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Publication numberUS3399559 A
Publication typeGrant
Publication dateSep 3, 1968
Filing dateJun 3, 1965
Priority dateJun 3, 1965
Publication numberUS 3399559 A, US 3399559A, US-A-3399559, US3399559 A, US3399559A
InventorsGeorge A Mitchell
Original AssigneeGeorge A. Mitchell
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method and apparatus for processing tubing
US 3399559 A
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Description  (OCR text may contain errors)

S p 1968 A. MITCHELL.

METHOD AND APPARATUS FOR PROCESSING TUBING 3 Sheets-Sheet 1 Filed June 5, 1965 INVENTOR.

GEORE A. MITCHELL.

ATTQRNEY 0 3 NM H vm m mm l1 G. A. MITCHELL 3,399,559

METHOD AND APPARATUS FOR PROCESSING TUBING Sept. 3, 1963 5 Sheets-Sheet .5

Filed June 5, 1965 INVENTOR. GEORGE A. MITCHELL- ATTORNEY 3,399,559 METHOD AND APPARATUS FOR PROCESSING TUBING George A. Mitchell, 920A Kendis Circle, Youngstown, Ohio 44505 Filed June 3, 1965, Ser. No. 461,002 7 Claims. (Cl. 72-330) ABSTRACT OF THE DISCLOSURE Method and apparatus for forming reduced diameter points on tubing wherein a pointed shear severs the tubing, followed by forming an end of the severed tubing on one side of the shear into a compact cylindrical point without materially deforming the end of the tubing on the other side of the shear.

This invention relates to a method and apparatus for forming reduced diameter points on tubing, and more particularly to a method and apparatus of the type described which substantially simultaneously severs a tube while forming a reduced diameter point thereon. As used herein, substantially simultaneously means that severing and pointing are carried out in a single step, although severance of the tube will usually occur a fraction of a second before the pointing operation is completed.

In tube drawing operations, the diameter and wall thickness of the tube are reduced by drawing the tube over a stationary mandrel and through the drawing die of drawbench, bull block or the like. For example, in the drawing operation on a drawbench, a reduced diameter end of a tubular workpiece, mounted on a mandrel, is passed through a die and engaged by gripper jaws carried on a draw carriage or dolly which travels on a track extending parallel to the central axis of the die. As the draw carriage is forced along the track and away from the die, the workpiece is drawn over the aforesaid mandrel and through the die, in which process the diameter and wall thickness of the tube are reduced while it increases in length.

The starting material for drawin tubing is normally a pierced billet or bloom of relatively large diameter and wall thickness. This bloom must be initially pointed to form a reduced diameter section which can be passed through the die during the first drawing operation. The bloom is then drawn one or more times until its diameter is not much greater than that of the original point. At this stage, it is necessary to saw off or otherwise sever the point and from a new point of smaller diameter. The drawing operation is then repeated a number of times until the diameter of the tube is again not much larger than that of the point. By this time, the length of the workpiece has increased to the stage where it must be cut into a number of shorter sections to continue the diameter and wall thickness reduction process. Each of these sections must, in turn, be pointed before it is subsequently drawn; and it can be seen that the original starting billet will end up as a rather large number of individual lengths of tubing, the smaller the final diameter, the larger the number of individual lengths.

In the past, it has been the practice to saw the tube at points along its length as each intermediate length of tubing reaches the point where it must be cut into sections for further processing, and to thereafter point each individual length for further drawing operation. Needless to say, the cutting and pointing procedure is one of the most costly and time consuming in the production of drawn tubing, particularly since cutting and pointing are carried out as separate steps, and both require manual handling.

The present invention seeks to provide, as an overall atent O 3,399,559 Patented Sept. 3, 1968 object, a faster and less costly method for producing drawn tubing.

More specifically, an object of the invention is to provide a method for severing and pointing drawn tubing in a single step, thereby eliminating the costly two-step procedure of prior-art techniques.

A further object of the invention is to provide a method and apparatus for collapsing a section of tubing into a generally circular reduced diameter point While substantially simultaneously severing the tubing just beyond the point, severance of the tube being completed before completion of the pointing operation.

A further object of the invention is to provide tube pointing and severing apparatus which effects pointing and severing of tubes in a single stroke of one die element with respect to another.

Another object of the invention is to provide a severing and pointing procedure wherein severance is effected by shearing, but wherein thin-walled tubing is not materially deformed during shearing.

Still another object of the invention is to provide a severing and pointing procedure for tubing wherein slugs of metal are produced during shearing to effect severance, which slugs can easily be reclaimed for melting. This is in contrast to the usual sawing operation for tubular metal workpieces wherein the saw chips cannot readily be reclaimed.

In accordance with the invention, a tubular workpiece is passed between opposing die elements, and the workpiece severed at a, point just beyond the die elements while the die elements are forced toward each other to thereby compress the end of the tubing formed by severance into a compact, generally cylindrical shape.

Preferably, the die elements comprise a female die member defining a recess having converging side Walls, and a male die member received within the recess defined by the female die member. In order to sever the tube, a pointed shearing blade is secured to one of the die elements and arranged such that upon converging movement of the die elements with a tubular workpiece therebetween, the shearing blade will initially pierce the tube and begin to shear the same. Upon continued converging movement of the die elements, and after the tube is partially sheared, the workpiece will be compressed laterally by the converging side walls of the female die element. By the time the shearing operation has been completed, the cross section of the workpiece at the end produced by shearing will have assumed a generally elliptical configuration. The process is completed by further converging movement of the die elements to compress the elliptical configuration into a compact, generally cylindrical shape which characteristically defines a generally S-shaped cross-sectional configuration.

Wih the foregoing arrangement, a pointed end of reduced diameter will be formed on one side of the cut, while the other side will be substantially undeformed except for a small dimple which is formed at the beginning of the tube shearing operation when the shear initially pierces the tube. Thus, instead of separately cutting a length of tubing into smaller pieces and thereafter individually forming a point on each separate piece, the pointing and cutting operations are performed simultaneously. In this manner, a length of drawn tubing can be placed between the male and female dies such that only the previously-formed point projects beyond the die. Upon converging movement of the dies, the previous point is automatically sheared ofi, and a new point formed just behind the old point. The tubing is thereafter advanced through the dies to a desired length, and the dies again caused to converge, whereupon a pointed tube of the correct length is cut from the starting Work-piece, while a point is substantially simultaneously formed on one end of the next succeeding length of tubing. This procedure is repeated until the original length of tubing is cut into a number of smaller lengths, all of which are pointed without further processing.

The above and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIGURES 1A1F schematically illustrate the processing steps in forming drawn tubing in accordance wiih conventional procedures;

FIGS. 2A-2B are schematic illustrations showing the manner in which the combined cutting and pointing apparatus of the invention will automatically shear lengths of tubing while forming a point on the next succeeding tube;

FIG. 3 is an elevational view of one end of the combined forming die and shear of the present invention;

FIG. 4 is a side elevational view of the die and shear shown in FIG. 3;

FIG. 5 is an elevational view of the other end of the forming die and shear of the invention; and

FIGS. 6A6H are perspective and cross-sectional views illustrating the manner in which tubing is sheared and pointed in accordance with the invention.

With reference now to the drawings, and particularly to FIGS. lA-lF, a drawing operation usually begins with an extruded or pierced bloom 10 having a length usually of about to feet and provided with a central longitudinal bore 12. The bloom 10 is then pointed as shown in FIG. IE to form a reduced diameter section 14 which may be inserted through a die opening in a drawbench or the like and engaged by gripper jaws carried on a draw carriage.

Prior to the drawing operation, the pointed bloom 10 shown in FIG. 1B is passed over a mandrel such that during the drawing operation when the draw carriage moves away from the die, the diameter and wall thickness of the bloom 10 are reduced between the mandrel and the periphery of the drawing die, while its length is increased. After a number of successive drawing operations, the bloom 10 may then appear as shown in FIG. 1C wherein it now comprises a tube 16 which may, for example, be 120 to 160 feet in length. At this point, it will be seen that the point 14 is almost as large in diameter as the main body of the tube 16. Therefore, in order to further reduce the tube 16, it is necessary to sever the point 14 and form a new point thereon. Furthermore, since the tube 16 has now reached a length of 120 to 160 feet, it becomes necessary to divide it into a number of smaller lengths. Otherwise, the drawbench, which may be about 150 feet in length, cannot effect further reductions in diameter. The cutting operation is shown in FIG. 1D wherein the tube 16 is now cut into three lengths 18, 20 and 22 which are to be further processed, and a short section 23 which is severed to remove the old point 14. The pieces of tubing 18, 20 and 22 as shown in FIG. 1D, while of the proper length, cannot be further drawn until they are again pointed. Accordingly, as shown in FIG. 1E, each of the sections 18, 2t and 22 is pointed to provide reduced diameter sections 24, 26 and 28, respectively. Each of the sections 18, 20 and 22 is now separately drawn a number of times to provide three smaller diameter tube sections 30, 32 and 34 (FIG. 1F) which have again increased to a length of about 120 to 160 feet after repeated drawing operations wherein the diameter and wall thickness of each section are reduced. The foregoing process is repeated with the sections 30, 32 and 34 being cut into smaller sections and each individually pointed. These smaller sections are then drawn until their diameters are substantially equal to the diameter of the points formed thereon, whereupon a succeeding division into smaller lengths is made. As was explained above, the foregoing process is both costly and time consuming since every intermediate length of tubing must be initially cut into smaller lengths and these smaller lengths each individually pointed.

The method of the invention is schematically illustrated in FIGS. 2A and 2B wherein a piece of tubing, such as tube 16, for example, is initially passed through a die set, hereinafter described in greater detail, comprising an upper movable female die element 36, and a lower stationary male die element 38. The tube 16 is passed between the upper and lower die elements 36 and 38, respectively, and thence through an opening in a block 40 which is spaced from both the female and male die elements 36, 38. Carried on the right face of the female die element 36 is a shear 42, hereinafter described in greater detail. Upon downward movement of the upper female die element 36 and the shear 42, the shear 42 will sever the tube while the upper die element 36 is forced downwardly over the lower die element 38 to substantially simultaneously form a point on the tube. Thus, the previous point 14 is cut off and a new point formed in one stroke of the upper die element 36 and shear 42. After the cutoff and pointing operation, the tube 16 is then advanced on conveyor rolls 44 and now has a new point, corresponding to point 28 shown in FIG. 1E, formed thereon. The tube 16 is advanced on the rolls 44 to the de:ired length, and the upper die element 36 and shear 42 again forced downwardly. In this process, a length of tubing, corresponding to length 22 shown in FIG. lE, is formed; and the new point 26 for the next succeeding length 20 will be simultaneously formed. After formation of point 26 and severance of length 22, the tube 16 is again passed between the die elements 36 and 3 8, whereupon a length corresponding to length 20 shown in FIG. IE is severed, and a point corresponding to point 24 of FIG. 1B formed. It can thus be seen that the separate steps of sawing and then individually pointing the lengths 18, 2t and 22 is now combined into a single step process.

The tube forming apparatus per se comprising the male and female die elements 38 and 36 is described in detail in copending application Ser. No. 451,296, filed Apr. 27, 1965, and only the major elements will be described herein. With reference now to FIGS. 3, 4 and 5, the female die element 36 comprises an upper die block 46 secured to and supported by a suitable thrust member, not shown, for vertical reciprocal movement. That is, the die block 46 is forced downwardly to point the end of a tube and thereafter raised into the normally elevated position illustrated in FIGS. 3. 4 and 5. The arrow 48 represents the force applied by a conventional press during the pointing and severing operation.

The upper die block 46 includes an elongated recess 50 extending the entire length of the die block. Housed within the recess 50 is a pair of side die members 52 and 54, each of which rests on a support plate 56 secured to the underside of the die block 46. The side die members 52 and 54 are each provided with upper vertical, parallel portions 58 and lower inclined portions 60 and are normally disposed in spaced'apart relation. As will be described later, the side die members 52 and 54 are adapted to undergo converging upward movement relative to the die block 46 during the pointing of a tube and to undergo diverging downward movement relative to the die block when the same is lifted at the completion of a pointing operation.

As can best be seen in FIG. 5, an upper die member 62 is positioned between the upper ends of the side die members 52 and 54, and is supported on shoulders 64 provided therein. A retaining plate 66 is secured to the upper surface of each of the side die members 52 and 54 and extends laterally over the upper die member 62 for retaining the same in the space between the retaining plates 66 and the shoulders 64. The upper die member 62 is provided, as shown, with an elongated, downwardly opening concave die surface which cooperates with a similarly shaped lower die surface, hereinafter described, in

collapsing the wall of the tubing for pointing the same. The upper die member 62, the upper vertical portions 58 and thelower inclined portions 60 of the side die members 52 and 54 define an inverted Y-shaped trough through which the endof a tube 68 to be severed and pointed is received, as will be described.

The male. die element 38 comprises a base 70 which supports a stationary lower male die member 72 having an elongated, upwardly opening concave die surface at its upper end. Ahead of the lower die member 72, as best shown in FIG. 4, is a tapered transition die member 78 which rests on a die block 80 also supported on the base 70. Also carried on the die block 80 is a ring member 82 through which the tube 68 is inserted preparatory to a severing and pointing operation. As will hereinafter be explained, the lower transition die member 78 cooperates with a corresponding upper transition die member 84 to form .a taper in the tubing between a reduced diameter pointed end and the remainder of the tube. Upper transition die member 84 is carried forwardly of the side die members 52 and 54 by a block 86 secured to the upper die block 46 such that it will move downwardly with the upper die block during a severing and pointing operation.

Carried forwardly of the lower die member 72 on base 70 is a supporting block 88 (FIGS. 4 and 5) having an opening 90 extending therethrough in alignment with the longitudinal axis of the tube 68. The opening is adapted to receive any one of a number of bushings, one of which is shown in FIG. 4 and identified by the reference numeral 92. The bushing 92 is provided with an inner diameter slightly larger than the diameter of the tube which is to be severed and pointed and may be replaced by another bushing of different diameter, depending upon the size of the tube being processed.

Carried on the forward face of the die block 46 by means of plate 94 and bolts 93 is the shear 42, previously described in connection with FIGS. 2A and 2B. It comprises a perfectly flat blade 95 having a lower pointed end 97 normally above the tube 68 which is inserted through the ring 82 and the bushing 92. However, upon downward movement of the female die element 36 along the direction of arrow 48, the blade 95 will pass through the space 99 between bushing 92 and the die elements 36 and 38. In this process, it will initially pierce the tube 68. Thereafter, the sloped surfaces 101 and 103 forming the pointed end 97 will exert radially outward shearing forces to remove slugs of metal and sever .the tube. At the same time, forming of the tube end to the left of blade 95 and between die elements 36 and 38 progresses.

The process of the invention can perhaps be best understood by reference to FIGS. 6A-6H wherein FIGS. 6A- 6C are perspective views of a tube during the shearing operation; FIGS. 6D-6G are cross-sectional views of the tube during its formation into a point; and FIG. 6H is a perspective view of the finished product. The process starts as shown in FIG. 6A with the blade 95 initially piercing the tube 68. The forward end 96 of the tube 68, having been previously pointed, is not much smaller in diameter than the remainder of the tube due to the fact that the tube has been passed through successively smaller dies since the last pointing operation. Furthermore, the point 96 is now somewhat distorted and marked as at 98 by the teeth of the gripper jaws which pull the tube through the drawing die.

As the blade 95 initially contacts the tube, it produces a dimple or depression as at 100; and this dimple will persist on opposite sides of the sheared area following the cutting operation. However, the dimple is not severe enough to prevent the insertion of a mandrel into an end of a tube during successive drawing operations, as when a cutting operation is effected as in FIG. 2B where one section of tubing 22 is cut ofi for further drawing operations while a point 26 is formed on the next section.

Upon continued downward movement of the blade 95 as shown in FIG. 6B, the sloped surfaces 101 and 103 will exert radially outward shearing forces to remove lugs or ears 102 and 104 from opposite sides of thetube until a stage is reached as shown in FIG. 6C where the previous point 96 is completely severed from the remainder of the tube. At this time, the converging sides 60 of the side die members 52 and 54 have already started to laterally compress the remainder of the tube 68, thereby forming it into a somewhat modified ellipse in which the sides of the ellipse face inwardly toward each other as shown in FIGS. 6D and 6B. Thus, as the female die element 36 is moved downwardly, the converging guideways 60 initially contact the sides of the tube and exert lateral forces thereon. In this process, the side die members 52 and 54 move upwardly along with the upper die element 62 until they bottom against surface 67 shown in FIG. 5. Continued downward movement of the female die element 36 causes the elongated slot 109 between the sides 58 to pass over the tube as shown in FIG. 6D until the upper end of the modified ellipse formed by the lateral compression forces contacts the upper die 62. At this stage, further downward movement will compress the end of the tube into a generally S-shaped configuration as shown in FIGS. 6E, 6F and 6G.

Upon upward movement of the female die element 36, the tube will tend to move upwardly, but will be retarded by the ring member 82 (FIGS. 3 and 4) which effectively strips the newly-pointed end 106 shown in FIG. 6H from the side die members 52 and 54. The transition taper 108 formed between the reduced diameter point 106 and the remainder of the tube 68 is formed between the transition die members 78 and 84, as will be understood.

Thus, in one downward stroke of the female die element 36, the tube is initially severed and the end of the tube immediately adjacent the point of severance formed into a point of reduced diameter. The tube 68 may thereafter be advanced through the ring 82 and bushing 92 as shown in FIG. 2B to the desired length, and the foregoing process repeated, whereupon one section is cut from the tube 68 and a point formed on the next succeeding section.

Although the invention has been shown in connection with a certain specific embodiment, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. In the method for severing tubing and for substantially simultaneously forming a reduced diameter point on the severed tubing, the steps of passing the tubing between opposing die elements, severing the tubing without substantially deforming its cross section at a point just beyond the die elements, and forcing at least one opposing die element toward another to thereby compress the end of the tubing between the die elements into a compact point of reduced cross-sectional area.

2. In the method for severing tubing and for substantially simultaneously forming a reduced diameter point on the severed tubing, the steps of piercing the tubing and from the pierced opening in the tubing exerting radially outward shearing forces to remove slugs of metal and thereby sever the tubing without materially severing the same, compressing the tubing laterally on one side of the pierced opening before shearing is completed to form a section of the tubing into the shape of a modified ellipse with the sides of the ellipse extending inwardly toward each other, restraining the tubing to the width of said ellipse, and after shearing has been completed exerting a second force perpendicular to said first force to continue to deform the end of the sheared tubing into a compact, generally cylindrical shape.

3. In the method for converting a single length of tubing into a number of sections each having a reduced diameter point formed on one end thereof, the steps of initially positioning a section of the tubing between opposing die elements, severing the tubing just beyond the die elements without substantially deforming its cross section while forcing the opposing die elements toward each other to thereby compress the end of the tubing on one side of the cut formed by severance into a compact, generally cylindrical point of reduced diameter, thereafter advancing the tubing having the point formed thereon in the preceding step between the opposing die elements and again positioning it between the die elements at a point along its length, and finally again severing the tubing just beyond the die elements without substantially deforming its cross section while forcing the opposing die elements toward each other to thereby compress an end of the tubing formed by the last-mentioned severing step into a compact, generally cylindrical shape, the section of tubing thus formed in the last-mentioned severing step having a point formed on one end and being substantially undeformed at its other end.

4. In the method for processing a length of drawn tubing having a previously-pointed end thereon into a number of sections each having a smaller diameter point formed on one end thereof, the steps of initially positioning the tubing between opposing die elements such that the previously-formed point thereon projects just beyond the die elements, severing the tubing just beyond the die elements to cut off the previously-pointed end while forcing the opposing die elements toward each other to thereby compress the tubing on the side of the cut opposite the previously-pointed end into a compact, generally cylindrical point of reduced diameter, thereafter advancing the tubing having the new point formed thereon between the opposing die elements and again positioning it between the die elements at a point along its length, and

again severing the tubing just beyond the die elements to i.

cut off a section of tubing having said new point formed on its end removed from the die elements while forcing the opposing die elements toward each other to thereby compress an end of the original length of tubing into a compact, generally cylindrical point.

5. Apparatus for severing tubing and for substantially simultaneously forming a reduced diameter point on the severed tubing, comprising a female die member defining a recess having converging side walls, a male die member received within the recess defined by the female die member and arranged in such a way that upon converging movement of the die members with a tubular workpiece therebetween, the workpiece will be initially compressed laterally by the converging side walls into a generally elliptical configuration and thereafter further compressed between the male and female die members into a compact, generally cylindrical shape, a block disposed adjacent said die elements and having a cylindrical opening therein through which a tube is inserted prior to a severing and forming operation, said last-mentioned block being spaced laterally with respect to said die members, and a shearing blade carried on one of said die members and arranged to pass into the space between the die members and said block upon converging movement of the die members to thereby sever the workpiece.

6. Apparatus for severing tubing and for substantially simultaneously forming a reduced diameter point on the severed tubing, comprising a die block supported for forced vertical reciprocal movement and having an elongated recess, a pair of side die members supported in said recess in laterally spaced-apart relationship, an upper die member positioned between and supported by the upper ends of said side die members, said side die members having their upper vertical faces and lower inclined faces opposite one another and which form with said upper die member an inverted Y-shaped trough, a stationary lower die member arranged to support said tubing and press the same through said inverted Y-shaped trough and subsequently against said upper die member during the forced lowering of said die block to thereby form the tubing between the upper and lower die members into a com pact, generally cylindrical shape, and a shearing blade carried on one end of said die block in a plane extending perpendicular to the longitudinal axis of said tubing and arranged to sever said tubing upon forced downward movement of said die block.

7. Apparatus for severing tubing and for substantially simultaneously forming a reduced diameter point on the severed tubing, comprising an upper die block supported for forced vertical reciprocal movement and having an elongated recess, a pair of side die members supported in said recess in laterally spaced-apart relation, an upper die member positioned between and supported by the upper ends of said side die members, said side die members having upper vertical faces and lower inclined faces opposite one another and which form with said upper die member an inverted Y-shaped trough, a stationary lower die block arranged to support said tubing and press the same through said inverted Y-shaped trough and subsequently against said upper die member during the forced lowering of said upper die block to thereby form the tubing into a compact, generally cylindrical shape of reduced cross-sectional area, a shearing blade carried on an end face of said upper die block in a plane extending perpendicular to the longitudinal axis of said tubing, a supporting block positioned adjacent said lower die block and having a generally cylindrical opening extending therethrough so as to receive tubing to be formed between said upper and lower die blocks, said supporting block being on the side of said upper die block having the shearing blade thereon and spaced from the shearing blade in an amount sulficient to permit the shearing blade to pass between said lower die block and said supporting block, the arrangement being such that upon downward movement of said die block, the shearing blade will initially sever the tubing While the severed end of the tubing between the die blocks will thereafter be formed into a compact, generally cylindrical shape.

References Cited UNITED STATES PATENTS 3,040,611 6/1962 Tournaire 83-636 3,144,070 8/ 1964 Mieszcak 72400 3,228,228 1/1966 Myotte 72402 3,263,465 8/1966 Way et al. 72-294 CHARLES W. LANHAM, Primary Examiner.

E. M. COMBS, Assistant Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3040611 *Nov 15, 1956Jun 26, 1962DuraluminGuillotine shears
US3144070 *Nov 10, 1961Aug 11, 1964William A MieszczakProcess for forming ends of tubing
US3228228 *Dec 3, 1962Jan 11, 1966Nat Copper Dev CompanyTube end forming device
US3263465 *Dec 14, 1961Aug 2, 1966Bivona Robert CApparatus for and method of severing and sealing hollow conduit
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3675458 *Jan 20, 1970Jul 11, 1972Schloemann AgHydraulic section-stretching machine
US4581912 *May 29, 1985Apr 15, 1986Mitsubishi Kinzoku Kabushiki KaishaApparatus for processing terminal ends of tubes
US5060500 *Oct 25, 1990Oct 29, 1991Showa Aluminum Kabushiki KaishaApparatus for automatically forming a pointed end of raw pipe to be drawn
US7114362 *Mar 27, 2004Oct 3, 2006George A. Mitchell CompanyMethod of making metal workpiece
US8162046Aug 12, 2011Apr 24, 2012T-3 Property Holdings, Inc.Blowout preventer with shearing blades
US8167031Oct 24, 2011May 1, 2012T-3 Property Holdings, Inc.Blowout preventer with shearing blades
US8443879Mar 14, 2012May 21, 2013T-3 Property Holdings, Inc.Blowout preventer with shearing blades
US8443880Jan 4, 2013May 21, 2013T-3 Property Holdings, Inc.Blowout preventer with shearing blades
Classifications
U.S. Classification72/330, 72/402, 72/370.12, 72/294, 72/464
International ClassificationB21C5/00, B23D21/00
Cooperative ClassificationB23D21/00, B21C5/003, B21C5/00
European ClassificationB21C5/00B, B23D21/00, B21C5/00