Roll grooving apparatus

BACKGROUND OF THE INVENTION

[0001] This invention relates to the art of roll grooving apparatus and, more particularly, to improvements in such apparatus relating to obtaining and maintaining a desired alignment between grooving rolls and a workpiece and thus obtaining and maintaining tracking between the grooving rolls and workpiece so that the rolled groove is transverse to the workpiece axis.

[0002] The present invention finds particular utility in conjunction with a portable roll groover which is adapted to be interengaged with a rigidly supported pipe so as to travel about the periphery of the pipe during the roll grooving operation. Accordingly, while the invention will be illustrated and described herein in conjunction with such a roll groover, it will be understood and appreciated that the invention is applicable to roll grooving apparatus of the character wherein the roll groover is rigidly supported and the pipe to be grooved rotates relative thereto during the grooving operation.

[0003] Roll grooving apparatus is well known and generally includes a pair of relatively displaceable housing components or support members which respectively rotatably support a drive or back-up roll and an idler or grooving roll between which a pipe to be grooved is interposed during a grooving operation. The two rolls are matingly contoured and, in this respect, the drive roll is provided with a peripheral groove and the grooving roll is provided with a peripheral projection such that a pipe therebetween is provided with a peripheral groove upon relative rotation of the grooving rolls and relative radial displacement of the rolls toward one another. The drive roll is rotated by a hand tool or by a drive motor depending on the particular type of roll grooving apparatus.

[0004] Often, relative displacement between the roll supports is achieved through the use of threaded feed screw arrangements between the supports and which include a screw component which is manually rotated either by hand or by a tool such as a wrench. The roll supports are interengaged for linear or pivotal displacement toward and away from one another and, in either instance, the feed screw is rotated in the direction to separate the rolls to facilitate the insertion of the end of a tube or pipe therebetween, and the feed screw is then rotated in the opposite direction to bring the grooving rolls into engagement with the pipe. The pipe, back-up roll and grooving roll are then relatively rotated, and the feed screw is manually rotated in the direction to displace the grooving roll toward the back-up roll to progressively form a peripheral groove in the pipe. When the desired groove diameter is reached, relative rotation is stopped and the feed screw is rotated in the opposite direction until there is sufficient clearance between the two rolls to accommodate removal of the grooved pipe therefrom.

[0005] It is well known that it is necessary for the pipe and grooving roll axes to be properly aligned during a roll grooving operation so that the track of the groove is transverse to the pipe axis. Misalignment at the beginning of the roll grooving operation can cause the track of the groove to spiral relative to the pipe axis, whereupon the pipe or the tool “walks” in the direction to axially separate the rolls and pipe. The tracking problem is attendant to the operation of any roll grooving apparatus including those in which the roll supports are relatively displaced other than by a feed screw and, for example, hydraulically as shown in U.S. Pat. No. 3,995,466 to Kunsmann, and manually through a pivotal lever arm as disclosed in U.S. Pat. No. 5,079,940 to Pulver, et al. Numerous efforts have been made to provide roll grooving apparatus with a self-tracking feature, and these efforts have included providing the back-up or drive roll with teeth on an outer surface thereof which urge the pipe and grooving rolls axially inwardly relative to one another as disclosed in U.S. Pat. No. 5,528,919 to McGrady, et al. Other efforts have included supporting the pipe to be roll grooved at an angle to the axes of the grooving rolls as disclosed in the aforementioned patent to Kunsmann, and by inclining the axis of the idler or grooving roll relative to the axis of the back-up roll as disclosed in U.S. Pat. No. 4,041,747 to Elkin and in U.S. Pat. No. 2,975,819 to Costanzo, et al. Still further efforts have included contouring the outer surface of the back-up or drive roll in the form of a frustum of a cone as disclosed in U.S. Pat. No. 5,279,143 to Dole, and by providing an auxiliary roller for engaging the outer surface of a pipe being grooved and having its axis inclined relative to that of a pipe being grooved as disclosed in the aforementioned patent to Costanzo, et al.

[0006] While all of the foregoing arrangements promote self-tracking, they add undesirably to the expense of the roll grooving apparatus by requiring additional and/or specially designed component parts for the apparatus, thus adding to the cost of maintaining the apparatus as well as the cost of manufacturing the same. Furthermore, in those devices using a feed screw for displacing the grooving rolls relative to one another, feed screw wear is often a problem as is the potential of jamming and a higher than desired input torque requirement. Moreover, there is a potential for damaging the feed screw through dropping of the roll grooving apparatus which is a common occurrence in the field. Still further, the forces required to groove thick wall pipe, such as 5 inch Sch. 40 pipe, cause the axis of the back-up or drive roll to deflect and thus adversely affect efforts to maintain proper tracking. Therefore, it has not been possible heretofore to roll groove a full range of pipe sizes from, for example, 1¼inch to 12 inch, using just one basic grooving unit.

SUMMARY OF THE INVENTION

[0007] In accordance with the present invention, improvements are provided in roll grooving apparatus which minimize or overcome the foregoing and other problems encountered in connection with the structure and operation of roll grooving apparatus heretofore available. In accordance with one aspect of the invention, roll grooving apparatus of the character wherein the back-up and grooving roll supports are relatively displaced through the use of a feed screw is provided with features which improve the strength and life of the feed screw while easing wear thereof and increasing the torque capabilities thereof, thus promoting the ability to groove thick wall pipe. In part in this respect, the feed screw is pivotally interconnected at its opposite ends with the two roll supports and, thus, is direct acting with respect to the application of force on the feed screw in a manner which minimizes or eliminates side thrust encountered in connection with the use of some of the feed screw arrangements heretofore available. Another improvement in connection with the feed screw arrangement is a release mechanism by which one of the two support members is released for displacement relative to the feed screw in response to an impact such as that resulting from dropping the apparatus. With such apparatus heretofore available, the force of such impact is imposed directly on the threads of the feed screw and cooperatively threaded portions of the roll grooving apparatus, thus imposing wear and/or damage resulting in difficulty in rotating the screw, increased maintenance and replacement costs, and/or shortening of the useful life of the feed screw component.

[0008] In accordance with another aspect of the invention, improved tracking is achieved through the provision of one or more features relating to the structures of the back-up or drive roll and the grooving roll and the support of the two rolls in connection with the performing of roll grooving operations. More particularly in this respect, the back-up or drive roll is provided with a knurling arrangement which minimizes twisting of a pipe relative to the back-up and grooving rolls during a roll grooving operation. Another feature with respect to improving tracking resides in supporting the grooving roll for the axis thereof to be at a fixed angle to the axis of the back-up roll and, in connection with the roll grooving of certain pipe, providing a taper on the grooving projection of the grooving roll which promotes relative axial displacement of a pipe and the grooving rolls inwardly of one another during a roll grooving operation. Yet another feature in connection with improving tracking in accordance with the invention is the provision of a support for the axially outer end of the back-up roll to minimize deflection of the latter during roll grooving operations which involve the application of heavy forces against the back-up roll and which deflection precludes maintaining proper orientation or alignment between the two rolls and a pipe therebetween and, thus, loss of the desired tracking. The latter support feature also advantageously enables one basic roll grooving unit to handle a full range of pipe sizes from 1¼inch to 12 inch diameter pipe, for example, whereas two or more different units were required heretofore to accommodate the roll grooving of such a full range of pipe sizes.

[0009] It is accordingly an outstanding object of the present invention to provide roll grooving apparatus of the character including a feed screw for relatively displacing the grooving and back-up rolls of the apparatus with improvements with respect to the application of forces against the feed screw during roll grooving operations.

[0010] Another object is the provision of roll grooving apparatus of the foregoing character with a feed screw arrangement which reduces wear of the screw, reduces jamming and reduces the required input torque in connection with roll grooving and improves the strength and longevity of the screw while enabling the roll grooving of thick wall pipe.

[0011] Yet another object is the provision of roll grooving apparatus of the foregoing character with an impact actuated release arrangement for protecting the feed screw and cooperatively threaded portions of the apparatus from damage resulting from an impact axially against the feed screw.

[0012] A further object is the provision of roll grooving apparatus with improved self-tracking capabilities.

[0013] Yet a further object is the provision of a back-up roll for roll grooving apparatus with a knurling arrangement for promoting tracking while minimizing the cost of achieving the same.

[0014] Still a further object is the provision of a grooving roll structure having improved self-tracking capability.

[0015] Another object is the provision of a grooving roll mounting arrangement providing improved self-tracking capabilities in roll grooving apparatus.

[0016] A further object is the provision of roll grooving apparatus with an arrangement for supporting the axially outer end of the back-up or drive roll against deflection resulting from the application of high roll grooving forces thereagainst.

[0017] Still a further object is the provision of a roll grooving unit capable of roll grooving a larger range of pipe sizes than possible with apparatus heretofore available.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The foregoing objects, and others, will in part be obvious and in part pointed out more fully hereinafter in conjunction with the written description of preferred embodiments of the invention illustrated in the accompanying drawings in which:

[0019]FIG. 1 is an exploded perspective view of roll grooving apparatus in accordance with the present invention;

[0020]FIG. 2 is a perspective view of the assembled components shown in FIG. 1;

[0021]FIG. 3 is a front elevation view of the roll grooving apparatus shown in FIG. 2 and showing a pipe to be grooved between the drive and grooving rolls;

[0022]FIG. 4 is a cross-sectional elevational view through the back-up and grooving rolls taken along line <b>4</b>-<b>4</b> in FIG. 3;

[0023]FIG. 5 is a front election view of the roll grooving apparatus with the support for the outer end of the drive roll removed and with another embodiment of a drive roll in accordance with the invention;

[0024]FIG. 6 is a cross-sectional elevational view of the feed screw and groove depth adjusting screw of the apparatus taken along line <b>6</b>-<b>6</b> in FIG. 5;

[0025]FIG. 7 is a side elevation view of a back-up or drive roll in accordance with the present invention;

[0026]FIG. 8 is a side elevation view of another back-up or drive roll in accordance with the invention;

[0027]FIG. 9 is a side elevation view of a grooving roll in accordance with the present invention; and,

[0028]FIG. 10 is a cross-sectional view through the back-up and grooving rolls taken along line <b>10</b>-<b>10</b> in FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0029] Referring now in greater detail to the drawings, wherein the showings are for the purpose of illustrating preferred embodiments of the invention only, and not for the purpose of limiting the invention, FIGS. <b>1</b>-<b>4</b> illustrate roll grooving apparatus <b>10</b> which comprises a first support in the form of a housing <b>12</b> and a second support in the form of an arm <b>14</b> mounted on housing <b>12</b> by means of a pivot pin <b>16</b> for pivotal displacement in opposite directions about a pivot axis <b>18</b>. Housing <b>12</b> supports a back-up or drive roll <b>20</b> for rotation about a roll axis <b>22</b> parallel to pivot axis <b>18</b>, and arm <b>14</b> supports an idler or grooving roll <b>24</b> for rotation about a roll axis <b>26</b>. In accordance with one aspect of the present invention, as described more fully hereinafter, roll axis <b>26</b> is fixed relative to arm <b>14</b> and is at a slight angle to roll axis <b>22</b>. Rolls <b>20</b> and <b>24</b> are adapted to receive the wall of a pipe P therebetween and, as described in greater detail hereinafter, respectively provide female and male grooving rolls cooperable to roll a peripheral groove in pipe P in response to relative rotation between the rolls and pipe and radial displacement of roll <b>24</b> toward roll <b>20</b> during such relative rotation.

[0030] In the embodiment illustrated in FIGS. <b>1</b>-<b>4</b>, back-up or drive roll <b>20</b> is adapted to be driven about axis <b>22</b> and, for this purpose and in the manner set forth more fully hereinafter, it is mounted on the axially outer end <b>28</b> of a drive shaft <b>30</b> which extends through housing <b>12</b> and is rotatably supported adjacent the front and rear ends of the housing by suitable bearings <b>32</b> and <b>34</b>, respectively. Drive shaft <b>30</b> carries a drive gear <b>36</b> which is suitably secured thereto against rotation relative thereto, and gear <b>36</b> and thus drive shaft <b>30</b> is adapted to be rotated by means of a crank <b>38</b> through a pinion and gear reduction arrangement, not shown. Thus, it will be appreciated that manual rotation of crank <b>38</b> results in rotation of drive shaft <b>30</b> and back-up roll <b>20</b> and, as will be described in greater detail hereinafter, the rotation of drive roll <b>20</b> with pipe P interposed between the latter and roll <b>24</b> during a roll grooving operation causes apparatus <b>10</b> to travel about the periphery of the pipe as the groove is rolled therein.

[0031] As best seen in FIG. 3, reaction arm <b>14</b> has a first end <b>40</b> pivotally secured to housing <b>12</b> by pin <b>16</b> such that pivot axis <b>18</b> is above and laterally offset to one side of roll axis <b>22</b>. The arm extends laterally across housing <b>12</b> and roll axis <b>22</b> and has a second end <b>42</b> laterally offset from roll axis <b>22</b> on the side thereof opposite that of pivot axis <b>18</b>. As described in detail hereinafter, end <b>42</b> of arm <b>14</b> is interconnected with housing <b>12</b> through a feed screw mechanism <b>44</b> by which the reaction arm is pivoted in opposite directions about axis <b>18</b> so as to displace grooving roll <b>24</b> radially toward and away from drive roll <b>20</b> and end <b>42</b> of the reaction arm further carries an adjusting screw <b>46</b> for limiting displacement of the arm and thus grooving roll <b>24</b> toward back-up roll <b>20</b> to provide a desired diameter of a groove being rolled in pipe P.

[0032] In the embodiment illustrated in FIGS. <b>1</b>-<b>4</b>, back-up or drive roll <b>20</b>, which is also shown in FIG. 7, has axially outer and inner ends <b>20</b><i>a </i>and <b>20</b><i>b</i>, respectively, and a circular outer surface which includes a first portion providing a peripheral recess <b>48</b> and a second portion defined by surfaces <b>50</b> and <b>52</b> which are axially outwardly and axially inwardly adjacent recess <b>48</b>, respectively. Outer end <b>20</b><i>a </i>of roll <b>20</b> is defined by a support shaft portion <b>54</b> having a spring clip recess <b>56</b> therein for the purpose set forth hereinafter, and inner end <b>20</b><i>b </i>of the roll is preferably defined by a circular flange <b>58</b> extending radially outwardly of surfaces <b>50</b> and <b>52</b> to provide an abutment for positioning a pipe P to be grooved relative to the grooving rolls during a roll grooving operation. Further in accordance with this embodiment, as best seen in FIGS. 1 and 4, roll <b>20</b> has an axial bore <b>60</b> therethrough and the support for the roll is provided by the axially outer end <b>28</b> of drive shaft <b>30</b> which is received in the inner end of bore <b>60</b> in roll <b>20</b> and a support member <b>62</b> which is removably mounted on housing <b>12</b> to support the outer end of the roll. More particularly in this respect, support member <b>62</b> includes a base portion <b>64</b> by which the support member is removably mounted on the front wall of housing <b>12</b> through the use of a pair of socket cap screws <b>66</b>, a sleeve portion <b>68</b> and a bridging portion <b>70</b> by which the sleeve portion is supported axially outwardly of housing <b>12</b> and coaxial with roll axis <b>22</b>. Sleeve portion <b>68</b> is adapted to receive and rotatably support shaft portion <b>54</b> of roll <b>20</b>, preferably with a bearing sleeve <b>72</b> interposed therebetween. Such support limits deflection of roll axis <b>22</b> in response to the imposition of high forces against backup roll <b>20</b> during a roll grooving operation. Without such support for the axially outer end of roll <b>20</b>, such deflection would likely occur in connection the roll grooving of 4 inch Sch. 40 to 12 inch Sch. 10 pipe using component parts of the roll grooving apparatus sized to handle 1 ¼inch to 3 ½inch Sch. 40 pipe. Thus, the use of support member <b>68</b> and the structure of back-up roll <b>20</b> for the axially outer end thereof to be supported by the support member enables a single roll grooving base unit to handle a full range of pipe sizes from 1 ¼inch to 12 inch. As will become apparent hereinafter, support member <b>62</b> is adapted to be removed from housing <b>12</b> and back-up roll <b>20</b> replaced with a similar roll without support shaft portion <b>54</b>, whereby the apparatus is then operable in connection with the rolling of grooves in the thinner wall pipes from 1 ¼inch to 3 ½inch Sch. 40.

[0033] It will be appreciated that the support of roll <b>20</b> against the deflection of roll axis <b>22</b> as described hereinabove promotes the desired tracking in conjunction with the rolling of grooves in thick wall pipe. With respect to the mounting of support member <b>62</b> and roll <b>20</b> on housing <b>12</b>, roll <b>20</b> is first assembled with the support member by introducing support shaft portion <b>54</b> through bearing sleeve <b>72</b> and sleeve portion <b>68</b> and axially intereingaging the latter components through the use of a spring clip <b>74</b> which is received in recess <b>56</b> in the axially outer end of support shaft portion <b>54</b>. The axially inner end of roll <b>20</b> is then introduced onto outer end <b>28</b> of drive shaft <b>30</b> and the drive roll is secured to drive shaft <b>30</b> by a socket cap screw <b>76</b> which extends through bore <b>60</b> and into threaded interengagement with outer end <b>28</b> of drive shaft <b>30</b>. Cap screws <b>66</b> are then introduced through openings <b>78</b> therefor in base portion <b>64</b> of the support member and into threaded openings <b>80</b> provided therefor in the front wall of housing <b>12</b> to securely mount support member <b>62</b> on the housing.

[0034] As mentioned above, and as will be appreciated from FIGS. 5, 8 and <b>10</b> of the drawing, when support member <b>62</b> and roll <b>20</b> are removed from housing <b>12</b> a similar back-up roll designated <b>20</b>A in the latter figures can be mounted on the axially outer end <b>28</b> of drive shaft <b>30</b> to accommodate the roll grooving thin wall pipe. As will be appreciated from the description hereinabove, roll <b>20</b>A has an axial bore, not shown, for receiving outer end <b>28</b> of shaft <b>30</b>, and the roll is secured to the shaft by a socket cap screw similar to but shorter than screw <b>76</b> by which roll <b>20</b> is secured to the drive shaft.

[0035] As will be appreciated from FIGS. 4 and 9 of the drawing, idler or grooving roll <b>24</b> is of a mating contour with respect to back-up roll <b>20</b> and, accordingly, includes axially outer and inner ends <b>24</b><i>a </i>and <b>24</b><i>b</i>, respectively, circular outer surface portions <b>82</b> and <b>84</b> respectively overlying surface portions <b>50</b> and <b>52</b> of roll <b>20</b> and <b>50</b><i>a </i>and <b>52</b><i>a </i>of roll <b>20</b>A, and a radially outwardly extending circular rolling projection <b>86</b> between surfaces <b>82</b> and <b>84</b> and overlying recess <b>48</b> of roll <b>20</b> or recess <b>48</b><i>a </i>of roll <b>20</b>A. Grooving roll <b>24</b> is mounted on reaction arm <b>14</b> for rotation relative thereto by means of a pin or shaft component <b>88</b> and a bearing component <b>90</b> interposed between the shaft and grooving roll. In accordance with another aspect of the invention, rolling projection <b>86</b> includes an outer rolling surface <b>92</b> having axially inner and outer ends <b>92</b><i>a </i>and <b>92</b><i>b</i>, respectively. For most roll grooving operations, surface <b>92</b> is parallel to axis <b>26</b> of the grooving roll. However, in connection with the roll grooving of 4 inch-6 inch Sch. 40 pipe, surface <b>92</b> is tapered at an angle x relative to axis <b>26</b> so as to converge relative to the axis in the direction from outer end <b>92</b><i>a </i>toward inner end <b>92</b><i>b</i>. The taper preferably is 2° and, as will be appreciated from the structural relationship between grooving roll projection <b>86</b> and back-up roll recess <b>48</b> shown in FIG. 4, when projection <b>86</b> engages the outer side of a pipe interposed between the grooving and back-up rolls, tapered surface <b>92</b> biases the pipe axially inwardly against flange <b>58</b> of the back-up roll to promote the desired tracking. The taper on the rolling surface of the grooving roll also compensates for any bending deflection which may occur through the application of high forces in the roll grooving of thick wall pipe.

[0036] In accordance with another aspect of the invention, as shown in FIGS. 7 and 8, surface portions <b>50</b> and <b>52</b> of back-up roll <b>20</b> and surface portions <b>50</b><i>a </i>and <b>52</b><i>a </i>of roll <b>20</b>A are provided with teeth, preferably in the form of diamond knurling, and the axially inner and outer surfaces relative to the inner end of the corresponding roll have an axial length L1 and L2, respectively. The length L2 is less than the length L1 for the purpose of precluding misalignment of a pipe being roll grooved relative to the grooving rolls during the initial phase of a roll grooving operation. More particularly in this respect, when the grooving roll initially engages against a pipe to be roll grooved and the material of the pipe is displaced into the groove or recess in the back-up roll, the portion of the pipe overlying surface portion <b>52</b> or <b>52</b><i>a </i>tends to flare radially outwardly from the surface, thus decreasing the area of contact between the roll surface and the pipe. Accordingly, if the length L2 initially is equal to the length L1 twisting or misalignment is promoted by the loss of contact between the pipe and surface <b>52</b> or <b>52</b><i>a</i>. Therefore, by making the length L2 less than the length L1, the flaring leaves the area of engagement between surfaces <b>50</b> and <b>52</b> or <b>50</b><i>a </i>and <b>52</b><i>a </i>and the pipe equal to one another, whereby misalignment is minimized or eliminated and tracking is improved. While diamond knurling is preferred, it will be appreciated that other tooth configurations can be provided. In connection with the roll grooving of a full range of pipe sizes from 1 ¼inch to 12 inch, the length L1 is a minimum length that is necessary to preclude slippage or misalignment between the back-up roll and the pipe being roll grooved and, as an example, L1 is in the range from 0.354 inch to 0.383 inch. Further, as an example with regard to the various pipe sizes, length L1 for the back-up roll for roll grooving 1 ¼inch to 1 ½inch Sch. 10 and Sch. 40 steel is 0.380 inch; for 2 inch to 6 inch Sch. 10 and 2 inch to 3 ½inch Sch. 40 steel is 0.358 inch; for 4 inch to 6 inch Sch. 40 steel is 0.354 inch; for 8 inch to 12 inch Sch. 10 steel is 0.383 inch; and for 2 inch to 8 inch copper is 0.358 inch. Lengths L1 &amp; L2, and especially L1, are determined in party by the geometry of the groove form and, preferably, L1 is as long as possible and L2 as short as possible within geometric and functional limits. Accordingly, it will be appreciated that dimensional relationships different from the foregoing can be developed for achieving the desired control with respect to misalignment.

[0037] In accordance with yet another aspect of the invention, as shown in FIG. 10, the grooving rolls <b>24</b> for the full range of pipe sizes to be roll grooved are mounted on reaction arm <b>14</b> such that axis <b>26</b> of the grooving roll is at an angle y to axis <b>22</b> of the back-up roll in a plane which is transverse to a reference plane through axis <b>22</b> of the back-up roll and which reference plane is vertical in the orientation of the component parts shown in FIGS. 3 and 5 of the drawing. As will be further appreciated from FIG. 10, the angle y provides for rolling projection <b>86</b> of the grooving roll to be at the same angle y<b>1</b> relative to rolling groove <b>48</b> of back-up roll <b>20</b>. The angle y can be from 1° to 2° and, preferably is 2°. The angle of the axis of the grooving roll relative to the axis of the back-up roll in the transverse and reformer plane relationship referred to above promotes better tracking.

[0038] Each of the features described above, namely the provision of different length knurling surfaces, the taper on the rolling surface of the grooving roll and the grooving roll mounting at an angle to the back-up roll axis will function individually, to some extent, to improve alignment and tracking. However, optimum results are realized when the knurling and grooving roll mounting features are combined with respect to roll grooving the full range of pipe sizes referred to hereinabove and, in addition thereto, through the use of the support for the outer end of the back-up roll in conjunction with roll grooving heavy wall pipe, and through the use of a grooving roll having a tapered rolling surface in conjunction with roll grooving 4 inch-6 inch Sch. 40 pipe.

[0039] In accordance with still another aspect of the present invention, as best seen in FIGS. 2 and 6, feed screw mechanism <b>44</b> referred to hereinabove is structured and structurally interrelated with housing <b>12</b> and reaction arm <b>14</b> so as to preclude the imposition of side thrust on the feed screw during a roll grooving operation and to protect component the feed screw from damage resulting from an impact thereagainst resulting, for example, from dropping the roll grooving apparatus. More particularly in this respect, the feed screw mechanism comprises a feed screw member <b>100</b> having upper and lower ends <b>102</b> and <b>104</b>, respectively, in the orientation of the apparatus shown in FIG. 4 of the drawing. Upper end <b>102</b> includes a tool head <b>106</b> having a non-circular opening <b>108</b> extending axially thereinto for receiving a suitable tool such as a ratchet wrench by which the feed screw is rotatable about the feed screw axis <b>110</b>. Tool head <b>106</b> further includes pairs of diametrically opposed openings <b>112</b> therethrough for receiving the ball detent of a ratchet wrench to secure the latter to the feed screw. Feed screw <b>100</b> further includes a shank portion <b>114</b> extending axially from the inner end of tool head <b>106</b> to lower end <b>104</b> of the feed screw, and shank <b>114</b> includes an unthreaded shank portion <b>116</b> extending axially downwardly from tool head <b>106</b> and a threaded shank portion <b>118</b> extending from shank portion <b>116</b> to lower end <b>104</b> of the feed screw. The upper end of feed screw <b>100</b> is pivotally mounted on reaction arm <b>14</b> by means of a pivot pin <b>120</b> having a pivot axis <b>122</b>, and the lower end of the feed screw is pivotally interconnected with housing <b>12</b> by means of a pivot pin <b>124</b> having a pivot axis <b>126</b>. Pivot pin <b>120</b> is provided with a bore <b>128</b> which extends transversely through the pin to receive and rotatably support unthreaded shank portion <b>116</b> of the feed screw, and pivot pin <b>124</b> is provided with a threaded bore <b>130</b> extending transversely therethrough to threadedly interengage with threaded shank portion <b>118</b> of the feed screw. Accordingly, it will be appreciated that rotation of the feed screw in opposite directions about axis <b>110</b> displaces reaction arm <b>14</b> toward and away from housing <b>12</b> and, thus, displaces grooving roll <b>24</b> radially toward and away from back-up roll <b>20</b>. The ability of feed screw <b>100</b> to pivot relative to both housing <b>12</b> and reaction arm <b>14</b> advantageously eliminates the imposition of side thrust against the feed screw when the latter is rotated to displace grooving roll <b>24</b> into engagement with a pipe interposed between the grooving roll and back-up roll during a roll grooving operation. It will be appreciated, of course, that such pivotal movement of the feed screw is enabled by enlarged openings <b>132</b> and <b>134</b> in housing <b>12</b> and reaction arm <b>14</b>, respectively, and through which the corresponding portions of the feed screw shank extend.

[0040] As mentioned hereinabove, depth adjusting screw <b>46</b> is adapted to limit the displacement of reaction arm <b>14</b> toward housing <b>12</b> and, thus, the displacement of grooving roll <b>24</b> toward back-up roll <b>20</b> which, accordingly, determines the depth of the groove rolled in a pipe and, thus, the diameter of the groove. For this purpose, adjusting screw <b>46</b> has a threaded shank <b>136</b> threadedly interengaged with a threaded bore <b>138</b> extending transversely through pivot pin <b>120</b> and a tool head <b>140</b> at the upper end of shank <b>136</b> and which is provided with a non-circular recess <b>142</b> for receiving an appropriate tool by which the adjusting screw is rotatable relative to pin <b>120</b>. Lower end <b>144</b> of shank <b>136</b> overlies pivot pin <b>124</b> so as to engage therewith to limit displacement of the reaction arm toward housing <b>12</b>. Accordingly, it will be appreciated that the initial spacing between end <b>144</b> and pin <b>124</b> in conjunction with the roll grooving of a given pipe is adjustable for determining the depth of the groove to be rolled in the pipe.

[0041] Housing <b>12</b> is provided with a handle <b>146</b> by which the roll grooving apparatus is adapted to be carried from one location to another and, generally, during such transportation the feed screw and adjusting screw are positioned relative to pivot pin <b>124</b> on housing <b>12</b> such that end <b>144</b> of the adjusting screw is considerably spaced from the pivot pin. In accordance with a further aspect of the invention, the feed screw and reaction arm are adapted to be relatively displaceable axially of the feed screw in response to an impact which, otherwise, would impose undesirable and potentially damaging forces on the threads of the feed screw and bore <b>130</b>. More particularly in this respect, as shown in FIG. 6, pivot pin <b>120</b> is provided with a bore <b>148</b> axially therethrough and unthreaded portion <b>116</b> of the feed screw shank is provided with a circumferentially continuous arcuate recess <b>150</b> which is located in bore <b>148</b> when tool head <b>106</b> is engaged against pivot pin <b>120</b>. The end of bore <b>148</b> extending into the axially outer end of pivot pin <b>120</b> is threaded to receive an externally threaded ball detent insert housing <b>152</b> which supports a detent ball <b>154</b> and a spring <b>156</b> by which the ball is biased axially of the pivot pin and into recess <b>150</b>. It will be appreciated, therefore, that an impact downwardly on reaction arm <b>14</b> in FIGS. 2 and 6 will result in the displacement of detent ball <b>154</b> radially outwardly of recess <b>150</b> and thus the release of the reaction arm for axial displacement relative to the feed screw along shank <b>114</b> thereof to the limit determined by the spacing between adjusting screw end <b>144</b> and pivot pin <b>124</b>. It will be further appreciated that such release between the reaction arm and feed screw protects the feed screw threads on shank portion <b>118</b> and the threads in bore <b>130</b> of the pivot pin from potential damage resulting from forcing the threads axially against one another.

[0042] While considerable emphasis has been placed herein on the structures of and the structural interrelationships between the component parts of preferred embodiments of the present invention, it will be appreciate that many changes can be made in the embodiments disclosed herein and that other embodiments can be devised without departing from the principals of the present invention. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.