simplifying the manufacturing process while maintaining reliable sealing.
Solution Approach 2:
The threaded insert is designed to perform multiple functions simultaneously: providing the threaded connection for the filter element and creating the sealing interface with the plastic filter head through its radial arms and sealing portion. This multi-functionality reduces the number of separate components needed.
2Ease of manufacture
If plastic filter head is used instead of metal, then cost is reduced, but durability problems occur due to plastic creep
Solution Approach 1:
The patent applies local quality enhancement by adding radial arms that terminate in a ring structure at the critical sealing location. This localized reinforcement with higher stiffness material or structure compensates for the inherent creep susceptibility of plastic in the filtering area, while the rest of the filter head remains cost-effective plastic construction.
Solution Approach 2:
The filter head combines plastic material for the main body with a metallic threaded insert for the filtering function. This composite construction allows the cost-effective plastic to be used for the bulk of the structure while the metal insert provides the necessary durability and creep resistance for the critical filtering area.
3Reliability
If threaded insert is manufactured with high precision, then sealing is improved, but manufacturing cost increases
Solution Approach 1:
The patent incorporates a recess in the plastic filter head that is pre-formed to receive the threaded insert. This preliminary action of creating the recess allows the threaded insert to be manufactured with standard tolerances while still achieving reliable sealing, as the recess provides the necessary dimensional accommodation and sealing interface without requiring ultra-precise manufacturing of the insert itself.
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 enables cost-effective production of plastic filter heads with improved sealing and rigidity, reducing creep and enhancing the pull-out force of the threaded connector insert, while ensuring reliable fixation and reduced manufacturing complexity.
Implementation Method 1
A gap remains between the threaded insert and the slide wall, which is later filled with plastic. Plastic is then injected into the injection mold. The pressure of the injected plastic presses the threaded insert, with its axial sealing surface, against the injection mold, sealing it.
Implementation Method 2
In order to absorb the forces required for sealing, the threaded insert has radial arms that terminate in a ring and by means of which the threaded insert is sealed against the plastic filter head.
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for manufacturing a filter head (6) from plastic with a threaded connection insert (1) injected at least partially into the filter head and said threaded connection insert designed as a cold extrusion part, wherein - the threaded connection insert (1) is inserted in a complementary cylindrical holder (7) of a plastic injection mould (4), - the threaded connection insert (1) is pushed into the holder until it is in contact with a holder edge (8) with an axial sealing surface (3), - a mandrel (9) is pushed through the threaded connection insert (1) until said mandrel engages interlockingly in a recess (12) on an opposite wall (10) of the injection mould (4), wherein a distance remains between the threaded connection insert (1) and the wall (10) of the slider (11), - plastic is injected into the plastic injection mould (4), - the mandrel (9) is pulled after the plastic has cured, the slider (11) is displaced and the filter head (6) is removed from the plastic injection mould (4).