TECHNICAL FIELD
The present disclosure relates to compression fittings for relatively large diameter conduits.
BACKGROUND
This disclosure teaches how to secure a fitting to a relatively large diameter, thick-walled metal conduit. Thick-walled conduits that are 1 inch in diameter may have a wall thickness of about 0.120 inches. Thick-walled conduits that are three quarters of an inch in diameter may have wall thickness of about 0.109 inches. Thick-walled conduits that are ½ inch in diameter may have wall thickness of about 0.083 inches. Conventional compression fittings may not work well for such conduits when the conduits are made of particularly hard materials or when the operating pressures are particularly high.
Conventional compression fittings rely to some extent on the ability of one or more ferrules to bite into the tube wall as the fitting is tightened in place. At the same time the ferrule(s) may smooth irregularities in the surface of the conduit, irregularities such as scratches from manufacturing or rough handling. When the conduit is made of a hard material or the walls are relatively thick, the ferrule may not be able to perform the required functions effectively. One solution has been to machine a groove in the conduit into which the ferrule(s) may be driven to effect the seal. Another solution has been to roll form a groove into the conduit. See, e.g., U.S. Pat. No. 5,907,966. Both techniques have drawbacks in that they may not reproducibly form a groove of uniform depth. Machining may be difficult outside of a factory setting. Both roll forming and machining may result in fittings that do not seal properly against the conduit.
SUMMARY
According to this disclosure, the problem is solved by rolling the end of a metal conduit both to form one or more seats into which a ferrule can bite and to smooth the outside surface of the conduit. In addition to assist proper assembly of the fitting into the conduit, the leading end portion of the conduit can be tapered inward to make it easier to install, and witness lines can be formed in the conduit. Witness lines serve to signal that the seat is formed to the proper depth, and also to assure the leading end portion of the conduit is inserted fully into the fitting when the fitting is finger tight and that the fitting is thereafter properly made up.
A tool for rolling the conduit end portion has a C-shaped body, smooth rollers to support the conduit on one arm of the C and a contoured forming roller mounted to be tightened against the conduit opposite the smooth rollers. The contoured roller has at least one ridge which forms a seat in the conduit shaped, proportioned and positioned to engage a ferrule as the fitting is tightened on the conduit. The contoured roller may also include a tapered surface that bears against an end portion of the conduit to form a taper, and raised edges to form witness lines to confirm that the seat has been formed to the proper depth and that the fitting has been correctly installed. The smooth rollers and the contoured roller also smooth the outer surface of the conduit to help assure a leak-tight seal. The tool may have stop for positioning the conduit axially. The stop may limit axial movement of the conduit in one or both axial directions.
BRIEF DESCRIPTION OF THE DRAWINGS
While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed that the same will be better understood from the following description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a plan view of a tool used to roll form an end portion of a thick-walled conduit and having a forming roller and two opposing supporting rollers;
FIG. 2 is a side elevation view of the tool of FIG. 1.
FIG. 3 is a side elevation view, partly in section, of the tool of FIGS. 1 and 2 showing a forming roller and two supporting rollers.
FIG. 4 is a side elevation view of the forming roller of FIG. 3, and an end portion of a conduit after a rolling operation has been completed.
FIG. 5 is an enlarged view of a portion of FIG. 4 showing the seat created by the forming roller.
FIG. 6 is a cross-section view of the rolled conduit of FIG. 3 fully inserted into a fitting, with the fitting shown finger tight, to nearly expose a rear witness line.
FIG. 7 is a view similar to FIG. 6 but showing the fitting after it has been made up by tightening it's nut sufficiently to expose a forward witness line.
FIG. 8 is a plan view of a second tool used to roll form an end portion of a thick-walled conduit and including a tube stop locator and mandrel that cooperate to hold the conduit against axial movement in both axial directions during roll forming.
FIG. 9 is a perspective illustration of a portion of the tool of FIG. 8.
FIG. 10 is a perspective illustration of a mandrel that may be used with the tool of FIG. 8.
FIG. 11 is a side elevation view of the mandrel of FIG. 10.
FIG. 12 is a section view of a portion of the forming roller of FIG. 9.
DETAILED DESCRIPTION
Tool 10 (FIGS. 1 and 2) is used to roll form an end portion 12 (FIG. 4) of a thick walled conduit 14. The tool 10 includes a frame 16. The frame 16 is C-shaped, and at one leg 18 of the C carries a support 20. The support 20 may be a pair of cylindrical rollers 22 that are mounted in bearings so that they rotate freely. The rollers 22 have smooth outside surfaces.
Tool 10 also includes a forming roller 26 described in detail below. The forming roller 26 is carried by a transport mechanism 32 for moving it toward and away from the support 20 so as to engage the outside surface of a conduit 14 as described below. The transport mechanism 32 can include the second leg 34 of the C-shaped frame 16. The leg 34 includes a threaded passage 36 (FIG. 3). The transport mechanism 32 also includes a threaded shaft 38 that fits in the passage 36 and a carrier 40.
The forming roller 26 is rotatably mounted to the carrier 40 and the threaded shaft has one end 50 received in a bore 52 in the carrier 40. When the shaft 38 is rotated, it advances or withdraws the carrier 40 toward or away from the leg 18 of the frame 16, depending upon the direction of rotation. As an alternative to the manually turned threaded shaft 38, the shaft 38 may be connected to a motor to effect its rotation, or it may be replaced by a hydraulic cylinder.
The frame 16 also includes a stop surface 56. Stop surface 56 serves to position the leading end 102 (FIG. 4) of the conduit 14 (FIGS. 4 and 5) with respect to the forming roller 26.
The forming roller 26 is shown in FIG. 4 abutting a thick walled conduit 14 after the roll forming operation has been performed. The forming roller 26 has a cylindrical surface 70, and it is rotatably mounted in the carrier 40 for rotation parallel to the axes of rotation of the rollers 22 (shown in FIG. 2). A first circumferential ridge 72 (FIG. 4) rises from the cylindrical surface 70. When the tool 10 has been used to roll form the conduit 14, the ridge 72 forms a seat 74 in the end portion 12 of the conduit 14. The ridge 72 rises a first distance above the cylindrical surface 70 so as to form the seat 74 of a predetermined depth.
The seat 74 is shaped and proportioned to receive a ferrule 80 (FIGS. 6 and 7) when a compression fitting 82 is connected to the conduit 14. To this end the seat 74 (FIG. 5) may have wall 84 that is approximately 7° from perpendicular to the outside surface of the conduit 14, and a wall 86 that is approximately 7° from parallel to the outside surface of the conduit 14. Both angles may be varied between 1° and 15°. The seat 74 may be approximately 0.005 to 0.010 inches deep, depending upon the nature of the materials of which the ferrule 80 and conduit 14 are made.
The forming roller 26 (FIG. 4) also includes a first edge 90 and a second edge 92 that rise above the surface 70 of the forming roller. The edges 90 and 92 serve to form witness lines 94 and 96 on the conduit 14. The first and second edges 90 and 92 rise a second distance, less than the height of the ridge 72. The edges 90 and 92 normally extend only 0.001 to 0.003 inches above the cylindrical surface 70 of the forming roller 26. The edges 90 and 92 may be continuous walls perpendicular to the surface of the forming roller 26, or nearly so. Alternatively, the edges 90 and 92 may be defined by a series of small projections of the same height as the edges they define.
When the tool 10 has been used to roll form the end portion 12 of the conduit 14, the first and second edges 90 and 92 form witness lines 94 and 96, respectively. During the rolling process, the witness lines do not appear until the seat 74 is formed to a sufficient depth by the ridge 72. This is true because the edges 90 and 92 do not contact the surface of the conduit 14 until after ridge 72 has penetrated sufficiently to create the seat 74.
The forming roller 72 also includes a tapering surface 98. The tapering surface 98 is located at one end of the forming roller 26, on the opposite side of the ridge 72 from the edges 90 and 92. When the forming roller 26 is mounted on the carrier 40, the tapering surface is immediately adjacent the stop surface 56. The tapering surface 94 serves to bevel the leading end portion 100 of the conduit 14. A bevel on the leading end portion 100 of the conduit 14 helps to assure that the conduit 14 will seat fully and squarely within the fitting 82 (FIGS. 6 and 7).
To make the tapered leading end 102, the seat 74, and the witness lines 94 and 96 (FIG. 4) the end portion 12 of the conduit 14 is placed in the tool 10 with its leading end face 102 abutting the stop surface 56 (FIGS. 1 and 2). The shaft 38 is turned by means of knob 104 until the forming roller 26 engages the outside surface of the conduit 14. The tool 10 is then rotated about the conduit 14, and the carrier 40 is advanced by turning the knob 104. Rotation of the tool 10 about the conduit 14 with incremental advances of the carrier 40 continues until the witness lines 94 and 96 appear. When the witness lines 94 and 96 appear, the seat 74 is a proper depth, and the tool 10 may be removed.
FIG. 6 shows the conduit 14 inserted into a conventional fitting 82 with the nut 106 of the fitting finger tight. Before the leading end face 102 has seated in the fitting 82, both witness lines 94 and 96 are visible. As the leading end face 102 approaches bottoming out in the fitting 82, first the leading witness line 96 disappears from view inside the nut 106. When the end face 102 of the conduit 14 is fully inserted into the fitting, the first witness line 94 (formed by the first edge 90 of the forming roller 26 (shown in FIG. 4) is just barely visible or will have just disappeared from view inside the nut 106. If the conduit 14 is not inserted fully into the compression fitting 82, more than just the edge of witness line 94 will be visible. Once the conduit 14 is properly, i.e., fully, inserted in the fitting 82, the nut 106 is turned 1¼ turns to drive the ferrule 80 into the seat 74. The spacing between the witness lines 94 and 96 is such that the second witness line 96 becomes just visible when the nut 106 has been turned 1¼ turns, as shown in FIG. 7. The spacing between the two witness lines 94 and 96 depends upon the design of the fitting 82 to which the conduit 14 is to be connected. One and one-quarter turns is a common industry-standard from finger tight to fully made up, but other designs are possible for which a different spacing between the witness lines would be required.
FIG. 8 shows a second tool 108 for roll-forming an end portion of a conduit 14′. The tool 108 controls the axial position of the conduit in two directions during the roll forming operation. The tool 108 includes a mandrel 110 (FIG. 9) and a tube stop locator 114. The same numerals with a prime (′) added are used for parts of the tool 108 illustrated in FIGS. 8-11 which are similar to corresponding parts in FIGS. 1-5.
In the tool 108 (FIG. 9), the forming roller 112 is mounted to the leg 18′ of the C-shaped frame. Supports 20′ (only one shown) are rotatably mounted to a carrier 40′. The carrier 40′ can be advanced and retracted by means of a threaded shaft 38′.
The tube stop locator 114 is mounted to the leg 18′. The tube stop locator 114 has parallel faces 116 and 118 (FIGS. 8 and 9). A U-shaped opening 120 extends between the faces 116 and 118 and opens toward the carrier 40′. As discussed below, the faces 116 and 118 of the tube stop locator 114 serve to limit axial movement of the conduit 14′ while the roll forming operation is being performed.
The mandrel 112 (FIGS. 10 and 11) grips the interior surface of the conduit 14′ to be roll-formed and engages the faces 116 and 118 (FIG. 9) of the tube stop locator 114 to limit axial movement of the conduit during role-forming. The mandrel 112 (FIGS. 10 and 11) includes gripping fingers 132 which fit inside the conduit 14′ to be roll formed. A conical wedge 134 moves the fingers 132 radially outward when the bolt 136 is tightened. In use, the mandrel 130 is inserted into a conduit until, with the fingers 132 inside, the end face 102′ (FIG. 9) of the conduit 14′ seats flush against the shoulder 138 (FIG. 11) on the body 140 of the mandrel 112. Next, the bolt 136 is tightened to hold the mandrel 130 firmly in place, fixed with respect to the conduit 14′.
The body 140 of the mandrel has an annular groove 142 with opposing end faces 144 and 146. The end faces 144 and 146 are spaced apart slightly more than the thickness of the tube stop locator 114, i.e., the distance between faces 116 and 118 (FIG. 9). As a result, the annular groove 142 is received in the U-shaped slot 120 when the conduit 14′ is being roll formed. Engagement of face 144 of the mandrel 130 with the face 118 of the tube stop locator 114 and face 146 of the mandrel 112 with the face 116 of the tube stop locator prevents axial movement of the conduit, while clearance between the faces is sufficient to permit rotation.
The forming roller 112 shown in FIGS. 9 and 12 is similar to the roller 26 shown in FIGS. 1-4, and operates it much the same way. The forming roller 112 includes edges 90′ and 92′ that form witness lines. The forming roller 112 also includes a ridge 72′ that forms a seat for the forward ferrule 80 (FIG. 6), and a tapering surface 98′ that forms a bevel on the leading end of a conduit to be formed. The forming roller 112 also includes a second ridge 130 (FIGS. 9 and 12) spaced rearward from the ridge 72′. The second ridge 130 forms a seat to receive the rear ferrule 134 when the fitting has been secured in place. The seats 74 and 134 are preferably about 0.005 to 0.010 inches deep. Accordingly, the ridges 72′ and 130 rise about 0.005 to about 0.010 inches above the cylindrical surface 136 of the forming roller 112.
Forming two seats for ferrules in a conduit may be beneficial when the conduit to be formed is made of a material that is relatively more difficult to shape because of its material properties (e.g., hardness, toughness etc.), because of the thickness of the wall of the conduit, or because the application requires an especially secure connection between the fitting and the conduit.
In addition, forming two seats, one for each ferrule, reduces the torque necessary to make up the fitting. In some cases the maximum torque required may be reduced by 25%, an advantage for a worker who may have to make up many fittings in a day. Also, using a forming roller such as the roller 112 with two ridges 72′ and 130 helps keep the conduit from moving axially as the roll forming process takes place.
Variations of the device illustrated may include using a motor driven machine to operate the tools 10 and/or 110. In such case the forming roller 26 and supports 22 may be mounted in a machine for rotation about the conduit while the forming roller is forced into the surface of the conduit. In addition, the mandrel 112 may have an expandable rubber element in place of the fingers 132. Because the forming roller 112 with two ridges 72′ and 100 3010 s to inhibit axial movement of the conduit during forming, it may be used within axial stop like the stop 56 (FIGS. 1-3) rather than the mandrel 110 and tube stop locator 114 (FIGS. 8-11).
While the inventive principles have been illustrated by the description of various embodiments thereof, and while the embodiments of been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will be readily apparent to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus, methods and examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive principles.
Patent Application
20150107323
