SUPPORT ARM

Abstract: A support arm may have outlets at the outer end of the arm providing access to compressed air, fume and dust extraction, and electrical power. All utility conduits such as electric welding power supply conductors, air hoses, extraction ducts and electrical control conduits may be encased within the arm to protect them from damage, remove the hazard posed by conduits laying upon the shop floor and to provide for simple access to multiple utilities at a distance from the utility sources. The arm comprises an inner boom (1) pivotally mounted to a stationary supporting structure (4), an outer jib (2), and a knuckle (3) pivotally joining the boom and jib. The boom, jib and knuckle are operable in a horizontal plane to provide access to utility connections at the outer end of the jib within an arc (51-54) defined by the outer extent of the arm. A linkage (62-70) between the boom, knuckle and jib maintains equal angles between the boom, the axis of the knuckle and the jib to avoid uncontrolled movements of the knuckle relative to the boom and jib and to avoid kinking of the flexible conduits connecting from the outer end of the boom, through the knuckle to the inner end of the jib.

Description: Support Arm The present invention relates to improvements in support arms having a rigid inner boom having a longitudinal axis; mounting means, pivotally connected to the inner end of the boom, for pivotally mounting the boom to a stationary supporting structure; a rigid outer jib having a longitudinal axis; a knuckle having an inner end pivotally connected to the outer end of the boom and having an outer end pivotally connected to the inner end of the jib, said knuckle having a longitudinal median axis; and support means, connected to the outer end of the jib for supporting a suspended load. Such support arms are described for example in U.S. patent No. 5,025,126 dated June 18, 1991 in the name of the applicant. A problem with prior support arms is that of uncontrolled movement of the knuckle relative to the boom and of the knuckle relative to the jib when the arm is pivoted toward or away from a position intended to be serviced by the arm. Such uncontrolled movements can result in pressures being applied to portions of the arm which may result in mechanical damage. In advantageous forms of the support arm, flexible members, such as flexible tubing, span between the boom and jib adjacent the knuckle. The uncontrolled movements referred to above may result in kinking or pinching of such flexible members. The present invention provides a support arm comprising: a rigid inner boom having a longitudinal axis; mounting means, pivotally connected to the inner end of the boom, for pivotally mounting the boom to a stationary supporting structure; a rigid outer jib having a longitudinal axis; a knuckle having an inner end pivotally connected to the outer end of the boom and having an outer end pivotally connected to the inner end of the jib, said knuckle having a longitudinal median axis; and support eans, connected to the outer end of the jib for supporting a suspended load; characterized by a drive connecting said boom, knuckle and jib and pivoting each of said boom and jib relative to the median axis of the knuckle through an angular displacement equal to the angular displacement of the other of said boom and jib relative to said median axis when said other is pivoted relative to said median axis. With the arrangement of the invention, the angle between the boom and the median axis of the knuckle . is maintained equal to the angle between the jib and the median axis of the knuckle, so that uncontrolled movements of the kind referred to above are avoided. In the preferred form, the boom and jib are each constructed of rigid open-ended longitudinal tubes for providing an at least partially encased access channel between the suspended load and the inner end of the boom. Flexible tubes or other flexible members adjacent the knuckle span between the rigid tubes of the boom and of the jib. With the present arrangement, kinking or pinching of the flexible tubes or other members is avoided, so that, for example, flow of service fluids through the tubing is not obstructed. As will be appreciated by those skilled in the art, various forms of drive may be used to provide equiangularity between the axis of the knuckle and the boom on the one hand and the jib on the other. For example mechanical, pneumatic, hydraulic or electrical drives may be employed. Such drives may comprise a position responsive device connected between each of the knuckle and the boom and the knuckle and the jib, and a motor which may be pneumatically, hydraulically or electrically-activated also connected between each of the knuckle and the boom and the knuckle and the jib. The arrangement is such that on pivoting movement of one of the boom and the jib relative to the knuckle, the position responsive device actuates the motor connected to the other and pivots it through a corresponding angle relative to the knuckle. Various known forms of servo mechanism can be adapted for this purpose. The drive may, for example comprise a pair of opposed hydraulic or pneumatic piston and cylinder devices, the cylinders of which are coupled so that an extension of one piston is matched by a corresponding retraction of the other. Preferably, however, by reason of its simplicity, low cost, and reliability of operation, the drive is a positive mechanical drive such as a toothed belt, chain or gear drive and preferably comprises a gear train having one gear connected to each of the boom and the jib and an even number of idler gears journalled on the knuckle. Preferably the gear train comprises a train of spur gears having parallel axes. The preferred form of support arm is capable of supporting a load at its outer end and accommodates utility conduits within the longitudinal tubes of which the boom and jib are constructed. The arm folds upon itself and may be stored against the supporting structure in a compact configuration. This arm is particularly suited to welding operations since it may support a welding wire feeder at its outer end. The tubes of the boom and jib may accommodate dust and fume extraction hoses in addition to all M.I.G. welding conduits. In order that the invention may be readily understood, a preferred embodiment will be described by way of example with reference to the accompanying drawings. Figure 1 is a bottom plan view of the arm in an outstretched configuration. Figure 2 is a bottom plan view of the arm in a folded configuration stored adjacent to a supporting wall. Figure 3 is a partial plan view showing a gear train drive between the boom, knuckle and jib. Figure 4 is a section taken on the line IV-IV in Figure 3. Figure 5 is a somewhat schematic plan view showing a hydraulic drive connected between the boom, knuckle and jib. Referring to Figures 1 and 2, the general construction and operation of an arm according to the invention may be readily observed. For details of the construction and operation of the arm, reference should be made to applicant's above-mentioned U.S. patent No. 5,025,126. Briefly, the support arm includes an inner boom 1, an outer jib 2, and a knuckle 3. The boom 1 and jib 2 each have a longitudinal axis and operate in a plane in the embodiment illustrated. A mounting bracket 4 connected to the inner end of the boom 1 pivotally mounts the boom 1 on a hinge to a stationary supporting structure such as a wall or column so that the inner boom 1, outer jib 2 and knuckle 3 operate substantially in a horizontal plane. The knuckle 3 has an inner end pivotally connected to the outer end of the boom 1, and has an outer end pivotally connected to the inner end of the jib 2. As shown in Figures 1 and 2, the pivotal connections between the mounting bracket 4, boom 1, knuckle 3 and jib 2 enable the arm to present the outer end of the jib 2 at a range of distances from the supporting structure and also enable the arm to fold upon itself adjacent a supporting wall for compact storage when not in use. For example when used in association with M.I.G. welding equipment in an auto body shop as illustrated the arm is designed to provide access to utilities in three adjacent repair bays. A supporting bracket is connected to the outer end of the jib 2 for supporting a suspended load. In the embodiment illustrated the load includes a planetary welding wire feeder 5 for M.I.G. welding and a supporting housing 6 accommodating a number of utility outlets. A planetary feeder 5 is preferred over conventional feeders due to its relatively light weight and superior feeding characteristics. A handle 7 is also provided to manually guide the arm. The boom 1 and jib 2 are each constructed of rigid open-ended tubes. The rigid tubes define an at least partially encased access channel between the housing 6 and the inner end of the boom 1 adjacent the supporting structure. A welding , power supply conductor passes through the rigid tubes of the boom 1 and jib 2 between the housing 6 and an associated welding power supply source (not shown) positioned adjacent the support structure. For M.I.G. welding, an inert gas line and cooling water lines also pass through the rigid tubes of the boom 1 and jib 2 between their respective sources and the wire feeder 5. A coil 8 of consumable welding wire may be rotatably mounted to the arm. The wire passes through a protective sheath to the housing 6 then through the wire feeder 5 to a welding gun. In the preferred embodiment shown in the drawings, the boom 1 and jib 2 are constructed of three longitudinal rigid tubes. Each rigid tube is fixed at its inner and outer ends in relation to the other two rigid tubes. The rigid tubes pass through the holes of a truncated triangular end plate and the rigid tubes and end plates are welded together to form a rigid joint. The end plates may include a central hole through which various utility conduits may be threaded if desired. The three rigid tubes of the boom 1 and jib 2 are transversely spaced from each other with their respective axes centred at the vertices of an equilateral triangle. Such a construction results in members of high strength which have open ended tubes to encase utility conduits. The arm may advantageously include flexible tubes 10 within the area of the knuckle 3. The flexible tubes 10 span between the rigid tubes of the boom 1 and jib 2. The flexible tubes 10 may be used to encase and protect conduits passing between the interiors of the rigid tubes of the boom 1 and jib 2. In order to encase conduits as they pass out of the inner end of the boom 1 adjacent the mounting bracket 4, further flexible tubes 10 may be connected to the inner ends of the rigid tubes of the boom 1. The arm may include utility outlets within the housing 6 to enable connection of fume extraction hoses and dust extraction hoses to the outer end of the jib 2. In the embodiment illustrated, a first jib tube 11 operates as a conduit for extracting fumes, a second jib tube 12 provides an encased access channel through which the utility supply conduits may pass, and a third jib tube 13 operates as a conduit for providing vacuum suction to extract particulate matter such as dust, slag and flux. A fume extraction outlet 14 is located within the housing 6 and provides for the connection of a fume extraction hose (not shown) in a known manner. A fume extraction conduit communicates between the fume extraction outlet 14 and the outer end of the first jib tube 11. As shown in Figure 1, a first flexible fume extraction conduit 16 communicates between the inner end of the first jib tube 11 and the outer end of a first boom tube 17. Preferably, to reduce kinking of the first flexible fume extractor conduit 16 in the area of the knuckle 3 as the arm is folded, the flexible conduit 16 crosses over the knuckle's longitudinal axis from the first jib tube 11 to communicate with a first boom tube 17 on an opposite side of the longitudinal axis. A second flexible fume extraction conduit 18 communicates between the inner end of the first boom tube 17 and a fume extraction apparatus (not shown) such as a blower and filter assembly. Fume extraction control cables pass from a fume extraction control switch 19 through the second jib tube 12, a first flexible utility conduit 20 (communicating between the inner end of the second jib tube 12 and an associated second boom tube 21) , through the second boom tube 21, and through a second flexible utility conduit 22 to the fume extraction apparatus (not shown) . It will be apparent that other utility supply conduits, such as compressed air lines, and welding power supply conductors, may also pass through such a route from their . respective utility sources to the housing 6. In a like manner, a vacuum outlet 23 is located within the housing 6 and provides for the connection of a vacuum hose (not shown) in a known manner. A rigid vacuum conduit communicates between the vacuum outlet 23 and the outer end of the third jib tube 13. A first flexible vacuum conduit 25 communicates between the inner end of the tube 13 and the outer end of a corresponding third boom tube 26. A second flexible vacuum conduit 27 communicates between the inner end of the third boom tube 26 and a vacuum apparatus (not shown) such as a centrifugal cyclone precipitator. A vacuum control switch 28 is provided within the housing 6 to initiate and halt the operation of the vacuum apparatus. Vacuum control cables pass through the second boom tube 21 and the second jib tube 12 between the vacuum control switch 28 and the vacuum apparatus in a manner analogous to the fume extraction control cables described above. The knuckle 3 preferably has a longitudinal central opening through which the flexible tubes 16, 20 and 25 extend. The central opening is of transverse dimensions sufficient to permit unrestricted lateral arching of the flexible tubes between the rigid tubes of the boom 1 and jib 2 when the longitudinal axis of the knuckle 3 is not colinear with the longitudinal axes of the boom 1 and jib 2 as shown in Figure 2, for example. From the foregoing description therefore, it is apparent that an arm in accordance with the invention may provide any number of utility outlets mounted to support means at the outer end of the jib 2 for allowing connection to an associated utility at a distance from an associated utility source. Utility supply conduits engage the interior of the rigid longitudinal tubes of the boom 1 and jib 2 and span between the rigid tubes of the boom 1 and jib 2 adjacent to the knuckle 3. In this way, the utility supply conduits communicate between an associated utility outlet and the associated utility source. The utility supply conduits are protected within the arm. The conduits are raised above the shop floor and simple connection to utilities is enabled. The preferred embodiment illustrated in the drawings is adapted for use in M.I.G. welding operations but it will be apparent that such an arm may be adapted for other uses in an analogous manner. In the present invention, means are provided to prevent random pivoting of the boom and the jib relative to the knuckle, which would tend to kink or pinch the flexible tubes 16, 20 and 25 which span between the boom and the jib through the knuckle. For example if, starting from the position shown in Figure 2, the jib 2 were to be rotated relative to the knuckle 3 through 180° so that it is directed away from the knuckle 3 in the direction opposite to the boom 1, the tubes 10, 16 and 25 would become compressed, pinched and kinked between the adjacent ends of the boom 1 and of the jib 2 which are pivotally connected to the knuckle 3, with the result that gas or other fluid flow would be obstructed and there would be the risk of damaging or permanently deforming the tubes. Such means comprise a drive as described above between the boom and the knuckle and between the knuckle and the jib to maintain the jib and boom at symmetrical angles relative to the median axis of the knuckle and to avoid the above noted compression, pinching and kinking problems. Various forms of such drive may be employed as will be apparent to those skilled in the art. Figures 3 and 4 show one example wherein a train of spur gears 51, 52, 53 and 54, of which gear 51 is keyed to a shaft 56 journalled in a bearing 57 in an upper plate 3a of the knuckle 3 and fixedly connected, for example by welding, to an upper plate la forming part of the boom 1. Idler gears 52 and 53 are journalled on bearings 58 connected to the plate 3a. Gear 54 is keyed to a shaft 59 secured, for example by welding, to an upper plate 2a forming part of the jib 2. As will be appreciated, with this drive, rotation of one of the elements 1 and 2, for example the jib 2, relative to the median axis 60 of the knuckle 3 results in equiangular rotation of the other element, such as the boom 1. Considering Figure 3, clockwise rotation of the jib 2 results in clockwise rotation of the gears 54 and 52 and equal anticlockwise rotation of the gears 51 and 53 meshing therewith so that as the jib 2 swings outwardly, the boom 1 swings outwardly relative to the axis 60 of the knuckle by an equal extent. In this manner as the wire feeder 5 is swung out to a desired operating position within the arc of operation of the support arm, the boom 1 and jib 2 are maintained at symmetrical angles relative to the axis of the knuckle 3 and compression, pinching and kinking of the tubes 16, 20 and 25 are avoided. Figure 5 shows somewhat schematically a further example wherein a cylinder 62 is pivotally connected on the boom 1 at 63 and a piston 64 working in the cylinder 62 is pivoted on the knuckle 3 at 66. An opposed cylinder 67 is pivoted on the knuckle 3 at 68 and its piston 69 is pivoted on the jib 2 at 70. The working fluid, preferably hydraulic liquid, of the cylinders 62 and 67 is placed in flow communication through a conduit 71. As will be appreciated the arrangement illustrated couples the rotational movement of one of the elements 1 and 2 relative to the axis of the knuckle 3 so that equiangularity or symmetry may be maintained.

Claims: CLAIMS : 1. A support arm comprising: a rigid inner boom having a longitudinal axis; mounting means, pivotally connected to the inner end of the boom, for pivotally mounting the boom to a stationary supporting structure; a rigid outer jib having a longitudinal axis; a knuckle having an inner end pivotally connected to the outer end of the boom and having an outer end pivotally connected to the inner end of the jib, said knuckle having a longitudinal median axis; and support means, connected to the outer end of the jib for supporting a suspended load; characterized by a drive connecting said boom, knuckle and jib and pivoting each of said boom and jib relative to the median axis of the knuckle through an angular displacement equal to the angular displacement of the other of said boom and jib relative to said median axis when said other is pivoted relative to said median axis. 2. An arm according to claim 1 characterized in that said drive comprises, a gear train having a gear connected to each of said boom and said jib and an even number of at least two idler gears journalled on said knuckle, and preferably comprises a train of spur gears having parallel axes. 3. An arm according to claim 1 characterized in that said boom and said jib are each constructed of rigid open- ended tube means for providing an at least partially encased access channel between the suspended load and the inner end of the boom. 4. An arm according to claim 3 wherein the boom and jib each comprise three rigid tubes, each tube being fixed at its inner and outer ends in relation to the other two tubes. 5. An arm according to claim 4 wherein the three rigid tubes of the boom and jib are transversely spaced from each other with their respective axes centred at the vertices of an equilateral triangle. 6. An arm according to any preceding claim characterized by flexible members adjacent the knuckle, the flexible members spanning between the boom and the jib. 7. An arm according to claim 6 characterized in that said inner boom and said outer jib each comprise at least two horizontally spaced rigid tubes; and said flexible tube means comprise two sets of flexible tubing connecting from adjacent said stationary supporting structure to the inner ends of said horizontally spaced tubes of said inner jib, respectively, and from the outer ends of said tubes of said inner jib and through said knuckle and to the inner ends of said tubes of said outer boom, and wherein the outer ends of said rigid tubes connect to a fume extraction outlet and a vacuum outlet, respectively, provided on said support means, whereby fume extraction services and vacuum services can be provided adjacent said support means from fume extraction apparatus and vacuum apparatus adjacent said stationary supporting structure.

Inventors: HANSEN HENNING, HANSEN, HENNING
Applicants: HENNING HANSEN INC, HENNING HANSEN INC.
Application year: 1992
Main classification: F16L3
IPC codes: B23K9, B60S5, F16L3, F16M11