Conveyors: power-driven – Conveyor section – Endless conveyor
Reexamination Certificate
2002-04-23
2003-11-11
Hess, Douglas (Department: 3651)
Conveyors: power-driven
Conveyor section
Endless conveyor
C198S810010, C198S810020, C198S810040
Reexamination Certificate
active
06644465
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to novel and advantageous improvements to belted conveyor safety devices. It is common to have a pull chord extending longitudinally along the side of industrial materials handling conveyors, sometimes one chord on each side of the conveyor. These chords are generally rigidly attached at one end, then threaded through the center of eyebolts along the length of the conveyor, and are finally fastened at the other end to a trip mechanism, or safety switch. These devices are un-affectionately known as ‘Dead-Man Switches’.
2. Description of the Prior Art
There are various types of conveyor safety switching mechanisms on the market essentially comprising of a chord or cable operated type. However, all are presently manually-activated, to my knowledge. That is, they need to be pulled or actuated by an operator or attendant.
A person pulling on this chord activates the switch, which de-energizes the conveyor by opening the electrical circuit to the drive motor, thus stopping the conveyor belt. All are located along the sides of the conveyors.
SUMMARY OF THE INVENTION
A number of serious accidents have occurred in the industry which have resulted in injury, or worse, due to unprotected nip points at the return idlers under belted conveying systems. The nip point is the pressure point between the moving rubber belt and the return idler roller. It is analogous to the double-roller squeezing action of the antiquated wringer-washer. The return idlers are located cross-directionally to the belt travel, on the underside, or belly of the conveyor.
Extensive guarding, or barriers, could be installed to restrict access underneath these conveying structures while they are in operation. These barriers ultimately become inefficient in terms of safeguarding devices, especially when affecting housekeeping in these areas, because there is a likelihood of:
the barriers are inevitably opened or removed;
the guards are not replaced, or;
the guards are simply left open if they are hinged.
Tools (such as brooms, rakes, or shovels) and personal loose clothing can become entrained into these nip points. Although longitudinal pull chords and trip mechanisms are meant to be a protective device as a combination, chances are if and while an accident occurs, the casualty does not have the reach, or the thought process, to manually activate the tripping mechanism by pulling the longitudinal chords. Hence, these mechanisms are also not effective safeguarding devices.
In this invention, a simple, inexpensive, yet efficient device has been developed to minimize the risks of injuries with consideration to housekeeping requirements on the underside of belted conveyors.
I have found that the inaccessibility to, and the inefficient manual activation of the longitudinal pull chord can be easily overcome.
In this invention: a primary pull chord length is sleeved with a shorter semi-rigid support rod; this primary pull chord spans in parallel closely upstream of a conveyor return idler nip point; each end of the said pull chord is inserted through guides rigidly attached onto each side of said conveyor; at least one end of the primary pull chord is linked to a secondary pull chord, longitudinal to the conveyor, this secondary pull chord in turn is connected to a conveyor-disabling safety device; and the other end of the primary pull chord, if not attached to another secondary pull chord on the opposite side of the conveyor to the first secondary pull chord, it is then rigidly attached onto that opposite side of the conveyor.
Additionally, the semi-rigid support rod may be encapsulated in a lightweight foamy tube to give it bulkiness by increasing the surface area.
In the event of an incident, the primary pull chord, being close to the leading edge of the nip point, is automatically entrained into the nip point. The primary chord in turn draws the secondary longitudinal pull chord, which then trips the safety switch, thus effectively de-energizing the conveyor belt.
The added bulkiness of the lightweight foamy tube encapsulating the semi-rigid support rod improves the likelihood the primary pull chord will get entrained into the nip if an external force displaces it from its original position.
Although the intent of this device is to serve as a more efficient means of activation of the tripping mechanism, it is not meant to act as a barrier. If an incident does occur, this device will minimize the extent of the injury. It also serves as a more direct and accessible pull chord even if it is not actually entrained, for one reason or another, into the nip point.
It is an overall aim of the present invention to provide a conveyor belt nip point protection device.
It is also an aspect of this invention to provide a more efficient and automatic conveyor-tripping mechanism by providing a direct and accessible pull chord close to the nip point.
Yet another advantage of this invention is to afford a semi-rigid mechanism that can be reset into place after having been activated.
Still another aim of the present invention is for a product to be pliable with minimal replacement parts after having gone through the nip point a number of times.
Finally, one last objective of this invention is to offer a product that can be easily and inexpensively manufactured.
Other objects and advantages of the present invention may present themselves from the following description when considered with the accompanying drawings.
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patent: 6131727 (2000-10-01), Nelson
patent: 6431348 (2002-08-01), Malmberg
patent: 3333832 (1985-04-01), None
patent: 3619528 (1987-12-01), None
patent: WO87/02017 (1987-04-01), None
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