Casting Device Inclined Bore Pins Counteract Cylinder Tilt
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Solution Overview
Problem
In casting multi-cylinder engine cylinder blocks, the outermost cylinder bores tend to tilt inwardly toward the crankcase, leading to reduced adhesion between the piston and cylinder bore wall, increased gas escape, and poorer fuel economy due to residual stress from shrinkage or deformation.
Innovation Solution
A casting device with inclined bore pins in the second mold, which are angled outwardly before release, counteracting the inward tilt caused by residual stress, ensuring the cylinder bores remain straight and maintaining better piston adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional casting molds with straight bore pins are used, then the manufacturing process is simple, but the outermost cylinder bores tilt inwardly toward the crankcase due to residual stress, reducing piston adhesion and fuel economy
Solution Approach 1:
The outermost bore pins are pre-inclined outwardly before casting to counteract the inward tilt that will occur due to residual stress during solidification and mold release. This preliminary anti-action ensures that the cylinder bores remain straight after the casting process, solving the technical contradiction by achieving high manufacturing precision without requiring complex post-processing or additional support structures.
Solution Approach 2:
The mold structure is designed with pre-calculated outward inclination angles for the outermost bore pins based on anticipated residual stress distribution. This preliminary action of pre-positioning the bore pins at specific angles before casting allows the cylinder bores to achieve the desired straightness after solidification and mold release, maintaining manufacturing precision while keeping the mold structure relatively simple.
2Use of energy by moving object
If the outermost cylinder bores are allowed to tilt inwardly, then the mold structure remains simple, but gas escapes from the combustion chamber and fuel economy deteriorates
Solution Approach 1:
By pre-inclining the outermost bore pins outwardly, the design compensates for the harmful inward tilt that would otherwise occur, preventing gas escape paths and maintaining combustion chamber integrity. This ensures good fuel economy without requiring complex seal structures or additional components.
Solution Approach 2:
The invention converts the harmful residual stress that causes inward tilting into a beneficial effect by pre-positioning the bore pins with outward inclination. The residual stress, which would normally be harmful, becomes part of the design calculation to achieve the final straight bore configuration, thereby improving fuel economy while maintaining a simple mold structure.
3Use of energy by moving object
If bore pins are inclined outwardly to counteract residual stress, then fuel economy improves, but the mold design becomes more complex
Solution Approach 1:
Instead of inclining all bore pins, the design applies outward inclination only to the outermost bore pins where residual stress causes the most significant inward tilting. This local quality approach improves fuel economy by addressing the specific problem area while keeping the overall mold design relatively simple and maintaining uniformity in the majority of the bore pins.
Data Source
AI summary
Provided are a stationary mold configured to form a portion of a bearing portion of a crankshaft and a portion of a crankcase, and a movable mold including a plurality of bore pins respectively defining cylinder bores of cylinders. The bore pins are arranged to correspond to a cylinder bank including the plurality of cylinders. The movable mold is matched with the stationary mold such that portions of outermost ones of the plurality of bore pins in a series direction are each inclined away from another one of the plurality of bore pins adjacent to the outermost bore pin in the series direction toward a distal end of the outermost bore pin, where the series direction represents a direction in which the plurality of bore pins are arranged.