Exchangeable Drill Bit Connection for Stable Force Transmission
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Solution Overview
Problem
Existing drill bits with exchangeable cutting sections suffer from instability during drilling and tensile loads, and there is a risk of the plug-turn connection opening unintentionally when trying to remove a jammed bit, leading to incomplete force transmission and misdirection of cooling media.
Innovation Solution
The design incorporates a positive connection between the drill shaft section and the cutting section using a nose and groove arrangement, which enhances stability and prevents unintentional disconnection, along with a larger outer plug-in element diameter to ensure secure force transmission and efficient cooling medium flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a plug-and-twist connection is used between the cutting section and drill shank section, then the cutting section can be replaced, but axial play exists and force transmission is incomplete
Solution Approach 1:
The connection system is divided into multiple independent elements: pin elements for rotational connection, slot-shaped recesses for positioning, and a nose-groove arrangement for axial retention. Each segment performs a specific function, collectively ensuring both replaceability and reliable force transmission without axial play.
Solution Approach 2:
The pin elements are inserted into the slot-shaped recesses, creating a nested configuration where the cutting section's outer plug element contains the pin elements which in turn engage with the inner plug element's recesses. This nested arrangement ensures multiple points of contact for stable force transmission while maintaining the ability to disconnect and replace the cutting section.
2Ease of operation
If the bit jams in the ground and manual freeing is attempted, then the operator can apply pulling force, but the plug connection may unintentionally open
Solution Approach 1:
The nose-groove arrangement and the pin elements within slot-shaped recesses create preliminary anti-actions against tensile loads. The nose prevents axial withdrawal, while the pin elements positioned in the recesses resist rotational disengagement. These pre-established mechanical constraints counteract the unintentional opening force that occurs during manual freeing operations, ensuring the connection remains stable even when the bit jams and pulling forces are applied.
3Ease of manufacture
If a gap forms between the plug elements, then the connection can be assembled, but cooling fluids are diverted and not delivered to the machining point
Solution Approach 1:
The pin elements are pre-positioned within the slot-shaped recesses during assembly, creating a preliminary mechanical constraint that guides and secures the cutting section in the correct axial position. This preliminary action ensures that when the connection is assembled, the components are properly aligned and seated, preventing the formation of gaps that would divert cooling fluids away from the machining point.
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
Drill bit (10), which is rotatable in a direction of rotation (21) about an axis of rotation (22), having: a cutting portion (11) with an annular portion (13), which is connected at a first end to one or more cutting elements (14) and has at a second end an outer insertion element (15) and a stop shoulder (59), and a drill shaft portion (12) with a cylindrical drill shaft (16), which has at an end towards the cutting portion (11) an inner insertion element (17) with an end face (33). In a direction of insertion parallel to the axis of rotation (22), the insertion elements (15, 17) form a plug-in connection and can be additionally connected by way of at least one pin element (25), which is movable in at least one slit-shaped clearance (26). The at least one pin element (25) is fastened to an outer side (27) of the inner insertion element (17) and the outer insertion element (15) has the at least one slit-shaped clearance (26).