Advancing material of indeterminate length – By orbitally traveling material-engaging surface – Including details of roll or mount
Reexamination Certificate
2000-06-16
2001-10-16
Mansen, Michael R. (Department: 3653)
Advancing material of indeterminate length
By orbitally traveling material-engaging surface
Including details of roll or mount
C222S146500, C242S615300, C254S374000
Reexamination Certificate
active
06302309
ABSTRACT:
This invention relates to an apparatus for forwarding a rod which is primarily but not exclusively designed for use in an arrangement for thermoplastic welding using high pressure injection.
BACKGROUND OF THE INVENTION
In U.S. Pat. No. 4,711,746 issued Dec. 8
th
, 1987, the present inventor disclosed a device for forming a thermoplastic weld between two plastic parts in which a thermoplastic material is forced into a chamber and melted within the chamber so as to generate a molten plastic material under a pressure of at least 1000 psi and more preferably of the order of 2500 psi. The molten plastic is expelled through an orifice so that the molten plastic under pressure from the heating chamber is forced into the space between two plastic components to effect a weld therebetween. It will be appreciated that the pressure set forth above is orders of magnitude higher than the pressure necessary for a conventional simple glue gun in which a hot melt adhesive is expelled simply under low or zero pressure.
The thermoplastic welding system disclosed in the above patent has achieved considerable commercial success. However in order to successfully operate the device it is necessary to inject into the heating chamber a thin rod or wire of the thermoplastic material so that the pressure generated within the chamber is obtained by forcing the rod into the chamber with a longitudinal force which is sufficient to generate the required pressure. The thermoplastic material in rod form generally has a diameter of the order of one sixteenth to one quarter inch and more preferably of the order of one eighth inch. This relatively small diameter reduces the longitudinal force necessary on the rod to generate the required pressure but makes the rod more pliable and difficult to feed.
The original patent disclosed a technique for feeding the rod in which the rod passes between two feeding disks with the rod tangential to each of the disks and lying in a common plane with the disks. Each disk has a groove in its outer periphery so as to attempt to trap the cylindrical rod between the rollers. However in practice this arrangement was ineffective and was replaced by a reciprocating clamping arrangement which acted to feed or stuff the pliable rod into the tube leading to the chamber. This device using the reciprocating clamp arrangement has achieved commercial success, but the rod feed has remained a source of concern and potential problem in that it is relatively expensive, complex and prone to breakdown.
Attempts have been made to replace the reciprocating clamp of the commercial embodiment and one attempt is set forth in U.S. Pat. No. 5,971,212 of the present inventor which is issued Oct. 26
th
, 1999. This device provides a friction block on one side of the rod which reciprocates back and forth so as to feed the rod forwardly along a channel. The use of the reciprocating drive arrangement however requires a component to prevent reverse movement of the rod when the reciprocating device reverses to commence a further feeding stroke. This device unfortunately has failed to overcome the above problems and has not been adopted.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide an improved apparatus for driving a pliable rod longitudinally under sufficient force to generate significant pressure in the rod.
According to the present invention there is provided an apparatus for forwarding a pliable rod comprising:
a housing;
a channel through the housing including an inlet portion for receiving the pliable rod and an outlet portion for ejecting the pliable rod under longitudinal force;
at least the outlet portion forming a tubular closed surface surrounding the rod and dimensioned to closely surround the rod to prevent buckling of the rod when forwarded under longitudinal force into the outlet portion;
a drive disk rotatable about an axis of the disk for forwarding the rod from the inlet portion into the outlet portion, the disk having an outer cylindrical surface surrounding the axis for engaging one side of the rod;
the disk and the channel being arranged such that the channel lies in a radial plane of the axis of the disk;
the disk and the channel being arranged such that a contact portion of the outer cylindrical surface extends along and defines one side of the channel;
and a counteracting surface portion in the channel in opposition to the contacting portion of the disk arranged such that the rod in the channel is pinched between the contacting portion of the disk and the counteracting surface portion whereby angular movement of the disk around the disk axis acts to forward the rod along its length along the channel.
The term disk as used herein is not intended to imply any particular structure of the member except that it has an axis and a peripheral surface around which the surface rotates. Normally the disk will be relatively narrow so that its diameter is greater than its width and its width is relatively small to match that of the rod, but these dimensions are not essential to the invention.
Preferably the counteracting surface portion is formed by a stationary surface of the channel. However in alternative arrangements, the counteracting surface may be formed on another member inserted into the channel and even may be another similar opposing disk.
Preferably the counteracting surface portion of the channel is arcuate so as to lie on a circle surrounding the disk axis so that the rod is pinched by the surface of the disk and the arcuate surface portion as it is carried around the arcuate surface portion by movement of the disk. This ensures that the disk has contact over an extended arc preferably as much as 90 degrees to provide enough grip to ensure driving without slip.
Preferably the housing includes a slot therein for receiving at least a part of the disk, the slot having two parallel sides each lying closely adjacent a respective side of the disk such that the outer cylindrical surface of the disk projects into the slot, the channel being arranged at the slot adjacent the outer cylindrical surface of the disk.
Preferably the channel has a width substantially equal to the width of the slot so as to have sides contiguous with the sides of the slot. Thus the disk which closely matches the shape of the slot has a width matching that of the channel which is approximately equal to the width of the rod.
Preferably the disk has transverse, angularly spaced serrated edges thereon for engaging the rod and driving the rod.
Preferably the tubular closed surface forming the outlet portion commences at a position immediately adjacent the outer cylindrical surface of the disk such that the rod as it leaves the outer surface of the disk forwarded thereby immediately enters the tubular closed surface and is confined thereby to prevent buckling under the longitudinal forces on the rod.
Preferably the outlet portion is tangential to the outer surface of the disk.
Preferably the channel and the tubular portion are integrally and contiguously formed in an integral structure forming the housing.
Preferably the inlet portion of the channel has one side thereof defined by the outer surface of the disk.
Preferably the counteracting surface portion extends around an angle of the order of 90 degrees of the disk.
Preferably the outlet portion of the channel is connected to a chamber into which the rod is fed under the longitudinal force, the chamber having a heating element for effecting melting of the rod such that the melted rod in the chamber is under a pressure from the forwarding of the rod and wherein there is provided a discharge nozzle connected to the chamber for receiving the melted rod therefrom through which the melted rod is forced by the pressure for effecting a thermoplastic welding action. However the rod forwarding device disclosed herein can be used for other end uses and the thermoplastic welding technique disclosed herein is only one example.
REFERENCES:
patent: 2802636 (1957-08-01), Sandford
patent: 3250453 (1966-05-01), Halstead
patent: 3281576 (1966-10-01), Coop
Battison Adrian D.
Dupuis Ryan W.
Mansen Michael R.
Williams Michael R.
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