Circular Knitting Machine Sinker Actuation with Alternating Pusher Cams
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Solution Overview
Problem
Existing circular knitting machines for hosiery often experience excessive tensioning of loops by sinkers on needles not actively knitting, leading to defects in the finished product, and current solutions like pneumatic actuators are complex and unreliable.
Innovation Solution
The machine employs alternating pusher cams actuated by an electric motor, allowing selective movement of sinker actuation to control tension on loops, ensuring only actively knitting needles receive tensioning, while those not knitting are tensioned minimally or not at all.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sinkers are continuously actuated to tension loops during needle rotation, then knitting loops are properly formed, but non-knitting needles experience excessive tension causing defects
Solution Approach 1:
The sinker actuation system is made dynamic by selectively enabling and disabling pusher cams based on whether needles are actively knitting. The control system monitors needle position and yarn feed status, then dynamically adjusts sinker actuation to apply tension only when needed, preventing excessive tension on non-knitting needles while maintaining proper loop formation on active needles
Solution Approach 2:
Different tension control strategies are applied to different spatial zones of the needle cylinder. Knitting needles receive full sinker actuation for proper loop formation, while non-knitting needles receive reduced or no sinker actuation to avoid defects. This localized quality control ensures each needle type receives appropriate treatment
2Measurement precision
If pneumatic actuators are used to selectively move pusher cams, then tension control precision is improved, but device complexity and reliability worsen
Solution Approach 1:
The patent replaces complex pneumatic actuators with a simplified mechanical control system. Instead of using pneumatic cylinders to move pusher cams, the invention employs a cam-based mechanical linkage system controlled by sensors and a microcontroller. This substitution maintains precision while dramatically reducing system complexity and improving reliability
Solution Approach 2:
The control system uses the existing mechanical motion of the needle cylinder and yarn feed mechanisms to generate control signals for sinker actuation. The system monitors its own operational state through sensors detecting needle position and yarn presence, then automatically adjusts sinker actuation without requiring external complex actuation systems
3Object-affected harmful factors
If pusher cams are moved to selectively actuate sinkers, then tension on non-knitting needles is reduced, but actuation system complexity increases
Solution Approach 1:
The sinker actuation system is segmented into multiple independent pusher cams, each controllable based on needle knitting status. Instead of a single unified actuation mechanism, the patent divides the system into discrete controllable units (pusher cams) that can be independently enabled or disabled. This segmentation allows selective tension application while maintaining a relatively simple overall structure
Solution Approach 2:
The pusher cams serve multiple functions: they actuate sinkers for active knitting needles, remain inactive for non-knitting needles, and can be controlled through a unified sensor-based system. This multi-functionality reduces the need for separate specialized mechanisms, keeping the actuation system simple while achieving selective tension control
Data Source
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AI summary
A circular machine for knitting, hosiery or the like, with sinker actuation device, comprising a needle cylinder (2), arranged so that its axis (2a) is substantially vertical and actuatable with a rotary motion about the axis (2a) in both directions of rotation. The needle cylinder (2) has, on its lateral surface, a plurality of axial grooves (3), each of which accommodates a needle (4) that can move on command along the corresponding axial groove (3) in order to pick up at least one yarn dispensed at least one feed or drop (5) and form knitting. The machine also comprises needle actuation cams (10), which face the lateral surface of the needle cylinder (2) and define paths that are extended around the axis (2a) of the needle cylinder (2) and can be engaged by at least one heel (4a) of the needles (4), which protrudes from the lateral surface of the needle cylinder (2), in order to actuate the movement of the needles (4) along the corresponding axial groove (3) with respect to the needle cylinder (2) as a consequence of the rotation of the needle cylinder (2) about its own axis (2a) with respect to the needle actuation cams (10) and the at least one feed (5). The machine also comprises a sinker ring (6), which is integral with the needle cylinder (2) in rotation about its own axis (2a) and is arranged coaxially to the needle cylinder (2) at its upper end. The sinker ring (6) supports a plurality of sinkers (8) that can move radially with respect to the needle cylinder (2) and to the sinker ring (6). The machine also comprises a sinker cap (9), which is arranged above and coaxially with respect to the sinker ring (6) and supports sinker actuation cams (10) that define at least one path that is extended around the axis (2a) of the needle cylinder (2) and can be engaged by a heel (8a) of the sinkers (8), which protrudes upwardly from the sinker ring (6), in order to 2 actuate the movement of the sinkers (8) along a radial direction with respect to the needle cylinder (2) and to the sinker ring (6) as a consequence of the rotation of the needle cylinder (2) about its own axis (2a) with respect to the sinker cap (9), to the at least one feed (5) and to the sinker actuation cams (10). The needle actuation cams (41) comprising two needle lifting cams (45, 46), respectively a first cam for lifting the needles to the tuck or dropped position (45) and a second cam for lifting the needles to the tuck or dropped position (46), which are arranged on mutually opposite sides with respect to an imaginary plane that passes through the axis (2a) of the needle cylinder (2) and through the at least one feed or drop (5) of the machine. The sinker actuation cams (10) comprise two pusher cams (12, 13), respectively a first pusher cam (12) and a second pusher cam (13), arranged on mutually opposite sides with respect to an imaginary plane that passes through the axis (2a) of the needle cylinder (2) and through the at least one feed or drop (5) of the machine. The pusher cams (12, 13) can engage the heel (8a) of the sinkers (8) to cause the movement of the sinkers (8) toward the axis (2a) of the needle cylinder (2). In the machine, the first pusher cam (12) and the second pusher cam (13) are arranged respectively at the first cam for lifting the needles to the tuck or dropped position (45) and at the second cam for lifting the needles to the tuck or dropped position (46) and can move with respect to the sinker cap (9) toward or away from the axis (2a) of the needle cylinder (2). Actuation means (15) are provided which act on the first pusher cam (12) and on the second pusher cam (13) in order to move alternatively the first pusher cam (12) or the second pusher cam (13) toward the axis (2a) of the needle cylinder (2) or away from the axis (2a) of the needle cylinder (2).