SELF-HEATING WAX MODELING SPATULA

• US 3,800,122 A
• Filed: 01/17/1973
• Issued: 03/26/1974
• Est. Priority Date: 01/17/1973
• Status: Expired due to Term

• Current Assignee: Farmer Everett W
• Original Assignee: Farmer Everett W
• Inventors: Farmer, Everett L.
• Primary Examiner(s): Bartis, A.
• Application Number:
  US05/324,252
• Time in Patent Office: 433 Days
• Field of Search: 219/221-242,533 32/70
• US Class Current: 219/239
• CPC Class Codes: A61C 13/0028 Instruments or appliances for wax-shaping or wax-removing

Abstract

A self-heating wax modeling spatula is disclosed, having disposed within a handle an electrc heating element with a thermal controlled switch, which turns on the current when the element cools below a predetermined temperature and turns off the current when the element heats above a predetermined temperature. The working tip is thermally connected to the heating element through a heat conductor of a known heat conductivity rate, so that the working tip is maintained between upper and lower temperature limits that are closer than the thermal controlled switch is capable of maintaining the heating element. The heating element, the heat conductor, and the working tip being separate items and are biased, in turn, against one another in butting relationship by a suitably disposed spring means to allow heat flow. To further bring the upper and lower temperature limits together at the working tip, the tip is made of a metal that has a relatively high density, is non-corrosive and is a good heat conductor.

Claims

1. In combination:

a heat insulated tubular handle;

electrical leads extending out of one end of said handle;

a thin metallic sleeve secured at one end to the other end of said handle and extending from the other end of said handle;

a resistance heating cylindrical axially disposed element connected to said leads and having a portion slidably disposed within said handle and the rest thereof within said sleeve;

means within said handle for biasing said element out of said handle toward the other end of said sleeve;

a cylindrical heat conductor having a portion fixedly positioned in the other end of the sleeve and having an exterior end extending out of said sleeve;

said heating element being biased by said means for biasing into heat transfer engagement with the portion of the heat conductor within said sleeve;

a metallic working tip fixed to the exterior of said conductor; and

a thermally activated switch in the circuit with said heating element and positioned in said handle relative to said heating element so as to be responsive to the temperature of said heating element to open the electrical circuit of the heating element whenever said element is at a predetermined elevated temperature limit and closing the circuit whenever said temperature is below a predetermined lower temperature limit, to cool and heat said element respectively.

2. The combination of claim 1 wherein:

means are provided on the outer end of said sleeve to prevent the heat conductor from moving axially out of said sleeve to allow said means for biasing to cause said heating element to bear against said heat conductor and said heat conductor having a thermal conductivity which is lower than the thermal conductivity of said metallic tip.

3. The combination of claim 1 wherein:

said metallic working tip is made of a thin non-corrosive metal, having a good thermal conductivity.

4. The combination of claim 3 wherein said metal is chosen from a group consisting of brass, copper, silver, gold, alloys of iron, alloys of copper-zinc-nickel and stainless steel.

5. The combination of claim 3 wherein said metal is brass.

6. The combination of claim 3 wherein said metal is silver.

7. The combination of claim 3 wherein said metal is stainless steel.

8. The combination of claim 3 wherein said metal is an alloy of copper and zinc and nickel.

9. The combination of claim 1 wherein said tip and said conductor are fixed together by an axially disposed screw thread means.

10. The combination of claim 3 wherein means are provided on the outer end of said sleeve to prevent said heat conductor from moving axially out of said sleeve to allow said means for biasing to cause said heating element to bear against said heat conductor, and said heat conductor having a low rate of thermal conductivity than said working tip.