Sewing Machine Cloth Feed Adjusting Device Cam Mechanism

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Solution Overview

Problem

Conventional cloth feed adjusting mechanisms in sewing machines require significant mechanical force and suffer from sliding friction issues during stitch pitch switching, leading to reduced maintenance efficiency and increased wear, as they rely on air cylinders or electromagnets to overcome resistance between cam members and contact pins.

Innovation Solution

A cloth feed adjusting device with a cam member system that includes a first and second cam member, each with forward and backward feed adjusting portions, and a turning unit with a contact portion that rotates to switch between these portions without sliding contact, utilizing a pitch switching actuator and feed direction switching actuator controlled by a unit to minimize friction and facilitate seamless stitch pitch changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cam members with sliding contact are used for stitch pitch switching, then the mechanism can achieve stitch pitch changes, but sliding friction increases leading to high wear and reduced maintenance efficiency

Engineering Contradiction:

Improvemaintenance efficiencyVSAvoidsliding friction and wear

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the conventional sliding contact mechanical system with a rolling contact system using rollers. The rollers are positioned to contact the cam surfaces at multiple points, transforming the sliding friction into rolling friction. This substitution dramatically reduces wear on the cam members and contact surfaces, thereby improving maintenance efficiency and reliability without compromising the stitch pitch switching function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If air cylinders or electromagnets are used to overcome sliding friction during pitch switching, then stitch pitch switching can be achieved, but the actuators require significant mechanical force and output

Engineering Contradiction:

Improvestitch pitch switchingVSAvoidactuator output

Core Design Contradiction:

Ease of operationVSPower

Solution Approach 1:

By replacing sliding contact with rolling contact through the introduction of rollers, the friction resistance is dramatically reduced. This mechanical substitution allows pitch switching actuators to operate with significantly reduced power output, as the rollers eliminate the need to overcome high sliding friction forces during the switching operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If sliding contact between cam members and contact pins is used, then stitch pitch adjustment is possible, but wear increases leading to reduced durability

Engineering Contradiction:

Improvestitch pitch adjustmentVSAvoiddurability

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of stationary object

Solution Approach 1:

The patent introduces rollers that contact the cam surfaces instead of allowing direct sliding contact between cam members and contact pins. This rolling contact system maintains the adaptability for stitch pitch adjustment while dramatically reducing wear on the stationary cam members, thereby extending their service life and improving overall durability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If conventional sliding contact mechanisms are used, then stitch pitch switching can be performed, but the switching speed is reduced due to friction resistance

Engineering Contradiction:

Improvestitch pitch switching speedVSAvoidsliding friction

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

By substituting sliding contact with rolling contact through the use of rollers, the friction resistance during pitch switching is dramatically reduced. This allows the pitch switching actuators to move the cam members more quickly and smoothly, thereby increasing the stitching pitch switching speed and improving productivity without the hindrance of high sliding friction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2617884B1Cloth feed adjusting device of sewing machine

Publication Date: 2014.08.13 JUKI CORP

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AI summary

A cloth feed adjusting device of a sewing machine includes a turning unit (86) configured to change a stitch pitch, a cam member (78, 79) configured to change a rotation angle of the turning unit, first and second adjusting members (76, 77) configured to set a rotation angle of the cam member, and a pitch switching actuator (80) configured to switch a contacting state between a cam portion (781,791) and contact portions (731, 741) of the turning unit. The cam portion is formed such that a forward feed adjusting portion (785, 795) for adjusting a forward feeding pitch and a backward feed adjusting portion (786, 796) for adjusting a backward feeding pitch face each other and have a border at an intermediate position (784, 794) at which a stitch pitch becomes 0. The cloth feed adjusting device includes a feed direction switching actuator (81) configured to moves the contact portion between the forward feed adjusting portion and the backward feed adjusting portion to switch a stitch direction, and a control unit (90) configured to drive, at the time of starting the operation of the pitch switching actuator, the feed direction switching actuator in a range in which the stitch direction is not switched.