Drilling Jig Pressing Force Control for Workpiece Deformation
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Solution Overview
Problem
Drilling apparatuses with low holding rigidity, especially those used as end effectors in multi-joint robots, suffer from machining accuracy deterioration due to insufficient rigidity and machining reactions, leading to misalignment and deformation during drilling, particularly in machining tasks involving flat workpieces.
Innovation Solution
A drilling method employing a drilling jig with positioning holes and a pressing unit where the relative position of the pressing member to the drill is fixed, allowing the pressing member to fit within the jig, thereby maintaining precise alignment and applying a predetermined pressing force to suppress deformation and displacement during drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rigidity of the holding structure is increased to suppress displacement, then machining accuracy is improved, but device complexity and size increase
Solution Approach 1:
A drilling jig is introduced as an intermediary component between the workpiece and the drilling apparatus. The jig includes positioning holes that guide the drill and pressing surfaces that stabilize the workpiece, thereby improving machining accuracy without modifying the drilling apparatus itself. This mediator approach resolves the contradiction by achieving precision through an auxiliary component rather than increasing the complexity of the main system.
2Manufacturing precision
If a pressing body is used to press the work during drilling, then misalignment is suppressed, but workpiece deformation occurs due to excessive pressing force
Solution Approach 1:
The pressing force is applied locally at specific pressing surfaces of the drilling jig rather than uniformly across the entire workpiece. The jig is designed with localized pressing areas that apply force only where necessary to prevent misalignment, while leaving other areas free to avoid deformation. This local quality approach resolves the contradiction by concentrating the pressing action in specific zones.
Solution Approach 2:
The workpiece is positioned and pressed by the drilling jig before drilling begins. The positioning holes and pressing surfaces are prepared in advance to establish the correct position and orientation, and the pressing force is applied preliminarily to stabilize the workpiece before the drilling process starts. This preliminary action prevents misalignment from occurring in the first place, rather than correcting it during drilling.
3Manufacturing precision
If the work is pressed from the drill advancing side, then misalignment is reduced, but deformation occurs on the rear surface due to lack of support
Solution Approach 1:
The drilling jig provides support not only from the drill advancing side but also from the rear surface side through its structural design. The jig extends to contact and support the rear surface of the workpiece, creating a stabilizing effect in another dimension (the rear side). This multi-dimensional support approach resolves the contradiction by balancing the pressing force from the front with supporting force from the rear, preventing deformation while maintaining positioning accuracy.
Data Source
Figure 1
Figure 2~3
Figure 4A~4C
AI summary
There is provided a drilling apparatus. A drilling apparatus 1 includes a drill 12 rotatable about a center axis Ax and capable of advancing and retracting along the center axis Ax, and a pressing member 13 for pressing a work W in a drill advancing direction Z+. The drilling apparatus 1 advances the drill 12 while rotating the drill 12 about the center axis Ax to form a hole in the work W, in a state in which the work W is pressed by the pressing member 13. A pressing force applied on the work W by the pressing member 13 is set to a predetermined pressing force P on the basis of machining reaction applied to the drill from the work during drilling and the pressing force causing deformation of the work in the advancing direction of the drill, the machining reaction and the pressing force being calculated in a drilling test performed in advance. The predetermined pressing force P is capable of suppressing deformation of the work W and displacement of the drill 12 due to the machining reaction.