Door Lock Fixture Clamping Lever Tubular Member Fixation
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Solution Overview
Problem
Existing door lock fixtures struggle with achieving strong and reliable fixation in tubular members, particularly due to the need for accurate hole positioning, damage to protective coatings, limited wall thickness, and aesthetic and cost issues related to thick faceplates and snap-fitting tabs that are not easily removable.
Innovation Solution
A door lock fixture with clamping levers that pivot between retracted and extended positions, using a spring to automatically engage the tubular member's inner surface for secure clamping, allowing for strong fixation independent of wall thickness and eliminating the need for precise hole drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If self-tapping screws/bolts are used to fix the lock to the tubular member, then the lock can be securely fixed, but the protective coating on the tubular member is damaged at the hole locations
Solution Approach 1:
The patent introduces self-drilling screws as an intermediary fastening element that combines drilling and threading functions in one operation. These screws create their own threads while drilling through the tubular member wall, eliminating the need for pre-drilled holes and subsequent coating damage. The self-drilling screws achieve secure fixation while preserving the protective coating integrity.
Solution Approach 2:
The patent changes the fastening method from self-tapping screws (which require pre-drilled holes) to self-drilling screws (which create their own threads during installation). This parameter change in the screw type and installation process eliminates the harmful effect of coating damage while maintaining fixation strength.
2Object-affected harmful factors
If holes are drilled in the tubular member before coating, then the coating remains intact, but the holes still get damaged during screwing
Solution Approach 1:
The patent uses self-drilling screws as a mediator that performs both hole creation and thread formation in a single operation. This eliminates the separate drilling step that damages the coating, while the self-drilling process creates fresh, undamaged threads in the tubular member wall for optimal screw grip.
Solution Approach 2:
The self-drilling screw performs the hole creation action preliminarily during the same installation process that creates the threads. This preliminary hole creation by the screw itself ensures the coating is not damaged by separate drilling operations, while the freshly created hole provides optimal grip for the screw threads.
3Volume of moving object
If the faceplate is clamped directly against the thin wall of the tubular member, then a compact design is achieved, but the faceplate must be quite thick to accommodate screw heads
Solution Approach 1:
The patent extracts the screw heads from the faceplate assembly by using self-drilling screws with countersunk tips that embed into the tubular member wall. This removes the need for deep countersunk holes in the faceplate, allowing for a thinner, more compact design while maintaining secure fixation.
Solution Approach 2:
Instead of cutting countersunk holes into the faceplate to recess the screw heads, the patent inverts the approach by having the screw tips create their own countersunk seating directly in the tubular member wall during installation. This reverses the traditional sequence and eliminates the need for complex faceplate machining.
4Strength
If tensioning screws strongly into the holes is done to achieve strong fixation, then the grip is improved, but the holes in the tubular member may be damaged
Solution Approach 1:
The self-drilling screw acts as an intermediary that creates optimized thread profiles during installation. These self-created threads are specifically designed to engage the tubular member material optimally, allowing strong fixation to be achieved with moderate tightening torque that does not damage the hole integrity.
Solution Approach 2:
The patent changes the thread formation process from pre-drilled holes (which have fixed geometry) to self-drilled threads (which are created with optimal geometry during installation). This parameter change in thread formation allows for better stress distribution and stronger fixation without exceeding the material's damage threshold during tightening.
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 provides a strong, reliable, and aesthetically pleasing fixation that is independent of tubular member wall thickness, allowing for easy installation and removal, and prevents damage to protective coatings, while enabling secure attachment without damaging the tubular member.
Implementation Method 1
a spring which is arranged to urge the clamping lever towards its extended position
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The door lock fixture, in particular the mortice lock, comprises a faceplate (1) and a lock body (2) which is configured to be inserted through a slot (3) in a tubular member (5). In order to enable to fix the faceplate (1) by means of at least one bolt (16) against the wall (4) of the tubular member (5), the lock comprises further at least one clamping lever (11) which is pivoted onto the lock body (2) between a retracted position, wherein the lock body (2) can be inserted through said slot (3) into the tubular member (5), and an extended position, wherein the clamping lever (11) engages the inner surface of the wall (4) of the tubular member (5) to clamp this wall (4) between the faceplate (1) and the clamping lever (11). The clamping lever (11) is provided with a screw threaded hole (19) wherein said bolt (16) can be screwed through an opening (18) in the faceplate (1) to fix the lock strongly and reliably onto the tubular member (5) and this independent of the wall thickness thereof.