Clamshell pipe lathe having improved bearing arrangement

Abstract: A clamshell machining lathe for cutting and finishing pipes in industrial settings comprises a split-ring assembly, including a clamping ring that is positioned about the pipe, and journaled to the clamping ring is a rotatable gear ring that supports a tool block carrying a cutting tool. The improvement resides in the bearing arrangement used to journal the gear ring to the stationary clamping ring. One face of the gear ring includes an annular groove whose side walls define a bearing race. The race is dimensioned to receive a plurality of roller bearings therein, the roller bearings being affixed to a planar surface of the clamping gear in a circumferential arrangement so as to fit into the bearing race when the gear ring is coupled to the clamping ring. The arrangement can support greater loads without canting, thus reducing wear on the moving parts.

Description: I. Field of the Invention : This invention relates to a bearing and race structure according to the preamble of claim 1. Bearings of this kind are used into a machining lathe, and more particularly into a split frame clamshell-type portable machining lathe for cutting and finishing relatively large diameter pipes. II. Description of the Prior Art : Split frame clamshell lathes of the type described herein are known in the art. My earlier U.S. Patents 4,739,685 and 4,939,964 are illustrative of the technology involved. The split frame pipe machining lathe generally comprises first and second semicircular halves that are designed to be joined together so as to surround the pipe to be machined. The resulting annular assembly includes a stationary ring portion that becomes clamped to the pipe and an abutting rotatable portion including a ring gear that is journaled to the stationary portion for rotation about the concentrically disposed pipe. An air-operated, hydraulically-operated or electrically-operated motor is operatively coupled to the assembly and includes a drive gear designed to mesh with the ring gear on the rotatable segment of the pipe lathe. Also mounted on the rotatable segment of the pipe lathe is a tool block for supporting a cutting tool that can be made to advance in the radial direction against the pipe to be machined in incremental steps upon each revolution of the ring gear. A problem has heretofore existed in the prior art in the manner in which the ring gear has been journaled to rotate relative to the stationary clamping ring. In Figure 2 of my earlier U.S. Patent 4,739,685, which is reproduced herein as Figure 1, there is shown a cross-section illustrating the manner in which the gear member 10 is journaled for rotation relative to the stationary ring member 11. A first set of roller bearings 12 cooperate with the straight arcuate surface of a circular race member 14, which is bolted onto the ring gear member 10 by bolts 13. The race member 14 also cooperates with a second set of bearings 15. The bearings in set 15 have opposed beveled segments for cooperating with a W-shaped surface 16 formed on the race member 14 and with a V-shaped extension or protuberance 17 formed on the inner side wall of the cavity 18. It has been found that under load, the race member 14 behaves like a fulcrum, allowing the ring gear 10 to rock back and forth which results in undue wear on the bearings and slight variation in the cutting circle as the ring gear orbits the pipe being finished. Moreover, the assembly is costly to manufacture because of the intricacies in the machining required to produce the ring gear 10 and the tolerances that need to be maintained between the ring gear 10 and the circular race member 14 so that these parts will provide the appropriate contact with the associated bearings 12 and 15. In the low clearance pipe lathe described in my earlier Patent 4,939,964, the problems inherent in the journaling of the ring gear to the stationary member described in the '685 patent were partially resolved. Figure 2 herein taken from the '964 patent shows the way the ring gear is journaled in that earlier invention. The problem of undue wear occasioned by the ability of the ring gear 19 therein to rock under loads was still present. Again, the race member 20 was fabricated separately from the ring gear 19 and affixed to it by bolts which made it difficult to maintain the desired degree of contact between the race member 20, the W-shaped segment 21 on the ring gear and the notched roller bearings 22 affixed to the stationary member 23. US-A-5054342 discloses pipe machining apparaters having a bearing and race structure generally similar to that disclosed in US-A-4739685, described above. The precharacterising part of Claim 1 is based on the disclosure of US-A-5054342 and the distinguishing features of the present invention are set out in the characterising part of Claim 1. An object of the invention is to provide a bearing and race structure which resists rocking under load, and minimises any undue wear in use. DESCRIPTION OF THE DRAWINGS The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings in which: Figure 1 illustrates a first prior art structure for journaling a ring gear to a stationary ring member in a clamshell-type pipe machining lathe; Figure 2 depicts another prior art structure for journaling the ring gear of a portable clamshell-type pipe machining lathe to its associated stationary ring member; Figure 3 is a perspective view of a pipe lathe constructed in accordance with the present invention; Figure 4 is a side elevation of the embodiment of Figure 3; Figure 5 is a partial cross-sectional view taken along the line 5-5 in Figure 4; Figure 6 is a partial cross-sectional view taken along the line 5-5 In Figure 4, but with an alternative roller bearing configuration; Figure 7 is a cross-sectional view taken along the line 7-7 in Figure 5; Figure 8 is a cross-sectional view of an alternative embodiment taken along the line 8-8 in Figure 4; and Figure 9 is a cross-sectional view taken along the line 9-9 in Figure 8. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Figure 3, there is shown a perspective view of clamshell-type pipe lathe constructed in accordance with the present invention. It is indicated generally by numeral 30 and is seen to comprise a first annular member 32 that is adapted to be concentrically clamped about the periphery of a cylindrical pipe to be finished (not shown). The annular member 32 is shown as being split diametrically along lines 34 and 36, with the two semicircular segments being fastened together by swing bolts as at 38. While the assembly 30 is shown as being comprised of two semicircular halves, to increase its portability, the device can be constructed as four quarter segments that may be joined together about the pipe. For proper centering, a plurality of pads 40 are positioned about the interior wall surface of the stationary ring member 32 and held in place by bolts 42 (Figure 4). Rotatably journaled to the interior face of the stationary ring member 32 is a second, rotatable, annular member 44 also comprised of two semicircular halves 46 and 48 held together by swing bolts as at 50. Enclosed within a protective shroud 52 attached to the stationary annular member is a ring gear 54 having a pattern of gear teeth formed in the outer peripheral surface thereof. As will be explained in greater detail hereinbelow, the ring gear 54 is journaled to the stationary annular member 32 and cooperates with a spur gear 56 which is driven by a suitable motor 58, the motor being mounted on a bracket 60 secured to the stationary annular member 32. The spur gear 56 meshes with the teeth on the ring gear 54 and when the motor 58 is driven, the ring gear 54 rotates within the shroud 52. The motor used may be air driven, hydraulically driven or electrically driven. Affixed to the exterior face 62 of the ring gear 54 is a tool slide block assembly indicated generally by numeral 64. The cool slide block 64 supports a metal cutting tool 66 therein and upon each rotation of the gear ring, as the cutting tool orbits the pipe being finished, a star wheel 68 on the slide block assembly engages a pin 70 disposed in the path of travel of the star wheel, causing the threaded shaft to which the star wheel is affixed to rotate through a predetermined angle and thereby advance the slide block 64 in the radial direction. In this fashion, the tool 66 can be advanced in incremental steps through the wall thickness of the pipe being finished to cut off an end segment thereof. Also shown in Figures 3 and 4 is a bracket 71 attached to the exposed side face surface of the ring gear 54. Bracket 71 supports an end finishing tool 72 mounted in a threaded arbor 74 and adjustable in the longitudinal direction by rotation of a crank wheel 76. The crank wheel 76 is shown as being manually operated to advance the tool 72 against a cut end surface of a pipe, but those skilled in the art can appreciate that the tool can also be advanced using a step-motor drive, if desired. Turning next to Figures 5 and 6, a first embodiment of the invention will be explained, showing the improved manner in which the ring gear assembly 54 is journaled for rotation relative to the stationary annular member 32. The stationary member 32 and the rotatable annular gear ring member 54 abut one another along a line 78 which are machined flat. An annular recess 80 of a predetermined depth dimension is also machined into the stationary member 32 and formed inwardly therefrom are a series of threaded bores as at 82 which are adapted to receive a threaded spindle or axle 84 of a roller bearing assembly 86. The bearing assembly itself comprises upper and lower ball bearing mounted rollers 88 and 90 separated from one another by a washer-type spacer 92. The outer race of the roller bearings 88 and 90 are inwardly beveled to form a V-shaped notch, as shown, when the two roller bearings 88 and 90 are juxtaposed on the threaded axle 84. Formed inwardly from the interior face of the ring gear 54 is an annular groove 93, having a pair of opposed side walls 94 and 96. Each of the walls 94 and 96 is provided with an annular protuberance 98, which has a cross-sectional appearance of a truncated isosceles triangle, and, as such, conforms to the shape of the V-notch 92 formed in the roller bearing assemblies 86. Figure 6 illustrates an alternative roller bearing configuration from that shown in Figure 5. Instead of positioning the individual roller bearings 88 and 90 with their beveled ends facing one another as in Figure 5, in the arrangement of Figure 6, the roller bearings are inverted such that the beveled ends thereof are directed away from one another and the spacer washer 99 is relocated to be adjacent the surface 80 of the housing 32. By configuring the roller bearings 88 and 90 as indicated in Figure 6, it obviates the need for a somewhat difficult-to-form, projecting annular ridge as at 98 in Figure 5. Instead, the gear 62 has angled corner edges as at 95, 97, 101 and 103 in Figure 6. Thus the bearing race formed in the gear 62 is made to conform closely to the outer profile of the roller bearings 88 and 90. With reference to the cross-sectional view of Figure 7, it can be seen that the roller bearing assemblies 86 do not lie on a common bearing circle, but instead, have their rotational axles 84 radially offset. That is to say, a first set of roller bearings labeled 86a lie on a first bearing circle, such that the peripheries thereof engage the wall 96 of the bearing race 93 while the roller bearings labeled 86b fall on a bearing circle radially displaced form the bearing circle in set 86a whereby their peripheral surfaces engage the bearing race wall 94. The roller bearings of the set labeled 86a alternate with those in the set labeled 86b around the circumference of the annular member 32. It has been found that the staggered arrangement of the roller bearings and their cooperation with the walls on the bearing race 93 prevents any lateral shifting of the rotatable ring member 54 relative to the stationary ring member 32, even when subjected to relatively high loads as the ring gear and attached tool assemblies are driven to orbit the pipe being finished. Also, the construction of the assembly is greatly simplified in that it does not require a separate race member bolted to the ring gear as in the prior art arrangements of Figures 1 and 2. ALTERNATIVE EMBODIMENT Referring next to Figures 8 and 9, an alternative embodiment is illustrated. In this arrangement, there is again a ring gear member 100 journaled for rotation on an interior planar surface 102 of a stationary annular member 104. More particularly, the stationary annular member 104 has its surface 102 provided with regularly, circumferentially spaced bores or wells 105 which are dimensioned to receive with a slip fit an eccentric cam member 107. The cam 107 is cylindrical and has a threaded bore 109 into which is screwed the stud 84 of the bearing assembly 106. The threaded bore 109 is offset from the center line of the cylindrical cam by a predetermined eccentricity and, as such, when eccentric cam 107 is rotated within the bore 108, the bearing assembly 106 is shifted. When a desired position for the bearing assembly is established, it is locked in place by a set screw 124. Formed inwardly from the interior surface of the ring gear 100 is a bearing race 114 having opposed side walls 116 and 118. Again, the side walls of the bearing race may include a triangular protuberance, as at 120 and 122, which conform to a V-notch in the bearing assembly resulting when the beveled surfaces of the upper and lower roller bearing members 110 and 112 are juxtaposed. If the bearing assembly of Figure 6 is used, no such triangular protuberance is required. Because of the eccentric mount, the individual roller bearing assemblies 106 can be adjusted by rotating the eccentric cam 107, using an Allen wrench or the like and then subsequently advancing a threaded lock screw 124 in a threaded, radially extending bore against the eccentric cam to lock the eccentric orientation. As such, the roller bearing assemblies 106 can be adjusted to engage the triangular protuberances 120 and 122 and the walls 116 and 118 of the bearing race 114 with a desired clearance therebetween. It is found that this alternative embodiment also provides the desired stability under load of the ring gear as it is driven in its orbital path. Moreover, this desired result is achieved with a simpler, less expensive implementation compared to the prior art. This invention has been described herein in considerable detail in order to comply with the Patent Statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment details and operating procedures, can be accomplished without departing from the scope of the invention itself.

Claims: A bearing and race structure, for a clamshell machining lathe used in finishing pipes, comprising a stationary, first annular member (32), adapted to be concentrically clamped about the periphery of a cylindrical pipe segment to be finished, the first annular member having an inner arcuate face, an outer arcuate face and a planar surface (78) extending therebetween, a second, one-piece annular member (54) having an inner arcuate face, an outer arcuate face having gear teeth thereon, and a planar surface extending therebetween and juxtaposed in facing relationship with the planar surface (78) of the first annular member, the second annular member being rotatable relative to the first annular member, a first circumferential bearing race wall (94) between the planar surfaces (78) and on the second annular member, and a plurality of roller bearing assemblies (86) each having a roller bearing (88,90) rotatably mounted on an axle (84), the roller bearing assemblies being affixed to the annular member (32) the axles thereof perpendicular to the planar surface (78) of the first annular member to define a generally circular track, peripheral surfaces of the roller bearings (88,90) co-operating with the bearing race wall (94) so as rotatably to support the second annular member (54) relative to the first annular member(32); characterised in that the planar surface of the second annular member (54) is provided with a circumferential groove (93) having opposed parallel walls (94,96) defining a bearing race which receives said roller bearings (88,90) therein, one of said groove walls defining said first bearing race wall (94) and the opposite wall defining a second bearing race wall (96), and further characterised in that the roller bearing surfaces co-operate with both bearing race walls (94,96). A bearing and race structure according to Claim 1, wherein the roller bearing assemblies (86) include first and second circumferentially arrayed sets (86a,86b) with the axles (84) of the first set lying on an imaginary circle radially spaced from those of the second set, the roller bearings (88,90) of the first set (86a) having perphural surfaces co-operating with the first race wall (94) and the roller bearings of the second set having perphural surfaces co-operating with the second race wall (96). A bearing and race structure according to Claim 2, wherein each roller bearing (88,90) in the first set (86a) is adjacent to a roller bearing in the second set (86b). A bearing and race structure according to Claim 3, wherein the roller bearings of the first set (86a) alternate with the roller bearings of the second set (86b). A bearing and race structure according to Claim 1, wherein the roller bearings (106) are eccentrically mounted. A bearing and race structure according to any preceding claim, wherein the roller bearing (88,90) of each assembly (86) defines a circumferential v-notch, which cooperates with a circumferential protuberance (98) on the bearing race walls (94,96), which conforms to the shape of the notch. A bearing and race structure according to claim 6, wherein, in each roller bearing assembly (86), the circumferential v-notch is defined between first and second roller bearings (88,90) each rotatable on the axle (84) and each having a bevelled periphery to define the notch. A bearing and race structure according to Claim 7, including a spacer (92) between the first and second roller bearings (88,90). A bearing and race structure according to any preceeding claim, including motor means (56,58) affixed to the first annular members (32) and including a spur gear (56) for engaging the gear teeth on the second annular member (54) for rotating the latter relative to the first annular member. A bearing and race structure according to any preceeding claim, including a tool block (64) secured to the second annular member (54) for rotation therewith and including means (68,70) for advancing a cutting tool in a radial direction in incremental steps upon each revolution of the second annular member.

Inventors: RICCI DONATO L, RICCI, DONATO L.
Applicants: RICCI DONATO L, RICCI, DONATO L.
Application year: 1996
Main classification: B23B5
IPC codes: B23Q9, B23B5, B23Q1