Dual-Threaded Spindle Adjustment for Rotary Cutting Die
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Solution Overview
Problem
Prior art cutting apparatuses for manufacturing plastic bags lack precise adjustment mechanisms to maintain the distance between the rotary anvil and cutting die, leading to over- or under-compensation for die blade wear, resulting in inconsistent cuts.
Innovation Solution
A cutting apparatus with a dual-threaded spindle adjustment mechanism that allows for fine adjustments of the anvil and cutting die position, enabling precise control through a motor or manual input, and includes a spring to maintain alignment, with automated adjustments based on die blade wear and process parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-threaded adjustment mechanism is used, then the structure is simple, but the adjustment precision is insufficient leading to over- or under-compensation for wear
Solution Approach 1:
The adjustment mechanism is segmented into two independent threaded portions with different pitches. The first threaded portion has a larger pitch for coarse adjustment, while the second threaded portion has a smaller pitch for fine adjustment. This segmentation allows the operator to first make rough adjustments to compensate for significant wear, then use the second portion for precise fine-tuning, thereby achieving high adjustment precision without requiring an overly complex mechanism.
Solution Approach 2:
The adjustment mechanism operates along the same linear dimension but introduces a second degree of freedom through dual-threaded portions with different pitches. This allows independent control at two different resolution levels along the adjustment axis, enabling both coarse and fine adjustments to be made sequentially on the same dimensional parameter (distance between anvil and cutting die) without adding spatial complexity.
2Manufacturing precision
If manual adjustment is performed frequently, then cutting precision is maintained, but time is lost and productivity decreases
Solution Approach 1:
The dual-threaded mechanism is designed to accommodate preliminary coarse adjustment followed by fine adjustment in a single operational sequence. The larger pitch of the first threaded portion allows rapid initial compensation for die blade wear, reducing the frequency and duration of adjustment interventions needed during production runs, thereby maintaining cutting precision while minimizing time loss.
3Reliability
If the adjustment mechanism allows large movements, then wear compensation is achieved, but over-compensation occurs reducing precision
Solution Approach 1:
The adjustment range is segmented into two stages: the first threaded portion with larger pitch handles the bulk of the wear compensation (large movements), while the second threaded portion with smaller pitch provides the final positioning (small movements). This segmentation ensures that large movements are made in controlled increments that can be precisely terminated, preventing over-compensation while still achieving full wear compensation capability.
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 solution enables precise and consistent cutting by allowing for fine adjustments of the anvil and cutting die distance, reducing wear-related issues and maintaining optimal cutting performance throughout the die blade's lifespan.
Implementation Method 1
an adjustment mechanism including a rotatable spindle having a first threaded portion and a second threaded portion, the pitch of the first threaded portion being different, i.e. larger or smaller, from the pitch of the second threaded portion, the first threaded portion engaging a threaded portion of the first or said second frame structure and the second threaded portion engaging a threaded portion of the apparatus frame
Implementation Method 2
a spring connected with the apparatus frame supports the first frame structure or the second frame structure. This spring prevents or limits undesired movements resulting from any play, such as within the hinge pivotally coupling the frame structure to the apparatus frame or within the adjustment mechanism proper, whereby the anvil is maintained as close to the cutting die as allowed for by the adjustment mechanism, which balances the force applied by the spring
Data Source
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AI summary
The present invention relates to cutting apparatus (20) including an apparatus frame (21) and a cut-ting station (26), for forming plastic bags interconnected along trans-verse lines of weakness, said cutting station (26) comprising a rotary anvil (28) having a first axis of rotation (A1) and mounted to a first frame structure (70), a rotary cutting die (30) disposed adjacent to said rotary anvil (28) and having a second axis of rotation (A2) substantially parallel to said first axis (A1) of rotation, said rotary cutting die (30) including a rotatable cylindrical shaft (32) carrying a die blade, said rotary cutting die (30) being mounted to a second frame structure (50), and an adjustment mechanism (M) for varying the distance between said anvil (28) and said cutting die (30), said mechanism (M) including a rotatable spindle (105, 105') having a first threaded portion (107, 107') and a second threaded portion (106, 106'), the pitch of said first threaded portion (107, 107') being different from the pitch of said second threaded portion (106, 106'), said first threaded portion (107, 107') engaging a threaded portion (75, 75') of said first or said second frame structure (50, 70) and said second threaded portion (106, 106') engaging a threaded portion (160, 160') of said apparatus frame (21).