1. Field of the Invention
This invention relates to non-rotating circular knives used in cutting cores to length.
More specifically, this inventions relates to means for automatically indexing a core cutting knife to present a fresh cutting edge to the work.
2. Background of the Invention
Non-rotating circular knifes are a preferred instrument for cutting cores to length.
A common mode of cutting cores is to mount a length of core on a mandrel and position the core relative to a knife that is movable towards and away from the core. The core is then rotated and the knife advanced into the core until a core segment of the desired length is severed from the core. The knife is then retracted and the core advanced on the mandrel to a new cutting position and the cycle is repeated.
The materials and methods used in forming cores are intended to make cores as tough and durable as is practical. The result is that cores are not easy to cut. Knife wear and thermal degradation as well as some mechanical damage are present in nearly every cut. This results in a relatively short life for the cutting edge and the frequent need to provide a new cutting edge.
Present practice is for an operator to monitor the cut and when he becomes aware that the knife had degraded to a point where the degradation is adversely effecting the cut, the knife is rotated to provide a new edge. Both the knife indexing apparatus and the method of indexing the knife are simple and straightforward.
Upon determination that the knife degradation requires the provision of a fresh cutting edge, an operator stops the cutting process, loosens the knife on its mount, rotates the knife to present a new edge, tightens the knife on its mount, and restarts the cutting process.
Heretofore, it has been common practice in the art to rotate the knife on a fixed mandrel to present a new cutting edge to the work. Typically, the rotation is done by hand and by eye and without regard to the direction in which the knife is rotated relative to the direction of rotation of the work being cut. As a consequence of this imprecise and unknowing approach, the number of knife repositionings that were had before the useful perimeter of the knife was consumed was often four or less.
The indexing apparatus of this invention increases the number and quality of the cuts that can be made with a single knife while reducing knife cost and machine down time.
The indexing means of this invention enables the precise repositioning of the knife without interrupting a cutting cycle, and as a consequence makes practical the programing and automating of knife indexing so that operator intervention relating to the knife is required only to remove a consumed knife and replace it with a fresh one.
The present invention involves methods wherein the number of cuts are summed and when they reach a predetermined number, the knife is rotated to present a new edge. The core cutting operation is thereby rendered more efficient and safe. Advancements in technologies and techniques have permitted the improvement of the knife indexing apparatus to the point wherein it can be fully automatic and requires only infrequent operator attention.
It has been discovered that the pattern of knife edge degradation is not symmetrical about the radius of the knife along which the knife is advanced. This discovery has lead to the discovery that the angle through which a knife needs to be rotated to provide a new cutting edge for the cutter is greater in one direction of rotation than it is in the other direction of rotation. If the knife is rotated so that it moves with the direction of rotation of the core the angle of rotation needed to reach a fresh edge is less than the angle of rotation needed to reach a fresh edge if the knife is rotated against the direction of rotation of the core.
This invention combines discoveries of the inventor with advances in the art to provide novel and unobvious improvements in a core cutting knife indexing apparatus.
It is an object of this invention to provide a knife indexing apparatus that combines known mechanisms and means with new discoveries and art knowhow to provide a knife indexing apparatus for non-rotating circular knife core cutters that is an improvement in the state of the art.
It is further an object of this invention to provide the knife indexing apparatus as described above wherein the combinations of mechanisms and means admit to automation to the degree that operator interaction is not required during the useful life of the circular knife.
It is further an object of this invention to provide the knife indexing apparatus as described above wherein art knowledge and discoveries are incorporated with suitable mechanisms and means to provide a knife indexing apparatus that is more efficient, accurate, and reliable than prior art core cutting knife indexing apparatus.
Other objects will be made apparent by the following specifications, claims and the attached drawings.
The prior art does not provide an apparatus for automatically indexing a non rotating core cutting knife in the direction of rotation of the core to be cut.
Most of the technologies and mechanisms used in this invention are known in the core cutting art.
Prior art practices in repositioning non-rotating core cutting knives have been to rotate the knife against the rotation of the core to be cut to avoid introducing lash or play into the knife holding assembly or the rotations have been made without regard to the direction of rotation of the core to be cut.
It has been discovered that the degradation of the edge of the knife is not symmetrical about the radius along which the knife is advanced into the core. This invention embodies that discovery in an apparatus that repositions the core cutting knife by rotating it in the direction of least degradation. This permits the rotation of the knife through a smaller angle to reach a fresh edge than would be the case if the knife were rotated in the opposite direction. Depending on the thickness of the core being cut and the material that it is made of, this procedure results in the increase of one or more knife indexing cycles before the edge of the knife is completely degraded than would be the case if the knife were rotated in the opposite direction with the same degree of precision as provided by the index of this invention.
The invention in one of its simplest forms is; a knife indexing apparatus comprising; a rotatable mandrel, a circular knife fixedly mounted on said mandrel, a worm gear fixedly mounted on said mandrel, a worm having a shaft and the worm is operably engaged with said worm gear, an overrunning coupling engaged with said shaft of said worm, a rotary actuator connected to the overrunning coupling and a means for actuating said coupling so as to rotate said knife through a set angle in the direction of rotation of a core to be cut.
The method of operating said knife indexing apparatus comprises the steps of; advancing a knife indexing apparatus into a core to effect a core cut, withdrawing the knife indexing apparatus, incrementing a counter, interrogating the counter, repeating the cycle until the counter indicates a preestablished condition, activating a rotary actuator which rotates the overrunning coupling to rotate the shaft of the worm a preestablished distance which causes the worm gear to rotate the mandrel which causes the knife to rotate through a preestablished angle, returning the overrunning coupling to its starting position, returning the counter to its starting position, and starting a new knife indexing cycle.