GB2093796A - Manipulators for working in heat exchangers - Google Patents

Abstract

A manipulator for working a vertical type heat exchanger and adapted to be disposed in a water chamber (2) of the heat exchanger delimited by a drum end plate and a lower end header plate (3) on which a large number of vertically extending heat transfer tubes are arrayed, has a support frame (11) disposed within the water chamber. The base end portion of a freely extensible and retractable main arm (101) is mounted on the support frame and is rotatable about its base end portion and vertically swingable about a fulcrum at its base end portion. A base end portion of a sub-arm (401) is mounted at the outer end portion of the main arm (101) and is rotatable about its base end portion and vertically swingable about a fulcrum at its base end portion to enable it to be positioned parallel to the header plate (3). A vertically movable clamp shaft (351) which can be inserted into the heat transfer tube is provided coaxially with the rotational axis of the sub-arm (401). A position detector in the form of a fiber head for positioning the clamp shaft (351) coaxial with a heat transfer tube is provided on the clamp shaft (351), and is optically coupled by fiber bundle (366) to a television camera (368) equipped with a scale plate and connected to a monitor (369). <IMAGE>

Description

SPECIFICATION Manipulators for working in heat exchangers The present invention relates to a manipulator for working in a heat exchanger.

Heretofore, various manipulators have been used for working in or for making various measurements and inspections in a dangerous environment or in a narrow space. For performing inspections and carrying out workings while traversing or scanning a header plate surface where a large number of heat transfer tubes of a heat exchanger are arrayed, a manipulator is also used. However, most of the manipulators of the prior art were such that control was effected from a predetermined reference point and hence the apparatus was necessarily complex because of the complex control system, and it became a requirement not only to make the apparatus light and compact, but also it was necessary to work at a dangerous location or in a narrow space upon installation of the apparatus.In addition, the prior art manipulators had the disadvantage that they employed a walking type guide system and hence the weight that could be guided was limited and thus they were also restricted in their working.

It is therefore one object of the present invention to provide a novel manipulator which is free from the above-described disadvantages of the prior art manipulators, and which is compact, light in weight, simple to control and also simple to install.

According to one aspect of the present invention, there is provided a manipulator for working in a vertical type heat exchanger, characterized in that a support frame is adapted to be disposed within a water chamber delimited by an end plate and header plate on which vertically extending heat transfer tubes are arrayed, a base end portion of an extensible and retractable main arm is mounted on said support frame, said main arm being rotatable about said base end portion and vertically swingable about a fulcrum at said base end portion the base end portion of a subarm is mounted at the outer end portion of said main arm, said sub-arm being rotatable about its base end portion and vertically swingable about a fulcrum at its base end portion so that it is capable of being positioned parallel to said header plate, a vertically movable clamp shaft which is adapted to be inserted into a selected heat transfer tube is provided coaxially with the rotational axis of said sub-arm, and a position detector for positioning said clamp shaft so as to become coaxial with a heat transfer tube is provided on said clamp shaft.

A preferrled embodiment of the invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a perspective view showing the external appearance of the manipulator of the preferred embodiment which is designed for working in a heat exchanger by being disposed within a water chamber of the heat exchanger, Figure 2 is a diagrammatic view showing the relation between the polar coordinates and the rectangular coordinates, according to which the positioning of the manipulator is controlled, Figure 3 is a schematic view showing the difference between the set directions of a fixed table and a fixed pin of the manipulator, Figure 4 is a diagram for explaining the operations upon disposing a support frame of the manipulator within the water chamber, Figure 5 is a transverse cross-section view of a main arm of the manipulator (R-axis), Figure 6 is a perspective view looking in the direction of arrow B in Figure 1, of a drive mechanism for the main arm, Figure 7 is a central cross-section view of a turn table of the manipulator (0-axis), Figure 8 is a perspective view looking in the direction of arrow B in Figure 1 of a drive mechanism for a vertical swing cylinder (-axis) of the manipulator, Figure 9 is a cross-sectional view showing a part of the drive mechanism for the vertical swing cylinder to an enlarged scale, Figure 1 O(a) and 1 O(b) are schematic views to be used for explaining the operations of the vertical swing cylinder, Figure 10(a) being a plan view and Figure 1 O(b) a front view, Figure 11 is a perspective view looking in the direction of arrow A in Figure 1, of an extreme end portion of the main arm, Figure 12 is an enlarged cross-sectional view of a vertical swing mechanism (axis) of a sub-arm of the manipulator and its detector, Figure 13 is a diagrammatic view for explaining the relationship between the main arm and the vertically swung sub-arm, Figure 1 4 is a cross-sectional view showing the rotational drive mechanism of the sub-arm to an enlarged scale, Figure 1 5 is a diagrammatic view for explaining the scope of traversing or scanning by the subarm, Figure 1 6 is a diagrammatic view for explaining the traversing or scanning points covered by the sub-arm, Figure 1 7 is a partial and enlarged crosssectional view showing the clamp shaft (C-axis) of the manipulator, Figure 1 8 is a schematic view of a scale plate of the manipulator, Figure 1 9 is a diagrammatic view for explaining the operation of a position detector of the manipulator, Figure 20 is a perspective view for explaining assembly of rocking mechanism (Ic-axis, A-axis) for the turn table of the manipulator, Figure 21 is a perspective view of the external appearance of a tc-axis holding frame on a support frame, Figures 22 and 23 are diagrammatic views for explaining operations of the rocking mechanisms for the turn table, and Figure 24 is a diagrammatic view for explaining adjustment to parallelism of the turn table by means of the rocking mechanisms.

Referring now to Figure 1, the external appearance of a manipulator according to the present invention is shown in perspective view.

The manipulator is operable within a water chamber 2 delimited by a lower end header plate 3 on which vertically directed heat transfer tubes of a heat exchanger are arrayed and a hemispherical drum end plate covering the header plate from below.

Firstly a general explanation of the construction of the entire manipulator will be given. The manipulator has a support frame 11 one end of which is supported by a ball 10 disposed at the bottom of the water chamber 2 and the other end of which is supported by engaging a hook 18 on the frame 11 with a fixed pin 12 provided in an access opening in the form of a manhole 6.The support frame 11 is fixedly located within the water chamber 2, inter alia, by means of a pair of laterally openable support arms 1 3a and 1 3b, and various mechanisms are provided for performing traversing or scanning according to polar coordinates (R, 0, (p) as shown in Figure 2 with reference to the support frame 1 These mechanisms include a turn table 151 (O-axis) which can be rotated in a horizontal plane on the support frame 11, a freely extensible and retractable main arm 101 (R-axis) provided on the turn table 151, and a shaft (-axis) about which the main arm 101 is vertically swingable.A subarm 401 is provided at the outer extremity of the main arm 101, and this sub-arm 401 is also provided with a rotational shaft (a-axis), a vertical swing shaft (axis) and a clamp shaft 351 (C-axis) which is vertically movable with respect to the sub-arm 401. In addition, there are provided rocking shafts (axis, A-axis) which are orthogonal to each other for the purpose of adjusting the reference turn table 1 51 so as to become parallel to the traversed or scanned surface (header plate 3). In operation an appropriate tool or inspection device is mounted the outer extremity of the sub-arm 401 so that it can be traversed through any arbitrary position.

There now follows a description of a fixing mechanism for the above-described support frame 11 which serves as a reference plane for the R-, 0and q-coordinate axes of the polar coordinates (R, 6, ), the a-, p- and C-axes, and further the tc- and A-axes, respectively.

First the fixing mechanism for fixing the support frame 11 and the fixed table 14 which serve as reference members for the traversing or scanning, will be explained. One end of the support frame 11 is fixed relative to the fixed table 14. The table 1 4 is located in the manhole 6 and has its upper extremity fixed to the manhole 6 by means of a bolt 1 5. The support frame 11 has at one end a hook 1 8 engaging with a fixed pin 12 provided at the upper end of the fixed table 14, and the other end of the support frame 11 is placed on the ball 10.The axis of the fixed pin 12 is disposed at right angles to a line which extends at an angle 77 (Figure 3) to a line drawn from the pin 12 to the center of the water chamber 2, so that upon inserting the support frame 11 into the water chamber 2 as will be described later, the support frame 11 does not interfere with a partition wall 5.

In addition, in order to facilitate insertion of the support frame 11 into the chamber 2, an auxiliary table 1 6 is rotatably mounted at the upper end of the fixed table 14 by means of a pin 17, and guide grooves 23 are provided along the sides of the table 1 6, so that the support frame 11 can be inserted by sliding guide rails (not shown) of the support frame 11 along the guide grooves 23.

After the support frame 11 has been inserted with one end thereof placed on the ball 10 and the other end engaged via the hook 1 8 with the fixed pin 12, the laterally operable support arms 1 3a and 1 3b are opened out i.e. displaced to a splayed position on the left and right sides of the support frame 11 by rotation about pins 21a and 21 b, respectively in order to further fixedly locate the support frame 11.

Support rollers 25a and 25b are provided at the outer ends of the support arms 1 3a and 1 3b.

Opening/closing cylinders 1 9a and 1 9b for opening and closing the support arms 1 3a and 1 3b have one end pivotably mounted on the support frame 11 via pins 22a and 22b respectively, and their other end pivotably mounted at the outer end of a respective one of the support arms 1 3a and 1 3b via pins 20a and 20b respectively. Accordingly, to fixedly locate the support frame 1 1, first the support arm 1 3a is opened by extending the opening/closing cylinder 1 9a as shown diagrammatically in Figure 4. Since an extension force fa of the opening/closing cylinder 1 9a produces a component force f2 acting on pin 20a the support arm 1 3a will rotate in the clockwise direction about the pin 20a and the cylinder will simultaneously extend and rotate about its pin 22a.When the opening/closing cylinder 1 9a has rotated through a predetermined angle, the rotation of the support arm 1 3a is restricted by its engagement with a stop 24a provided on the opening/closing cylinder 1 9a, so that only an extension of the support arm 1 3a is effected and eventually the support roller 25a butts against the outer wall of the water chamber 2 and is fixed there. At the same time the support frame 11 is moved towards the partition wall 5 by the reaction force to the extension force component f3 of the opening/closing cylinder 1 9a, so that the side surface of the support frame 11 butts against the partition wall 5 and the support frame becomes jammed in position. Due to a frictional force along the abutting surface the support frame 11 is also fixed in the direction perpendicular to the plane of the Figure 4 drawing. Subsequently, the support frame 11 can be further fixedly located by extending the other opening/closing cylinder 1 9b in a similar manner to the cylinder 1 9a but in this case the support arm 1 3b butts against the partition wall 5 before the stop 24b butts against the support arm 1 3b, and hence the function of the stop is achieved by the partition wall 5.

Although a component force f4 which tends to move the support frame 11 leftwards as viewed in Figure 4 is generated as a result of the abovedescribred operations of the support arms 13 and the opening/closing cylinders 19, this component force f4 is balanced by a constraining force exerted upon the support frame 11 by the aforementioned fixed pin 12, and hence it is insignificant. Thus the support frame 11 can be firmly fixed within the hemispherical water chamber 2 by means of the fixed pin 12, hook 18, support arms 13, support rollers 25 and ball 10.

Next, there will be described in turn an R-axis member, a 0-axis member and a (p-axis member which move according to the polar coordinates (R,0, (p) established on the support frame 11. The R-axis member (see particularly Figures 1,5 and 6) is main arm 101 which includes a mechanism for converting forward and reverse rotations of a lead screw 102 into back and forth reciprocating movements, and which has a freely extensible and contractible double telescopic structure consisting of an outer tubular shaft 103 (R1-axis), a middle tubular shaft 104 (F2-axis) and an inner shaft 105 (R3-axis). The main arm 101 is provided on a 0-axis member, comprising turn table 151 as will be described later.As shown in detail in Figure 5, the R-axis member 103, F2-axis member 104 and R3axis member 105 are held in a mutually slidable manner via guide rails 106 and 107 provided on the F2-axis member 104 and R3-axis member 105 and rollers 112 and 118. The guide rails 106 are fixed on the R2-axis member 104 by means of bolts 108 and nuts 109, and the rollers 112 are supported through bearings 111 by support pins 110 fixed on the R-axis member 103. Likewise, the guide rails 107 are fixed on the R3-axis member 105 by means of bolts 113 and a holding frame 115 for the lead screw 102, and the rollers 118 are mounted through bearings 11 7 on support pins 11 6 fixed on the F2-axis member 104.

In order to drive the R-axis member 101, as best shown in Figure 6, a pinion 120 coupled to an R-axis drive motor 11 9 meshes with a gear 121 fixed to the lead screw 102. A nut 122 fixed to the R3-axis member 105 (not shown in Figure 6) is engaged with this lead screw 102, and thereby a rotational motion can be converted into a reciprocating motion.In addition, as a detector means for detecting the amount of extension and contraction of the R-axis member 1 01, there is provided a detecting gear 1 23 fixed to the lead screw 102, which gear intermeshes with a gear 125 fixed to an encoder 124 at an appropriate gear ratio and hence, the amount of extension and retraction of the R-axis member 101 can be detected from the amount by which the lead screw 102 is rotated. it is to be noted that during the extension and contraction operations, since the amount of extension of the F2-axis member 104 and the F3-axis member 105 is restricted by restriction stops (not shown), the extensions and retractions of the respective axis members are effected in an appropriate proportion.

As shown in Figure 7 at the centre of the 0-axis member, i.e. turn table 1 51 which is rotatable in a horizontal plane, there is provided a downwardly projecting rotary tube 1 52. The turn table 1 51 and the rotary tube 1 52 are rotatably supported by ball bearings 1 54 and 1 55 and a thrust bearing 1 56 provided on a fixed gear table 1 53 which is coupled by its links 457 and 458 (Figures 20 and 21) to Ic-axis hold frame 459 forming one of the parallelism adjustment mechanisms for the turn table 1 51 as will be described later.A support plate 163 which carries the main arm 101 is fixed by bolts 164 to the upper surface of the turn table 1 51 so that the plate 1 63 can be readily separated from the turn table 1 51. The drive mechanism for the turn table 1 51 is shown in Figure 8. The drive mechanism has a pinion 158 and a drive pinion 161 fixed to a 0-axis drive motor 1 57 which is fixed on the turn table 1 51.

The drive pinion 1 61 meshes with a gear 162 fixedly secured on the fixed gear table 1 53.

Detection of the amount of rotation of the turn table 1 51 is effected by the pinion 1 58 meshing with gear 1 60 of an encoder 1 59 provided on the turn table 151. Upon operation of the O-axis member, the 0-axis drive motor 1 57 rotates and its torque is transmitted via the drive pinion 1 61 to the fixed gear 1 62 on the fixed gear table 1 53, so that the turn table 1 51 is rotated by the reaction torque thus generated.In addition, by separating the support plate 163, the abovedescribed R-axis member and 0-axis member and the (p-axis member, c'-axis member and axis member as will be described later can be separated from the turn table 1 51. The amount of rotation can be measured by the encoder 1 59.

Now description will be made on the (p-axis member, comprising a vertical swing shaft. This (p-axis member achieves vertical swinging of the main arm 101 (F-axis). As shown in Figure 8, a pivot pin 202 provided at the base end of the R,-axis member 103 is rotatably supported by bearings 204 held in a bearing frame 203 which is fixed on the turn table 1 51. On the both sides of the R-axis member 101 a pair of vertical swing cylinders 201 (Figure 1), are pivotably mounted at one end to the upper end of the R,-axis member via pins 208.At the other end of one of the vertical swing cylinders 201 the right hand one as seen in Figure 8 there is provided a lead screw 212 (see Figures 9 and 10) engaging with a nut 214 fixed to an inner cyclinder 215 of the vertical swing cylinder 201, and to the lower end of the lead screw 212 is fixedly secured a bevel gear 217. The other vertical swing cylinder 201 has a similar construction its lead screw being referenced 21 9. In addition, bevel gears 207 and 218 are provided at the opposite ends of a rotary shaft 206 supported by a bearing housing 205 which is provided at one end portion of the support plate 1 63. The bevel gear 207 meshes with the bevel gear 217. The drive mechanism for the right vertical swing cyclinder 201 is seen in Figure 8 and part of it is shown in Figure 9 to an enlarged scale. The lead screw 212 is provided with a rotary gear 213. A (p-axis drive motor 209 is provided on an outer cylinder 216 of the vertical swing cylinder 201 and a drive gear 210 is provided on the shaft of the (p-axis drive motor 209 and meshes with the rotary gear 213 on the lead screw 212 via an idler gear 211. The corresponding bevel gear 218 of the other vertical swing cylinder 201 is also driven in a similar manner, and thereby smooth vertical swinging movement is made possible. Detection of the amount of vertical swing is effected by a detection gear 220 fixed to the rotating pivot pin 202 at one end of the R-axis member 101 and meshing with a detection gear 222 of an encoder 221.Upon operation of this (p-axis member, as shown in Figures 8 and 10(a), the torque of the (p-axis drive motor 209 is transmitted via the idler gear 211 and rotary gear 213 to the lead screw 212.

At the same time, a torque is transmitted to the lead screw 21 9 located at a symmetric position to the lead screw 212 through the bevel gear 217, the bevel gear 207, the bevel gear 218 of the rotary shaft 206, the bevel gear 223, and hence the lead screw 219 is rotated by the same amount as the lead screw 212. Thus a drive force f5 as shown in Figure 10(b) is generated at the pinjoint portions 208 of the R-axis member 101, and since the R-axis member 103 is held by the bearings 204 at the position of the pivot pin 202, a component force f6 of the drive force f5 acts as a torque to make the R-axis member 101 swing vertically with its pivot pin 202 by a corresponding amount.

The R-axis member, O-axis member and (p-axis member are provided at what will be termed the base end portion of the main arm 101 and they jointly achieve traversing or scanning of the outer end of the main arm 101 through any arbitrary traversing or scanning points by their respective extension/retraction, rotation and vertical swing.

At the outer end of the main arm 101 is provided a sub-arm 401 for mounting a tool or the like, and various workings can be achieved by means of the tool or the like mounted at the outer end portion of the arm 401. In this sub-arm 401 are also provided a axis member, an axis member and a C-axis member for the purpose of enlargement of the scope of traversing or scanning, adjustment of attitude upon traversing or scanning, holding of a load, etc.

First, description will be made of a p-axis member. As shown in Figure 11, at the outer end portion of the R-axis member 101 is provided a p-axis member comprising an auxiliary vertical swing shaft for the purpose of correcting the attitude of the sub-arm 401. In order to support this axis member, a p-axis frame 305 is fixedly secured to the R3-axis member 105 by means of bolts 304. On this axis frame 305 is provided a projecting frame 301 bearings are provided on this frame 301 to rotatably hold a pin 303, and the sub-arm 401 is fixedly secured to the rotational pin 303. A mechanism for driving the sub-arm about the p-axis comprises a p-axis drive motor 306 mounted on the axis frame 305 and projecting from it to the side of the R3-axis member 105.A pinion 307, coupling gears 309 and 310, a worm gear311, a worm shaft312,a worm wheel 313, a speed reduction gear 314 and a drive gear 302 are all provided within the p-axis frame 305. When the p-axis drive motor 306 is actuated, the pinion 307 of the p-axis drive motor 306 rotates the worm shaft 312 via the coupling gears 309 and 310. Rotating the worm gear 311 on the worm shaft 312 causes in turn rotation of the worm wheel 313 and the speed reduction gear 314 which is provided on the same shaft as the worm wheel 313, the drive gear 302 provided on the rotational pin 303, and the torque of the motor 306 is thus transmitted to the rotational pin 303.

As shown in Figure 12, detection of the amount of vertical swing is achieved by a pinion 31 sub fixed on the worm shaft and meshing with an encoder gear 31 5a provided on the encoder 316 and thereby the encoder 31 6 is rotated. The operation of the p-axis member is to prevent the change of attitude of the sub-arm 401 relative to the header plate 3 which will be caused by the above-described operation of the (p-axis member.

As is apparent from Figure 13, if the sub-arm 401 could not swing vertically about the p-axis and it lies parallel to the header plate 3 in the horizontal state of the R-axis member 101, as the angle P changes in the clockwise direction as a result of the vertical swing of the R-axis member 101 the attitude of the sub-arm 401 would also change from the horizontal and if eventually the R-axis member 101 reaches the vertical state, the subarm 401 also becomes perpendicular to the header plate 3. Therefore, if the sub-arm 401 can swing vertically about the p-axis so as to compensate for the variation of the angle qw, then the sub-arm 401 can be always maintained parallel to the header plate 3.

Next, with regard to the rotation about the a-axis member, comprising clamp shaft 351 for rotating the sub-arm 401, as shown in Figure 11, a gear 402 is provided on the sub-arm 401 which is supported from a clamp shaft 351 via bearings (not shown). Drive mechanism for this a-axis member as shown in Figure 14 is composed of an a-axis drive motor 403, a pinion 410, an idler gear 404, a speed reduction gear 405, a reduction gear box 406 and a drive gear 407. Detection of the amount of rotation is effected by rotating an encoder 409 via a detection gear 408 which meshes with the speed reduction gear 405. The rotational operation of the sub-arm 401 is carried out in such manner that the torque of the a-axis drive motor 403 is transmitted to the gear 402 through the path of pinion 410, idler gear 404, speed reduction gear 405, reduction gear box 406, drive gear 407.In this way,-by rotating the sub-arm 401, traversing or scanning can be achieved over the entire region even up to the corner of the water chamber 2 or the vicinity of the partition wall 5, and nevertheless the traversing or scanning would not interfere with the wall of the water chamber 2 and the partition wall 5. This capability of traversing or scanning is illustrated in Figure 1 5. In this figure, a small circle 411 conceptually represents the entire configuration of the a-axis drive section, reference numeral 412 designates a scanning point, and small circles depicted by double dot chain lines represent the positioning of the a-axis drive section in the case where the sub-arm 401 is not provided, the hatched area representing the state of interference.It is to be noted that by selecting the length of the sub-arm 401 equal to either 5-fold or its multiple or 13-fold or its multiple of the pitch of the tube array (in the case of forming a square array over the traversed or scanned surface), the number of the heat transfer tube positions which can be traversed or scanned when the sub-arm 401 is rotated, is increased. This is illustrated in Figure 1 6. In this figure, the respective cross-points represent the positions of the heat transfer tubes, and in this case the length of the sub-arm 401 is selected equal to 5-fold of the pitch of the tube array, so that 12 cross-points around a circle can be scanned by rotating the sub-arm 401.

Description will now be made of the C-axis member, that is, the clamp shaft 351 which is provided at the outer end portion of the main arm 101 and which is also the base end portion of the sub-arm 401. The clamp shaft 351 is adapted to be clamped in a thin tube 7 of the header plate 3.

It is pivotably and vertically supported on the subarm 401, and it is vertically movable. A clamp mechanism at the upper end portion of the clamp shaft 351 is constructed with a tapered recess adjacent its tip. A 4-division claw 352 is provided within the tapered recess, and the outer circumference of the claw 352 is held by an O-ring 353, as shown in detail in Figure 17. At the other end of the clamp shaft 351 is provided an integral clamp piston 354. The clamp shaft 351 is assembled inside an elevating shaft 359, and the clamp piston 354 is disposed within a clamp cyclinder 358 formed by the interior of the elevating shaft 359 which is widened out to define the cylinder 358. The outer circumference of the clamp cylinder 358 forms an elevating piston 361, which is disposed within a cylinder 360.Feed of air into the clamp cylinder 358 is effected through air feed duct 364 in block 355 provided at the lower end portion of the clamp shaft 351. The air is led from duct 364 through a central bore in the clamp shaft 351 and via a port 356 extending through the clamp piston 354. Release of the clamp action is effected by an air feed pipe 357 which extends from an air feed duct 365 in the block 355 through the inside of the elevating cylinder 360 and communicates with the clamp cylinder 358. For the purpose of elevating and lowering of the shaft 359, an elevating air feed hole 362 is provided in the bottom of the cyclinder 360 and a lowering air feed hole 363 is provided at the top of the elevating cylinder 360.As a position detector, a fiber head 367 is provided at the tip of the clamp shaft 351, which fiber head is optically coupled through a fiber bundle 366 to a television camera 368 equipped with a scale plate (See Figure 18), which is in turn connected to a TV monitor 369 (See Figure 1). Accordingly, observation of the thin tube hole 7 as well as positioning of the clamp shaft 351 can be achieved easily.

The clamping operation of the clamp shaft 351 is effected after the clamp shaft 351 has been brought to a position right under the orifice of the thin tube 7 by traversing it with respect to the R-axis, 6-axis and (p-axis, respectively. Figure 1 7 shows the state where clamp has been completed.

At first, compressed air is fed from an air feed apparatus not shown through the air hole 362 into the cylinder 360. Hence the piston 361 rises, and the shaft 359 and the clamp shaft 351 rise together and enter into the thin tube 7.

Subsequently, compressed air is fed into the clamp cylinder 358 through the duct 364 and the port 356, so that the clamp shaft 351 which is integral with the clamp piston 354 is lowered, and the claw 352 is circumferentially expanded by moving over the tapered portion of the clamp shaft 351 and pressed against the tube wall.

Accordingly, the clamp shaft 351 is firmly fixed in the thin tube 7 by a frictional force. Upon releasing the clamp shaft 351 by the reverse sequence of operations to clamping, the clamp shaft 351 is raised by feeding compressed air through the unclamp air feed duct 365, so that the claws 352 are contracted by the contracting force of the O-ring 353 and disengaged from the tube wall, and then the elevating piston 361 is lowered by feeding compressed air through the lowering air hole 363, so that the clamp shaft 351 is withdrawn from the thin tube 7.

With regard to the operation of the position detector provided at the tip end of the clamp shaft 351, since the television camera 368 is coupled via a scale plate 370 to the fiber bundle 366, the lateral displacement as well as vertical distance of the clamp shaft 351 from the thin tube 7 can be ascertained by observing the position and size of the image of the orifice of the thin tube 7 on the TV monitor 369. More particularly, with reference to Figures 19(a) to 19(e), in the state shown in Figure 19(a) where the clamp shaft 351 is remote from the header plate 3, an image 374 of the orifice of the thin tube 7 is smaller than a preliminarily measured reference image size 373 of it. As the clamp shaft 351 approaches to the header plate 3, the image 374 becomes larger as shown in Figure 19(b). By reading the size of the image 374 on the scale plate 370, one can appreciate the distance from the header plate 3 to the clamp shaft 351. In addition, if the clamp shaft 351 is displaced in the horizontal direction, then the displacement will appear on the TV monitor 369 as shown in Figures 19(d) and 19(e), and therefore, the horizontal displacement of the clamp shaft 351 can also be ascertained.

Thus any arbitrary position can be traversed to or scanned by actuating the above-described R-axis member, 6-axis member, (axis member, p-axis member, a-axis member and C-axis member, respectively. However, since a fixed directional error of the support frame 11 serving as a reference surface would influence the plane of the turn table 151, there is provided means for correcting the orientation of the turn table 1 51 on the support frame 11 so as to bring it parallel to the surface of the header plate 3, and thereby the directional error of the support frame 11 is compensated for. For that purpose, rocking mechanisms, that is, a tc-axis member and a A-axis member are provided at orthogonal positions above the support frame 11 and under the turn table 1 51.With regard to the support for the tc-axis member and axis member, as shown in Figures 20 and 21, a tc-axis supporting block 459 is provided on the support frame 11 and the turn table 151 is placed above the block 459. The tc-axis member is supported by the block 459 so as to tilt the plane of the turn table 1 51. The A-axis member positioned orthogonally to the tc-axis member is supported by the support frame 11 so that it may tilt the turn table 151 by tilting the tc-axis block 459.

The tc-axis member has support frames 462 and 463 projecting from the bottom surface of the turn table 151 and rotatably supported by the block 459 via pins 460 and 461. In the direction orthogonal to the pins 460 and 461 there are provided projections on the bottom surface of the turn table 151. Links 457a and 457b and links 458a and 458b are rotatably supported from these projections via pins 451 and 452, respectively. Between the links 457a and 457b and links 458a and 458b, respectively, are fixedly secured nuts 455 and 456 to form U-shaped links.

tc-axis lead screws 453 and 454 are threadedly engaged with the nuts 455 and 456 respectively.

These tc-axis lead screws 453 and 454 are threaded oppositely to each other, and so, when they are rotated in the same direction, the nuts 455 and 456 will move in the opposite directions to each other and thus will tilt the turn table 1 51.

The drive of the lead screws 453 and 454 is effected by a drive pinion 468 of a tc-axis drive motor fixed on the block 459 and which meshes via an idler gear 467 with lead screw drive gears 465 and 466 provided at the end portions of the lead screws 453 and 454. A tilting mechanism having a similar construction is also provided for the A-axis member which serves to tilt the turn table 1 51 in the direction orthogonal to that of the axis member. The taxis member comprises pivot pins 511 and 512 provided on the tc-axis support block 459, and these pivot pins are rotatably held by bearings 513 and 514 mounted on the support frame 11.In addition, on the tc-axis hold block 459, there are provided axis lead screws 501 and 502 on a line which is orthogonal to the line connecting the tc-axis lead screws 453 and 454. The lead screws 501 and 502 threadedly engage with nuts 503 and 504 provided on links 505 and 506 respectively. The links 505 and 506 are rotatably supported by the block 459 via pins 507 and 508, respectively. The drive of the A-axis lead screws 501 and 502 is effected by drive gears 518 and 519 provided at the end portions of the A-axis lead screws 501 and 502 meshing via an idler gear 51 7 with a drive pinion 516 of a A-axis drive motor 516.

The adjustment of parallelism of the turn table 1 51 with respect to the surface of the header plate 3 is carried out by means of the tc-axis member and A-axis member in the following manner. As shown in Figures 22 and 23, the torque of the tc-axis drive motor 464 is transmitted from the drive pinion 468 to the idler gear 467, and is further transmitted to the lead screw drive gears 465 and 466 to rotate the lead screws 453 and 454. Since the lead screws 453 and 454 are oppositely threaded, the nuts 455 and 456 are displaced in the opposite directions by the same amount. Accordingly, the link mechanism consisting of the links 457 and 458, pins 451 and 452 rotates about the pivot pins 460 and 461, resulting in tilting of the turn table 151.To tilt the turn table about the axis orthogonal to the above-mentioned tc-axis also, the tc-axis block 459 is tilted as a whole by means of a similar mechanism.

The constructions and operations of the individual ones of the R-axis member,0-axis member, (p-axis member, p-axis member, a-axis member, C-axis member, tc-axis member and axis member have been described above. In a traversing or scanning operation to be achieved by making use of these respective members in combination, at first the fixed table 14 and the support frame 11 are fixed within the water chamber 2, and thereafter, in order to bring the turn table 151 on the support frame parallel to the header plate 3, adjustment of parallelism is effected by means of the rocking mechanism.In this adjustment, the tc-axis member and axis member are used as described above, and the parallelism is detected by means of the fiberscope position detector including the fiber bundle 366 and ending at the tip end of the C-axis member, i.e. of the clamp shaft 351, and the parallelism is realized according to the principle illustrated in Figure 24.More particularly, with respect to the plane including the two axis lead screws, assuming that an inclination angle P is given by (p = (p, if the distance between the header plate 3 (the orifice of the thin tube 7) and the fiber head 367 (Figure 17) is Za, and when the apparatus has been turned by 1800 is Z2, then the attitude error A(p between the support frame 11 and the header plate 3 is calcuiated, by the following formulae: : AZ=Z2-Z1 z2-z1 = tan-l ------- (if Z1 + Z2) 2R sin , Accordingly, if the tc-axis support block 459 is tilted about the A-axis so as to realize Z1 = Z2, that is, AZ = 0, then the tc-axis block 459 becomes parallel to the header plate 3. Likewise, by tilting the turn table 1 51 about the axis, the turn table 151 becomes completely parallel to the header plate 3. Through these operations, the reference surface can be established.Subsequently, by realizing the respective coordinates (R, O, (p) with the respective axis members on the reference surface, that is, on the turn table 1 51, the corresponding coordinate position can be traversed or scanned while detecting the amounts of actuation of the respective axis members.

During this traversing or scanning, since a visual monitoring apparatus is used, the orifice of the thin tube 7 can be always observed in the field of the visual monitor before clamping, and hence, some deviation in position can be corrected by means of the end of the clamp shaft 351. After the traversing or scanning has been carried out in the above-described manner, the clamp shaft 351 of the sub-arm 401 can be clamped in the thin tube 7. Thereafter, a desired operation is carried out by means of a tool or an inspection device mounted on the sub-arm 401. At this time, as noted previously, a large number of thin tubes 7 can be scanned during the rotation of the sub-arm 401 by selecting an appropriate value for the length of the sub-arm 401.In addition, upon replacement of a tool in order to effect a change of the operation, the sub-arm 401 can be brought to the vicinity of the manhole by folding the apparatus and so, the replacement of the tool can be achieved easily.

As described in detail above with reference to its preferred embodiment, by employing the manipulator for working in a heat exchanger, the manipulator can be easily fixed without entering a narrow space in a water chamber of a heat exchanger, and also the error in positioning upon fixing can be corrected, so that a reference surface for traversing or scanning can be obtained precisely. In addition, since variables corresponding to the polar coordinates are used for positioning on a particular point, the method of control is simple and the entire apparatus can be made compact and light in weight. Moreover, owing to the provision of the sub-arm, the entire region of the header plate surface can be traversed or scanned, and upon carrying out a positioning operation, the distance from the header plate as well as the lateral deviation can be measured by making use of a position detector provided in the clamp shaft. Furthermore, the manipulator can be clamped in the thin tube by means of the clamp shaft, and hence the load holding capability can be greatly enhanced. Accordingly, the manipulator is little restricted by the kind of the work, and positioning and correction of a deviation can be also achieved precisely. Also, various effects and advantages are obtained such that upon replacement of a tool mounted on a sub-arm, since the sub-arm is brought to a position near to the manhole when the apparatus is folded, the tool can be replaced easily.

Claims (14)

1. A manipulator for working in a vertical type heat exchanger, characterized in that a support frame is adapted to be disposed within a water chamber delimited by an end plate and a header plate on which vertically extending heat transfer tubes are arrayed, a base end portion of an extensible and retractable main arm is mounted on said support frame, said main arm being rotatable about said base end portion and vertically swingable about a fulcrum at said base end portion, the base end portion of a sub-arm is mounted at the outer end portion of said main arm, said sub-arm being rotatable about its base end portion and vertically swingable about a fulcrum at its base end portion, so that it is capable of being positioned parallel to said header plate, a vertically movable clamp shaft which is adapted to be inserted into a selected heat transfer tube is provided coaxially with the rotational axis of said sub-arm, and a position detector for positioning said clamp shaft so as to become coaxial with a heat transfer tube is provided on said clamp shaft.

2. A manipulator according to claim 1 and adapted to be inserted into the water chamber through an access opening of the water chamber, wherein the support frame has a pair of support arms which can be splayed after insertion of the manipulator into the water chamber.

3. A manipulator according to claim 2, wherein said support arms are also extensible for fixing said manipulator in the water chamber by jamming said support frame between side walls.

4. A manipulator according to any preceding claim, wherein said main arm comprises a plurality of telescopable sections which are slidable relatively to each other by the action of a lead screw mechanism to effect extension and retraction of said main arm.

5. A manipulator according to any preceding claim, wherein a turn table is mounted on said support frame and the base end portion of said main arm is mounted on said turn table whose rotational axis defines the rotational axis of the base end portion of said main arm.

6. A manipulator according to claim 5, wherein the plane of said turn table is adjustable by rocking relatively to said support frame.

7. A manipulator according to claim 6, wherein a tilting mechanism for said turn table enables rocking of said turn table in two orthogonal directions.

8. A manipulator according to any one of claims 5 to 7 wherein said fulcrum at the base end portion of the main arm is provided in the mounting mechanism by which the main arm is mounted on said turn table.

9. A manipulator according to any preceding claim, wherein a replaceable working or inspection tool is mounted at the outer end of said sub-arm.

10. A manipulator according to any preceding claim, wherein said clamp shaft is provided with claw means which are pneumatically actuated to cause them to grip the inside of a heat transfer tube.

11. A manipulator according to any preceding claim wherein said clamp shaft is vertically movable by a pneumatic actuating mechanism.

12. A manipulator according to any preceding claim, wherein said position detector has an optical light guide extending to the upper extremity of the clamp shaft whereby the position of a heat transfer tube in relation to the clamp shaft can be viewed.

13. A manipulator according to claim 12, wherein said optical light guide also serves to detect the parallelism of said sub-arm with said header plate.

14. A manipulator according to any preceding claim, wherein in use the support frame is secured to a support table mounted in an access opening of the water chamber.

1 5. A manipulator according to claim 4, wherein said support frame at one end hooks over a pin member fixed to said support table.

1 6. A manipulator substantially as hereinbefore described with reference to the accompanying drawings.