US3901110A

US3901110A - Hot wire cutting device

Info

Publication number: US3901110A
Application number: US429041A
Authority: US
Inventors: Frank P Priestly
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-12-28
Filing date: 1973-12-28
Publication date: 1975-08-26
Anticipated expiration: 1992-08-26

Abstract

An improvement in a poly-styrene cutter by which a continuous electrical contact for heating a taut working wire is achieved. Previous devices have not provided against the accumulation of waste material on the apparatus at the wire''s electrical contact. In this invention, shim and contact eyelets are crimped on the cutting wire and within a table top recess mounted in an opening in which the electrical contact for the wire is disposed. As the wire is deflected by the force of a workpiece sliding across the table top, an electrical connection is made by reason of the length of the contact eyelet striking a conductor eyelet press fit in the table top opening and included in an electrical circuit. The contact eyelet includes a flanged wall or annular ring normal to and which proscribes the conductor eyelet. As the wire is heated to cut the polystyrene material of the workpiece, the material is prevented from accumulating in the table top opening so as to deny a continuous electrical contact, by reason of the proscribing ring or wall functioning as a shield, while the contact eyelet simultaneously physically strikes the connector eyelet to maintain a continuous electrical contact. Deterioration of the wire at its contact point is also averted by providing a length of contact as distinguished from a point contact. Also, the improvement lends itself to immediate repair of the cutting device upon parts thereof wearing out.

Description

United States Patent Priestly Aug. 26, 1975 HOT WIRE CUTTING DEVICE the apparatus at the wires electrical contact. In this [76] Inventor: Frank P. Priestly, 17159 Stare Ave., i Sh im and (iorltact eyelets are crimped on Northridge, Calif. 91324 the cutting wire and withln a tabletop recess mo unted in an openlng 1n wh1ch the electrical contact for the [22] Filed: Dec. 28, 1973 wire is disposed. As the wire is deflected by the force [211 App! NO; 429,041 of a workpiece sliding across the table top, an electrical connection is made by reason of the length of the contact eyelet striking a conductor eyelet press fit in [52] US. Cl 83/171; 83/65 1 .l the table top opening and included in an electrical cir- [51] Int. Cl 1326f 3/ 12 cuit, The contact eyelet includes a flanged wall or an- [58] Field of Search 83/17 I l7(), 16, 651.1 nular ring normal to and which prescribes the conductor eyelet. As the wire is heated to cut the polystyrene [56] R f n s C t material of the workpiece, the material is prevented UNITED STATES PATENTS from accumulating in the table top opening so as to 2,987,598 6/196l Chace et al. 83/651.1 X deny a continuous electrical Contact by reason of the 3,017,487 1/1962 Priestly 83/171 pfoscribing ring Or Wall functioning as a Shield, While Primary ExaminerJ. M. Meister Attorney, Agent, or FirmFrank L. Zugelter [57] ABSTRACT An improvement in a poly-styrene cutter by which a continuous electrical contact for heating a taut working wire is achieved. Previous devices have not provided against the accumulation of waste material on the contact eyelet simultaneously physically strikes the connector eyelet to maintain a continuous electrical contact. Deterioration of the wire at its contact point is also averted by providing a length of contact as distinguished from a point contact. Also, the improvement lends itself to immediate repair of the cutting device upon parts thereof wearing out.

10 Claims, 2 Drawing Figures PATENTEB AUG 2 6 I975 FIG FIG.

HOT WIRE CUTTING DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention generally relates to cutting devices, and in particular, to a hot wire member for cutting thicknesses of a plastic material an example of which is expanded polystyrene.

2. Prior Art See my two previously issued U.S. patent Nos.; Re. 25016, issued Aug. 1, 1961 on original No. 2,916,595 issued Dec. 8, 1959; 3,017,487, issued Jan. 16, 1952; and the prior art cited in these two patents.

Problems in the Prior Art It was found in the utilization of the embodiments of my previous inventions disclosed in my forementioned patents that the waste material from the polystyrene being worked upon would entrap itself in the table top opening or hole wherein physical or direct contact between the heated cutting wire and its conductor eyelet was disposed. Such entrapment between the wire and the connector eyelet would prevent a continuous closed switch condition, thereby not maintaining a continuous heating of the wire while cutting the workpiece. Or at best, a vacillating closed-and-open switch position would occur were trapped waste material to fall away and more would take its place. This affected the efficiency and utilization of operation of my cutter as it would be necessary to clean out such hole area from time to time. Also, the point contact between the heated wire and the connector eyelet caused deterioration of the wire.

This invention solves these problems of noncontinuous heating of the wire and its deterioration.

SUMMARY OF THE INVENTION This invention relates to a cutting device, and particularly to a cutter utilizing a heated wire passing through a material to cut same, an example of which being expanded polystyrene.

An object of this invention is to provide continuous heating of a wire suitably strung in its device to cut a material, such as expanded polystyrene.

Another object of this invention is to prevent deterioration of the wire at its otherwise point contact with a connector eyelet by including contact means of a suffrcient linear dimension so as to provide a large contact area while the wire is in its deflected position.

Another object of this invention is to prevent the lack or omission of a continuous electrical contact for such a cutting wire and which otherwise would not adequately or properly heat the wire for an efficient cutting function.

A further object of this invention is to eliminate the action of waste or cut material from jamming or discontinuing electrical contact for the heated wire.

Another object of this invention is to provide a simple, inexpensive, and readily repairable hot-wire cutting apparatus.

These and other objects and advantages will become more apparent from a full and complete reading of the following description, appended claims thereto, and the accompanying drawing comprising one sheet.

DESCRIPTION OF THE DRAWING FIG. 1 is a view in section of an embodiment of my invention.

FIG. 2 is a substantially sectional veiw of a modification of a portion of such embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing in which reference characters refer to like numerals hereinafter in the following description, the character 10 denotes generally the cutter article to which the invention is adapted. For purposes of describing this invention, it is to be understood that the disclosures of my two previous and above noted patents are incorporated by reference to show how the subject matter of my invention may be adapted to a hotwire cutting apparatus.

The cutter 10 comprises a wire 11 constituting a cutting means 12 tautly suspended between its one end secured on a resilient goose-neck conductor arm 14 and its other end secured to a dielectric, insulating or otherwise non-conducting member 18. The wire 11 extends or is disposed through a non-conducting table or platform 16 intermediate the ends of the wire. The taut condition for the cutting means 12 is maintained by forming an eye 20 on the upper end of the wire 11 and hooking it upon an extension 22 to the arm 14. The other end of the wire 11 is suitably hooked to a sleeve member 24 having a base seated below and to the dielectric member 18 by reason of the wires tautness. The member 18 is held in forced engagement with a metal tubular member or rivit 26 press fit or otherwise securely mounted in an opening 28 normally provided in the platform 16. The rivit 26 constitutes a conductor eyelet, which is illustrated in the aformentioned U.S. Pat. No. 3,017,487 as element 42, and includes a curled end 32 which abuts an apertured offset portion 30 which corresponds with the element 41 disclosed in such patent. However, the length of eyelet 26 is abbreviated such that its other or non-curled end does not project above the base of a recess 34 provided in the platform 16. The recess 34 is provided so that a workpiece (not shown) may be smoothly pushed or pulled, without interruption, across the platform 16 and into and from the cutting wire 11.

A contact member or eyelet 36 together with a shim eyelet 38 are mounted upon the wire 11 within the confines of the recess 34 and vertical opening 28. Both

elements

36, 38 are crimped upon the wire 11 and mounted thereon as shown in FIG. 1. Such crimping retains them on the wire 11, and are of such a size that their circular portions extending parallel with the wire 11 in the recess 34 and opening 28 do not directly contact the wall of the connector or conductor eyelet 26 when the wire 11 is in a non-deflected and tautly suspended position between its ends. I.e., each contact means includes a length co-extensive with and disposed in spaced relation to a substantial length of the conductor 26 in the opening 28.

The shim 38 with its circular portion includes an annular ring 40 which seats on a corresponding and complementing flanged or annular ring 42 formed on the contact eyelet 40. The eyelet 40 circumscribes the circular portion of the shim 38. The

rings

42, 40 function as a shield against the introduction of waste material into the opening 28 and which otherwise could deny continuous electrical contact. To this end the annular ring 42 is of such a diameter that it conceals, covers or proscribes the space remaining below in the opening 28 after mounting of the eyelet 26 therein. Both

annular flanges

40, 42 are wholly disposed within the confines of the recess 34 so that they do not obstruct sliding movement of a workpiece across the table top 16 and against the wire 11.

Optionally, the shim and

contact members

36, 38 may be made as a single integral piece on a screw machine in known fashion, or as described above, in two separate pieces, one to fit within the other. I found that a single flanged member which could be'both crimped on the wire and provide a sufficiently radiused annular ring for the opening 28 was not available. So I turned to utilization of two

eyelets

36, 38 which were and are available in the market place. They include very small dimensional characteristics complementing each other to form a crimpable component in the fabrication and assembly of my improvement. In this regard, the annular ring 40s primary and sole function is to hold its shim eyelet 38 in proper position to the contact eyelet 36 during the crimping step of such elements of the wire 11.

An air gap of, say 0.010 inch is preferably provided between the wall of the connector or conductor eyelet 26 and the portion of the contact member 36 disposed interiorly of such wall and within the thickness of the platform 16. Upon deflecting the taut wire 11 by movement of a workpiece thereagainst, such deflection ensures physical contact between the

elements

26 and 36. Such contact constitutes a closed switch for passing on current to the wire 11 and thereby heating it.

In operation, an expanded polystyrene workpiece (not shown) is seated on the platform 16, and manually impressed against the wire 1 1. The wire is deflected by the force of the material, thereby causing direct contact between the conductor eyelet 26 and the contact eyelet 36. An electrical current (for a useable circuit, see my mentioned US. patents) is thus passed through the wire 11, heating it, and thereby providing the necessary heat to cut the polystyrene material of the workpiece. Waste material cannot drain or find its way into the opening 28 as the

annular rings

42, 40 shield such opening 28 from introduction thereof.

The assembly of the device makes for ease of repairability in addition to its produceability. The wire 1 1 is threaded through the

eyelets

40, 42 after which they are together crimped or swaged to a length of the wire. The wire 1 1 is then threaded first through the conductor eyelet 26, and then through the dielectric member 18 and then through the hooking member 24. With the assistance of a fingernail, a space is maintained between the annular ring 42 and the uncurled end of the conductor eyelet 26, while the end of the wire is concurrently hooked about the member 24 which is seating the dielectric member 18 against the curled end of the conductor eyelet 26. Now the other end of the wire 11 is threaded upwardly through the opening 28. It may be noted that the annular ring 42 passes through the table top opening 28 prior to insertion or fit of the conductor eyelet 26. Thereafter the free end of the wire 11 may be formed into the eyelet 20 which is then hooked onto the arm 22 whereby a taut wire 11 is suspended in the cutter apparatus. In the event repair is required, it is a simple matter to unhook eyelet 20, and then to force

eyelets

36, 38 and 26 down and out of the opening 28, after which a facile and rapid re-assembly can be immediately accomplished with a new set of the above described elements.

FIG. 2 illustrates a modification for supporting the one end of the taut wire 11. A non-conducting overhanging wall member 50 includes a depending apertured lug 52 which supports a heavy gauge, coiled (or leaf) spring member 54 on the other end of which the formed eye20 on the wire 11 is secured or supported. A lead wire 56 is attached to the spring member 54 to complete the electrical circuit to the wire 11. The heavy gauge of the spring member 54 provides sufficient area contact through which electrical current can pass.

Preferably, the wire 11 is Nichrome wire, the conductor eyelet 28 is made from a zinc-plated brass or copper material, the contact eyelet 36 from a zincplated copper or brass material, and the shim 38 made from a zinc-plated copper or brass material. However, other suitable materials may also be utilized.

My improvement is also easily mountable to a flashlight head, and to other similar portable devices which utilize batteries as a source of energy for heating the wire 11.

In accordance with the patent statutes, I have described the principles of construction and operation of my improvement in a hot-wire cutting device, and while I have endeavored to set forth, the best embodiment thereof, I desire to have it understood that changes may be made within the scope of the following claims without departing from the spirit of my invention.

Therefore, what I claim as patentably novel is: 1. In a hot wire cutter having a taut, suspended wire for cutting materal upon heating thereof;

said wire extending through a table top recess and through a table top opening in which a conductor element is disposed, the improvement comprising,

contact means secured to said wire and disposed within the table top opening, and

means disposed in therecess for shielding the table top opening against introduction of waste from the cut material, whereby a continuous heating of the wire is achieved upon deflection of the wire to cause engagement between said conductor element and contact means,

2. The improvement of claim 1 wherein said contact means comprises at least one eyelet secured upon the wire and having a length coextensive with but in spaced relation toa substantial length of the conductor element in the opening.

3. The improvement of claim 1 wherein said shielding means comprises an annular ring formed on the contact means and disposed within the recess.

4. The improvement of claim 3 wherein said contact means comprises a shim eyelet and a contact eyelet circumscribing said shim eyelet, both eyelets secured to the wire.

5. The improvement of claim 1 wherein said contact means comprises at least one eyelet secured upon the wire and having a length coextensive with but in spaced relation to a substantial length of the conductor element in the opening, and

said shielding means comprises an annular ring formed on said one eyelet and disposed within the recess and proscribing the conductor element.

6. In a hot wire cutter device, the improvement comprising in combination a contact member secured to a wire and having a length coextensive with but in spaced relation to a substantial length of a conductor element mounted in an opening provided in a platform or the like of the cutter device and an annular ring mounted on said contact member and disposed in a recess atop the opening for shielding the opening against the introduction of waste cut material, deflection of the wire causing physical engagement between lengths of the contact member and conductor element.

7. In a hot wire cutter having a taut wire supported upon an arm or the like on the one hand and passing through a recess and opening in a dielectric table or the like to be supported thereunder on the other,

the improvement comprising in combination, means secured upon the wire and having a length disposed in the opening for direct contact with a length of a conductor eyelet secured in such opening upon deflection of the wire between its supports, and annular means mounted on said secured means and disposed in the recess for shielding the opening against entry of waste material.

8. The improvement of claim 7 wherein said secured means comprises a shim eyelet and a contact eyelet circumscribing said shim eyelet.

9. The improvement of claim 8 wherein said annular means comprises a ring formed on said contact eyelet and disposed in the recess while proscribing the opening.

10. The improvement of claim 7 wherein said secured means comprises a shim eyelet and a contact eyelet circumscribing said shim eyelet, and said annular means comprises a ring formed on said Contact eyelet and disposed in the recess while proscribing the opening.

Claims

1. In a hot wire cutter having a taut, suspended wire for cutting materal upon heating thereof; said wire extending through a table top recess and through a table top opening in which a conductor element is disposed, the improvement comprising, contact means secured to said wire and disposed within the table top opening, and means disposed in the recess for shielding the table top opening against introduction of waste from the cut material, whereby a continuous heating of the wire is achieved upon deflection of the wire to cause engagement between said conductor element and contact means.

2. The improvement of claim 1 wherein said contact means comprises at least one eyelet secured upon the wire and having a length coextensive with but in spaced relation to a substantial length of the conductor element in the opening.

5. The improvement of claim 1 wherein said contact means comprises at least one eyelet secured upon the wire and having a length coextensive with but in spaced relation to a substantial length of the conductor element in the opening, and said shielding means comprises an annular ring formed on said one eyelet and disposed within the recess and proscribing the conductor element.

7. In a hot wire cutter having a taut wire supported upon an arm or the like on the one hand and passing through a recess and opening in a dielectric table or the like to be supported thereunder on the other, the improvement comprising in combination, means secured upon the wire and having a length disposed in the opening for direct contact with a length of a conductor eyelet secured in such opening upon deflection of the wire between its supports, and annular means mounted on said secured means and disposed in the recess for shielding the opening against entry of waste material.