Metal Cable Tray Knockout Structure for Low-Stress Cable Openings
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Solution Overview
Problem
Existing cable tray components face issues with knockout openings that can introduce significant tension and damage cables, especially in longer components, and are not suitable for cyclic sequences of knockout openings.
Innovation Solution
The design features break-out slugs that are almost completely punched out and embossed with a stiffening structure, such as a bead, which reduces the base area and eliminates tension, allowing for easy removal without damaging the cable tray material, and can be levered out from both sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If knockout openings are created in cable tray components, then cable entry and exit is enabled, but significant stress is introduced into the cable tray material especially in longer components
Solution Approach 1:
The knockout opening is segmented into two parts: a permanent rim portion that remains in the cable tray and a removable knockout portion that is punched out. This segmentation allows the opening to be created without compromising the structural integrity of the cable tray, as the permanent rim maintains the material continuity while still enabling cable passage when the knockout portion is removed.
Solution Approach 2:
The knockout opening features non-uniform wall thickness with a thicker rim portion and a thinner knockout portion. This local quality variation allows the rim to bear the structural load and resist stress in the cable tray material, while the thinner knockout portion is easier to remove and creates the opening for cable entry and exit.
2Ease of operation
If knockout openings are dimensioned larger for cable passage, then cable accessibility is improved, but more material is removed and structural integrity is compromised
Solution Approach 1:
The knockout opening employs varying wall thickness throughout its structure. The rim portion maintains greater thickness to preserve structural integrity and bearing capacity, while the knockout portion has reduced thickness to facilitate easy removal and provide adequate cable passage space. This localized quality differentiation resolves the contradiction between large opening size and structural strength.
3Adaptability or versatility
If knockout openings are created in cyclic sequences over the length of cable trays, then cable routing flexibility is improved, but tension accumulates in the cable tray material
Solution Approach 1:
Each knockout opening in the cyclic sequence is segmented with a permanent rim and a removable knockout portion. This segmentation allows multiple openings to be created along the cable tray length without continuous stress accumulation, as each opening maintains material continuity through its rim portion while providing independent cable access points for flexible routing.
Data Source
Figure 1~2
Figure 3a~3c
AI summary
The invention relates to a cable tray component (1) made of metal and having knockout openings (7) for creating, as needed, one opening each, which extends through the cable tray component (1), by the removal of a knockout piece (8), for example in order to provide a cable outlet, the knockout openings being distributed over the length of the cable tray component (1) and being closed by means of one knockout piece (8) each, wherein, in such a knockout opening (7), the knockout piece (8) sits as a punched piece within the punched opening but is connected to the edge region (10) of the knockout opening (7) of the cable tray component (1) by means of at least one connecting portion (11), and wherein at least one structure (13) stiffening the knockout piece (8) is stamped into the knockout piece (8) closing the knockout opening (7), by means of which structure the base area of the knockout piece (8) is reduced in comparison with the base area of the punched piece punched out to provide the knockout opening (7) – the later knockout piece (8).