US 3859892 A
A present variety of composite ceramic armor for protection against small arms fire consists of a dense ceramic plate bonded to a laminated fiberglass backing. the resistance of such armor to hits close to a free edge can be significantly improved by extending the backing over the edge of the plate and bonding it thereto, or by folding over the backing at the free edges and bonding it to itself.
Claims available in
Description (OCR text may contain errors)
[ Jan. 14, 1975 Primary Examiner-Stephen C. Bentley Attorney, Agent, or FirmCushman, Darby &
Cushman  ABSTRACT A present variety of composite ceramic armor for protection against small arms fireconsists of a dense ceramic plate bonded to a laminated fiberglass backing. the resistance of such armor to hits close to a free edge can be significantly improved by extending the backing over the edge of the plate and bonding it thereto, or by folding over the backing at the free edges and bonding it to itself.
1 Claim, 5 Drawing Figures F4111 5/04 89/36 R, 36 A; 161/404,
Samuel H. Coes, 385 Daris Rd., Northboro, Mass. 01532 Mar. 14, 1969  Appl. No.: 809,060
Related U.S. Application Data Continuation of Ser. No. 594,649, Nov. 14, 1966, abandoned.
References Cited UNITED STATES PATENTS United States Patent Coes [ COMPOSITE CERAMIC ARMOR  Inventor:
 Int.  Field of Search...........
COMPOSITE CERAMIC ARMOR This application is a continuation of application Ser. No. 594,649 filed Nov. 14, 1966, now abandoned.
BACKGROUND OF INVENTION There has recently been developed a new armorsystem for protection against high energy projectiles such as small arms fire. Thisarmor consists of a hard high density ceramic plate backed by a bonded laminate of glass cloth bonded thereto. When such armor is struck on its ceramic face by a projectile of sufficiently high energy, the ceramic face will fail and the energy delivered to the laminated glass cloth backing will be dissipated in delamination of the bonded layers of cloth. When this occurs, persons or objects protected behind the armor will suffer no injury from the projectile.
However, when the projectile hits the armor within a few diameters of the projectile from a free edge of the armor, delamination, of the backing occurs at the edge permitting particles of ceramic and the projectile to escape behind the armor and thus personnel or equipment behind the armor, but in the path of such projectiles will not be protected.
SUMMARY OF THE INVENTION THE DRAWINGS FIG. 1 shows a cross-section of a conventional type of ceramic composite armor which has been hit by a projectile centrally of the plate and by a projectile near the edge of the plate;.
FIG. 2 shows a cross-section of a piece of ceramic armor according to one modification of the present invention;
FIG. 3 shows a cross-section of the armor of FIG. 2 which has suffered an edge hit;
FIG. 4 shows a modification of the armor of the present invention in cross section;
FIG. 5 shows the affect of an edge hit on the armor of FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 it may be readily seen that although the armor of conventional design consisting of ceramic plate and glass cloth laminate 11 is adequate to protect against an impact such as at 12, an impact at 14 results in delamination and separation of the glass cloth backing and essentially in failure of the armor to perform its function. At 13, although the glass cloth laminates have separated in an area at and around the point of impact, the surrounding glass cloth remains bonded and effectively retains the integrity of the composite plate. However, at 14 where the impact was close to an edge, delamination of the glass backing occurs at the edge and frees the particles shattered from the ceramic plate and the projectile itself to travel in paths behind the armor. r
FIGS. 2 and 3 show preferred embodiments of the present invention in which the type of failure shown at 15 in FIG. 1 is avoided.
The particular materials of which the ceramic plates 10 and are formed is of no moment insofar as the present invention is concerned. Typically, such materials may be high temperature fabricated polycrystalline alumina, silicon carbide or boron carbide. The backing element 21 is formed ofa plurality of plies of glass cloth bonded together with a suitable resin such as a standard commercial catalyzed polyester resin system. The backing 21 is bonded to the Ceramic 20 by means of any suitable commercial resin adhesive such as an epoxy resin adhesive. I
The particular dimensions of the ceramic plate and the backing depend upon the specific requirements for the armor and the particular materials which are employed in its manufacture. Merely for purposes of illustration, the plates in FIGS. 1, 2 and 3 are three-fourths inch in overall thickness with the ceramic plate being one-half inch thick and the laminated glass fabric being one-fourth inch thick.
As can be seen by examination of FIG. 1, an area 13 in the glass cloth ll undergoes delamination around the site of the projectile impact on the plate 10 shown in the drawing at 12. Where the impact occurs near the edge of the plate closer than that diameter of the area 13 to the edge, failure such as indicated at 15 will occur. Such failure is avoided in the embodiment of FIG. 2 by folding the backing element 21 over the edge of the ceramic armor plate and bonding it thereto. This simple expedient entirely eliminates the spreading of the delaminating forces occasioned by a hit such as at 14 to the extreme edge of the glass cloth laminate. FIG.
3 shows the effect of an edge hit at 24 on the plate 20. As shown, while the glass cloth laminate delaminates at 23, the separation of the laminations does not extend all the way to the outer edge of the glass cloth.
FIG. 4 shows another embodiment of the invention wherein protection against edge hits on the armor is improved. Instead of folding the glass cloth laminate backing down over the edge of the ceramic plate 30 as in the embodiment of FIG. 2, the glass cloth is folded back over itself at the free edges of the plate and securely bonded at and along the fold. As shown in FIG. 5, delamination of the backing occasioned by projectile impact at 34 is limited in its spread due to the fold at 32 and no failure of the backing occurs at its extreme edge.
The composite armor referred to herein may be of various shapes and sizes. It may generally be described as plate-like or planar. The plates are, in many instances, slightly curved, and so by planar or plane as used in the appended claims, we do not mean absolutely flat in the mathematical sense.
I claim: i
l. A composite armor plate having a free edge, including a ceramic front plate and a resin bonded glass fiber cloth laminated backing plate bonded to said front plate, for protection against high energy projectiles, the edge portion of said backing plate being bent at an angle of substantially folded back onto and bonded to itself, to reinforce said free edge against impact of high energy small arms projectiles near said free edge.
UNITEDSTATES PA NT OFFICE I CERTIFICATE 01 CORRECTION Patent No. 3,859,892 I hated Jan. 14, 975' Inv'entor(s) Samuel H. COES Itis certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
At paragraph  on the front page format, after "Samuel Hn Coes," delete "385 Daris Rd." and insert --385 Davis Rd.a-
After paragraph [761 insert: --[-73] Assignee: Norton Company, Worcester, Massachusetts 01606-- At paragraph  entitled "Abstract", line 4, delete "the" and insert -The-- v Signed and sealec this 151: day of July 1975.
' C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Arresting Officer and Trademarks UNITEDISTATES PATENT OFFICE A CERTIFICATE OF CORRECTION Patent No. 3,859,892 a Dated Jan. 14, 1975 i Inventor(s) Samuel H. COES It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
At paragraph  on the front page format, after "Samuel H, Coes," delete "385 D'a 'r i-s Rd." and insert 385 Davis Rd.
After paragraph  insert: -[-73] Assignee: Norton Company, Worcester, Massachusetts 01606-- At paragraph  entitled "Abstract", line 4, delete "the" and insert -The- Signed and sealed this let day of July 1975.
C. MARSHALL DANN RUTH C. I'IASOIZ Commissioner of Patents Arresting; Officer and Trademarks