Abstract:
A tube scraping apparatus comprises a body having a passageway for receiving a piping component; and a first blade and a second blade. The first blade and second blade each: are mounted to the body and shiftable between a first condition and a second condition; and having an engagement portion positioned to engage an outer diameter (OD) surface of the received piping component in at least one condition, the first blade engagement portion comprising a cutting edge for removing material from the OD surface. The second blade engagement portion comprises a partial thread for engaging the piping component to convert a rotation of the piping component relative to the body to an axial movement of the piping component relative to the body.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Benefit is claimed of U.S. Patent Application No. 61/989,681, filed May 7, 2014, and entitled “Tube Scraper with Biased Blades”, the disclosure of which is incorporated by reference herein in its entirety as if set forth at length. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to plastic piping. More particularly, the invention relates to preparation of plastic pipe/tube material for electro-fusion bonding. 
     In order to connect thermoplastic piping systems together via electro-fusion methods it is standard practice to remove the outer oxidized surface of the pipe to expose clean un-contaminated plastic. Previous methods rely on fixed or pivoting cutting tools and/or internal drive mandrels to remove the outer oxidized layers. 
     An exemplary fixed diameter tool does not adequately scrape pipe that has an oval shape due to coiling. 
     An exemplary pivoting tool scraper relies on an internal drive mandrel to limit the forward helical cutting motion. On occasion it is necessary to connect two different thicknesses of pipe wall. This would require use of two different internal drive scrapers. 
     Examples of prior tools include those shown in U.S. Pat. Nos. 5,600,862, 6,434,776, and 6,698,321 and US patent application publication 2011232434A1. One additional previously proposed alternative features two spring-loaded scraping blades mounted in a generally tubular body. 
     SUMMARY OF THE INVENTION 
     One aspect of the disclosure involves a tube scraping apparatus comprising: a body having a passageway for receiving a piping component; and a first blade and a second blade. The first blade and second blade each: are mounted to the body and shiftable between a first condition and a second condition; and have an engagement portion positioned to engage an outer diameter (OD) surface of the received piping component in at least one condition. The first blade engagement portion comprises a cutting edge for removing material from the OD surface. The second blade engagement portion comprises means for engaging the piping component to convert a rotation of the piping component relative to the body to an axial movement of the piping component relative to the body. 
     A further embodiment may additionally and/or alternatively include at least one spring biasing the first blade and the second blade from the second condition toward the first condition. 
     A further embodiment may additionally and/or alternatively include the first blade being mounted for rotation about a first pivot axis between the associated first and second conditions and the second blade being mounted for rotation about a second pivot axis between the associated first and second conditions. 
     A further embodiment may additionally and/or alternatively include the first blade and the second blade each having a lever portion depressable to shift the respective first blade and second blade from the associated first condition to the associated second condition. 
     A further embodiment may additionally and/or alternatively include the first blade comprising an edge protruding radially inward from a portion of the first blade axially outboard thereof. 
     A further embodiment may additionally and/or alternatively include the means comprising a partial thread. 
     A further embodiment may additionally and/or alternatively include the partial thread comprising a plurality of thread segments. 
     A further embodiment may additionally and/or alternatively include a third blade positioned to cut material from a location on the piping component prior to said location encountering a cutting edge of the first blade. 
     A further embodiment may additionally and/or alternatively include the third blade being a fixed blade. 
     A further embodiment may additionally and/or alternatively include the third blade having a circular cutting edge. 
     A further embodiment may additionally and/or alternatively include a method comprising: inserting the piping component into the passageway; rotating the piping component in a first direction, the rotating causing the engagement of the second blade engagement portion with the OD surface to convert the rotation into further axial insertion of the piping component relative to the body; the rotation causing the first blade cutting edge to remove material from the OD surface; shifting the first blade and second blade toward the second condition against spring bias; and with the first blade and second blade shifted toward the second condition, extracting the piping component. 
     A further embodiment may additionally and/or alternatively include, with a third blade, cutting material from a location on the piping component prior to said location encountering the cutting edge of the first blade. 
     Another aspect of the disclosure involves a tube scraping apparatus comprising: a body having a passageway for receiving a piping component; and a first blade and a second blade. The first blade and second blade each: are mounted to the body and shiftable between a first condition and a second condition; and have an engagement portion positioned to engage an outer diameter (OD) surface of the received piping component in at least one condition. A fixed position third blade is positioned to cut material from the piping component. 
     A further embodiment may additionally and/or alternatively include the third blade being reorientatably mounted to allow a fresh cutting edge portion to be brought into an operative position. 
     Another aspect of the disclosure involves a method for processing a piping component. The method comprises: inserting a portion of the piping component into a tube scraping apparatus, the piping component having an inner diameter (ID) surface and an outer diameter (OD) surface; rotating the piping component relative to the tube scraping apparatus, the rotating and inserting causing a first blade to remove material from the OD surface. A second blade engages the piping component to convert the rotation of the piping component relative to the apparatus to an axial movement of the piping component relative to the apparatus. 
     A further embodiment may additionally and/or alternatively include the second blade having a plurality of thread segments for engaging the piping component OD surface to convert the rotation to the axial movement. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of a tube scraper. 
         FIG. 2  is an exploded view of the scraper of  FIG. 1 . 
         FIG. 3  is a first view of a scraping blade of the tube scraper. 
         FIG. 4  is a second view of the scraping blade. 
         FIG. 5  is a top view of the tube scraper. 
         FIG. 6  is a right side view of the tube scraper. 
         FIG. 7  is a left side view of the tube scraper. 
         FIG. 8  is a front end view of the tube scraper. 
         FIG. 9  is a rear end view of the tube scraper. 
         FIG. 10  is a transverse sectional view of the tube scraper taken along line  10 - 10  of  FIG. 5 . 
         FIG. 11  is a transverse sectional view of the tube scraper taken along line  11 - 11  of  FIG. 7 . 
         FIG. 12  is a central longitudinal sectional view of the scraper taken along line  12 - 12  of  FIG. 8 . 
         FIG. 13  is a front end view of the tube scraper with levers depressed. 
         FIG. 14  is a central longitudinal sectional view of the scraper taken along line  14 - 14  of  FIG. 13 . 
         FIG. 15  is an x-ray view of the scraper during an intermediate stage of tube scraping. 
         FIG. 16  is a central longitudinal sectional view of the scraper taken along line  16 - 16  of  FIG. 15 . 
         FIG. 17  is a central longitudinal sectional view of the scraper taken along line  17 - 17  of  FIG. 15 . 
     
    
    
     Like reference numbers and designations in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
       FIG. 1  shows a tube scraper (scraper)  20 . The scraper  20  comprises a body  22  extending from a first rim  23  at a first end  24  to a second rim  25  and a second end  26  and having an interior surface  28  along a central passageway  30  and an exterior surface  32 . The exemplary passageway  30  is a full end-to-end passageway centered about a central longitudinal axis  500 . 
     In operation, the tube scraper receives an end portion of the tube into the passageway  30  through the end  24 . Unless explicitly indicated otherwise, the identified tube end portion may be an end portion of tubing or pipe stock or an end portion of a fitting or the like. The exterior surface  32  may bear an indicia  40  representative of the position of the end (rim) of the tube when fully inserted. Exemplary indicia  40  is a circumferential groove. The exemplary body also includes a window  42  between the interior and exterior surfaces  28  and  32  to allow viewing of the end in the fully inserted condition. For engaging the tube end portion, the scraper  20  further includes three blades  44 ,  46 , and  48  mounted to the body. 
     The exemplary blades  44  and  46  are spring-biased and shiftable between first and second conditions noted below.  FIG. 2  shows the blades  44  and  46  as having respective engagement portions  50  and  52  for engaging the outer diameter (OD) surface of the received tube end portion. The exemplary springs bias these two portions  50  and  52  into engagement/contact with the tube OD surface.  FIGS. 1-12  show an extended/deployed condition at the terminal end of travel driven by the spring bias. A retracted condition has the portions  50  and  52  relatively removed/withdrawn from the tube OD surface. The exemplary movement between extended and retracted conditions is a pivoting movement about respective pivot axes  510  and  512  under bias of respective springs  54  and  56 . The exemplary blades  44  and  46  are formed as levers with the portions  50  and  52  to one side of the associated pivot axis and lever portions (lever arm portions)  58  and  60  to the opposite side. The exemplary springs  54 ,  56  are coil compression springs mounted in associated blind compartments in the body (e.g., open radially outward) and engaging inboard surfaces  66 ,  68  of the respective lever portions to in turn bias the tube-engagement portions  50 ,  52  radially inward. Exemplary pivoting is provided by axles  70 ,  72  received in respective bores  74 ,  76  of the blades  44 ,  46  and associated bores within the body. The exemplary body comprises longitudinal slots  80 ,  82  receiving the blades with the pins  70 ,  72  spanning the associated slots. Lock screws  84 ,  86  may lock the pins in place. As is discussed further below, in operation, the user may manually engage outboard surfaces  90 ,  92  of the lever portions  58 ,  60  and press these surfaces inward to compress the springs and retract the tube engagement portions  50 ,  52  ( FIGS. 13 and 14 ). This may allow easy withdrawal of the tube end portion after scraping. 
     As is discussed further below, the exemplary blades  44 ,  46  differ from each other in the nature of their engagement portions  50 ,  52 . The engagement portion  50  is a scraper having an edge  100  ( FIGS. 3 and 4 ) for engaging the tube OD surface to remove material as the pipe is rotated against the edge. The exemplary edge  100  protrudes slightly radially inward of a surface  102  of the blade thereahead so as to define a depth of cut. The exemplary blade has a passageway  110  formed as an open channel extending outboard from the edge along one face of the blade which allows passage of the cut material out of the scraper. 
     The function of the portion  52  is not material removal or thickness reduction but rather movement regulation. It comprises a partial thread in the form of a sequence of thread segments  120  ( FIG. 2 ) at a given non-zero helix angle. The thread segments bite into the tube OD surface. As the tube is rotated, the helix angle converts the rotation into axial movement. The helix angle is selected in view of the size of the cutting edge to insure that a full rotation of the tube yields a translation equal to or less than the engagement length of the edge  100  so as to ensure full coverage of scraping. Each of the blades  44  and  46  comprises a convexly curved surface  104  leading into the edge  100  or thread segments  120 . For the blade  44 , this may be adjacent the surface  102  or the surface  102  may be a portion of the surface  104 . This lead-in surface may help receive the pipe by contacting the rim and allowing the rim to cam the blade working portions radially outward (and thus the lever portions radially inward against spring bias) as the pipe is initially inserted. 
     The exemplary blade  48  provides a lead-in trimming blade that is positioned to cut material from locations on the tube end portion prior to such locations encountering at least the edge  100  of the blade  44 . This may function the partially cut down high spots (e.g., along only a portion of the circumference).  FIG. 7  shows a position of a cutting edge  130  of the blade  48  slightly forward of the edge  110 . The exemplary blade  48  is an off-the shelf item such as indexable insert part number RCGT 0803MOFN-ALU of ARNO-Werkzeuge USA LLC, |Harvard, Ill., US. Said insert is “indexable” in that it can be rotated about its axis (e.g., by loosening its screw and then retightening) to bring a fresh portion of the cutting edge into operable position protruding into the passageway. This particular exemplary insert has an approximately frustoconical body with a circular cutting edge. Other edge shapes are possible as are other general blade configurations. 
     The blade  48  may be positioned to knock down diameter to the nominal pipe diameter. This may be particularly relevant to scraping molded fittings rather than extruded pipe. The molding process may involve a draft angle causing proximal portions of the fitting branch to exceed the nominal diameter. The blade  44  may be configured more to scrape a given amount (depth) of material (e.g., 0.005-0.007 inch (0.13-0.18 mm)). This functions more to remove debris and oxidation rather than resize or round. 
       FIG. 12 , however, shows how the forwardmost thread segment  120  is slightly ahead of at least a portion of the edge  130  so as to guide initial movement before the tube engages the edge  110 . 
     The exemplary edge  130  is a circular edge of an approximately frustoconical blade  48  having a central aperture receiving a screw  140 . A base portion of the blade  48  is accommodated in a tangentially open compartment  150  at a gap  152  in a forward rim portion of the body. Along the passageway, the body longitudinal cross-section has a lead-in round  154 . The edge  130  sits slightly proud of that round to cut material from the tubing end. 
       FIGS. 15-17  show an intermediate stage of scraping of a pipe  200  having an interior or inner diameter (ID) surface  202  and an exterior or outer diameter (OD) surface  204 . The pipe has a first end at a rim  206 . The pipe is shown cut away so that an opposite end is not shown. It is accordingly seen that an end portion  210  of the pipe is received in the scraper. The exemplary embodiment shows the end  206  to be shy of the window  42  ( FIG. 17 ) and the indicia  40 . Thus, it would be readily apparent to the user that the pipe has not yet reached its fully scraped condition. 
     Exemplary body material is machined aluminum. Alternative body material may be a molded and/or machined plastic or composite. Exemplary blades  44  and  46  are machined of stainless steel plate stock and heat treated. Exemplary springs are steel (e.g., stainless). Exemplary pins  70  and  72  are machined from steel (e.g., stainless) rod stock. Exemplary screws may be steel (e.g., stainless). 
     For larger diameter pipe, rather than just increasing blade size, it may be desirable to add blades. One example of added blades involves adding two more opposed spring-biased blades (e.g., 90° offset from blades  44  and  46  if blade  48  is shifted circumferentially by about) 30°-60°. In that example, the added blades could both be like the scraping/cutting blade  44  or one could be like the blade  46  to govern axial movement. In a further variation, the thread segments  120  may be replaced by an alternative angled edge such as a small edged wheel oriented with its edge slightly off-tangential. 
     One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.