Spreading Tool for Isosceles Corner Folds in Tubular Sacks

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Solution Overview

Problem

Existing sack manufacturing plants face challenges in forming geometrically precise open bottoms on tubular sack bodies during continuous transport, leading to warped bottoms and reduced throughput, especially when processing sack bodies made of stretched plastic ribbons which tend to slip and are difficult to fold.

Innovation Solution

A method and device that transport tubular sack bodies flat and open their end regions during continuous processing, using a spreading tool to form isosceles triangular corner folds, which are then pressed to create geometrically precise open bottoms, allowing for higher quality sack production and improved handling of materials like stretched plastic ribbons.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If intermittent operation is used to form open bottoms with high geometric precision, then manufacturing precision is improved, but productivity deteriorates

Engineering Contradiction:

Improvegeometric precision of open bottomsVSAvoidthroughput of sack bodies

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent implements continuous transport of tubular sack bodies through the base opening process, eliminating intermittent stopping and starting. The spreading tool continuously forms isosceles triangular corner folds on moving sack bodies, maintaining constant production flow while achieving geometric precision through controlled material spreading and folding mechanics

Inventive Principle:

Principle #20Continuity of useful action

2Productivity

If continuous transport is used to increase productivity, then productivity is improved, but manufacturing precision deteriorates due to warping

Engineering Contradiction:

Improvethroughput of sack bodiesVSAvoidgeometric precision of open bottoms

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The spreading tool performs preliminary spreading and pre-folding actions on the sack body layers before final bottom formation. By pre-positioning the material in isosceles triangular configurations during continuous transport, the system establishes geometric accuracy early in the process, preventing warping in subsequent operations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The spreading tool acts as an intermediary device between the continuous transport system and the final bottom formation process. It mediates the transformation of flat sack body layers into precisely folded isosceles triangular configurations, ensuring geometric precision is maintained throughout continuous operation

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If stretched plastic ribbons are used to create strong sack bodies, then strength is improved, but ease of manufacture deteriorates due to slipping and difficult folding

Engineering Contradiction:

Improvestrength of sack bodiesVSAvoidease of folding and handling

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The spreading tool applies localized spreading and folding actions at specific regions of the sack body where corner folds are required. By concentrating manufacturing complexity only at the corner fold locations rather than throughout the entire strong but difficult-to-handle plastic ribbon structure, the system maintains material strength while achieving necessary geometric transformations

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP2441574B1Method and device for constructing open bases at end sections of tubular bag bodies

Publication Date: 2013.05.15 STARLINGER & CO GESELLSCHAFT MBH

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AI summary

In a device (1) for forming an open bottom at an end region (10e) of a tubular bag body (10), the bag bodies (10) are transported flat in the transport direction (T) transversely to their longitudinal extent (L) at a transport speed (V), and the end regions are opened by an opening device (20). A spreading tool is inserted into the opened end regions (10e) of the bag bodies during their transport on the transport device and moved in the transport direction (T) at a speed (V1R) increased relative to the transport speed (V) until it runs against the inside of the bag body at the front part (10v) of the opened end region with front contour points (23p, 24p; 33p, 34p). In doing so, it spreads the front part (10v) into a front corner fold (10j) in the shape of an isosceles triangle.After the corner fold (10j) is formed, the spreading tool (21, 30, 32) is moved out of the front corner fold (10j) by slowing its movement relative to the transport speed (V). The corner fold is then pressed by a pressing device (28, 35, 36).