Brown & Sharpe Mfg. Co. v. KAR Engineering Co.

59 F. Supp. 820, 64 U.S.P.Q. (BNA) 458, 1945 U.S. Dist. LEXIS 2457
CourtDistrict Court, D. Massachusetts
DecidedFebruary 14, 1945
DocketCivil Action No. 2419
StatusPublished
Cited by3 cases

This text of 59 F. Supp. 820 (Brown & Sharpe Mfg. Co. v. KAR Engineering Co.) is published on Counsel Stack Legal Research, covering District Court, D. Massachusetts primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Brown & Sharpe Mfg. Co. v. KAR Engineering Co., 59 F. Supp. 820, 64 U.S.P.Q. (BNA) 458, 1945 U.S. Dist. LEXIS 2457 (D. Mass. 1945).

Opinion

Findings of Fact and Conclusions of Law

WYZANSKI, District Judge.

Fdg. 1. This is a suit for infringement of United States patent to Bower No. 2,-053,177 issued September 1, 1936, on application filed December 6, 1934, for a work holder or chuck with permanent magnets. The claims of the Bower patent relied upon are 1, 5, 7 and 14.

Fdg. 2. The alleged invention was made in England by William Leslie Bower.' He assigned it to his employer, James Neill & Company (Sheffield), Limited, of Sheffield, England. The patent was issued to that company which gave an exclusive license to plaintiff, Brown and Sharpe Manufacturing Company. Defendant, The Kar Engineering Company, Inc., is a Massachusetts corporation located at Great Barring-ton, Massachusetts, engaged in the manufacture of the device of. which complaint is made.

Fdg. 3. The basic principles of magnetism, so far as necessary to an understanding of the patent and of this case, may be briefly summarized.

Fdg. 4. Every magnet has at the extremities of its axis two regions where the magnetic flow concentrates and the attractive power is greatest. These regions are known as magnetic poles. One pole, known as north or positive or plus, is the pole that points to the North Pole of the earth. The other pole is known as south [821]*821or negative or minus. Lines of force emanate from one pole, form closed continuous loops passing to the other pole and continue through the magnet itself. Magnetic lines always form a complete magnetic circuit.

Fdg. 5. Only iron and certain alloys of iron exhibit magnetic properties. Not only can they be magnetized but through them magnetic flux flows with greater ease and density than through air or other nonmagnetic materials.

Fdg. 6. Magnetic flux will take the ■easiest path. Thus if a piece of iron or •steel is placed in a magnetic field, the lines of force passing through the air will tend to pass through the iron and concentrate there more than they would in a similar space of air.

Fdg. 7. If across the poles of a magnet is directly placed a work piece of magnetic material, the magnet will hold the work piece. If across the poles of a magnet is first placed a piece of iron and then on top of the iron a work piece of magnetic material, most of the lines of force will concentrate in and pass through that iron and practically none of the lines of force will reach that work piece and exert any pull on it. If between the poles.of a magnet and a work piece of magnetic material there are air gaps of an eighth of an inch only a small amount of the magnetic force will reach the work piece and ■exert any pull on it.

Fdg. 8. There are two principal types ■of magnets, electro magnets and permanent magnets. They have similar qualities of .attraction. An electro magnet is created "by placing a bar of soft iron in the center ■of a coil of wire carrying an electric current. So long as the electric current continues, but no longer, the bar of soft iron .acts as a magnet. A permanent magnet is created by placing a bar of hard steel or •of certain alloys, such as cobalt magnet steel or Alnico, within a coil of wire carrying an electric current. Even after the ■current is turned off, this type of bar will ■retain a substantial part of its magnetism.

Fdg. 9. On the basis of these widely ¡known principles of magnetism, work holders or chucks, with electro magnets or with •permanent magnets, were devised at least as early as the end of the nineteenth century.

Fdg. 10. A work holder or chuck is an ■instrument for holding by magnetic attraction a work piece of iron, steel or similar -.magnetic property. It is particularly useful if the work piece is to be machined or ground.

Fdg. 11. The difficulties with chucks of the electromagnetic type were that they depended on direct, not alternating, electric current which was not always available and which therefore sometimes had to be procured through rectifying alternating current; that electric current cost money; that if the current broke down the chuck became inoperable; that if the current suddenly ceased the work piece might fly off and damage the workman or the work piece or other property; that waterproofing was necessary to prevent short circuiting; and that electromagnets generate heat which might distort the work and interfere with precision grinding.

Fdg. 12. Before Bower, the difficulty with chucks of the permanent magnet type was that they had no means for readily removing or releasing, rather than forcing, a work piece from the chuck.

Fdg. 13. These difficulties are recited by Bower in his application. He specifically points out that with chucks using permanent magnets the difficulty has been to remove a work piece without force. His invention overcomes this difficulty by covering the poles of the permanent magnets with separate pole pieces which can be moved relative to the magnets. When this movement occurs, all or almost all the magnetic flux between adjacent magnetic poles passes through these separate poles. This movement reduces the magnetic force attracting the work piece, and thus enables the work piece to be removed readily while the work remains in the normal work holding zone.

Fdg. 14. The construction of the Bower patent is illustrated in his Fig. 2. There are’ shown as permanent magnets four W-shaped magnets. Each of those four W-shaped magnets has a central pole of one polarity and end poles of the opposite polarity. These four magnets with their twelve poles are housed in a casing. The casing has a flat cover or face plate which forms a table for a work piece. The face plate itself is made of non-magnetic material. In that plate, however, are cast twelve inserts of magnetic.material. These inserts have straight sides. They are separated from one another by the non-magnetic material of which the face plate is composed. The four W-shaped magnets with their twelve poles are connected by links to an eccentric pin on a shaft which [822]*822can be rotated by a .handle. By turning the handle, the user can place the twelve poles of the four W-shaped magnets so that the twelve poles inserted in the face plate either are directly over the twelve poles of the four W-shaped magnets or bridge the gaps between the twelve poles of the four W-shaped magnets. In the former case, almost all the magnetic flux will flow from the north pole of each W-shaped magnet through the magnetic insert directly above, through any appropriate work piece of magnetic material laid on the face plate, through the adjoining magnetic insert to the south pole of the same W-shaped magnet — thus providing magnetic attraction to hold firmly a work piece laid upon, the face-plate. In the latter case, almost all the magnetic flux will flow from the north pole of each W-shaped magnet through the magnetic insert which acts as a bridge to the south pole of the same W-shaped magnet — thus reducing to a negligible amount the magnetic attraction holding a work piece laid upon the face plate. The former case is called the “on” position; the latter case the “off” position.

Fdg. 15. Claim 5 is representative of the four claims, 1, 5, 7 and 14 in issue. It reads as follows:

“5.

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Related

Falkenberg v. Bernard Edward Co.
175 F.2d 427 (Seventh Circuit, 1949)
Brown & Sharpe Mfg. Co. v. O. S. Walker Co.
70 F. Supp. 937 (D. Massachusetts, 1947)
Brown & Sharpe Mfg. Co. v. Kar Engineering Co.
154 F.2d 48 (First Circuit, 1946)

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Bluebook (online)
59 F. Supp. 820, 64 U.S.P.Q. (BNA) 458, 1945 U.S. Dist. LEXIS 2457, Counsel Stack Legal Research, https://law.counselstack.com/opinion/brown-sharpe-mfg-co-v-kar-engineering-co-mad-1945.