US3894357A

US3894357A - Security door

Info

Publication number: US3894357A
Application number: US455787A
Authority: US
Inventors: James L Stanfield
Original assignee: California Crime Technological Research Foundation
Current assignee: California Crime Technological Research Foundation
Priority date: 1974-03-28
Filing date: 1974-03-28
Publication date: 1975-07-15
Anticipated expiration: 1992-07-15

Abstract

To deter burglary, an exterior door includes a wire mesh for elastic toughness and resistance to penetration; a non-resisting marginal edge falsework which yields, so as to defeat prybar efforts, before the entire door is displaced far enough to withdraw the latch bolt from the strike plate; and steel stiffener plates to resist high concenterated prybar loads on the portion of the lock mechanism unprotected by the falsework.

Description

[451 July 15,1975

[ SECURITY DOOR 8/l960 Kelly et 1/1972 Yeager et al. 49/503 Inventor: James L. Stanfield, Rancho Cordova, Calif.

FOREIGN PATENTS OR APPLICATIONS 275 992 8/l927 United Kingdom................... 52/6l5 42l.602 l2/l934 United Kingdommwm.,.t... 52/6l5 [73] Assignee: California Crime Technological Research Foundation, Sacramento, Calif.

Primary Examiner-Philip C. Kannan [22] Flled' 1974 Attorney, Agent, or Firm-Lothrop & West [2|] Appl No.: 455,787

ABSTRACT .mwm 6 dm m w mm .lmtmm rl o.me own m dl .mna m m enm nh 32. m mi r a kfl m an u mm be Urn. d.m 0 0 Tmfi 00 0 ZNMZ $36M 2 .2 5&5.) 5 6 lE 6 2 1 5 2 "2 5 n3 m0 3 0 u t e m 9. 4 "5 9 u4 J .mr e S I M mrw UIF NH 555 yields, so as to defeat prybar efforts, before the entire door is displaced far enough to withdraw the latch bolt from the strike plate; and steel stiffener high concenterated prybar loads on the [56] References Cited UNITED STATES PATENTS plates to resist portion of the ework.

52/615 lock mechanism unprotected by the fals 52/6l5 x 49/50 12 Clalms, 5 Drawlng Figures 1.917.871 7/l933 1,931 [25 l0/l933 Balduft........... 2,791.809 5/1957 Lincoln,

SECURITY noon In the effort to provide an improved barrier against unauthorized entry, it is not practical merely to add bulk or substitute materials of known greater strength, particularly where a residential type of door, for example, rather than a commercial type, is involved. A balance between cost and effectiveness must be made, bearing in mind that resistance to standard expected threats, not extraordinary ones, is the objective.

It is therefore an object of the present invention to provide a security door which uses relatively inexpensive materials, yet which is put together in such a way as to afford an effective deterrent to several of the more frequent kinds of criminal threats, such as a prybar inserted between a door and the adjacent lock jamb and used to free the latch bolt.

It is another object of the invention to provide a security door which is effective to frustrate most onslaughts directed toward the door, both laterally, in the plane of the door, and perpendicular thereto, such as foot or shoulder impact, battering ram, heavy hammer, or the like.

It is still another object of the invention to provide a security door which is not only effective to accomplish its practical purpose but it also esthetically acceptable in that it presents the traditional appeal of a solid or flush door.

It is a further object of the invention to provide a security door which is well-balanced, relatively compact in size, light in weight, and compatible with all kinds of door hardware.

It is yet another object of the invention to provide a generally improved security door.

Other objects, together with the foregoing, are attained in the embodiment described in the following description and illustrated in the accompanying drawing in which:

FIG. 1 is an isometric view, to a reduced scale of a preferred embodiment with portions broken away to reveal interior details;

FIG. 2 is a fragmentary view of the lower, left-hand corner of the door as shown in the broken ellipse;

FIG. 3 is an exploded fragmentary view of the upper left-hand corner of the door;

FIG. 4 is similar to FIG. 3 but illustrating the upper, right-hand corner; and

FIG. 5 is similar to FIG. 3, but showing the structure in the vicinity of the lock end of the middle rail as indicated by the broken ellipse.

While the security door of the invention is capable of being built and used in numerous ways, the particular embodiment shown and described herein has proven to be eminently effective in accomplishing its intended purposes.

The security door of the invention, generally designated by the reference numeral 12, comprises a top rail 13, a middle rail 14 and a bottom rail 15, the rails being connected at their hinge ends to a divided, but colinear, hinge stile l7 and at the lock end to a divided, but co-linear, lock stile 19.

An upper middle stile 21 and a co-linear, lower middle stile 22, respectively, span the top and middle rails and the middle and bottom rails.

As appears most clearly in FIGS. 2 5, the joints between the stiles and rails are mortised for added strength. For additional rigidity, triangular gussets 26 can be installed.

Since the middle rail 14 is the member ordinarily subjected to the greatest threat, the middle rail is of primary concern. Exhaustive tests have shown that 2 inches X 8 inches Select Structural Douglas Fir satisfactorily meets the requirements of cost effectiveness for the middle rail 14 in most security door installations.

In like manner, it has been determined that 2 inches X 6 inches Select Structural Douglas Fir serves adequately for the top rail 13 and the bottom rail 15. Gussets 26 can be made from 2 inches X 4 inches Douglas Fir (Dense No. 1).

Conventional hinges 28 and a lock mechanism 29 are installed as shown. FIG. 5 discloses the appropriate openings 31 in the middle rail 14 for a common lock mechanism.

In many instances, the threat to a door will consist of a prybar effort brought to bear against the lock end 33 of the middle rail 14. Powerful leverage can be directed against the middle rail by inserting the end of a crowbar between the lock end 33 and the adjacent lock jamb 34 of the door frame 35 shown in broken line in FIG. 1. The concentrated force is sometimes sufficient to compress and deform the wood adjacent the front plate of the lock, enabling the attacker to spring or destroy the latch structure.

In order to circumvent this approach, an opposing pair of stiffener plates 36, at least one of which is gained into the door, as at 37, is mounted adjacent the lock end 33 of the middle rail. If desired, the stiffener plate 36 on the outer side of the door is blank, i.e. it has no exposed openings. The connecting bolts in such case could be welded to the inner side of the blank stiffener plate with the threaded ends of the bolts inserted through respective openings in the door and the matching stiffener plate, for appropriate fastening. The stiffener plates, preferably, are 1/16 inch thick and of ASTM 1020 or 1025 steel; and instead of being installed separately, as shown and described, the plates 36 could be incorporated in the lock design.

The steel stiffener plates 36 located adjacent the latch mechanism 29 resist high concentrated loads at the latch. The two plates, acting as a bolt-spacer combination, distribute the load over a larger area of the door, thereby changing the concentrated latch load to a pressure distribution compatible with the woods resistance to compression and destructive deformation.

A further effective measure to defeat crowbar attack on the edges of the door is the peripheral falsework structure, generally designated by the reference numeral 41.

Most prybar attacks are made on the lock end of the door in the vicinity of the lock mechanism, in an effort to displace the door in the direction of the hinges far enough so that the latch is withdrawn from the strike plate, thereby allowing the door to be opened.

In order to achieve this result, however, the crowbar must find a door edge which affords sufficient reaction for the force to be transferred from the point of engagement to the entire door.

The falsework 41 is therefore so constructed that it collapses under the very considerable concentrated force which must be brought to bear on the edge in order to displace the door in its own plane by an amount necessary to disengage the latch from the strike plate.

As appears most clearly in FIGS. 1, 4 and 5, the falsework 41 includes an upper lock edge closure 42 and a lower lock edge closure 43. Both closures are preferably strips of 1 inch X 2 inches clear soft pine. The upper closure 42 extends from the top 44 of the door 12 to the lock end of the middle rail 14 and the lower closure 43 reaches between the middle rail 14 and the bottom 46 of the door. Both strips are parallel to and spaced outwardly from the adjacent edge of the lock stile 19.

The soft pine edge closures, in other words, defeat crowbar attack by yielding to a force less than that required to displace the door. The falsework does not provide the necessary reaction for a crowbar owing to the relatively soft, non-resisting, low compressive strength of the

respective closure strips

42 and 43.

In comparable fashion, a second portion of the falsework 41 is located on the hinge end of the door. However, since the hinges must be attached to the ends of at least two of the

rails

13, 14 and 15, the falsework 41 must necessarily be interrupted. Thus, as shown most clearly in FIGS. 1, 2 and 3, the falsework comprises a top slat 51, or strip, a bottom slat 52 and a pair of

intermediate slats

53 and 54. As before, the slats 51 54 are of clear soft pine having a cross-sectional size of 1 inch X 2 inches.

Along the top 44 of the door the falsework 41 includes a horizontal top strip 56 of 1 inch X 2 inches clear pine extending horizontally along the top of the door and being fastened at the hinge end to the top slat 51. At the lock end, the top strip 56 is secured both to the upper lock edge closure 42 and to the top of an upper horn 57 provided by an upward extension of the lock stile 19.

A comparable structure is provided at the bottom of the door, the falsework 41 there including a strip 61, of 2 inches X 2 inches clear pine extending horizontally between the bottom slat S2 and the lower lock edge closure 43, the bottom strip also being anchored to the bottom of a lower horn 63 formed by extending the lock stile 19 downwardly. The bottom strip 61 is thicker than the other strips in order to accomodate for Weatherstripping and trimming, if necessary.

The falsework 41, in other words, provides a peripheral structure extending substantially around the entire margin of the door except for discontinuities required by the door hardware; and in the case of the particularly vulnerable area in the vicinity of the lock, the exposed end of the middle rail is hardened by the stiffener plates 36.

As previously indicated, high impact loads are also sometimes directed against a door perpendicular to the plane of the door, such as by the attackers shoulder or foot, or by a heavy hammer or battering ram. Against threats of this nature, it has been found that a significant-increase in the dynamic load resistance, with but a small increase in weight over the customary flush wooden door, is attained by the use of a steel reinforcing mesh 66 covering a substantial portion of one side of the door, as shown. In order that the exposed surface of the mesh 66 is flush, the mesh is inset into a corresponding shallow recess 67 formed in the door (see FIG. 4).

The beneficial effect of the mesh 66 which is preferably of expanded metal screen, 1/16 inch thick, ASTM 1010 steel, and which is secured to the door by staples and epoxy resin glue, is attributed to the increase in the elastic limit in bending achieved by the mesh.

Thus, instead of going plastic under dynamic loads, the door remains relatively elastic and returns more energy to the person attempting to gain entry by force than is the case with either conventional hollow or solid core doors.

Covering both sides of the door is a pair of

planar panels

71 and 72, of A inch exterior grade plywood, glued to the underlying facing portions of the structure heretofore described. The plywood panels and particularly the interposed expanded metal screen 66 also serve effectively to resist cutting through the door.

In tests conducted with the security door herein, In comparison with hollow and solid core doors, the results showed that the security door is capable of withstanding substantially higher dynamic input loads. Yet, at the same time, in a comparative weight test, the security door of the invention weighed only 67 pounds as contrasted with about 28 pounds for a far weaker hollow core door and about pounds for a weaker, yet much heavier solid core door.

It can therefore be seen that the security door disclosed herein corrects many of the weaknesses heretofore found in the customary solid and hollow core doors used in homes, apartments, and the like, and accomplishes this in an attractive, cost effective manner.

What is claimed is:

l. A security door comprising:

a. a top rail;

b. a middle rail;

c. a bottom rail;

d. a hinge stile connected to the hinge ends of said rails;

e. a lock stile connected to the lock ends of said rails;

f. a lock mechanism mounted on said middle rail adjacent the lock end thereof;

g. a first falsework portion mounted on the lock end of said door, said first falsework portion including a strip spaced outwardly from and parallel to said lock stile, said strip being yieldable under a predetermined force bearing against said strip in a direction toward said lock stile;

the ends of said lock stile being extended to form an upper horn and a lower horn, and including a pair of second falsework portions comprising a pair of relatively yieldable strips mounted horizontally on the top of said upper horn and the bottom of said lower horn, said strips extending horizontally the width of said door and being spaced, respectively, above said top rail and below said bottom rail;

h. a pair of planar sheaths covering both sides of said door; and,

i. an expanded metal screen panel on at least one side of said door beneath one of said sheaths.

2. A security door as in claim 1 including a metal stiffener plate secured to said middle rail between said latch mechanism and the lock end of said middle rail.

3. A security door as in claim 2 in which there are two of said metal stiffener plates on opposite sides of said door, the outside one of said metal stiffener plates being blank.

4. A security door as in claim 1 including an addi' tional falsework portion mounted on the hinge end of said door, said additional falsework including a strip spaced outwardly from and parallel to said hinge stile, said strip being yieldable under a predetermined force bearing against said strip in a direction toward said hinge stile.

5. A security door as in claim 4 in which at least some of the joints between aid stiles and said rails are mortised.

6. A security door as in claim 5 in which said expanded metal screen panel is inset into the underlying portions of said door to provide a flush surface.

7. A security door as in claim 6 including a pair of middle stile members one of said middle stile members spanning said top rail and said middle rail, and the other spanning said middle rail and said bottom rail.

8. A security door as in claim 7 including a plurality of triangular gussets mounted in at least some of the corners formed at the intersections of some of said rails and some of said stiles.

9. A security door comprising:

a. a top rail;

b. a bottom rail;

c. a hinge stile connected to the hinge ends of said rails;

d. a lock stile connected to the lock ends of said rails;

e. a lock mechanism mounted on the lock end of said door adjacent the lock edge thereof; and,

f. a falsework strip mounted on the lock end of said door, said falsework strip being spaced outwardly from and parallel to the lock edge of said lock stile, said falsework strip being fabricated from material having a cross-section less than the cross-section of said lock stile and being collapsible under a predetermined force bearing against said strip in a direction toward said lock stile, said predetermined force being less than the force required to collapse said lock stile.

10. A security door as in claim 9 in which said outwardly spaced falsework strip includes an upper lock edge closure extending upwardly from a location adjacent said lock mechanism toward the top of said door and a lower lock edge closure extending downwardly from a location adjacent said lock mechanism toward the bottom of said door; and including a metal stiffener plate secured to the lock end of said door adjacent said latch mechanism.

1]. A security door comprising:

a. a top rail;

b. a bottom rail;

c. a hinge stile connected to the hinge ends of said rails;

d. a lock stile connected to the lock ends of said rails;

e. a lock mechanism mounted on the lock end of said door;

f. hinges mounted on the hinge end of said door; and

g. a peripheral falsework structure spaced outwardly from and extending substantially around the entire margin of the door except for discontinuities resulting from the presence of said lock mechanism and said hinges, said falsework structure being fabricated from material having a cross-section and strength less than the cross-section and strength of said stiles and said rails.

12. A security door as in claim 11 further including a stiffener plate mounted on the lock end of said door adjacent said lock mechanism.

Claims

1. A security door comprising: a. a top rail; b. a middle rail; c. a bottom rail; d. a hinge stile connected to the hinge ends of said rails; e. a lock stile connected to the lock ends of said rails; f. a lock mechanism mounted on said middle rail adjacent the lock end thereof; g. a first falsework portion mounted on the lock end of said door, said first falsework portion including a strip spaced outwardly from and parallel to said lock stile, said strip being yieldable under a predetermined force bearing against said strip in a direction toward said lock stile; the ends of said lock stile being extended to form an upper horn and a lower horn, and including a pair of second falsework portions comprising a pair of relatively yieldable strips mounted horizontally on the top of said upper horn and the bottom of said lower horn, said strips extending horizontally the width of said door and being spaced, respectively, above said top rail and below said bottom rail; h. a pair of planar sheaths covering both sides of said door; and, i. an expanded metal screen panel on at least one side of said door beneath one of said sheaths.

4. A security door as in claim 1 including an additional falsework portion mounted on the hinge end of said door, said additional falsework including a strip spaced outwardly from and parallel to said hinge stile, said strip being yieldable under a predetermined force bearing against said strip in a direction toward said hinge stile.

9. A security door comprising: a. a top rail; b. a bottom rail; c. a hinge stile connected to the hinge ends of said rails; d. a lock stile connected to the lock ends of said rails; e. a lock mechanism mounted on the lock end of said door adjacent the lock edge thereof; and, f. a falsework strip mounted on the lock end of said door, said falsework strip being spaced outwardly from and parallel to the lock edge of said lock stile, said falsework strip being fabricated from material having a cross-section less than the cross-section of said lock stile and being collapsible under a predetermined force bearing against said strip in a direction toward said lock stile, said predetermined force being less than the force required to collapse said lock stile.

11. A security door comprising: a. a top rail; b. a bottom rail; c. a hinge stile connected to the hinge ends of said rails; d. a lock stile connected to the lock ends of said rails; e. a lock mechanism mounted on the lock end of said door; f. hinges mounted on the hinge end of said door; and g. a peripheral falsework structure spaced outwardly from and extending substantially around the entire margin of the door except for discontinuities resulting from the presence of said lock mechanism and said hinges, said falsework structure being fabricated from material having a cross-section and strength less than the cross-section and strength of said stiles and said rails.