AU2001288561A1 - Et-plus: head assembly for guardrail extruder terminal - Google Patents

Description

ET-PLUS: HEADASSEMBLYFOR GUARDRAILEXTRUDERTERMINAL

Cross-Reference to Related Applications

[0001] This application claims the priority of U.S. Provisional Patent Application No.

60/229,486 filed August 31, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0002] The invention relates to guardrail extruder devices used with guardrail

installations. In particular aspects, the invention relates to the design of impact head

assemblies for such devices.

2. Description of the Related Art

[0003] Guardrail extruder terminals are a popular and effective end treatment for

guardrail installations. During an end-on impact to a guardrail end, a guardrail extruder

terminal will flatten and bend a corrugated rail member and extrude the flattened portion

away from the roadway. Terminals of this type are described in U.S. Patents 5,078,366

and 4,928,928.

SUMMARY OF THE INVENTION

[0004] The present invention provides an improved head assembly for a guardrail

extruder terminal device. An exemplary head assembly is described that is lighter and

more effective than prior art head assemblies. The exemplary head assembly provides

a throat that receives a corrugated guardrail. In preferred embodiments, the throat is a

squeezing throat that is narrower at the upstream end than at the downstream end. The squeezing throat compresses a rail and flattens it. A curved plate contacts the rail and

extrudes it away from the head assembly. The throat is constructed from a pair of side

members. In a first described embodiment, the first side member is an elongated, S-

shaped plate while the second side member is a short curved plate. Alternative head

constructions are described wherein the tliroat is constructed from side members that are

formed of flat plates rather than curved plates. The flat plates may be tapered such that

the upstream end of the tliroat is narrower than the downstream end. Alternatively, the

flat plates may be non-tapered wherein the squeezing is accomplished through combined

action of the throat and curved deflector plate.

[0005] The impact plate of the head assembly is vertically elongated and presents upper

and lower overhangs that assist with vehicle engagement. In addition, the impact plate

is provided with flanges on either side to help stiffen the plate. The head is also

asymmetrical and streamlined. When the impact head is mounted on a rail member, the

central point of impact is off-center with respect to the axis of the head.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is an isometric view of an exemplary guardrail extruder terminal head

constructed in accordance with the present invention.

[0007] Figure 2 is a plan, cross-sectional view of the head taken along the lines 2-2 in

Figure 1.

[0008] Figure 3 is an exploded view of the head shown in Figures 1-2.

[0009] Figure 4 is a plan view of the head of Figures 1-3 shown affixed to a support

post. [0010] Figure 5 is a side view of the head shown in Figure 4.

[0011] Figure 6 is a plan, cross-sectional view of an alternative head having a throat

with side members that are substantially flat and angled relative to each other.

[0012] Figure 7 is a plan, cross-sectional view of a further alternative head having a

throat with side members that are substantially flat and parallel to each other.

[0013] Figure 8 is an isometric illustration of an guardrail head having an exemplary

feeder chute bumper device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Figures 1-5 illustrate a first improved head assembly 10 used for a guardrail

extruder terminal of the type described generally in U.S. Patents 5,078,366 and

4,928,928. The general operation of guardrail extruder terminal devices is described in

those two patents and they are incorporated herein by reference. The head assembly 10

is shown (in Figure 1) positioned on the end of a corrugated, or W-beam, guardrail 12.

[0015] The head assembly 10 generally includes an impact portion 14 and an elongated

rail feeder chute 16. The rail feeder chute 16 surrounds the upstream portion of the rail

member 12 and is made up of an upper, U-shaped channel member 18 and a lower, U-

shaped channel member 20 which are secured in a spaced relation from one another by

strap plates 22. L-shaped brackets 24, 16 are affixed to the upper and lower channels

members 18, 20, respectively.

[0016] The impact portion 14 of the head assembly 10 has, at its upstream end, an

impact plate 28. The impact plate 28 is bent on either lateral side to present flanges 30,

32. The flanges 30, 32 lend strength to the impact plate 28, stiffen it, and assist with engagement of an impacting vehicle.

[0017] The impact plate 28 is secured by welding to a rail receiving portion 34 of the

impact portion 14. The rail receiving portion 34 includes a top plate 36 and a bottom

plate 38. The top and bottom plates 36, 38 are affixed by welding to left and right side

members 40, 42, respectively. The left side member 40 consists of a curved plate 44,

horizontal connecting plate 46, and a lateral brace 48. The lateral brace 48 is welded to

the curved plate 44, and the connecting plate 46 is welded to the brace 48 in an abutting

relation. It is noted that the curved plate 44 has an "S" shape such that it provides an

upstream first curved portion 50 and a downstream second curved portion 52 that curves

slightly in the opposite direction from the first curved portion 50. The brace 48 is affixed

to the curved plate 44 in between the first and second curves 50, 52. The right side

member 42 includes a short curved plate 54 with vertical and horizontal braces 56, 58,

respectively that are welded to the plate 54 to stiffen it. It is noted that, in this

embodiment, the side plates 40, 54 are curved. The side plate 54 is, unlike prior art

designs significantly shorter in length than the plate 40, as measured from upstream to

downstream. This difference in length is due to the fact that there is no forward curved

portion of plate 54 that would correspond to the curved portion 50 of the longer plate 40.

[0018] It is noted that the horizontal brace 58 extends some distance outwardly from

the right side of the head 10. This is done deliberately as the horizontal brace 58 is

intended to engage and break the support post 60 during a vehicular impact to the impact

plate 28 of the impact head 10 that moves the head 10 downstream upon the rail member

12. [0019] Figures 4 and 5 illustrate the impact head 10 having been affixed to a support

post 60 by connectors (not shown) that are disposed through the brackets 24, 26.

[0020] It is further noted that the impact plate 28 is vertically elongated, thereby

extending both above and below the rail receiving portions of the impact portion 14, as

shown by reference numerals 62, 64 in Figure 5. These overhangs permit the impact

head 10 to be easily engaged by either the high bumper of trucks, SUV's and other taller

vehicles and the low set bumpers of smaller cars impacting in a frontal manner, as well

as engaging the vehicle frame or rocker panel to reduce vehicle intrusion when the

upstream end of the head 10 is impacted by a vehicle in a sideways manner.

[0021] In a preferred embodiment, when the head 10 is assembled, the curved plate 44

and short curved plate 54 are secured in a spaced relation from one another to form a

squeezing throat 66, best seen in Figure 2. The throat 66 narrows in width as it

approaches the upstream end of the impact head 10. During collision wherein the impact

head 10 is impacted by a colliding vehicle (not shown), the throat 66 squeezes and

flattens the rail member 12 as the head 10 is pushed downstream by the vehicle onto the

rail member 12. The first curved portion 50 bends the flattened portion of the rail

member 12 and extrudes it to the side of the head 10.

[0022] There are a number of important differences between the inventive impact head

10 and the guardrail extruder heads described in U.S. Patents 5,078,366 and 4,928,928.

First, the portion of the head 10 that is used to bend and extrude the flattened portion of

the rail 12 consists only of a single curved surface, specifically, the rail contacting surface

of portion 50 on curved plate 44. Thus, an opening is provided opposite the portion 50 upstream of the end of the small curved plate 54. h prior arrangements, a pair of curved

portions were provided by two plate members that formed a narrow opening. Elimination

of one curved portion, i.e. the most downstream curved portion) reduces the extrusion

force required to extrude the rail member 12 and potentially improves the trajectory of

the extruded rail as it departs the head 10. The required extrusion force is reduced at least

because friction created by the removed downstream curved portion has been eliminated.

[0023] Also, as Figures 2 and 4 illustrate, the inventive head 10 provides a reduced and

streamlined profile along the traffic side (i.e., the side of the head 10 that will be directed

toward a roadway). Figure 2 illustrates a central longitudinal axis 70 that is taken along

the center line of the rail member 12. The traffic side of the head 10 (shown at the

bottom portion of Figures 2 and 4) does not extend as far from the axis 70 as the opposite

side of the head 10 ( shown at the top portion of Figures 2 and 4). This streamlining is

permitted by the fact that the top and bottom plates 36, 38 each have a flattened traffic

side edge 72 as opposed to the outwardly extending, generally triangular shape of the

opposite sides of those plates. The head 10 is always installed on the rail 12 so that the

"traffic" side is facing roadway traffic. This streamlined design ensures that the head 10

does not extend outwardly into to the stream of traffic, thereby reducing the frequency

of impacts by passing vehicles and the associated maintenance costs. The flattened

traffic side edge 72 should lie approximately flush with the strap plates 22 or other

portions of the feeder chute 16, or else extend only an inch or two beyond those

components in the direction of the traffic lane. This "flush-side" feature helps ensure that

the head 10 is less likely to be knocked off of the rail member 12 by a reverse end impact where a vehicle impacts the head from the downstream direction.

[0024] It is also noted, particularly with reference to Figure 2, that the center of impact

for the head 10 (shown at around 74) is not aligned with axis 70 of the rail 12. This non-

symmetrical design actually improves the function of the head 10 during a collision.

Rather than distributing the forces of the impact substantially equally to either side of the

head, as in prior designs, the force is primarily transmitted via connecting plate 46 and

brace 48 to the curved plate 44. Thus, the connecting plate 46 and brace 48 serve as the

axis of force transmission for the head 10. The curved plate 44 is the portion of the head

10 that works to bend and extrude the flattened rail member 12. Because impact force

upon the impact plate is transmitted directly to the side member 44 via the axis of force

transmission, the head 10 is more efficient in collapsing the rail 12 wherein the exterior

of the housing played a greater role in transmitting impact forces.

[0025] The impact head 10 of the present invention is advantageous because it has a

substantially lighter weight and mass than prior art impact heads. The inventive impact

heads typically weigh around 170 pounds versus 260 pounds for many prior art heads.

The reduction in weight and results in improved performance for the rail terminal since

a lighter head has less inertial resistance by the head during an impact. Initial movement

of the impact head and extrusion of the rail member 12 will be performed with less

resistance. In addition there is less of a jolting impact to a colliding vehicle due to the

reduced weight of the head. The reduction in weight and mass results from a number of

changes over prior art heads, including the use of thinner metals for fashioning of the

head, the removal of a largely unnecessary external housing, and the removal or change in size of various plates making up the head.

[0026] Turning now to Figures 6 and 7, there are shown alternative heads 10' and 10".

The heads 10' and 10" are similar in many respects of construction and operation to the

head 10 already described except where indicated otherwise. Therefore, like components

between the two embodiments are numbered alike. Head 10' has left and right side plates

40' and 54' that form a throat 66 The plates 40' and 54' provide essentially straight, flat

sidewalls for the throat 66'. As can be seen, the throat 66' narrows in width as it

approaches the upstream end of the head 10. Head 66" has a throat 66" that is formed

from side member plates 40" and 54". The throat 66" is essentially of a constant width

along its length as the two side members 40", 54" lie substantially parallel to each other

along the length of the tliroat 66".

[0027] Figure 8 illustrates a further feature of the invention wherein a feeder chute

bumper device is incorporated into the impact head. With reference once again to

Figures 1 and 5, it may be seen that the impact head 10 has a flared downstream end 78

on the feeder chute 16. The use of a flared end, such as end 78 is preferred because it

assists in ease of placement of the head 10 onto the rail member 12. This flared end 78

provides upper and lower extreme downstream edge portions 80, 82 that are formed to

present an acute angle and, thus, are somewhat sharp. During an end-on impact to the

head 10, the edge portions 80, 82 tend to impact the support posts as the head is pushed

downstream along the rail by the impacting vehicle. While the presence of such edge

portions 80, 82 is not normally a problem when wooden support posts are used, it

becomes a problem when metal support posts are used. For example, when steel wide flange support posts are used, the sharp edge portions 80, 82 may actually cut the flanges

of the support post downstream of the head 10. When this occurs, the support post may

pull the head 10 downwardly and, thus, resist further travel of the head 10. This is

undesirable. Figure 8 depicts a means of preventing that outcome. Pipe or round metal

stock members 84 are secured by welding to the edge portions 80, 82 so as to provide a

blunt, rounded impacting portions to the downstream end 78 of the head 10. The pipe

or round stock members 84 preferably have a length that is the same as the width of the

edge portions 80, 82.

[0028] While the invention has been shown or described in only some of its forms, it

should be apparent to those skilled in the art that it is not so limited, but is susceptible to

other various changes without departing from the scope of the invention.

Claims (20)

CLAIMSWhat is claimed is:

1. An impact head for a guardrail extruder terminal comprising:

an impact portion having an impact plate;

a rail feeder chute for receiving a rail member therein;

a rail-receiving throat located between the impact plate and the rail feeder chute

being formed by:

a first side member that comprises an elongated plate having an upstream

curved portion; and

a second side member that comprises a short plate member.

2. The impact head of claim 1 wherein the upstream curved portion of the first side

member presents a bending surface for bending a rail member.

3. The impact head of claim 1 wherein the impact plate is vertically elongated and

provides upper and lower overhangs.

4. The impact head of claim 1 wherein the impact plate is bent to provide flanges

on each lateral side.

5. The impact head of claim 1 wherein the impact portion further comprises a top

plate and a bottom plate, each being fastened to the first and second side members, each plate also having an outwardly extending side and an opposite flattened traffic side edge

to provide a streamlined traffic side to the impact head.

6. The impact head of claim 1 further comprising a connecting plate affixed between

the impact plate and the first side member, the connecting plate providing an axis of force

transmission for the impact head.

7. The impact head of claim 6 wherein the axis of force transmission is offset from

the central longitudinal axis of the impact head.

8. The impact head of claim 1 wherein the first and second side members define a

rail-receiving throat that narrows as the upstream curved portion is approached.

9. The impact head of claim 1 wherein the first and second side members lie

essentially parallel to one another to provide a rail-receiving throat of relatively constant

width.

10. The impact head of claim 1 wherein the first and second side members are curved.

11. The impact head of claim 1 further comprising:

a flared downstream end to the rail feeder chute, the flared downstream end

having upper and lower edge portions that form an acute angle; and a rounded member secured by welding to each edge portion.

12. An impact head for a guardrail extruder terminal comprising:

an impact portion presenting an impact plate;

a rail feeder chute for receiving a rail member therein;

a squeezing throat having a downstream end and an upstream end that is narrower

in width than the downstream end; and

a rail bending portion located upstream of the squeezing throat and being formed

from a single curved plate.

13. The impact head of claim 12 further comprising a connecting plate and a brace

affixed between the impact plate and the first side member, the connecting plate

providing an axis of force transmission for the impact head, the axis of force further

being offset from the central longitudinal axis of the impact head.

14. The impact head of claim 12 wherein the squeezing throat is formed by a first,

substantially S-shaped side member and a second, curved side member that is shorter in

length than the first side member.

15. The impact head of claim 14 wherein the substantially S-shaped side member also

provides the rail bending portion.

16. An impact head for a guardrail extruder terminal comprising:

an impact portion presenting an impact plate;

a rail feeder chute for receiving a rail member therein;

a rail-receiving tliroat formed of a pair of side members and having a downstream

end and an upstream end;

a rail bending portion located upstream of the tliroat and being formed from a

single curved plate; and

the rail bending portion providing a gap on the side opposite the single curved

plate.

17. The impact head of claim 16 wherein the rail-receiving throat is narrower in width

at the upstream end than the downstream end.

18. The impact head of claim 16 wherein the side members forming the rail-receiving

throat are curved.

19. The impact head of claim 16 wherein the side members forming the rail-receiving

throat are substantially flat.

20. The impact head of claim 16 wherein the rail-receiving throat is substantially the

same width from the upstream end to the downstream end.