US2517307A - Pump plunger and method of making such plungers - Google Patents

Description

1950 D. T. HARBISON 2,517,307

PUMP PLUNGER AND METHOD OF MAKING SUCH PLUNGERS Filed 8, 1947 2 Sheets-Sheet 2 INVENTOR. Dixon 7. Hark/son A TTORNEYS Patented Aug. 1, 1 950 PUBIP PLUNGER AND METHOD OF MAKING SUCH PLUNGERS I Dixon '1. Hal-bison, Fort Worth, Tex.

Application February 8, 1947, Serial No. 727,351

Claims. I

This invention relates to new and useful improvements in pump plungcrs, and methods of making such plungers.

Heretofore, pump piungers of many types have been utilized, but it has been diflicult to provide satisfactory plungers for use in oil well tubing pumps.' Such pumps are customarily quite a few feet in length and receive in their working barrels closely fitting pump plungers, which also may be several feet in length. In contrast to their length, the diameter or bore of these pumps may be of the order of only an inch or a few inches or fractional multiples thereof. The pumps are positioned thousands of feet in the earth and are not readily accessible for servicing, lubrication, and the like. The pumps are of the reciprocating, direct-displacement type, and are operated from the surface, usually by a string of sucker rods.

Due to the considerable depth of most wells, the pump must be capable of withstanding high operating pressures often thousands of pounds in lifting a column of fluid to the top of th well. It is therefore necessary for the plunger to have a close fit in the working barrel. Within certain limits, the closer this fit the better so long as the ease of reciprocation is not materially impaired. At the same time, fluids must be pumped which have considerable abrasive action and/or friction engenderin characteristics.

The fluid inmost oil wells contains oil, water, probably gas, and in most instances sand or dirt, or bits of rock, along with the other extraneous matter found in well fluids. Thus, oil alone is not the pumped medium. In addition, the well fluid may be extremely corrosive in nature, while quite often, the water present (usually salt) exceeds the oil in quantity, and large amounts of sand 'or other abrasive matter may be present in the well fluid. In these instances, which are the rule rather than the exception, very little if any lubricating action is imparted by the fluid. The pump must be constructed so as to function properly in such a fluid and to resist the abrasive action of the sand and the corrosive conditions encolmtered, while at the same time exerting and maintaining a pressure sufiicient to raise the well fluid to the top of the zvell in the desired quantities. This lift may amount to several thousand feet.

Previously, in an effort to provide a satisfactory pump, various types of pump plungers have been employed. Metallic plungers have been used so as to have a plunger which may be machined to a close fit and which will resist the abrasive action of' the well fluid. The

abrasion resistance of this type plunger was satisfactory, but corrosion was severe, and in addition, the plungers showed a tendency to stick and gall within the working barrel due to their close fit and the lack of lubrication. Even in wells having very little water, the fluid level may become low so that the plungeroverheats and sticks.

Also, plastic plungers have been used. However, their success was limited since abrasion resistance was poor andthe plastic material swelled in the presence of the well fluid and stuck in the working barrel. One primary cause of the abrasion and the swelling was the limited density or hardness which could be imparted to the plastic. In a closely-fitting pump, 'aswelling of one-half of 1% to approximately suflicient to cause sticking.

The present invention contemplates overcomr ing these various faults of previous pump plungers by a new and novel structure which incorporates features set out hereinafter, the main object of the invention being the provision of a pump plunger for use in oil wells, which will not stick and which resists abrasion.

Another object of the invention is to provide an improved pump plunger formed of a plurality of relatively thin non-metallic rings which may be bonded together and compressed sunlciently to give a uniform, dense pump plunger.

A further object of the invention is to provide an improved pump plunger formed of nonmetalmaterial in which the tendency to swell in the presence of well fluids, has been considerably reduced; and which may be accurately machined to ti e desired closeness of fit within a working barrel.

Yet another object of the invention is to pro vide an improved method of fabricating pump plunger bodies in relatively thin sections which respond satisfactorily to a compressing force.

A still further object of.the invention is to provide an improved pump plunger having both metallic and non-metallic sections, so as to incorporate the desirable features ol both types of structures.

Another object of the invention is to provide.

from a reading of the following specification and by reference to the accompanying drawings, wherein an example of the invention is shown, and wherein:

Fig. 1 is a longitudinal view, partly in elevation and partly in section, of a pump plunger constructed in accordance with this invention,

Fig. 2 is an enlarged, fragmentary, longitudinal, sectional view of a modified form of the invention,

Fig. 3 is a fragmentary, transverse sectional view of one of the pump plunger sections,

Fig. 4 is a perspective view of one of the plunger sections,

Fig. 5 is a longitudinal view, partly in elevation and partly in section, of a further modification of the invention utilizing thicker metallic sections, and

Fig. 6 is a view similar to Fig. 5 and showing a difierent spacing of the metallic sections.

In the drawings, the numeral l designates an elongate tubular mandrel of the type presently being used in oil well tubing pump plungers and which may be of any suitable or desirable length. The mandrel is provided with an axial bore H through which the pumped fluid is conducted, and an internally screw-threaded box [2. at the lower end of said bore. The lower end of the mandrel is enlarged to form an annular collar I3 and an external, upwardly-directed, annular shoulder I 4. The collar carries wrench faces I which allow its engagement by a suitable tool (not shown).

External screw-threads it are provided on the upper end of the mandrel and receive an internally screw-threaded collar I! having wrench faces (8. It is noted the threads l6 extend a considerable distance downwardly from the upper end of the mandrel so that the collar I1 is posi- 'tioned a distance below the upper extremity of the former. Thus, a suitable valve rod or other connecting element (not shown) may be secured to the upper end of the plunger by engaging the upper portion of the threads IS.

A tubular pump plunger packing sleeve i9 is carried on the mandrel between the collars l 3 and (1. It is in this sleeve and its method of production that the invention lies.

Heretofore, it has not been possible to produce a sleeve which would function satisfactorily under substantially all conditions. The reasons for this failure have been pointed out hereinbefore. A plastic, or composition, or other non-metallic substance, was recognized as desirable as a material for fabrication of pump plungers. However, 'a material was not developed having the desired characteristics, such as wear resistance, machinability, and the like, and which still was resistant to swelling in the presence of well fluids.

It is highly desirable, especially in deeper wells, to have the pump plunger fit as closely as possible within the working barrel so as to allow the minimum amount of pump slippage with the eonse quent loss in pressure and cfliciency. Obviously, such a close fit cannot be employed when the plunger tends to swell. Nor can the amount of swelling be accurately estimated since it varies in accordance with the characteristics of each well. Thus, the desirable features of some plastic materials, such as their resistance to a few types of abrasion and freedom from the need of lubrication, are offset by their undesirable tendency to swell and stick in the working barrel as well as their poor overall abrasion resistance. Also, they do not stand up to simple friction wear as well as some metals.

The present invention solves this problem by utilizing a pump plunger packing sleeve 19 formed of a multiplicity of thin, disk-like, non-metallic rings or sleeve sections 20, as shown in Fig. 1. Each section or ring is in the form of a flat, circular disk 2| having a central opening 22 (Fig. 4) The mandrel l 0 has a sliding fit within the opening. The rings are bonded together in a column or unit in the shape of the tubular sleev 19 with the openings 22 forming an axial bore in which the mandrel is positioned. The upper and lower ends of the sleeve are engaged by the collars l3 and II, as stated hereinbefore.

The particular method of forming the sleeve l9, as well as its structure, is one cause of its usefulness and desirability. The problem heretofore has been to compact or density the sleeve to such an extent that its tendency to swell is negligible. This has been done in the present invention by using relatively thin rings to build up the sleeve. In a thicker ring, the compacting pressure is exerted at the two faces of the ring and. largely dissipated through internal friction within the ring itself, whereby. proper compacting is not achieved, and a ring and sleeve of non-uniform density results. In other words, although sufiicient pressure is exerted at the faces of the ring, this pres sure is not exerted in the intermediate portions, so that a ring results which is sufliciently dense and swell-resistant on the surface, but which is still relatively soft or porous in the center and does not resist swelling. Of course, this effect is even more pronounced in one piece non-metallic sleeves.

By using thin rings, the effect of the compacting pressure is eifectively transmitted to all portions of the ring so that uniform high density results, and swelling is greatly reduced. Each ring acts individually so that the effect of the total pressure exerted is brought to bear, substantially in full, on each ring.

A variety of substances are adaptable for use in these rings. Many of the plastics, such as phenolformaldehyde or urea-formaldehyde plastics, as well as many other similar substances may be employed. The resin may be reinforced by cloth, or lint, or asbestos material, or by many other suitable substances. It is desirable to have the grain of the rings, caused by this reinforcing material, run transversely to the longitudinal axis of the sleeve 19 (Fig. 3).

Prior attempts to make such a sleeve have failed because the laminations were run vertically, or because too thick sections were used; also, because the material was not sufficiently compacted in a uniform manner.

The rings 20 are cut or otherwise formed from sheets of suitable material, preferably previously finished, and assembled in a vertical stack or column on a suitable mandrel (not shown). A bonding agent, such as some of the Bakelite resins or other suitable agents, may be applied to the rings at any desired point in the process. The assemblage or rings is submitted to a compacting pressure, or heat and a compacting pressure, depending on the resin or plastic utilized. The function of the pressure is to compress or compact and density the rings as well as bond them into a uniformly dense unit or sleeve. The pressure or pressure and heat is continued for a suitable curing period, after which the pressure may be relieved. It is understood, of course, that various molding procedures may be followed, such as cooling, provision of a jacket around the sleeve during densiflcation, and so forth.

The sleeve may be molded or compressed to size, or it may be machined or otherwise finished to size after forming. The latter is usually preferable since closer tolerances may be maintained. Obviously, wide variations in the materials used, as well as the procedures followed, may be employed. The primary feature is the utilization of rings formed of previously finished, high density, hard, sheets and further compacting and bonding the rings in such a manner as to give substantially uniform high density and high resistance to swelling.

It is pointedout, that substantially no additional polymerization takes place within the rings 20 during the compressing step. This action is reserved for the bonding agent which may be relatively non-viscous in nature, and of which only very thin layers are present. This agent will not offer sufficient viscosity or internal resistance to decrease to any large extent the pressure exerted on the rings.

A packing sleeve formed in this fashion may be machined or finished to accurate dimensions and expected to hold those dimensions in the presence of well fluids. Thus, a closer fitting plunger may be utilized with its obvious advantages. The sleeve, because of its non-metallic nature, also possesses the characteristic of being substantially self-lubricating in water or oil whereby excessive friction is eliminated.

For more extreme abrasive conditions, it is desirable to incorporate some metallic abrasion resisting elements into the plunger so as to prevent channeling of the sand past the plunger with the consequent cutting of the packing sleeve. In Figs. 2, 5 and 6 are shown several arrangements for accomplishing this result.

In Fig. 2, a portion of the mandrel I0 is shown.

The same type of rings encircle this mandrel to form a packing sleeve. However, thin metallic rings 23, similar in shape and size to the rings 2 I, are interspersed at intervals between the nonmetallic rings. As an example, every fifth or sixth ring could be a metallic ring. These rings may be of any suitable metal and degree of hardness, although it is preferable to use a ring of a relatively hard iron or steel, or non-ferrous material, so that abrasion and wear is resisted to a substantial maximum. The usual objection to metallic rings or metallic packing does not apply, in that these rings do not stick and gall or show other undersirable results due to a lack. of lubrication. The non-metallic rings provide frictionreducing means for the metallic rings and act as a bearing surface.

If desired, a specific lubricant, such as graphite, may be incorporated into the non-metallic rings so as further to enhance the friction-reducing function of said rings.

Additional arrangements are shown in Figs. 5 and 6. In Fig. 5, relatively heavy or thick rings 24 are shown as positioned abuttin the upper and lower collars I! and I3. The rings 24 are similar in transverse dimensions to the rings 20, but are considerably thicker. These rings function in much the same manner as the rings 23 and are lubricated by the adjacency of the nonmetallic rings, which may have a specific lubricant incorporated thereinto, if desired. This thicker ring affords additional abrasion resistance and, if desired, may be formed of softer metal than the rings 23 since an increased peripheral area is provided.

In some instances, intermediate metallic rings 25, similar to the rings 24, may be used in addition to the latter and positioned at points intermediate the ends of the packing sleeve (Fig. 6). In this manner, a sleeve is provided having the desirable features of a completely metallic sleeve with the disadvantages of such a sleeve substantially eliminated, A hard metallic bearing and abrasion-resisting surface is obtained, yet ample provision is made for preventing sticking or galling of said surface. qualities of a non-metallic surface are retained, along with the latters friction-reducin and corrosion-resisting effects.

Obviously, the metallic rings 23, 24 and 25 may be incorporated into the sleeve assemblage and bonded thereto by some of the well-known resins or cements, such as Cycloweld, a commercially available, thermo-setting, plastic base cement. In this manner, a unitary sleeve is obtained, which is an important feature in both fabrication of explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within, the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A pump plunger including, a mandrel, a plurality of superposed plunger sections carried by the mandrel, said sections being rings cut from thin hard dense reinforced board having a synthetic resin content, said sections being bonded together by thin layers of bonding agent therebetween, and means for retaining said sections on the mandrel.

2. A pump plunger as set forth in claim 1, and a plurality of. thin metallic rings interspersed among the plunger sections.

3. A pump plunger including, a mandrel, a plurality of thin rings carried by the mandrel, said rings being cut from a thin hard dense reinforced synthetic resin board having its grain running transversely to the axes of the rings, said rings being bonded together by thin layers of bonding agent therebetween, and means for retaining said rings on the mandrel.

4. A pump plunger as set forth in claim 3, and

a plurality of metallic rings interspersed among the resinous rings.

5. A pump plunger as set forth in claim 1, and

a plurality of metallic rings interspersed among the plunger sections.

' DIXON T. HARBISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS The specific wear-resisting

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