A ram-type blowout preventer having a housing with a vertical bore, aligned ram guideways extending outward from opposite sides of the bore, a ram in each guideway, means for moving the rams inward and outward in the guideways to open and close on a drill or pipe string in the bore, a packer in each ram having a packing with an upper slotted plate thereon and a lower slotted plate therebelow, the plates being sufficiently flexible to move into close proximity to a string when the rams are closed thereon to support the packing against extrusion.

BACKGROUND 
Blowout preventers are used to maintain control of wells during drilling. 
Ram-type blowout preventers are used to close on the drill or pipe string 
to contain pressure in the well. At times it is necessary to strip or move 
the string through the closed rams. This stripping movement can severely 
wear or abrade the face of the resilient packers used in blowout preventer 
rams. Another reason the packers of ram-type blowout preventers are 
subject to wear is that to provide a seal they must tightly engage and 
conform to the irregular surface of the string when closed and such 
ability to conform causes the packers to be subject to pressure induced 
extrusion. The design of ram packers is thus a compromise to provide the 
needed conformity or feed of the resilient material with maximum abrasion 
and extrusion resistance. 
Examples of prior ram-type blowout preventers can be seen in U.S. Pat. Nos. 
2,883,141 and 3,692,316 which disclose the use of upper and lower packer 
plates designed to minimize extrusion damage. U.S. Pat. No. 4,323,256 
discloses the use of a polytetrafluoroethylene insert in the face of the 
packer to minimize wear in stripping of the string through the packer. 
U.S. Pat. No. 2,194,258 discloses a ram-type blowout preventer having 
upper and lower plates of the packer which include a series of strips 
which are generally parallel to the ram axis and can move independently of 
each other to engage a drill or pipe string on which the rams have closed 
to provide a uniform support for the resilient packing material. 
SUMMARY 
The present invention relates to an improved ram-type blowout preventer 
with an improved packer. The blowout preventer includes a housing with a 
bore therethrough and one or more pairs of opposed aligned ram guideways 
extending outward from the bore, a ram in each of the guideways, means for 
moving the rams in the guideways, a packer in the front of each of the 
rams having an upper plate, a lower plate and resilient packing means 
therebetween, said plates each having a drill or pipe string receiving 
recess and slots allowing the upper plate to flex about the axis of said 
bore or said recess and engage the string when the rams are closed about 
the drill or pipe string. 
An object of the present invention is to provide an improved ram-type 
blowout preventer with improved ram packer means which seals effectively 
on a drill or pipe string to retain well pressure. 
Another object is to provide an improved ram packer which is protected from 
extrusion damage. 
Another object of this invention is to provide an improved ram-type blowout 
preventer with ram front packer plates that flex or conform to effectively 
engage the drill or pipe string passing through the blowout preventer.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Blowout preventer 10 includes housing 12 having bore 14 with ram guideways 
16 extending outward from opposite sides of bore 14, with ram 18 in each 
guideway 16 and having means 20, such as a piston, connected to rams 18 by 
connecting rods 22, for moving rams 18 inward and outward in guideway 16. 
Each of rams 18 includes improved front packer 24. Groove 23 extends 
across the top of ram 18 and seal 25 is positioned therein to provide a 
seal extending from packer 24 on each side and across the top of ram 18, 
as is known in the art and shown in U.S. Pat. No. 3,102,709. While blowout 
preventer 10 shown in FIG. 1 only shows one guideway 16 it has two such 
guideways and each has substantially identical but opposed structure 
including ram 18. 
As shown in FIGS. 2 and 4, packer 24 includes upper plate 26, lower plate 
28 and resilient packing 30 between plates 26 and 28. Each of plates 26 
and 28 include face or front recess 32, rear projections 34 and side 
portions 36 and 38. Also each of plates 26 and 28 has a plurality of slots 
40 starting in holes 42 and extending to the front or rear surfaces of 
plates 26 and 28. It is preferred that slots 40 are substantially 
perpendicular to the surface on which they open. Holes 42 are provided to 
avoid any stress concentration in the plates. 
The radius of recesses 32 is slightly larger than the radius of the string 
on which packer 24 is to seal. This allows plates 26 and 28 to flex and 
conform to the string 44. The closing and sealing action of a pair of 
packers 24 is shown in exaggerated form in FIG. 3. 
As can be seen from the drawings, plates 26 and 28 are sufficiently 
flexible to move into close proximity to or into engagement with string 44 
to provide a substantially continuous support of resilient packing 30 
around string 44 whereby extrusion of resilient packing 30 is prevented. 
With the improved support supplied by the improved flexible plates it is 
possible to use a resilient material for the resilient packing which flows 
or conforms readily to improve the sealing characteristics of the ram 
packers. Such material is preferred to be acrylonitrile-butadiene rubber, 
fluorocarbon rubber or similar solvent resistant rubber.