Cutlery – Sheathed – Pivoted blade
Reexamination Certificate
2002-01-17
2003-12-30
Payer, Hwei-Siu (Department: 3724)
Cutlery
Sheathed
Pivoted blade
C030S155000
Reexamination Certificate
active
06668460
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a corrosion resistant lock blade knife with a blade made of titanium or titanium alloy and a locking arm (locking lever) made from a corrosion resistant substance that can be used for diving or in any other circumstance where a corrosion resistant knife is required. The locking arm can also be made of titanium or titanium alloy, or any other strong corrosion resistant substance. The invention also has a non-titanium corrosion resistant surface between the locking arm head of the locking arm and the end tang of the blade to prevent the negative effects of titanium/titanium or titanium/other metal rubbing during opening and closing of the knife.
PRIOR ART
Lock blade knives are relatively common. From the pocketknife to the utility knife there are many different kinds of lock blade knives employing different mechanisms of action. It is prior technology to have a locking arm received into a notch on the blade tang. A spring biases against the locking arm to keep locking arm in place and maintain the locked state of the knife.
Heretofore, most lock blade knives were made of stainless steel to take advantage of stainless steel's generally excellent qualities. With minimal care, stainless steel is generally resistant to tarnish or rust when exposed to normal oxygen and humidity conditions. Stainless steel is easy to clean, and resiliently hard so that it can be honed into a finely sharpened blade. It is very strong and resilient under most circumstances. However, stainless steel is an iron alloy. Because of the iron content, stainless steel is magnetic and highly conductive. Also because of the iron content, the stainless steel is reactive to reduction chemical reactions and is still susceptible to corrosion and rust. It is due to these qualities that stainless steel is a poor material for constructing a diving knife because it is susceptible to the ravages of corrosion by the minerals and pollutants contained in fresh water and salt water.
The problem with iron-based metals is that the oxide formed by oxidation does not firmly adhere to the surface of the metal and flakes off easily causing “pitting”. Extensive pitting eventually causes structural weakness and disintegration of the metal. Corrosion occurs in the presence of moisture. For example when iron is exposed to moist air, it reacts with oxygen to form rust.
The formation of rust can occur at some distance away from the actual pitting or erosion of iron. This is possible because of iron's conductive nature and the electrons produced via the initial oxidation of iron can be conducted through the metal and the iron ions can diffuse through the water layer to another point on the metal surface where oxygen is available. This process results in an electrochemical cell in which iron serves as the anode, oxygen gas as the cathode, and the aqueous solution of ions serving as a “salt bridge.”
The involvement of water accounts for the fact that rusting occurs much more rapidly in moist conditions as compared to a dry environment such as a desert. Many other factors affect the rate of corrosion. For example the presence of salt greatly enhances the rusting of metals. This is due to the fact that the dissolved salt increases the conductivity of the aqueous solution formed at the surface of the metal and enhances the rate of electrochemical corrosion. This is one reason why iron and steel tend to corrode much more quickly when exposed to salt water or moist salty air near the sea and the ocean.
Knife makers have realized this problem and tried to prevent the initial compromise of the metal by applying a protective coating to stainless steel knives, etc. However, if the coating is scraped, the corrosion will have a chance to begin. As explained above, due to the conductive nature of the iron content in steel, once compromised, the integrity of the metal is never the same. Because of the unique uses for which knives are intended, they are inevitably scrapped and scarred during use and thereby compromised. Because of its susceptibility to corrosion, stainless steel is a poor material from which to make a diving knife.
Titanium is well known in the metal industry as being very hard and durable. It is an excellent material from which to construct knife blades because of its strength and tendency to retain a very sharp cutting edge. However, titanium metal also has a negative point. When titanium metal comes into contact with and rubs against titanium and other metals including stainless steel, it experiences a galling effect (titanium galling effect) whereby binding and gripping to the other metal. This not only creates a generally unsatisfactory user experience, but it also causes a premature wearing of the contact surface between the titanium contact face and the other metal's contact face.
Knife makers have sought to take advantage of the unique properties of titanium enabling it to be polished into a highly refined cutting edge in both fixed and lock blade knives. However, they only have made fixed blade knives where the blade was made completely of titanium or titanium alloy. Heretofore, knife makers have not been able to take full advantage of the resiliency and strength of titanium in a lock blade knife without suffering the negative effects of the titanium galling effect. Knife makers have created complex dual-metal blades where the majority of the blade is stainless steel but a separate section of the blade that contains the cutting edge joined along a seam and made of titanium or titanium alloy. This involves a highly complex and very expensive manufacturing process and remains undesirable in the field of lock blade knives because the remainder of the knife blade is still made of corrosion susceptible metal.
SUMMARY OF INVENTION
The present invention relates to a corrosion resistant lock blade knife with a blade made of titanium. The blade is mounted in the handle along with a locking arm made of a substance that is also corrosion resistant. During opening and closing the tang contact edge rubs against the locking arm head. At least one of these surfaces must be composed of a corrosion-resistant non-metal or a corrosion-resistant soft metal substance to prevent the gripping and binding effects that would occur at the contact surface during opening and closing of the knife. The locking arm is biased against the tang of the knife blade by a biasing means. The biasing means pushes against the locking arm, automatically forcing it into the tang notch when the blade is pivoted into its fully open position. This action locks the lock blade knife in the open position. Titanium and titanium alloys are selected for the knife blade because of titanium's unique properties, including its strength and resistance to corrosion. These same qualities of titanium also make it a good substance from which to make the locking arm.
The present invention is a corrosion resistant knife designed for, but not limited to, use in and around salt water. Most lock blade knives are commonly made of stainless steel. With care, stainless steel knives are resistant for most normal uses. However, because of corrosion, these stainless-steel knives fair relatively poorly when exposed to the minerals of fresh water and harsh salt water. Furthermore, stainless steel is relatively heavy. If a common stainless steel lock blade knife is used during diving, it must be cleaned, rinsed, dried and then polished before storage or the stainless steel knife will rapidly show signs of corrosion and wear. If the blade is scraped during diving and corrosion has a chance to begin, the metal will forever be compromised and susceptible to further corrosion.
In order to avoid the negative effects of corrosion and rust associated with the wear of mineral and saltwater on stainless steel, it is best to make a knife out of a metal that is strong and resistant to corrosion. Metal alloys such as brass and copper-nickel are more resistant to the corrosion of salt water, but lack the strength, rigidity and resilience neces
Payer Hwei-Siu
Trojan Law Offices
LandOfFree
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