US3507024A

US3507024A - Method for assembling workpiece

Info

Publication number: US3507024A
Application number: US626111A
Authority: US
Inventors: Joseph E Powers; Alfred F Bastian
Original assignee: Kaiser Steel Corp
Current assignee: Kaiser Steel Delaware Inc
Priority date: 1967-03-27
Filing date: 1967-03-27
Publication date: 1970-04-21
Anticipated expiration: 1987-04-21

Description

April 21, 1970 J. E. POWERS E AL METHOD FOR ASSEMBLING WORKPIECE Filed March 27, 1967 16 Sheets-Sheet I.

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April 21, 1970 ,J, POWERS ET AL 3,507,024

METHOD FOR ASSEMBLING WORKPIECE 16 Sheets-Sheet 2 Filed March 2'7, 196'? s WH M Ewq. vo m MA W V B on ATTORNEY April 21, 1970 Y J. E. POWERS ET AL 3,507,024

' METHOD FOR ASSEMBLING WORKPIECE 16 Sheets-Sheet 5 Filed March 2'7, 196'? v 1 I 1. H... n 4 a J of n e. v s 1 iv x n. 4. a v c.

INVENTORS JOSEPH E. POWERS ALFRED F'. BASTlAN ATTORNEY I April 21, 1970 PQWERS ET AL 3,507,024 I 7 METHOD FOR ASSEMBLING WORKPIECE I 16 Sheets-Sheet 4 Filed March 27, 1%";

INVENTORS J OSEPH E. POWERS T B ALFRED:Z BVAS IAN ATTORNEY April 21, 1970 POWERS ET AL 3,507,024

METHOD FOR ASSEMBLING WORKPIECE Filed March 2'7, I967 16 Sheets-Sheet 5 INVENTORS JOSEPH E POWERS ALFRED F. BASTIAN ATTORNEY Q Q Q #2 $15 om. w o: $2 8.

April 21, 1970 J. E. POWERS ET L ,507

- METHOD FOR ASSEMBLING WORKPIECE Filed March 27, 19s", 1e Sheets Sheet a 1L. hm.

INVENTORS m I. .u 1 JOSEPH E. POWERS 9 ALFRED F. BASTIAN 11'! I i I BYaij Z ATTORNEY AprilZl, 1970 POWERS ET AL 3,507,024

METHOD FOR ASSEMBLING WORKPIECE 16 Sheets-Sheet 7 Filed March 27, 1967 INVENTORS JOSEPH E. POWERS ALFRED F. BASTIAN ATTORNEY April 21,1970

J. E. POWERS ET AL METHOD FOR ASSEMBLING WORKPIECE Filed March 27', 1967 ll Iiillh lbwl l l l 16 Sheets-Sheet 9 INVENTORS JOSEPH E. POWERS ALFRED F1 BASTIAN BYOJ ATTORNEY April 21, 1970 POWERS ET AL 3,507,024

' METHOD FOR ASSEMBLING WORKPIECE,

16 Sheets-Sheet 10 Filed March 27, 1967 INVENTOR. JOSEPH E. POWERS ALFRED F. BASTIAN ATTORNEY April 21, 1970 POWERS ET'AL 3,507,024

METHOD FOR ASSEMBLING WORKPIECE 16 Sheets-Sheet 11 Filed March 27, 19s? INVENTORS JOSEPH E. POWERS ALFRED F. BASTIAN ATTORNEY April 21, 1970 J E. POWERS ET AL I 3, 0

METHOD FOR ASSEMBLING WORKPIECE Fild March 27, 19a? 16 Sheets-Sheet 12 INVENTORS JOSEPH E. POWERS BY ALFRED F. BASTIAN ATTORNEY A ril 21, 1970 J. E. POWERS ET AL 3,507,024

METHOD FOR ASSEMBLING WORKPIECE 16 Sheets-Sheet 15 Filed March 27, 1967 INVENTORS JOSEPH E. POWERS Ohm vhm mbm wmm ATTORNEY April 21, 1 970 POWERS ET AL 3,507,024

- METHOD FOR ASSEMBLING WORKPIECE Filed March 27, 1967 l6 Sheets-Sheet 14 il lu l Il |I| g r I| 1 S O I! co v Q] q\ I": f I 5 U;

l I IHI I (O I I 0 gr I lg w m I" INVENTORS 2/ Q N JOSEPH E. POWERS LFR m I; III n B BY A ED F BASTIAN M 611i 2 m ATTORNEY April 21, 1970 POWERS ET AL 3,507,024

METHOD FOR ASSEMBLING' WORKPIECE 1e Sheets-Shet 15 Filed March 27, "19s? INVENTORS J OSEPH E. POWERS ALFRED F. BASTIAN ATTORNEY April 21, 1970 J owERS ET AL METHOD FOR ASSEMBLINGW ORKPIECE l6 Sheets-Sheet 16 Filed March 27, 1967 m wwfl mnu. BE HD7J HM w w www ATTORNEY United States Patent 3,507,024 METHOD FOR ASSEMBLING WORKPIECE Joseph E. Powers and Alfred F. Bastian, Napa, Califi,

assignors to Kaiser Steel Corporation, Oakland, 'Calif.,

a corporation of California Filed Mar. 27, 1967, Ser. No. 626,111 Int. Cl. P23p 21/00 U.S. Cl. 29-455 9 Claims ABSTRACT OF THE DISCLOSURE A method for assembling a workpiece, especially a modular workpiece, wherein a group of elements of the workpiece is oriented in predetermined angular and spaced relationship in one location; wherein these elements, with their angular and spaced relationship under control, are transferred as a group to another location where they are assembled in said predetermined relationship with another element of the workpiece; and wherein the assembled elements are interconnected.

BACKGROUND OF THE INVENTION The present invention pertains to a method for assembling a workpiece and more particularly to a method and apparatus for producing modular workpieces by positioning certain parts of each workpiece in predetermined positions against another part of the workpiece and for holding all the parts together while they are being interconnected in assembled relation.

Although the invention has broader utility, it is conveniently described in connection with the assembly of certain parts of a segment for a liner of a tunnel ring. As used for underground railroads, for example, many such tunnel rings are attached end-to-end to form a long, continuous tunnel, which, as is well known, prevents collapse of the surrounding earth. Each tunnel ring is usually made of steel and includes a plurality of arcuate reinforced segments. In turn, each segment is composed of an arcuate channel, end plates inserted in and attached to opposite ends of the channel, and T bars inserted in and attached to the channel between the end plates.

In order to constitute a strong modular segment, that is, one which is interchangeable with other segments and which will fit with several other segments to make up a complete ring, the end plates and T bars must be placed in intimate engagement with, and in precise positions within, the channels. Moreover, especially in view of the demand for such tunnels, the assembly of such segments must be performed with a minimum of time, labor and expense.

The prior methods for assembling tunnel ring segments are not suited to mass production of the segment because they depend too much on manual operations and are therefore relatively slow and subject to human error. For example, as disclosed in the Fine et al. U.S. Patent No. 2,366,961, it has been known manually to place the individual parts (skin plate, side flanges, end plates and T bar) of a tunnel ring segment in a jig, to clamp the parts in the jig, and thereafter to rotate the jig (which is mounted on trunnions for such purpose) into various positions of access for a welder. It is apparaent that such a manual operation is not conducive to producing tunnel ring segments or modules at a fast rate because the rate and manner of placing the parts in the jig is dependent on the human operator.

SUMMARY OF THE INVENTION The present invention avoids the shortcomings of the prior art by providing a method and for assembling several parts of a structural member or other workpiece (which is composed of certain auxiliary parts that must be fitted and attached in a predetermined manner to a main part) by precisely arranging the auxiliary parts separately from the main part in the manner in which they will eventually fit the main part, and then by moving the auxiliary parts as a group and with their relative positions and angles under control into fitted relationship with the main part. By following the concepts of the present invention, not only can the production rate be vastly increased but also the use of cumbersome and expensive jigs can be avoided. Moreover, since each workpiece, i.e. tunnel ring segment herein, is a mirror-image of every other workpiece the parts can be fitted together more intimately and with greater precision.

Accordingly, it is an object of the present invention to provide a method and apparatus for assembling several parts of a workpiece by arranging certain auxiliary parts of the workpiece in a predetermined manner in one location and then moving the auxiliary parts as a group, while maintaining control over their arrangement, into fitted relationship with another part of the workpiece.

Another object is to provide a method for assembling the parts of a workpiece, such as a tunnel ring segment, on a mass production basis.

Another object is to produce segments or modules of uniform construction and dimensions so that a number of the segments can be interfitted.

Another object is to pick up a plurality of elements which are in a certain relationship to each other, and to move them out of such relationship but under such control that they can readily be returned to said certain relationship.

Another object is to minimize the time and expense involved in precisely and intimately interfitting the parts of a tunnel ring segment, or other workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan of an apparatus embodying the principles, and capable of carrying out the method, of the present invention.

FIG. 2 is a longitudinal vertical section taken on line 22 in FIG. 1.

FIG. 3 is a transverse vertical section taken at a position indicated by line 33 in FIG. 1 with entry and exit conveyors for the apparatus included.

FIG. 4 is an end view of a tunnel ring the segments of which can be made by the method and apparatus of the present invention.

FIG. 5 is an enlarged plan of one of the segments in the tunnel ring of FIG. 4.

FIG. 6 is a longitudinal section taken on line 66 in FIG. 5.

FIG. 7 is an enlargement of a portion of FIG. 3 showing an assembly fixture of the subject apparatus in greater detail with conveyor sections of the fixture shown in level positions in full lines and in declined positions in dash lines.

FIG. 8 is an end elevation of the fixture shown in FIG. 7 in its horizontal loading and unloading position and with the channel of a tunnel ring segment being held therein.

FIG. 9 is also an end elevation of the assembly fixture of FIG. 8 but with the fixture in one of its tilted positions.

FIG. 10 is a transverse section taken on line 10--10 in FIG. 7 but with a tunnel ring segment being held in the fixture.

FIG. 11 is a transverse vertical section taken at a position indicated by line 11-11 in FIG. 2 showing a loading jig of the subject apparatus but with T bars and end plates shown in dash lines in the jig.

FIG. 12 is atop plan of the apparatus shown in FIG. 11 but with parts broken away and with the T bars and end plates omitted.

FIG. 13 is a vertical section taken on line 13-13 in FIG. 11.

FIG. 14 is an enlargement of a portion of FIG. 3 showing a carrier of the subject apparatus partially broken away and with certain hidden parts being indicated in dashed lines.

FIG. 15 is an end elevation, partially broken away and showing certain hidden parts in dashed lines, as seen from a position at the right of the carrier illustrated in FIG. 14.

FIG. 16 is an enlarged side elevation of an end plate pick-up unit which is part of the carrier shown in FIG. 14 and showing an end plate held in the unit.

FIG. 17 is an end view of the pick-up unit shown in FIG. 16 as viewed from a position indicated by line 1717 in FIG. 16 but with the end plate omitted.

FIG. 18 is a top plan of the pick-up unit shown in FIG. 16.

FIG. 19 is a top plan of a paddle frame constituting part of the end plate pick-up unit of FIG. 16, although reduced somewhat in scale.

FIG. 20 is a side elevation of the paddle frame shown in FIG. 19.

FIG. 21 is an end view of the frame shown in FIGS. 19 and 20.

FIG. 22 is a side elevation of a clamp frame constituting a part of the end plate pick-up unit shown in FIG. 16, although reduced somewhat in scale.

FIG. 23 is an end view of the clamp frame shown in FIG. 22.

FIG. 24 is a top plan of the clamp frame shown in FIG. 22.

FIG. 25 is an enlarged side elevation of a T bar pick-up unit constituting a part of the carrier shown in FIG. 14 and with a T bar being shown held by the unit.

FIG. 26 is a view taken on line 26-26 in FIG. 25.

DETAILED DESCRIPTION With particular reference to FIGS. 1, 2 and 3, an apparatus embodying the present invention includes a main frame 30, a loading jig 32 mounted in the main frame at a loading station 34-, first and

second assembly fixtures

36 and 38 mounted in the frame at first and

second assembly stations

40 and 42, in spaced relation to each other on opposite sides of the loading jig, and a carrier 44 mounted on the frame for movement between a loading position, not shown, over the loading jig and releasing positions located alternately over the first and second assembly fixtures, one of the latter positions being illustrated in FIGS. 1, 2 and 3. As mentioned above, the method and apparatus of the present invention are particularly suited for assembling parts of a workpiece such as a tunnel ring segment 50 as illustrated in FIGS. 5 and 6, and before describing the details of the jig, fixture and carrier, reference is made to this segment.

A plurality of these arcuate segments or modules 50 are interconnected in a tunnel ring 52, as shown in FIG. 4. The tunnel ring is circular so that the radii of curvature of the segments intersect in the center of the ring. Each tunnel ring segment (or main part or piece as hereinafter sometimes referred to) includes an elongated arcuate channel 56, a pair of rectangular end plates 58, and a plurality of T bars (the end plates and the T bars being sometimes referred to as reinforcing or auxiliary parts or pieces). The channel has a pair of spaced parallel side flanges 62 welded to opposite side edges of a skin plate 64 Whose concave inner surface 65 has a predetermined radius of curvature. The reference to various parts as being either inner or outer is with respect to the center of the tunnel ring, this center being regarded as the innermost part of the ring. Each end plate has an outer edge 68 intimately engaging the inner surface of the skin plate, a pair of side edges intimately engaging the inside surfaces of the side flanges, and an inner edge 72 generally in same plane as the inner edges of the side flanges. Each T bar has a stern plate 76, which has an outer edge 78 intimately engaging the inner surface of the skin plate and side edges 80 in intimate engagement with the inside surfaces of the side flanges, and a flange plate 82 perpendicular to its respective stem plate and likewise engaging the inside surfaces of the side flanges, it being noted that the flange plate of the T bar is spaced somewhat outward, along the radius of the tunnel ring, from the inner edges of the side flanges.

As disclosed herein, the main task of the subject method and apparatus is to assemble the channel 56, the end plates 58 and T bars 60- into a tunnel ring segment 50, since all of these parts are initially separate from each other. Briefly stated, this task is accomplished as follows: the channel 56 is positioned on one of the assembly fixtures, as 36 and the end plates 58 and T bars 60 are initially placed in the loading jig 32. The carrier 44 picks up the end plates and T bars from the loading jig, in the same orientation as they were in the jig, transfers them from the jig to the

assembly station

40 or 42 where the channel is located, orients the channel relative to the plates and bars, inserts the latter in the channel in said orientation, and once they are held in the channel by the assembly fixture, releases them and returns to the loading station 34 to repeat the cycle of operation with the alternate assembly fixure 38. The assembled channel, end plates and T bars are held together in the assembly fixture until they are at least temporarily secured together, as by welding, and thereafter the interconnected channel, plates and T bars (which may be thought of as a package) are discharged from the apparatus as a tunnel ring segment (although additional welding and machining are required).

Main frame In more detail, the main frame 30 is positioned on a foundation (FIG. 3) providing a horizontal slab 92 and a vertical peripheral wall 94. The main frame includes a base 98, lower longitudinal I-beams embedded in the slab and extending lengthwise of the apparatus, pairs of transversely extending I-beam 102, opposed pairs of

columns

106, 108, 110, and upper longitudinal I-beams 112 connected to the columns on each side of the main frame. Further, tracks 116 (FIG. 3) are supported on and secured to the upper I-beams 112. Latch plates 118 are mounted on the upper I-beams, on the inside surfaces thereof, between each pair of columns and each latch plate has an inwardly opening socket 120. In addition, a pair of stop plates 122 project inward from each upper I-beam respectively adjacent to the columns and slightly below the latch plates. All of the latch plates are in a common horizontal plane and all of the stop plates are likewise in a common horizontal plane which is slightly below the plane of the latch plates.

Assembly fixtures The assembly fixtures 3'6 and 38 at the assembly stations 4%) and 42 are identical and thus only one (i.e. 36) will be described in detail with the same reference numerals being applied to the same parts on each fixture.

The assembly fixture is provided to support the channels 56 while the end plates 58 and T bars 60 are being inserted therein and to hold the channel, the plates anl T bars in assembled relation while they are being at least temporarily interconnected, as by tack welding. The assembly fixture (FIG. 7, 8, 9, includes a pair of standards 130 secured to the main frame with each standard having a pair of upwardly opening notches 132 therein, it being noted that each notch in each standard is in horizontal alignment with a notch in the other standard. The assembly fixture also has U-shaped box frame 134 which includes a central beam 136 and a pair of legs 138 projecting from the central beam and terminating in spaced support arms 140. Stub shafts 142 project endwardly from each leg and individually pivotally rest in the notches of the standards.

The assembly fixture 36 also includes a plurality of C frames 146 having central portions 148 rigidly connected to the U frame 134 and individually located in radial planes which intersect in a common axis A above the assembly fixture, as is viewed in FIG. 3. It will be noted that the C frames are substantially equally spaced lengthwise of the central beam 136, and in the disclosed embodiment, there is a central C frame, an inside pair of C frames on opposite sides of the central C frame and in slight angular relation thereto and an outside pair of C frames spaced outward from the first pair and at a still greater angle with respect to the central C frame. Each C frame also has a pair of legs 150 (FIGS. 8, 10) a central ledge 152, a pair of side ledges 154, and notches 156 between the ledges. Blocks 158 are secured to the ledges and are in a common plane with respect to their individual C frame. Insofar as the blocks on all of the C frames are concerned, they are generally tangent to a curved surface having as its center the axis A referred to above.

A clamp 164 (FIG. 10) is associated with each C frame 146. Each clamp includes a pad 166 mounted on one of the legs 150 of each C frame above the adjacent block 158 and adjustable toward and away from the center of the C frame and a cylinder 168 mounted on the opposite leg of such C frame and including a piston rod 170 axially aligned with its associated pad and movable toward and away from the same upon actuation of its respective cylinder. The C frames are intended to support the channels 56 with skin plate 64 resting on the blocks 158 on all of the frames and with the piston rods 170 engaging one of the side flanges and pressing the other side flanges against the pads 166, as illustrated in FIGS. 8, 9 and 10.

The assembly fixture 36 also includes cradling conveyer sections 176 each including a rectangular frame .178 having opposite ends 180 and opposite sides 182 and a plurality of rollers 184 journalled in and extending between the sides of the frame. The conveyer sections are pivotally supported in opposite ends of the U frame 134 by pivot pins 186 (FIGS. 7 and 8) which project from the legs 138 into opposite sides 182 of the frame. The conveyer sections are thus pivoted for movement between substantially coplanar positions (also horizontal when the U frame 134 is positioned with its legs 138 projecting upward as in FIG. 7), as shown in full lines in FIG. 7, and obtusely angulated positions (also declined when the legs 138 project up), as shown in dashed lines in FIG. 7. In the angulated positions of the conveyer sections, the sides 182 of the frames 178 are received in the notches 156 of those C frames 146 that are on opposite sides of the central C frame; for this purpose, it is to be noted that two relatively large gaps are provided between certain rollers 184 to permit each conveyer section to fit within the notches and to avoid interference between the rollers and the central blocks 158. When the U frame has its legs 138 pointing upward and when the conveyer sections are in their coplanar positions, the conveyer sections can support a channel 156 with its arcuate skin plate 64 resting on the rollers; when the U frame legs point upward and the conveyer sections are pivoted into their angulated positions, they constitute a cradle along the which the channel can move by gravity (or be moved by an outside force) for the purpose of bringing the axis of curvature of the channel into coincidence with axis A. In their lowermost angulated positions, the sections lower the channel so that its skin plate rests on the blocks 158 and its side flanges 62 are between the pads 166 and the piston rods of the clamps 164. As an additional feature, the blocks 158 can include adjustable wedge pieces, not shown, to wedge the blocks tightly against the skin plate.

For pivoting the conveyer sections 176 between their coplanar and angulated positions, cradling cylinders 190 are pivoted within the central beam 136 of the U frame 134 and project upwardly through openings in the beam and have piston rods 192 pivoted to mounting pieces 194 on the frames 178 of the conveyer sections. When the cylinders are extended, they support the conveyer sections in coplanar positions and when they are retracted they move the conveyer sections in their angulated positions.

It should be noted at this point that the channels 5 6 are fed into the

assembly fixtures

36 and 38 on respective entry conveyers 19S, and they are removed from the assembly fixtures on exit conveyers 196, the exit and entry conveyers as well as associated assembly fixture in its upright position defining a conveying path along which the channel and segment 50 are moved. Also in FIG. 1, a conveyer 198 is shown for conveniently moving the end plate and T bars into a position adjacent to the loading jig 32.

The assembly fixture 36 is intended to be pivoted about the stub shafts 142 and for this purpose posts 200 are provided on the main frame 30 inwardly (FIG. 3) of the columns 106, it being noted that each pair of posts is spaced apart (FIG. 8) by about the width of the assembly fixture as measured by the width of one of the C frames 146. Tilting cylinders 202 have lower ends connected to the posts by pivot pins 204 and have piston rods 206 individually connected to the stub shafts 142 by collars 208. When both of the stub shafts 142 are in their respective notches 156 and the

legs

138 and 150 of the U and C frames 134 and 146 are pointing generally upward, the assembly fixture is in a conveying position. By expanding one set of tilting cylinders, on one side (as distinguished from the ends) of the assembly fixture, the fixture is tilted into a work position (FIG. 9) wherein the

legs

138 and 150 are directed outward in a generally horizontal direction; the assembly fixture can be returned to its conveying position by retracting this set of cylinders. By expanding the other set of cylinders, the assembly fixture can be tilted into another work position with the legs pointing outward on the opposite side from that shown in FIG. 9. The advantages of this arrangement are the stability of the assembly fixture when it is in a conveying position because the four stub shafts rest in four notches at the ends of the fixture and the accessibility to workmen, such as welders, of the assembled segment 50 when the assembly fixture is tilted into one of its two work positions.

Loading jig In order to locate the end plates 58 and T bars 60 in positions they will eventually assume within a channel 56, the loading jig 32 (FIGS. 11, 12 and 13) includes a pair of upstanding posts 230 mounted on I-beams 232 which extend between the pair of transverse I-beams 102 at the loading station 34. Cross-pieces 234 are secured to the tops of the posts, and a pair of spaced parallel vertical mounting walls 238 are secured on opposite sides of the cross-pieces and project upward therefrom. The mounting walls have upper edges 240, each having a series of fiat portions 242, and intermediate and end openings in the flat portions. With reference to FIG. 11,

intermediate, right end, and left end inserts 248, 250 and 252 are positioned in the openings of the upper edges 240 and are secured to the mounting wall. As used herein, the terms left and right are merely convenient designations for describing the method and apparatus :as shown in the drawings and as such have no limiting effect on the invention. The intermediate inserts have U-shaped slots 254 therein and the end inserts have L-shaped open slots 256 therein, it being noted, with reference to both walls 238, that there are opposed pairs of horizontally aligned slots. The left end and intermediate inserts are adjustable for making different sizes of segments 50, but the right end insert is stationary. It is also to be noted that the slots are located in radial planes which intersect in axis A (above and off the sheet in FIG. 11). Both the angular relationship and spacing of the slots in the loading jig 32 are the same as the angular relationship and spacing of the C-shaped frames 146 of the assembly fixture 36 (and 38 as is believed understood). This angular relationship and spacing correspond to the desired manner in which the end plates 58 and T bars 60 are to fit within a channel 56, and thus the

slots

254 and 256 respectively releasably receive a plurality of T bars and end plates; in the disclosed embodiment, the loading jig is constructed to receive three T bars and two end plates with the stem plates 76 of the T bars and the entire end plates disposed in the respective radial planes of the slots. As illustrated in FIG. 1, the

slots

254 and 256 of the loading jig 32 are preferably individually aligned longitudinally of the main frame 30 with corresponding C frames 14-6 of the

assembly fixtures

36 and 38.

The loading jig 32 also includes an auxiliary wall 260 (FIGS. 12 and 13) supported on one of the mounting walls 238 in spaced parallel relation thereto by brackets 262 and having an upper edge 264 which is higher than the upper edges 240 of the mounting walls. Adjustable stops 266 are mounted in the auxiliary wall in individual alignment with the pairs of aligned

slots

254, 256. The ends of the end plates 58 and T bars 60 engage the adjacent stops 266 when the end plates and T bars are disposed in the slots thereby correctly to locatethe end plates and T bars transversely of the loading jig. These stops 266 can be adjusted so as to be spaced closer to or farther from the mounting Walls.

Carrier The carrier 44 (FIGS. 1, 3 and 14 through 26) includes several significant features of the present invention. The carrier is provided with a frame 280 having a pair of vertical side walls 282 each of which has an intermediate portion 284 and a pair of end portions 286, the latter being interconnected by vertical end walls 288. Boxshaped trucks 292 are secured to and extend between adjacent end portions 286 of the side walls and project endwardly beyond the end walls 288. With particular reference to FIGS. 1 and 14, axles 294 are journalled in the trucks, and wheels 296 on the axles ride on the tracks 116 and thereby support the carrier for movement lengthwise of the main frame 30 into positions over the loading jig 32 and the

assembly fixtures

36 and 38 at the loading and assembling

stations

34, 40 and 42.

For driving the carrier 44 along the tracks 116, a connecting rod 300 is journalled in the frame 28 extends between the trucks 292, andis connected by couplings 302 to an axle 294 in each truck. A motor 306- is mounted on one of the trucks and is connected by a drive linkage, generally indicated by the number 308, to one of the axles thereby to rotate the connecting rod and the axle in the other truck. Thus, by energizing the motor, the carrier is propelled in either direction along the tracks.

In order precisely to locate the carrier 44 in the loading and assembling

stations

34, 40 or 42, latching cylinders 310 are mounted on the end walls 288 of the frame 280 and provide latching rods 312 movable endwardly of the frame into and out of the adjacent sockets of the latch plates 118 when the carrier is properly positioned in any one of the stations, as illustrated in FIG. 14. When the latching rods are within the sockets, the carrier is locked against movement lengthwise of the main frame 30. In addition, an L-shaped limit block 320 is secured to each end wall 288 and includes a horizontal flange 322 which is positionable under the adjacent stop plates 122 when the carrier is latched in any of the stations. This limit block also includes a vertical flange 324 which confronts the vertical edges of the stop plates when the carrier is latched as described. The relationship between the limit blocks and their associated stop plates is such as to limit upward movement of the carrier as well as movement of the carrier transversely of the mam frame. Fluid power for the latching cylinders is obtained from a power unit 330 mounted on top of the carrier frame 280'.

With particular attention being directed to FIGS. 3 and 14, it will be noted that the carrier 44 includes a plurality of T bars, pick-up

units

340, 342 and 344 and a pair of end plate pick-up

units

346 and 348, these units being mounted in the carrier frame 280 and individually disposed along generally radial planes. When the carrier is located in either

assembly station

40 or 42, the radial planes CTl, CT2, and GT3 of the T bar units are the same as the radial planes in which the central and inside C frames 146 are located, and when the carrier is located in the loading station 34, the T 'bar radial planes are the same as the planes in which the slots 254 are located. The end plate units are transversely adjustable into and out of similar coplanar relationship with the outside C frames and outside or end plate slots 256.

Each end plate pick-up unit as 346 (FIGS. 14, 16, 17, and 18) includes a rectangular mounting frame 356 having a pair of spaced parallel sides 358 provided with inwardly opening grooves 359, a forward end 360 and a rearward end 362. Adjustable stops 364 are provided in the forward end for movement inward and outward of the frame. Each end plate pick-up unit as 346 also includes a paddle frame 370 (FIGS. 16 through 21) ncluding a slide plate 372 coplanar with the mounting frame 356 and having side edges 374 slidably received in the grooves 359, a front edge 376 in spaced parallel relation to the forward end 360 of the mounting frame, and a rear edge 378 in spaced parallel relation to the rear end 362 of the mounting frame. The slide plate has a generally U-shaped opening 380- therein with a substantial portion of the opening existing in the forward portion of the plate and portions projecting into the rear half of the plate.

With continued reference to the paddle frame 370, a support plate 384 is secured to the slide plate 372 centrally thereof and projects both upward and downward in right angular relation to the slide plate, it being noted that the support plate is disposed transversely of the slide plate. The support plate has a front face 386, a rear face 388, a pair of slots 390 open at the lower edge of the support plate and extending upward therein above the slide plates (FIGS. 17 and 21), and slideways 392 on opposite sides of each slot. The three portions of the support plate which project below the slide plate are hereinafter collectively referred to as a paddle 396. To impart rigidity to the support plate, forward and

rear gussets

404 and 406 extend between the support plate 384 and the slide plate 372, and a front rib 408 extends transversely between the front gussets. From what has been described so far, it will be understood that the paddle frame 370 is movable lengthwise of the mounting frame 356 between a workpiece engaging position, with the front edge 376 of the slide plate relatively close to, and perhaps engaging, the stops 364, and a retracted position with this front edge spaced farther from the stops than when the paddle frame is in the workpiece engaging position. A primary