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BACKGROUND OF THE INVENTION  
       Field of the Invention  
         [0001]    This invention relates to oil well cleaning apparatus, and more particularly, to a reamer tool which can be used for scraping and removing paraffin, scale, ice, barium cement, salt, calcium and other accumulations from the inside surfaces of oil well tubing and casing. The tool can easily be adapted for use with a snubbing unit, cable rig, coiled tubing, cable, or electric wireline in an oil or gas well. The reamer tool may be operated in cooperation with a wire line typically fitted with a swivel joint, and with a load applicator such as one or more spanner jars, for alternately applying a repetitive impact load to the tool and sequentially repositioning the tool for further load application.  
           [0002]    The problem of restricted flow of hydrocarbons in oil wells due to the accumulation of paraffin and other deposits on the inside wall of the tubing is one of great concern in the oil field. Paraffin accumulation sometimes occurs in a relatively short period of time and can form a tough, semi-solid deposit which severely restricts the flow of fluid in the tubing. Accumulation thickness and character vary with the type and quantity of oil and hydrocarbon fluid produced, and frequently causes severe stress in pumping apparatus and equipment, with resulting equipment failure or low operating efficiency. Typically, the accumulation of paraffin deposits in oil well production tubing occurs at a point where the hydrostatic pressures and temperatures create favorable conditions for precipitation of solid paraffin from the oil. Other deposits such as rust, scale, salt, calcium cement, barium and ice must frequently be removed from production tubing and casing, particularly in corrosive environments, and in the case of ice, in regions characterized by prolonged low temperature.  
           [0003]    Paraffin and other deposit accumulations in production tubing are frequently removed by using expensive and sometimes complicated scraping tools which may be attached to the sucker rods deployed in the well This technique is time-consuming and expensive since the sucker rod string must first be removed, the paraffin scraper tool or tools then installed on the sucker rods, the rods and accompanying scraping tools reinserted in the well, the scraping operation completed, and the tools finally removed. Such a procedure can be prohibitively expensive in some wells and impractical in others, and the tools sometimes break and become jammed in the tubing. Furthermore, the accumulation of paraffin and asphalt in the tubing sometimes becomes too thick for removal by application of such equipment, and the tubing string must then be pulled out of the well and “burned” in order to remove the accumulated deposits. This procedure is extremely time-consuming and expensive, and is normally used only as a last resort when conventional tools cannot be used effectively. Further, while tools which have become inadvertently stuck or jammed in the well bore or casing can be jarred loose and removed easily and inexpensively in most cases, sometimes it is necessary to apply rotational force to the jammed tool in order to dislodge and remove the the tool from the well bore or casing.  
           [0004]    Another technique frequently used to remove accumulated deposits from well tubing includes pulling and disconnecting a sufficient number of sucker rods to facilitate insertion of a “hook and washer” type cleaning tool to the point of deposit accumulation, and subsequently pulling the tool out of the tubing to scrape the deposit loose. This technique is also time-consuming, and is relatively inefficient and expensive.  
           [0005]    Accordingly, an object of this invention is to provide a reamer tool which can be used to remove deposits and accumulations of paraffin, asphalt, scale, ice, salt, calcium, barium, cement and other materials from the inside surfaces of oil well tubing and casing.  
           [0006]    Another object of the invention is to provide a reamer tool which can be lowered into a well tubing or casing and repetitively loaded to clear the tubing and casing.  
           [0007]    Yet another object of this invention is to provide a casing and tubing reamer tool which is capable of cleaning deposits in well tubing and casing, which reamer includes a housing and a threaded shaft slidably displaceable in the housing, such that sliding of the shaft in the housing rotates the housing.  
           [0008]    A still further object of this invention is to provide a reamer tool which is capable of cleaning deposits in well tubing and casing, which reamer tool includes a housing capable of suspension in the well tubing or casing; a shaft slidably mounted in the housing; shaft threads provided on the shaft; a lock nut threadibly mounted on the shaft for removably engaging the housing; and a reset spring provided in the housing between the housing and the end of the shaft, such that displacement of the shaft in the housing causes the lock nut to engage the housing, and the lock nut rotates on the shaft threads and rotates the housing such that the housing rotates in the well bore or casing and removes paraffin, scale, ice, salt, calcium, cement, barium or other solid blockages from the well bore or casing.  
           [0009]    Yet another object of the invention is to provide a reamer tool for insertion in oil field casing and tubing, which reamer tool is capable of being adapted to run fishing tools in addition to removing accumulations of paraffin, scale, ice, cement, salt, calcium, barium and other material from the tubing and casing of oil and gas wells.  
           [0010]    Another object of this invention is to provide a reamer tool which can be easily adapted to and used on virtually any type of conventional oil or gas service application, including snubbing units and cable rigs, coiled tubing, drill string, cable, or electric wireline.  
           [0011]    Yet another object of this invention is to provide a reamer tool which can be adapted with a cutlip guide to facilitate maneuvering tubing, cable, electric wireline or other objects to the center of well casing, or adapted with an overshot to facilitate dislodging and removing immobilized or inadvertently released downhole tools from the well bore or casing.  
           [0012]    A still further object of this invention is to provide a reamer tool which can be used to penetrate tight segments of a well bore and is capable of extension through downhole valves for clearing the valves.  
         SUMMARY OF THE INVENTION  
         [0013]    These and other objects of the invention are provided in a reamer tool which is capable of removing paraffin, scale, ice, salt, calcium, cement, barium and other accumulations from the inside surfaces of oil well pump tubing and casing and can easily be adapted for use with coiled tubing, cable or electric wireline, which reamer tool may include a housing for suspension in the well tubing or casing; a shaft slidably mounted in the housing; shaft threads provided on the shaft; a lock nut threadibly mounted on the shaft for removably engaging the housing; and a reset spring provided in the housing between the housing and the end of the shaft, such that displacement of the shaft in the housing causes the lock nut to engage the housing, rotate on the shaft threads and rotate the housing such that the housing rotates in the well bore or casing and removes paraffin, scale, ice, salt, calcium cement, barium or other solid blockages from the well bore or casing. The reamer tool can be fitted with an overshot to facilitate dislodging and removing downhole tools or other immobilized or inadvertently released objects from the well bore or casing, or with a cutlip guide to facilitate maneuvering downhole objects to the center of the well bore or casing, as needed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The invention will be better understood by reference to the accompanying drawings, wherein:  
         [0015]    [0015]FIG. 1 is a perspective, partially exploded view of an illustrative embodiment of the reamer tool of this invention;  
         [0016]    [0016]FIG. 2 is a side view of the reamer tool illustrated in FIG. 1, with the shaft partially extended from the housing;  
         [0017]    [0017]FIG. 3 is a sectional view taken along lines  3 - 3  in FIG. 1, more particularly illustrating the reamer tool with the shaft in retracted configuration in the housing;  
         [0018]    [0018]FIG. 4 is a sectional view, also taken along  3 - 3  in FIG. 1, of the reamer tool, more particularly illustrating the shaft partially extended from the housing;  
         [0019]    [0019]FIG. 5 is an exploded, perspective view, partially in section, of the reamer tool;  
         [0020]    [0020]FIG. 6 is a front or rear view of the lock nut component of the reamer tool;  
         [0021]    [0021]FIG. 7 is a longitudinal sectional view of the lock nut illustrated in FIG. 6;  
         [0022]    [0022]FIG. 8 is a longitudinal sectional view of another illustrative embodiment of the reamer tool of this invention;  
         [0023]    [0023]FIG. 9 is a bottom view of the lock nut illustrated in FIG. 6;  
         [0024]    [0024]FIG. 10 is a longitudinal sectional view of a blade base component of the reamer tool of this invention, in an illustrative application of the reamer tool; and  
         [0025]    [0025]FIG. 11 is a side view of the reamer tool, with the blade base of FIG. 10 mounted on the reamer tool. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    Referring initially to FIGS. 1, 2 and  5  of the drawings, an illustrative embodiment of the reamer tool of this invention is generally illustrated by reference numeral  1 . The reamer tool  1  typically includes an elongated housing  19  having a top housing section  2 , a middle housing section  3  and a bottom housing section  4 , which are removably attached to each other, respectively, by means of cooperating threads, as hereinafter described. Removal of the top housing section  2  from the middle housing section  3  and the middle housing section  3  from the bottom housing section  4 , respectively, is typically achieved by applying a wrench (not illustrated) to wrench flats  13 , to unscrew the respective housing sections and disassemble the reamer  1 . Typically, as illustrated in FIG. 1, top housing internal threads  5  of the top housing section  2  receive upper external threads  9  of the middle housing section  3 , and lower external threads  9   a  of the middle housing section  3  receive interior bottom housing threads  11  (FIG. 5) of the bottom housing section  4  in assembly of the housing  19 . The top housing section  2  is typically additionally secured to the middle housing section  3  by means of housing set screws  14 , which are threaded in respective top housing set screw apertures  15 , as illustrated in FIG. 5. Similarly, the middle housing section  3  is typically further secured to the bottom housing section  4  by means of additional set screws  14 , which are threaded in respective bottom housing set screw apertures  17 . The top housing section  2  is further typically provided with a top housing collar  7 , which is capped by a top housing fishing flange  8 , provided with a top housing flange aperture  36  that opens the top housing section  2 , as illustrated in FIG. 5. Similarly, the middle housing section  3  is provided with a middle housing aperture  37  at the top thereof, and is further provided with a middle housing shoulder  21  for receiving the bottom edge of the top housing section  2 .  
         [0027]    Referring next to FIGS.  3 - 5  of the drawings, a shaft  25 , provided with course, double-lead shaft threads  29  and an upper, polished shaft segment  25   a,  is inserted in the top housing flange aperture  36  (FIG. 5) of the top housing fishing flange  8 . As particularly illustrated in FIGS.  3  and  4 , the polished shaft segment  25   a  of the shaft  25  projects through the top housing flange aperture  36  (FIG. 5), through the top housing collar  7  and into the top housing cavity  12  in the interior of the top housing section  2 , and through the middle housing aperture  37  into the middle housing cavity  18  of the middle housing section  3 , as illustrated in FIG. 3. The shaft  25  further extends into a spring cavity  6  of the bottom housing section  4 , as illustrated in FIG. 3. The shaft  25  is further provided with connector threads  26  at the upper end thereof for cooperating with a wire line apparatus (not illustrated), and is provided with a connector flange  27 , located immediately beneath the connector threads  26 . As illustrated in FIG. 5, the opposite end of the shaft  25  is fitted with shaft threads  34 , in order to accommodate a circular shaft nut  30 , provided with central interior nut threads  31 . It will be appreciated by those skilled in the art that the shaft threads  34  are typically provided on the shaft  25  in the same direction as the shaft threads  29 , and the shaft nut  30  is threaded to fit on the shaft threads  34 . One or more set screws  14  may be threaded through respective shaft nut set screw apertures  30   a  to engage the shaft threads  34  (FIG. 5) of the shaft  25  and further secure the shaft nut  30  on the shaft threads  34 . Alternatively, it is understood that the shaft nut  30  can be characterized by a conventional, self-locking, plastic-coated nut which is adapted for mounting on the shaft  25  according to the knowledge of those skilled in the art. The shaft  25  is maintained in essentially vertical configuration inside the housing  19  by means of the top housing collar  7 . As illustrated in FIGS. 3 and 4, a thrust washer  22  is typically provided in the top housing cavity  12 , against the top housing collar  7 , and encircles the shaft  25 . A lock nut  38 , provided with a pair of downwardly-extending lock nut lugs  39 , is fitted with internal lock nut threads  40 , as illustrated in FIG. 7, and is situated in the top housing cavity  12  for threadible cooperation with the shaft threads  29  of the shaft  25 . The lock nut  38  is free to rotatably traverse the shaft threads  29  on the shaft  25  inside the top housing cavity  12 , responsive to movement of the shaft  25  between a fully extended configuration from the housing  19 , as illustrated in FIG. 4, and the retracted position in the housing  19 , shown in FIG. 3. A lock nut lug seat  42  is provided in the top housing cavity  12  at the top end of the middle housing section  3 , and is fitted with at least two lug seat slots  43 , which are typically shaped to define lug seat bevels  44 , as more particularly illustrated in FIG. 5. The lug seat slots  43  are designed to receive the respective, downwardly-extending lock nut lugs  39  of the lock nut  38  when the lock nut  38  is seated on the lock nut lug seat  42 , as the shaft  25  is forced downwardly through top housing collar  7 , the top housing cavity  12  and the middle housing cavity  18  by operation of a downward load applied to the shaft  25 . The lug seat slots  43  may be slightly deeper than the length of the lock nut lugs  39 , in order to allow the lock nut  38  to contact the lock nut lug seat  42 . As illustrated in FIGS.  3 - 5  of the drawings, the depth of retraction or closing of the shaft  25  inside the housing  19  is limited by the shaft fishing flange  28 , provided on the shaft  25 , as illustrated. The shaft fishing flange  28  is typically formed integrally with the shaft  25  for maximum strength. As further illustrated in FIGS. 3 and 4, a wiper ring  32  and an o-ring  33 , seated in respective grooves provided in the top housing collar  7  of the top housing section  2 , encircle the polished shaft segment  25   a  of the shaft  25  for wiping and sealing, respectively, the polished shaft segment  25   a  as the shaft  25  reciprocates in the top housing collar  7 , which wiper ring  32  maintains the polished shaft segment  25   a  free from dirt and other contaminants and thus, prevents locking or sticking of the shaft  25  in the top housing collar  7 .  
         [0028]    Referring next to FIGS.  3 - 5  of the drawings, the bottom housing section  4  of the housing  19  is characterized by an internal spring cavity  6 , which communicates with a typically smaller-diameter bottom sucker rod receptacle  4   a,  provided with interior receptacle threads  4   b.  A coiled reset spring  16  is fitted in the spring cavity  6 , and rests against an annular spring shoulder  6   a  of the bottom housing  4 , between the spring cavity  6  and the sucker rod receptacle  4   a.  As illustrated in FIGS. 3 and 4, the shaft nut  30 , provided on the bottom end of the shaft  25 , impinges against the reset spring  16 , and the reset spring  16  is compressed between the shaft nut  30  and the spring shoulder  6   a  when the shaft  25  is disposed in the retracted configuration in the housing  19  as illustrated in FIG. 3. Conversely, the reset spring  16  is in the extended configuration in the spring cavity  6  when the shaft  25  is in the fully extended configuration from the housing  19 , as illustrated in FIG. 4, the purpose of which reset spring  16  will be hereinafter described. In one application of the reamer  1 , the sucker rod receptacle  4   a  is capable of receiving the threaded male element (not illustrated) on the upper end of a sucker rod (not illustrated) in the well bore or tubing for loosening the sucker rod in the event that the sucker rod inadvertently becomes immobilized in the tubing, as hereinafter described.  
         [0029]    Referring next to FIGS. 10 and 11 of the drawings, a blade base  45 , such as that described in my U.S. Pat. No. 4,452,307, can be mounted on the bottom housing section  4  of the reamer tool  1  to facilitate cleaning paraffin, scale, ice, salt, calcium, cement, barium or other material from a length or section of tubing or casing (not illustrated), as hereinafter described. The blade base  45  is tapered and, as illustrated in FIG. 10, includes a threaded base nipple  48  that threadibly engages the receptacle threads  4   b  (FIG. 3) of the bottom housing section  4 , in the sucker rod receptacle  4   a  thereof. Multiple set screws  14  threaded into respective set screw apertures (not illustrated) provided in the bottom housing  4  are typically caused to engage the base nipple  48  and further secure the blade base  45  on the bottom housing section  4 . As illustrated in FIG. 11, the blade base  45  is typically provided with multiple, parallel longitudinal blade slots  46 , each of which receives and mounts a corresponding blade  47  which is typically heat-treated for maximum hardness and strength and configured to define a blade head  49  that mates with a base blade support  6  at the lower, tapered end of the blade base  45 . The blades  47  are typically removably mounted in the respective blade slots  46  by means of multiple blade bolts (not illustrated).  
         [0030]    Referring again to the drawings, in typical operation, a reamer tool  1  having a shaft  25  fitted with left-handed shaft threads  29 , is utilized to clean a length or section of tubing or casing (not illustrated), as follows. One or more spanner jars (not illustrated) are threadibly connected to the connector threads  26  of the shaft  25 , and a wire line (not illustrated) having a conventional swivel joint (not illustrated) is attached to the opposite end of the spanner jar string. The reamer tool  1  is then lifted by means of the wire line into position for insertion in the tubing or casing such that the weight of the housing  19 , in combination with the upward biasing effect of the reset spring  16  against the shaft  25 , facilitates fill extension of the shaft  25  from the housing  19 , as illustrated in FIG. 4. At this point the lock nut  38 , supported on the shaft  25  by means of the shaft threads  29 , is initially in the uppermost position in the top housing cavity  12 , against the thrust washer  22 . The lock nut  38  then rotates on the shaft  25  as it downwardly traverses the shaft threads  29  by pull of gravity, until the lock nut lugs  39  of the lock nut  38  engage the lock nut lug seats  42  of the housing  19 . The reamer tool  1 , spanner jar or jars, and wire line are then lowered into the casing or tubing string until the reamer tool  1  is prevented from further penetration by an accumulation or deposit of paraffin, scale, ice, salt, calcium, cement, barium or other material in the casing or tubing string. At this point, the wire line and spanner jar assembly are lifted in conventional fashion until the spanner jars are raised to maximum position above the reamer tool  1 , after which the spanner jars are allowed to drop and impact on the connector flange  27  of the shaft  25 . This impact initially causes the shaft  25  to downwardly traverse the top housing cavity  12  of the top housing section  2  and non-rotatably extend downwardly through the lock nut  38 , whereupon the lock nut  38 , engaging the middle housing section  3  at the lock nut lug seats  42 , rotatably traverses the shaft threads  29  of the downwardly-moving and non-rotating shaft  25 . This clockwise rotation of the lock nut  38  on the shaft threads  29  effects clockwise rotation of the housing  19  and attached blade base  45  with the lock nut  38  on the non-rotating and downwardly-moving shaft  25 , when a shaft  25  and lock nut  38  having cooperating left-hand threads are used in the reamer  1 . This rotating action of the housing  19  and blade base  45 , imparted by the rotating lock nut  38 , effects removal of the deposits which are adjacent to the blades  47  due to the rotation of the blade base  45  and blades  47 . After the initial impact between the spanner jar or jars and the connector flange  27  of the shaft  25 , the spanner jar assembly is again lifted by means of the wire line, and is again caused to impact on the connector flange  27 , thus effecting additional rotation of the reamer tool  1  and additional contact between the blades  47  and the accumulated deposits to effect additional removal of the deposits. This repetitive  1  and dropping of the spanner jar or jars to achieve impact between the spanner jar system and the connector flange  27  on the shaft  25  is continued until the shaft fishing flange  28  contacts the top housing fishing flange  8 , as illustrated in FIG. 3 of the drawings. When this configuration of the reamer tool  1  is realized, the wire line is again placed in tension and the spanner jar or jars are lifted. Accordingly, the shaft  25  is again displaced from its retracted position in the top housing section  2  and the middle housing section  3 , as the lock nut lugs  39  disengage the lug seat slots  43  and the lock nut  38  is displaced upwardly with the shaft  25  in the top housing cavity  12 . Upward movement of the shaft  25  in the top housing cavity  12  and through the top housing collar  7  is assisted by the reset spring  16 , which impinges against the shaft nut  30  and tends to reset the original position of the shaft  25  and the lock nut  38  in the top housing cavity  12 . It will be appreciated from a consideration of FIGS. 3 and 4 of the drawings that when the shaft  25  is extended from the housing  19  as illustrated in FIG. 4, the lock nut  38  is initially and transiently raised against the thrust washer  22  inside the top housing collar  7  and then rotates as it downwardly traverses the shaft threads  29  by pull of gravity. At that point, the lock nut lugs  39  of the lock nut  38  engage the lock nut lug seats  42  of the housing  19  prior to non-rotating, downward movement of the shaft  25  through the top housing cavity  12  and the lock nut  38 , as heretofore described. Any rotation of the shaft  25  with respect to the wire line is handled by means of the swivel joint, which attaches the wire line to the spanner jar system, in order to prevent the wire line from twisting.  
         [0031]    It is understood that a shaft  25  having right-handed shaft threads  29  and a cooperating lock nut  38  can be installed in the reamer tool  1  to replace the shaft  25  and lock nut  38  having left-handed threads, as heretofore described. This replacement causes the housing  19  to rotate in a counter-clockwise direction when the reamer tool  1  is operated as described above.  
         [0032]    It will be further understood that the reamer tool  1  of this invention can also function as a fishing tool runner by removing the blade base  45  from the bottom housing section  4  to expose the sucker rod receptacle  4   a  to receive an “overshot” having a male fitting adapted for threadible cooperation with the sucker rod receptacle  4   a.  A wire line and fishing tool (not illustrated) can be suspended from the overshot to effect fishing operations, and the rotational motion of the reamer tool  1  responsive to hammer jar impact can be used to free immobilized tubing, casing, tools and the like, in the hole. It is also understood that a conventional bailer (not illustrated) can be attached to the sucker rod receptacle  4   a  to facilitate cutting salt, calcium, cement, barium, paraffin, ice, scale or other accumulations and removing the accumulations from the well bore in a single operation.  
         [0033]    It will be appreciated by those skilled in the art that the reamer tool  1  of this invention can perform many of the functions which otherwise require high-cost equipment, at a fraction of the cost and time. The reamer tool  1  is capable of cutting and removing virtually any type of accumulation or deposit in an oil well tubing and casing, including salt, calcium, cement, barium, hard paraffin, ice plugs, scale and asphalt, in non-exclusive particular. Additionally, by fitting a conventional bailer (not illustrated) on the reamer tool  1 , as heretofore described, both the cutting and bailing functions of the reamer tool  1  can be performed at the same time, thus significantly decreasing the time required for the cutting and excavating operations. By fitting the reamer tool  1  with the blade base  45  (FIG. 11), the reamer tool  1  can be used to penetrate tight segments or areas in tubing string or well casing. A cutlip guide (not illustrated) can be fitted on the bottom end of the reamer tool  1  for maneuvering downhole tools or other objects to the center of the well bore or casing by operation of the reamer tool  1 . The reamer tool  1  can be adapted to and used on virtually any type of ice application, including coiled tubing, snubbing units, cable rigs and electric wirelines, in non-exclusive particular, and can further be used to clear downhole valves clogged with deposit accumulations.  
         [0034]    Referring next to FIG. 8 of the drawings, in another embodiment of the reamer tool, generally illustrated by reference numeral  62 , the lock nut  38  has multiple lock nut lugs  39  which are upwardly-extending from the lock nut  38  in the top housing cavity  12 . Accordingly, multiple, congruent lock nut lug seats  42 , each having a lug seat bevel  44  (FIG. 5) and separated by lug seat slots  43  (FIG. 5), extend downwardly from the top housing section  2 , into the top housing cavity  12  and above the upwardly-extending lock nut lugs  39  of the lock nut  38 . A thrust washer  22  is typically seated on a washer seat  3   a  inside the top housing cavity  12 . Accordingly, the lock nut  38 , engaging the shaftthreads  29  of the shaft  25 , is situated to travel downwardly through the top housing cavity  12  with the shaft  25  upon application of a repetitive impact load to the connector flange  27  of the shaft  25 , until the lock nut  38  engages the thrust washer  22 . Upon subsequent upward pressure applied to the shaft  25  by operation of the wire line (not illustrated, attached to the connector threads  26  of the shaft  25 ), the shaft  25 , assisted by the compressed reset spring  16 , initially moves upwardly with respect to the housing  19 , through the middle housing cavity  18 , top housing cavity  12  and top housing collar  7 . The lock nut  38  travels upwardly with the shaft  25  through the top housing cavity  12 , until the lock nut lugs  39  of the lock nut  38  register with and are seated in the respective lock nut lug seats  42  of the top housing section  2 . Continued upward and non-rotating movement of the shaft  25  through the top housing collar  7  causes the shaft threads  29  to progressively engage and rotate the interior lock nut threads  40  (FIG. 7) of the lock nut  38  and facilitate rotation of the lock nut  38  on the shaft  25  and consequently, rotation of the housing  19 . Accordingly, the reamer tool  62  can be used to dislodge and remove a sucker rod (not illustrated) threadibly attached to the reamer tool  62  at the sucker rod receptacle  4   a  of the bottom housing section  4  of the housing  19 , for example. After full extension of the shaft  25  from the housing  19 , the spanner jar assembly (not illustrated) is again lifted by means of the wire line, and is again caused to impact on the connector flange  27 , thus effecting additional rotation of the housing  19  upon removal of the inpact load from the connector flange  27 , as needed.  
         [0035]    Referring again to FIGS. 3, 4 and  8  of the drawings, the pitch of the shaft threads  29  is ½ inch under circumstances where the shaft threads  29  are doublelead threads. The term “double-lead” is used to characterize shaft threads  29  which begin at points on the shaft  25  which are 180 degrees apart. The double-lead shaft threads  29  serve to more efficiently permit the lock nut  38  to freely rotate inside the top housing cavity  12  when the shaft  25  is displaced in the reamer housing  19  and the lock nut lugs  39  engage the lug seat slots  43 , to rotate the reamer housing  19 . It is understood that the shaft threads  29  of the shaft  25  and the lock nut threads  40  of the lock nut  38  can be either right-handed or left-handed, depending on the desired direction of rotation of the reamer housing  19  during application of the reamer tool  1 . For example, when the shaft threads  29  of the shaft  25  and the lock nut threads  40  of the lock nut  38  are right-handed, the reamer housing  19  of the reamer tool  1  illustrated in FIGS. 3 and 4 rotates in the counterclockwise direction upon downward movement of the shaft  25  in the reamer housing  19 , whereas the reamer housing  19  of the reamer tool  62  illustrated in FIG. 8 rotates in the clockwise direction upon upward movement of the shaft  25  in the reamer housing  19 . Conversely, when the shaft threads  29  of the shaft  25  and the lock nut threads  40  of the lock nut  38  are left-handed, the reamer housing  19  of the reamer  1  illustrated in FIGS. 3 and 4 rotates in the clockwise direction upon downward movement of the shaft  25  in the reamer housing  19 , whereas the reamer housing  19  of the reamer tool  62  illustrated in FIG. 8 rotates in the counterclockwise direction upon upward movement of the shaft  25  in the reamer housing  19 . Therefore, depending upon the desired application, the reamer housing  19  of the reamer tool  1  illustrated in FIGS. 3 and 4 can be adapted to rotate downwardly in the clockwise direction or downwardly in the counterclockwise direction, depending upon whether the shaft threads  29  are left-handed or right-handed, respectively, whereas the reamer housing  19  of the reamer tool  62  illustrated in FIG. 8 can be adapted to rotate upwardly in the clockwise direction or upwardly in the counterclockwise direction, depending upon whether the shaft threads  29  are right-handed or left-handed, respectively.  
         [0036]    While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications can be made in the invention and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the invention.

Summary:
A reamer tool which is capable of removing paraffin scale, ice, salt, calcium, cement, barium and other accumulations from the inside surfaces of oil well pump tubing and casing, which reamer tool may include a housing for suspension in the well tubing or casing; a shaft slidably mounted in the housing for attachment to an impact device; shaft threads provided on the shaft; a lock nut threadibly mounted on the shaft for removably engaging the housing; and a reset spring provided in the housing between the housing and the end of the shaft. Displacement of the shaft in the housing causes the lock nut to engage the housing, and the lock nut rotates on the shaft threads and rotates the housing such that the housing rotates in the well bore or casing and removes the solid blockages from the well bore or casing.