Screw Compressor Casing Drilled Cast Holes
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Solution Overview
Problem
The existing methods for forming oil feeding passages in screw compressor casings face challenges such as long processing times and drill run-out issues due to manufacturing errors, leading to productivity losses and potential damage to precision parts.
Innovation Solution
A method involving drilling with a flat inner wall surface cast hole, where the width of the drilling position includes a manufacturing error range, allowing for reliable communication between the interior and exterior of the cast hole, preventing drill run-out and enabling cost-effective production without increasing the size of the cast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a long drill is used to form oil feeding flow passages by drilling, then the holes can be formed with good precision, but the processing time becomes excessively long and productivity deteriorates
Solution Approach 1:
The patent segments the hole formation process into two parts: (1) cast holes are formed by casting process for positions where cores can be easily installed, and (2) additional drill holes are processed only for positions where cast holes cannot be formed due to core installation difficulties. This segmentation reduces the overall processing time while maintaining precision where drilling is necessary.
Solution Approach 2:
The patent performs preliminary action by forming cast holes during the casting process itself, before any drilling operations. This preliminary formation of holes eliminates the need for long drilling operations for those positions, thereby reducing total processing time while maintaining the precision benefits of controlled hole formation.
2Productivity
If cast holes are used instead of drilled holes, then processing time is reduced and productivity improves, but drill run-out occurs due to casting displacement and processing resistance becomes non-uniform
Solution Approach 1:
The patent applies local quality by providing different types of holes (cast holes vs. drilled holes) at different locations based on local requirements. Cast holes are used where positioning tolerance can accommodate casting displacement, while drilled holes are used where high precision is required and can be achieved through additional processing. This local differentiation optimizes both productivity and precision.
Solution Approach 2:
The patent changes the parameter of hole formation method from purely drilling to a combination of casting and drilling. By changing the formation method parameter, the patent achieves a balance between productivity (faster casting process) and precision (corrected by subsequent drilling where needed), resolving the contradiction between speed and accuracy.
3Reliability
If the cast hole width is increased to accommodate manufacturing errors, then drill run-out is prevented, but the cast size increases and cost disadvantage occurs
Solution Approach 1:
The patent segments the hole formation into cast holes and additional drilled holes, allowing the cast hole width to be optimized for its specific function without needing excessive width for overall precision. The precision requirement is segmented to be handled by the subsequent drilling operation, enabling the cast hole to be narrower while still ensuring drill stability through the combined approach.
Data Source
AI summary
A method for forming drilled cast which includes drilling with a drill so as to provide communication with a cast hole includes a casting step and a drilling step. The casting step is to cast a cast having a cast hole which includes a flat inner wall surface in which width of a position to be drilled with the drill is obtained by adding first length H1 serving as a manufacturing error range of the cast to a diameter D of the drill, which is a second length H2. The drilling step is to form a through hole providing communication between an interior of the cast hole and an exterior of the cast through the flat inner wall surface with the drill.