Bottle-Shaped Bore Honing Tool for Cylinder Block Friction Reduction
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Solution Overview
Problem
Conventional honing methods for cylinder blocks in reciprocating engines fail to adequately reduce friction, oil consumption, and wear, while also being prone to cylinder distortions that impair piston ring sealing and increase engine noise, due to the inability to maintain an ideal circular bore shape under varying operational conditions.
Innovation Solution
A honing method and tool that produce a bottle-shaped bore with a narrow first section, a larger second section, and a transitional section, utilizing a ring tool with radially expandable cutting groups to distribute machining forces evenly and maintain consistent contact, thereby reducing friction and wear while accommodating diameter variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional honing methods are used to machine cylinder bores, then the bore surface can be finished, but the bore shape deviates from ideal circular cylinder shape due to cylinder distortion, impairing piston ring sealing
Solution Approach 1:
The patent applies form honing to create a bore shape that intentionally deviates from a perfect circular cylinder shape. Instead of trying to achieve ideal circularity that cannot be maintained under operating conditions, the method inverts the approach by pre-distorting the bore shape during machining so that when the cylinder distorts under thermal and mechanical loads, the bore shape becomes more circular and maintains proper piston ring sealing. This inverse compensation strategy resolves the contradiction between manufacturing precision and operational reliability.
Solution Approach 2:
The patent performs preliminary deformation of the bore shape during the machining process itself, rather than attempting to correct distortion after assembly. By pre-establishing a compensated bore geometry that anticipates future thermal and mechanical distortion, the system ensures that the bore maintains its functional shape during operation. This preliminary action prevents sealing problems before they occur during engine operation.
2Ease of manufacture
If the bore shape is maintained as ideal circular cylinder, then machining is simplified, but friction and wear increase under operational conditions due to cylinder distortion
Solution Approach 1:
The patent applies local quality by creating non-uniform bore shapes with varying cross-sectional geometries along the bore length. Instead of a uniform circular cylinder, the bore is machined with specific local deviations (such as ovality or cloverleaf shapes) that are optimized for different sections. This allows the surface to maintain better contact and lubrication characteristics under operational distortion, reducing friction and wear while still being machinable through adapted honing processes.
3Productivity
If honing stones with large axial elongation are used, then material removal is efficient, but manufacturing precision decreases in the transition zone between cylindrical and elliptical regions
Solution Approach 1:
The patent segments the honing process into multiple operations with different honing stones having varying axial elongations. Instead of using a single honing stone for the entire bore, the method employs a sequence of stones with progressively different geometries - some with larger axial elongation for efficient material removal in cylindrical sections, and others with smaller axial elongation for precise control in transition zones. This segmentation allows each stone to be optimized for its specific operational zone, resolving the contradiction between productivity and precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method and tool design significantly reduce friction, oil consumption, and wear, improve piston ring sealing, and minimize engine noise by optimizing the bore shape and surface structure, ensuring consistent performance across different operational states.
Implementation Method 1
an expandable honing tool is moved up and down or back and forth within the bore to generate a stroke motion in the axial direction of the bore at a stroke frequency, and simultaneously rotated at a revolution frequency to generate a superimposed rotary motion
Implementation Method 2
The cutting material elements attached to the honing tool are pressed against the internal surface to be machined by a feed system with a feed force acting radially to the tool axis
Implementation Method 3
Honing is a machining process with geometrically undefined cutting edges... Honing creates a cross-hatch pattern on the internal surface, typical of honing, with intersecting machining marks
Data Source
Figure 1~2B
Figure 3A~3B
Figure 4A~4B
AI summary
In a honing method for machining the internal surface of a bore in a workpiece with the aid of at least one honing operation, during a honing operation an expandable honing tool is moved up and down within the bore in order to produce a reciprocating movement in the axial direction of the bore and at the same time is rotated in order to produce a rotary movement superimposed on the reciprocating movement. In the process, a bottle-shaped bore is produced, said bore having a first bore section with a first diameter after a bore inlet, a second bore section with a second diameter greater than the first diameter away from the bore inlet, and a transition section having a continuous transition from the first diameter to the second between the first and the second bore section. In this case, during at least one honing operation use is made of an annular tool (200) which has at least one annular cutting unit (220) with a plurality of radially adjustable cutting-material bodies that are distributed around the circumference of a tool body and are formed as honing segments that are wide in the circumferential direction and narrow in the axial direction, wherein an axial length, measured in the axial direction, of the honing segments is less than the width measured in the circumferential direction and the axial length of the cutting region equipped with cutting-material bodies is less than the effective outside diameter of the honing tool. The method is particularly suitable for honing cylinder running surfaces in the production of cylinder blocks or cylinder liners for reciprocating piston machines.