US3036339A - Method of making vented rubber members - Google Patents

Description

May 29, 1962 H. E. BOWERMAN METHOD OF MAKING VENTED RUBBER MEMBERS .Filed March 1.7, 1960 INVENTOR. HULIE E. BOWERMAN ATTORNEYS United States Patent 3,036,339 METHOD OF MAKING VENTED RUBBER MEMBERS Hulie E. Bower-man, 904 Meadow Oaks, Arlington, Tex. Filed Mar. 17, 1960, Ser. No. 15,706 1 Claim. (Cl. 18-475) This invention relates to improvements in the manufacture of rubber members for use under high pressures in oil wells, and especially to a method of improving sucker rod guides commonly used during the pumping of fluids such as oil and associated liquids from wells. In this type of service a sucker rod string is reciprocated by conventional means within a string of tubing near the lower end of which there is positioned a conventional working barrel with its standing valve, a traveling plunger and its valve and sealing elements being attached to the lower end of the rod string.

This is a continuation in part of my copendiug application entitled Sucker Rod Guides, Serial Number 735,- 312, filed May 14, 1958, now Patent No. 3,001,834.

Guides of the general type to which my novel improvements are directed are illustrated by Patent 2,604,364 to Ward showing a body of rubber-like material serving as a bearing whereby the sucker rod, its couplings and the like, are maintained centered within the tubing to prevent wearing of the metal parts as the rod moves up and down during stroking of the pump. An embedded metal clip serves to increase the grip on the rod by the rubber guide which is attached thereto by passing the rod radially through a slot or opening in the guide and spring clip. The rubber or rubber-like covering of the clip also serves to protect it from deterioration such as by electrolytic or chemical actions.

In the course of manufacturing these conventional guides, the clip is embedded in a suitable quantity of the rubber-like material in a mold and bonded therein during curing of the rubber as by vulcanization. However, in this process there are entrapped minute pockets of gases or other material resulting in voids in the rubber. There may also occur weak spots in the knitting together of the particles of the rubber mass or even undesirable laminations in the rubber structure.

When these guides are subsequently lowered on a sucker rod string into a well during pumping of the fluid therein, the guides are commonly immersed under hydrostatic pressures of several hundred pounds per square inch and in deeper wells these pressures may even exceed 2,000 to 3,000 pounds per square inch. Such submergence may continue for days, weeks or even months, during which time gas particles or liquids which gassify under lower pressures penetrate the body of the guide through its pores and occupy the voids therein.

Should the standing valve fall at the bottom of the tubing string and permit a lowering of the fluid column in the tubing about the guide these entrapped gases, or expansible liquids which turn to gases at lowered pressures, may expand the body of the guide to such a degree as to cause it to bind tightly in the tubing; then, when stroking of the pump is again attempted, the rod string binds and is caused to buckle or pull in two.

Also, when the rod string is pulled for servicing the pump, and the attached guides are retrieved from the well tubing and removed from the static pressure head of the fluid column, the entrapped gases or gassifying liquids may expand the guides inside the tubing and cause binding of the sucker rod, or may require a stripping job. Even if this should not occur while the rods and guides are being withdrawn from the tubing, these expansive forces continue to work while the guides are out of the well and frequently so expand them that they will not re- 3,035,339 Patented May 29, 1962 I method of improving cured rubber-like members wherein, after the members are molded and cured, they are pierced or otherwise cut by a sharp instrument to provide punctures of small cross-section which are relatively closely spaced, which extend deeply into the rubber-like members and which vent internal voids and pockets that otherwise tend to trap expansible fluids when the members are immersed at high pressures in well fluids. The improved method of treating a molded and cured rubber member produces the inobvious result that the useful life of the perforated rubber members is actually greatly increased even though it would appear upon casual consideration that piercing the members might tend to decrease their life expectancy.

My novel improvement in the method of making such members results in much longer life and in the elimination of many of the defects in conventional guides, and will be readily appreciated by those skilled in the art from the following description together with the accompanying drawings in which:

FIGURE 1 is an elevation view of a punctured guide mounted on a sucker rod, the punctures being exaggerated in width to make them clearly visible in the drawing.

FIGURE 2 is a section along line 2-2 of FIGURE 1.

In the several views like references indicate similar elements wherein: 5 is a sucker rod; 6 is a rubber-like guide body; 7 is a metal clip; 7a indicates the opening in .the clip registering with the opening 6a in the body for passing the rod into the bore 6b of the guide; 8-8 are voids in the rubber body, exaggerated for easy identification, 9-9 are punctures, exaggerated in width, extending into the voids from the periphery of the guide body.

My invention is directed to the provision of a method of manufacturing rubber parts, such as the illustrated sucker rod guide, said method including perforation of the body whereby the entrapped gases and gassifying liquids are permitted to escape from the body through punctures made in the body by a suitable sharp instrument driven inwardly into the rubber to a suitably predetermined depth, and at such intervals of spacing as are required to effectively perforate the objectionable voids in the rubber. In general, it appears that sufficient punctures are provided, Where such punctures are relatively deep, if the punctures are spaced apart by distances not exceeding the depths of the punctures. It is important that these providing escape passages not be of such depth as to expose the clip directly to the corrosive eiiects of the gases and liquids entrapped within the body of the guide.

It is also important that these punctures be pierced or otherwise cut in the rubber body after it is fully cured. The piercing is particularly effective after the body is cured since attempts to form such small openings during molding are frustrated by the tendency of the latter to seal over. Moreover, openings or depressions which are formed during molding and prior to completion of the curing step result in smooth bores having continuous sealed walls which are no more capable of venting the internal voids than are the other walls of the molded product. The piercings or fissures or punctures should extend deeply into the cured body in order to vent as many voids as possible, but should terminate short of metal parts embedded therein. Although the punctures are radially disposed as shown in the drawing there is no reason why other angles would not be satisfactory for the purpose of venting internal voids. In most cases, it is desirable that the punctures be made by a thin sharp piercing instrument without removal of rubber material so that the punctures tend to close when the instrument is withdrawn, thereby discouraging entrance into the punctured hole of foreign matter. I V I desire to point out that other types of well rubbers, such as guides comprising all-rubber sleeves which are stretched over the ends of rods or tubings and which may depend on the inherent resilient memory of the rubber to provide the necessary grip on a sucker rod or tubing or drill pipe, may be protected by my novel method from these injurious effects of gases and gassifying liquids entrapped under high pressures in their bodies. All such are intended to be embraced by the following claim,

I claim:

The method of making a rubber member for use at high pressures in oil wells including the following steps: molding the rubber member, curing the rubber, and sub- References Cited in the file of this patent UNITED STATES PATENTS 1,364,132, Miller Jan. 4, 1921 1,388,453 Davidson Aug. 23, 1921 1,983,464 Kitchen Dec. 4, 1934 2,604,364 Ward July 22, 1952 2,770,282 Herzegh Nov. 13, 1956

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