Cutting – Other than completely through work thickness or through work... – Grooving
Reexamination Certificate
1996-04-29
2001-05-15
Peterson, Kenneth E. (Department: 3724)
Cutting
Other than completely through work thickness or through work...
Grooving
C083S171000
Reexamination Certificate
active
06230603
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates to cutting or grooving of elastomers and like materials. More particularly, this invention relates to a cutting blade for resistance-heated cutters that allows for more efficient and better quality cutting.
It is known that resistance-heated cutters are widely used for cutting and grooving elastomers such as rubber. In a resistance-heated cutting process, electrical current from an external source is conducted through an electrically conductive cutting blade. Heat is generated in the cutting blade as an effect of resistance to electrical current flow.
Conventionally known electrically heated cutting blades, such as used in electrically heated tire groovers, are composed of a strip of electrically conductive material formed in a U-shape. In such prior art devices, the heat is not concentrated in the cutting edge of the blade, where it would be most effective in aiding the cutting of the material. Rather, just the opposite occurs during the cutting process, the cutting edge is cooled by the material being cut, and is the coolest part of the blade. Therefore, when sufficient heat is developed to maintain a favorable cutting edge temperature for optimum cutting performance, substantial excess heat is developed in the portions of the blade further from the cutting edge. This overheating causes severe damage and tends to reduce the life of the blade. The replacement of the burnt-out or heat damaged cutting blades is expensive and time consuming. The heat developed in portions of blade further away from the cutting edge also reduces the quality of cuts or grooves, produces undesired smoke by burning the elastomer, and transfers heat to other parts of the cutting assembly.
Thus, in Van Alstine, U.S. Pat. No. 4,797,999, there is disclosed a cutting head member allowing for rapid replacement means of the damaged cutting blades. This invention, however, does not address the problem of overheating of the parts of the blade away from the cutting edge.
In Wenger, U.S. Pat. No. 4,539,467, an electrically heated cutting tool is disclosed with means of airstream cooling of the parts of the blade away from the cutting region to reduce heat transfer to the blade holder and increase heat concentration in the cutting portion of the blade. Wenger's invention does not stop overheating of the blade, but only remedies it with cooling. Wenger also presents the disadvantage of requiring air supply means and is not energy efficient because a significant portion of heat energy is lost to the cooling system.
Another similar invention is disclosed in Lejuene, U.S. Pat. No. 3,850,222, where in order to concentrate thermal energy in the cutting zone, the cutting portion of the blade has a width that is significantly less than the width of the fastening zone so that the heating is greater in the cutting zone than fastening zone. Although this invention provides for means to concentrate the thermal energy in the cutting zone of the blade, the heat is not concentrated in the cutting edge of the blade. Therefore, the previously mentioned problems involved with overheating of the portions of the blade further away from the cutting edge are still likely to occur.
SUMMARY OF THE INVENTION
A primary object of this invention is to provide a cutting blade for resistance-heated elastomer cutters that greatly improves the efficiency and quality of elastomer cutting as compared to previously known devices.
The object is solved in accordance with the present invention, by a cutting blade that generates and concentrates most of the thermal energy in its cutting edge portion when electrical current flows through it.
The preferred embodiment facilitates a U-shaped cutting blade that can be shaped to accommodate a plurality of cutting and grooving operations. The disclosed cutting blade comprises two strips of different materials joined together edge-to-edge and formed in a U-shape. Alternatively, the two strips need not be joined together, but can simply be in a abutting relationship. Either way, the wider strip of material serves as support means for the narrower strip of material forming the cutting edge. The cutting edge is made of a material which preferably possesses significantly higher electrical and thermal conductivity than the supporting portion.
During the cutting process, the blade is placed in a convenient fixture. When electrical current from an external source flows through the cutting blade, the physical properties of the materials comprising the blade result in significantly greater generation of thermal energy in the cutting edge as compared with the remaining portion of the cutting blade. In the preferred embodiment, the cutting edge is sharpened which also facilitates more effective cutting.
In accordance with the present invention, the significant heat generation and concentration in the cutting edge of the cutting blade presents several advantages.
The life of the cutting blade is greatly increased because only the cutting edge, a relatively small portion of the cutting blade, is exposed to high cutting temperatures. Overheating of the rest of the blade is eliminated.
Another advantage of the present invention is increased energy efficiency of the resistance-heated cutting operation. Since significant thermal energy is generated only in a relatively small portion of the cutting blade, the amount of electrical energy required to generate that thermal energy is relatively small.
Yet another advantage of the present invention is increased quality of cuts or grooves made and reduction of undesired smoke produced during the cutting process. The concentration of heat in a relatively small portion of the cutting blade, namely the cutting edge, significantly eliminates heat damage done to the elastomer and smoke produced by burning of the elastomer during the cutting process.
Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.
REFERENCES:
patent: 1127665 (1915-02-01), Murphy
patent: 1834555 (1931-12-01), Tittle
patent: 2012938 (1935-09-01), Beuoy
patent: 2157151 (1939-05-01), Stackhouse
patent: 2359393 (1944-10-01), Sloan
patent: 2699485 (1955-01-01), Wolf
patent: 3054441 (1962-09-01), Gex et al.
patent: 3768482 (1973-10-01), Shaw
patent: 4501951 (1985-02-01), Benin et al.
patent: 4653362 (1987-03-01), Gerber
patent: 5046251 (1991-09-01), Scott
patent: 5064994 (1991-11-01), Urban
patent: 5065804 (1991-11-01), Kinuhata et al.
patent: 5092208 (1992-03-01), Rosa-Miranda
patent: 5308311 (1994-05-01), Eggers et al.
patent: 2914401 (1979-10-01), None
patent: 436743 (1974-12-01), None
LandOfFree
Cutting blade for resistance-heated elastomer cutters does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cutting blade for resistance-heated elastomer cutters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cutting blade for resistance-heated elastomer cutters will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2558539