Titanium Alloy Connecting Rod Bolt Hole Machining
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Solution Overview
Problem
Titanium alloys are harder to cut than steels, leading to high cutting resistance and requiring cutting tools with high rigidity, which are difficult to achieve due to interference issues and reduced tool lifetime during processing of titanium-alloy connecting rods.
Innovation Solution
The production method involves forming bolt holes by inclining the cutting tool's longitudinal direction with respect to the rod's longitudinal direction, allowing for a larger cutting tool diameter and enhanced rigidity, reducing processing time, and increasing the thickness of the big end for improved rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a cutting tool with high rigidity is used to cut titanium alloy, then cutting resistance is reduced and processing precision is improved, but the tool diameter must be large which causes interference with the workpiece structure
Solution Approach 1:
The patent changes the cutting direction from the conventional longitudinal direction (parallel to rod axis) to an inclined direction forming an angle of 10-30 degrees with the longitudinal direction. This dimensional change in cutting orientation allows the use of larger diameter cutting tools without interference with the big end structure, thereby improving tool rigidity while avoiding structural interference
2Manufacturing precision
If the cutting tool diameter is increased to improve rigidity, then processing precision and tool lifetime are improved, but the processing time increases
Solution Approach 1:
By cutting in an inclined direction rather than longitudinally, the patent enables the use of larger diameter cutting tools that have higher rigidity and can remove material more efficiently. The inclined cutting path, while slightly longer, allows for higher feed rates and deeper cuts due to the improved tool rigidity, resulting in net reduction of processing time compared to using smaller tools in the conventional longitudinal direction
3Weight of moving object
If titanium alloy is used for connecting rod to reduce weight, then weight reduction is achieved, but cutting resistance increases making machining difficult
Solution Approach 1:
The patent addresses the high cutting resistance of titanium alloy by changing the cutting orientation to an inclined direction. This allows the use of larger diameter cutting tools with higher rigidity that can effectively cut through the hard titanium alloy material, reducing cutting forces and improving machinability despite the material's inherent difficulty to machine
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
There is provided a production method for a titanium-alloy connecting rod that ensures high rigidity of a cutting tool. One embodiment of the present invention provides a production method for a titanium-alloy connecting rod (1) in which a rod portion (33) and a cap portion (34) of a big end (30) are fixed by using a bolt (40). The production method for the titanium-alloy connecting rod (1) includes a step of forming a bolt hole (32) for the bolt (40) to extend therethrough. The step of forming the bolt hole (32) includes: forming a first hole (61) in the cap portion (34) and the rod portion (33) in a direction from the cap portion (34) toward the rod portion (33); and forming a second hole (62) in the rod portion (33) in a direction from the rod portion (33) toward the cap portion (34). Once the first and second holes are formed, the first hole (61) and the second hole (62) communicate with each other. The longitudinal direction (LD2) of a cutting tool (52) used for forming the second hole (62) is inclined with respect to the longitudinal direction (y) of the rod main body (10) of the titanium-alloy connecting rod (1).