Hydraulic Piston Ball Head Sealing for Plastic-Coated Slider Shoe Assembly
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Solution Overview
Problem
The production of hydraulic pistons with a ball head and slider shoe is complex due to the need for precise positioning and injection of plastic material into a gap between the components, which complicates the assembly process.
Innovation Solution
A sealing surface is introduced at the end of the through channel with a conical form, allowing a pin to be inserted from the opposite side of the slider shoe to prevent molten plastic from entering the through channel while still forming an inner coating in the gap between the slider shoe and ball head, simplifying the assembly and ensuring precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a pin is inserted through the through channel to guide plastic material, then the plastic material can be distributed into the gap between slider shoe and ball head, but the positioning precision and tool complexity increase significantly
Solution Approach 1:
Instead of inserting the pin from the ball head side through the through channel as in conventional methods, the pin is inserted from the opposite side through the through hole in the slider shoe. This inversion of the insertion direction simplifies the positioning process and reduces tool complexity while achieving the same goal of guiding plastic material into the gap.
Solution Approach 2:
The pin acts as an intermediary element that temporarily occupies the through hole during the injection process. By positioning the pin in the through hole rather than using a complex tool to guide material through the through channel, the system achieves accurate material distribution with simpler positioning requirements.
2Ease of manufacture
If plastic material is injected through the through channel, then the gap between slider shoe and ball head can be filled, but the through channel may be blocked by molten plastic
Solution Approach 1:
The injection system is segmented into two separate pathways: the through hole in the slider shoe for pin insertion and material guidance, and the through channel in the ball head for hydraulic fluid flow. By preventing molten plastic from entering the through channel during injection, the functional pathway for hydraulic operation remains clear and reliable.
Solution Approach 2:
The pin inserted through the through hole performs a preliminary protective function by blocking the pathway that would otherwise allow molten plastic to enter and block the through channel. This preliminary anti-action prevents the harmful effect of channel blockage before it can occur during the injection process.
3Reliability
If the pin diameter is large to seal against the through channel, then plastic material is prevented from entering the channel, but the pin cannot be inserted through the slider shoe
Solution Approach 1:
The sealing function is localized to a specific region rather than requiring a long pin. The pin only needs to seal against the sealing surface at the end of the through hole where the plastic material enters, not along the entire length of the through channel. This local sealing approach allows the pin to be short enough to pass through the slider shoe while maintaining effective sealing.
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
This solution simplifies the production process by allowing easier alignment and injection of plastic material, enhancing mechanical stability and durability of the piston, while maintaining hydraulic balance and reducing friction between components.
Implementation Method 1
In contrast to oil water has not lubricating characteristics, so that the friction between sliding surfaces must be reduced in another way. In the present case, the friction between the ball head and the slider shoe is reduced by the plastic material.
Data Source
Figure 1~3
AI summary
A piston (1) of a hydraulic piston machine is described, the piston comprising a piston shaft (2), a ball head (3) at one end of the piston shaft (2), and a slider shoe (4) mounted to the ball head (3), wherein the ball head (3) comprises a through channel (5), the slider shoe (4) comprises a sliding surface (6) and a through hole (7) in communication with an end of the through channel (5), and a plastic material (8) is arranged in a gap between the slider shoe (4) and the ball head (3) and forms an inner coating (9) of the through hole (7). The production of such a piston should be facilitated. To this end a sealing surface (14) is arranged at the end of the through channel (5) wherein the sealing surface (14) surrounds the opening of the through channel (5) into the through bore (7) and an inner diameter of the sealing surface (14) is smaller than an inner diameter of the inner coating (9) of the through bore (7).