Tube Expansion Apparatus

Abstract

A tube expansion apparatus which includes a vertically supported frame, a main ram and a main cylinder which is affixed to the frame and has a piston which is affixed to a main ram guide carriage and reciprocally drives the latter and hence the main ram. The main cylinder is disposed such that its piston, upon being extended, moves vertically downwardly. This piston rather than being affixed to the main ram is affixed to main ram guide carriage to forcibly urge it and the main ram downwardly, the arrangement being such that the height of the tube expansion apparatus can be substantially reduced in comparison to that of a conventional vertical tube expander.

Description

This invention relates to an improved tube expansion apparatus for radially expanding a portion of a tubular member for the purpose of uniting it with a structural part having a performed aperture for receiving the tubular member.

Tube expansion apparatus of the above type generally are simply referred to as expanders, and are used to form plate-fin heat exchangers for air conditioners, refrigeration equipment and other heat exchange equipment. These plate-fin heat exchangers will hereinafter be referred to as coils. Most expanders are of the vertical type, however, some are horizontal.

The height of a vertical expander, or the length of a horizontal expander, generally can be determined approximately by multiplying the maximum length of the largest coil to be formed with the expander by a factor of 3, and then adding 7 feet to the result. For example, if the largest coil to be formed has a length of 48 inches, using the above rule of thumb, it can be determined that the expander will be approximately 19 feet in height, or length.

Most coil fabricators prefer vertical expanders since they require much less floor space than a horizontal expander. If large coils are to be formed, however, the height of the necessary vertical expander can present a problem unless the plant in which the expander is to be set up has exceptionally high ceilings. It is frequently found that a special penthouse has to be constructed to accommodate the vertical expanders.

Accordingly, many manufacturers have been trying to find a way in which to reduce the height, or length, of these expanders. So far, however, those expanders which have been designed are generally unsatisfactory, for one reason or another.

It is therefore an object of the present invention to provide a new and improved expander of a design providing a substantial reduction in height, or length, in comparison to presently available conventional expanders.

Another object is to provide an improved expander of the above type wherein the height, or length, reduction can approximate 30 percent.

Still another object is to provide an improved expander of a reduced height which will allow the use of a vertical expander in applications formerly reserved for horizontal expanders.

A still further object is to provide an improved expander which is substantially reduced in height, or length, in comparison to conventional expanders, and which is of an improved mechanical design which, among other improvements, provides better guiding and alignment of the working surfaces of the expander.

A still further object is to provide an improved expander of a reduced height having a construction such that the same "push type" hydraulic cycle with simple regenerative control used on conventional expanders can be used.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exmplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

FIG. 1 is a front plan view of an expander exemplary of the invention;

FIG. 2 is a side plan view of the expander of FIG. 1;

FIG. 3 is a rear plan view of the expander of FIGS. 1 and 2;

FIG. 4 is a side plan view of the expander of FIG. 1, illustrating the main ram in its lowered position;

FIG. 5 is a top plan view of the expander of FIG. 1; and

FIGS. 6 and 7 are schematic diagrams of the hydraulic and air systems of the expander.

Similar reference characters refer to similar parts throughout the several views of the drawings.

Referring now to the drawings, an expander 10 is shown including, generally, a frame 12 which is vertically supported upon a platform base 13; a main ram 14, a work sizing head 15 and a stop block 16 which are all slidably affixed to the frame 12; a nest tooling plate 17 which is affixed to the frame 12, at a fixed height above the platform base 13; and a main cylinder 18 which is affixed to the frame 12 and has a piston 19 which is affixed to a main ram guide carriage 20 and reciprocally drives the latter and hence the main ram 14. The expander 10 further includes hydraulic means and motor means which are shown schematically in FIG. 6, for operating it in the manner described below.

The frame 12 of the expander 10 is formed of two vertically supported, parallel, spaced-apart frame members 25 and 26 which preferably are heavy steel plates. These frame members 25 and 26 are affixed, as by welding, to the platform base 13, and are fixed in parallel, spaced apart relationship by means of a number (six, as shown) of heavy gauge steel tubular spacers 27 (FIG. 2) and two rectangular steel bars which serve as mounting for the main cylinder 18. As can be best seen in FIGS. 1 and 5, alignment plates 28 and 29 are integrally fixedly secured to the front edges of these frame members 25 and 26. The alignment plates 28 and 29 extend from the tops of the frame members 25 and 26 and terminate just above the nest tooling plate 17, and further extend laterally on each of the opposite sides of the respective frame members so as to form a pair of inner guide tracks 30 and 30' and a pair of outer guide tracks 31 and 31'.

The main ram 14, as can be best seen in FIGS. 1, 2 and 5, includes a vertically disposed back plate 34 which has a ram plate 35 secured thereto in a fashion such as to extend horizontally outwardly therefrom. This ram plate 35 is further supported by means of a pair of spaced-apart support plates 36 and 37. A rod tooling plate 21 supporting a number of expander rods 22 is removably secured to the underside of this ram plate 35.

The back plate 34 of the main ram 14 forms an integral part of the main ram guide carriage 20 which is generally rectangular-shaped and includes a pair of carriage side frames 39 and 40 which are fixedly secured in parallel, spaced relationship by means of a carriage cross frame 41 and the back plate 34 affixed to the lower and upper ends thereof, respectively. This main ram guide carriage 20, as can be best seen in FIG. 5, is of a width substantially corresponding to the width between the edges of the inner guide tracks 30 and 30', and has guide rollers 42 affixed to the carriage side frames 39 and 40 near the upper and lower ends thereof which engage the opposite sides of the inner guide tracks 30 and 30'. Brass slides 32 are affixed on the outside surfaces of the carriage side frames 39 and 40 adjacent to and slidably bearing against the inner edges of the alignment plates 28 and 29. There are two brass slides 32, mounted top and bottom of each of the two carriage side frames 39 and 40, and these brass slides 32 provide lateral stability and assure alignment of the main ram 14 during its vertical travel. The guide rollers 42 function to align and guide the main ram guide carriage 20 as the latter is reciprocally raised and lowered by the hydraulic cylinder 18.

The main cylinder 18 is not aligned atop the main ram 14 as it is with most conventional expanders but is, instead, offset therefrom and is disposed between the frame members 25 and 26. The main cylinder 18 is vertically disposed in a position such that its piston 19, upon being extended, moves downwardly, and is fixedly secured to and supported by the spacers 27 parallel to and substantially centrally between the frame members 25 and 26. It will be appreciated that more than one main cylinder can be provided, if the capacity of the expander is such that two or more are necessary for its operation. The piston 19 of the main cylinder 18 rather than being affixed to the main ram 14 is affixed to the carriage cross frame 41. Accordingly, when the hydraulic cylinder 18 is operated to extend its piston 19, the latter bears on the carriage cross frame 41 so as to forcibly urge it and hence the main ram guide carriage 20 and the main ram 14 affixed to it downwardly. This arrangement permits the height of the vertical expander 10 to be substantially reduced in comparison to that of a conventional vertical expander, as explained more fully below.

The work sizing head 15, as can be best seen in FIGS. 1, 2 and 5, includes a generally rectangular-shaped stripper plate 50 and a final expander plate 56. The stripper plate 50 has a rectangular opening in its bottom surface which is covered by a detachable stripper tooling plate 49. This tooling plate 49 has a number of strippers 23 removably retained therein.

The final expander plate 56 nests within a recessed cavity or channel 51 in the top surface of the stripper plate 50, and also has a detachable final expander tooling plate 62 on its underside. This tooling plate 38 has a number of final expanders 63 removably retained therein.

Spaced guide roller brackets 52 and 53 are provided at the rear portion of the stripper plate 50, and each of these guide roller brackets 52 and 53 supports four guide rollers 54 which are positioned to engage the opposite sides of the outer guide tracks 31 and 31', to align and to guide the work sizing head 15. For each set of front and rear guide rollers 54, there is a brass slide 71 on the inside surface of each guide roller bracket 52 and 53. These brass slides 71 bear slidably against the outer edges of the alignment plates 28 and 29, preventing side sway of the work sizing head 15.

The final expander plate 56 has a pair of sprockets 57 caged atop it, each of which has a hub (not shown) which is keyed into a keyslot (not shown) in respective ones of a pair of coil height adjustment screws 58. The coil height adjustment screws 58 pass through a clearance hole in the hubs of sprockets 57. Thus the adjustment screws 58 and the sprockets 57 will rotate together, with the sprockets 57 caged atop the final expander plate 56. Below the sprockets 57 are brass nuts (not shown) which are recessed into the final expander plate 56. These nuts are threaded internally and fastened inside a final plate recess. Power is supplied to rotate the sprockets 57 by a reversible motor (not shown), through a drive sprocket and idler sprockets to provide chain guiding for a drive chain which is driven by the motor and coupled to the sprockets. The sprockets 57 rotate the adjustment screws 58, which in turn raises or lowers the adjustment screws, both by the same increment.

As indicated above, the rod tooling plate 21 which supports a number of expander rods 22 is affixed beneath the ram plate 35. These expander rods 22 extend vertically downwardly and pass through the final expander plate 56, the final expander tooling plate 62, the final expanders 63, the stripper plate 50, the stripper tooling plate 49 and the strippers 23, as the main ram 14 is lowered. These expander rods 22 preferably also are extended through one or more rod alignment tooling plates 48 removably affixed to guide plate holders 43 and 44 which serve to support and to align them. These guide plate holders 43 and 44 are supported by means of support rods 45 and 46, respectively, which are fixedly secured to them and are extended through apertures (not shown) in the ram plate 35. The ends of the support rods 45 and 46 have enlarged stop nuts 47 affixed to them which will not pass through the apertures in the ram plate 35 so that the guide plate holders 43 and 44 normally are hangingly supported. When the main ram 14 is lowered, these guide plate holders 43 and 44 stack up atop the final expander plate 56, as illustrated in FIG. 4, and the support rods 45 and 46 merely slide or pass through the apertures in the ram plate 35. When the operation is reversed, the ram plate 35 engages the enlarged stop nuts 47 and raises or lifts the guide plate holders.

A pair of guide rods 59 and 60 are slidably extended through apertures (not shown) in the stripper plate 50, the guide holder plates 43 and 44, and the ram plate 35. The upper and lower ends of these guide rods 59 and 60 have enlarged stop nuts 61 on them which will not pass through the apertures (not shown) in the ram plate 35 and the stripper plate 50 while the final plate 56 is affixed to them such that it is vertically raised and separated from the stripper plate 50 a distance on the order of one inch when the main ram 14 is raised to its upper vertical limit. This vertical movement of the final plate 56 functions to release the stripper plate locks 64 which are pivotally affixed to the stripper plate 50, on each of the opposite sides thereof. These stripper plate locks 64 normally are biased so that the locking notches 65 thereon will lockingly engage beneath the lower edge of the lateral lock extensions 66 of the stop block 16 when the work sizing head 15 is lowered during the final sizing of the coils being formed. The arrangement further is such that the work sizing head 15 is held locked in its final sizing position until the expander rods 22 and the final expanders 63 are withdrawn from the coils, at which time the final plate 56 is raised by the guide rods 59 and 60. The final plate 56 upon being raised physically engages the arms 67 of the stripper plate locks 64 to pivotally operate them to disengage the locking notches 65 from the lock extensions 66. When the enlarged stop nuts 61 on the lower ends of the guide rods 59 and 60 engage the bottom side of the stripper plate 50, the latter is physically raised and the complete working sizing head is now returned upward.

The stop block 16 is a generally rectangular-shaped block having lateral lock extensions 66 on each of its opposite ends. The stop block 16 is slidably lockably affixed beneath the work sizing head 15, across the front of the alignment plates 28 and 29, by means of friction plate locks 68 which are adapted to be frictionally clamped to the outer guide tracks 31 and 31'. These friction plate locks 68 each include a lock plate 69 which is disposed to engage the back surface of the guide tracks 31 and 31', to frictionally clamp the latter between these lock plates 69 and a rear surface of the stop block 16 as the threaded bolts 70 are tightened, as can be best seen in FIGS. 2 and 3.

The stop block 16, in addition to functioning to lock the work sizing head 15 in its final sizing position while the expander rods 22 are being withdrawn from the coils, functions to set or establish the height of the coils being formed. The stop block 16 also provides a secondary safety feature in that it prevents the work sizing head 15 from accidentally dropping during set up of the expander 10. In each case, it functions in generally the same fashion, by stopping the downward movement of the work sizing head 15.

The coil height adjustment screws 58 function in conjunction with a pair of air cylinders 72 affixed to the nest tooling plate support 73 to initially support the work sizing head 15 as the main ram 14 is being lowered, to prevent premature crushing of the coils being formed. The coil height adjustment screws 58 are adjustably threadably positioned so that the ends thereof seat atop the pistons 74 when the latter are fully retracted and the work sizing head 15 is engaged with the stop block 16. The latter, of course, previously has been adjustably positioned to set or establish the final coil height. These coil height adjustment screws 58, as indicated above, both are simultaneously adjusted by means of a reversible motor which drives a chain that is linked about and rotatably drives the sprockets 57 caged atop the final expander plate 56. This manner of adjusting the coil height adjustment screws 58 is generally well-known, and hence the motor drive and the chain have not been shown.

The air cylinders 72 are normally operated so that their pistons 74 are fully extended, upon initiating a cycle of operation. As the main ram 14 is lowered, the work sizing head 15 likewise is lowered until the ends of the coil height adjustment screws 58 engage and seat atop the new extended pistons 74. The work sizing head 15 is cushioned in this raised position, dropping by a small increment as the guide holder plates 43 and 44 and the rod alignment tooling plates stack on top of it during the main ram 14 descent, until the main ram 14 engages the upper ends of the coil height adjustment screws 58 and forcibly urges them downwardly against the air pressure of the cylinders 72. The work sizing head 15, of course, is moved downwardly along with the coil height adjustment screws 58, and it engages and operates a mechanically operated air valve 76 supported on the stop block 16. This air valve 76 is operative to release the air pressure on the cylinders 72, and the work sizing head 15 is thereby permitted to lower until it engages the stop block 16.

At the bottom of the stroke of the main ram 14, when the adjustment screws 58 are contacted by the main ram, the final expander plate 56 bottoms into the recessed cavity or channel 51 in the stripper plate 50. At this point, the final expander tooling plate 62 extends through the opening in the stripper plate 50 and bottoms against the upper surface of the stripper tooling plate 49. The final expanders 63, like the strippers 23, are sleeves, and these final expanders 63 pass through the strippers 23 as the final expander tooling plate 38 lowers and bottoms against the stripper tooling plate 49. The expander rods 22 likewise pass through the strippers 23, as the main ram 14 is lowered, to physically expand the tubes as they are extended into the coils, in the well-known manner. It is the function of the final expanders 63 to "bell" the ends of the tubes in the coil to an internal diameter as required to receive the return bends (short 180.degree. bends) which are later soldered in place.

The hydraulic system for operating the main cylinder 18 of the expander 10 is illustrated schematically in FIG. 6, and that for the air cylinders 72 is similarly illustrated in FIG. 7. As indicated above, one of the advantages of the design of the expander 10 is that it permits the same "push type" hydraulic cycle with a simple regenerative control presently used with conventional vertical expanders to be used. The expander 10 therefore can operate with a fast main ram velocity, normally 18 to 25 feet per minute, during the major portion of the expansion cycle, and with maximum tonnage during during the final sizing operation when it is required as indicated by a rise in system hydraulic pressure. The piston rod 19 of the main cylinder 18 is of a diameter such that its cross-sectional area is approximately one-half the area of the piston head. This will provide a ram speed on the return stroke approximately equal to the speed of the power stroke on the regenerative cycle as explained below.

The operation may be generally described as follows. When the motor 80 is energized, it operates the pump 81. While idling, the hydraulic fluid pumped from the reservoir 82 is merely coupled through the hydraulic valve 87 back into the reservoir. When the expansion cycle is initiated, solenoids 84 and 85 are energized, and the hydraulic fluid is pumped through the line 86, the valve 87 and the line 88 to the cylinder 18 against the head 89 of the piston 19. Simultaneously, hydraulic fluid below the piston head 89 is caused to flow from the cylinder 18 through the line 90, the valve 91 and the line 92, to the line 88 where it is joined with the hydraulic fluid pumped to the cylinder 18 by the pump 81. A fast main ram velocity is therefore provided, until the main ram 14 engages the ends of the coil height adjustment screws 58, at which time the work sizing head 15 contacts the coil to perform the sizing operation and sizing of the tube ends. An increase in hydraulic pressure is experienced at this time, which is detected by the pressure switch 93. The latter then operates to de-energize the solenoid 85 so that the fluid in line 90 is directed through the four-way valves 91 and 87 into the reservoir. With solenoid 84 still energized, a slow main ram velocity results, along with maximum tonnage being exerted on the coils by the action of the main cylinder 18. These valves are spring-centered, so that when neither of the solenoids 85, 95 or 84, 94 are energized, the flow will take place through the center set of valve parts.

Upon completion of the final sizing of the coils, the main ram 14 is raised. To raise the latter, the solenoids 94 and 95 are energized so that the hydraulic fluid now flows through line 86, the valves 87 and 91, and the line 90 to the cylinder 18 below the piston head 89. The hydraulic fluid atop the piston head flows through the lines 88 and 92 and the valves 87 and 91 into the reservoir. When the main ram 14 is at its upper vertical limit, all of the solenoids 84, 85, 94 and 95 are de-energized. De-energizing Solenoids 84, 85, 94 and 95 any time during the cycle will stop ram movement and maintain its position until solenoids are re-energized.

A pilot operated counterbalance valve 106 is provided to prevent the downward creeping of the main ram 14, the guide plates 43 and 44, and the work sizing head 15 when the expander 10 is shut down by de-energizing the main ram pump motor 80, due to the weight of the main ram, the guide plates and the work sizing head and leakage through the hydraulic control valves. The spring force on the counterbalance valve 106 is preset to a value larger than the hydraulic pressure generated by the static weight of the main ram, the guide plates and the work sizing head, and the parts attached thereto. Thus, the spring pressure will offset the pressure in the pilot line 108, preventing flow through line 90, the counterbalance valve 106 to the valve 91. The check valve 107 will also prevent flow around the counterbalance valve 106, when oil flow is from bottom side of cylinder 18 through line 90, but will permit flow around the counterbalance valve when flow is from valve 91 to bottom of cylinder 18.

When the pump 81 is running and flow is established through valves 87 and 91, the pressure in line 90 will exceed the preset spring pressure of the counterbalance valve 106, and this pressure is transmitted to pilot the counterbalance valve 106 to the free flow position. Thus, during the expansion cycle, the hydraulic oil in line 90 returning from the lower side of the piston head 89 of main cylinder 18 pilots the counterbalance valve 106 to the open position. On the return stroke, flow is established through the check valve 107, applying pressure to the pilot line 108, also opening the counterbalance valve 106 to flow, and flow takes place through both the check valve 107 and the counterbalance valve 106.

A pilot operated bypass valve 109 also is provided to limit the maximum pump head pressure, by diverting flow back to the tank when the hydraulic pressure rises to its setting.

The operation of the air cylinders 72 can be seen in FIG. 7, wherein the mechanically actuated air valve 76 simply controls the supply of air thereto, from an air supply 96 which provides air at approximately 100 psi. A manually adjustable pressure regulator 97 also is provided, to permit the air pressure supplied to the cylinders to be adjusted to a desired operating level.

Having now described the construction of the expander 10, its operation can be generally described as follows. In setting up the expander 10, the stop block 16 is slidably adjustably positioned to establish or set the height of the coils to be formed. This is accomplished by lowering the work sizing head 15 so that it is seated atop the stop block 16, and the stripper plate locks 64 are lockingly engaged with the lock extensions 66. The threaded screws 58 should be raised at this time, so as not to interfere with the lowering of the work sizing head 15. With the stripper plate locks 64 engaged, the threaded screws 70 can be loosened to release the friction plate locks 68. If the stop block 16 is to be lowered, the final plate 15 is lowered so as to forcibly urge the stop block 16 to the desired position and the threaded screws 70 tightened to again engage the friction plate locks 68 with the outer guide tracks 31 and 31'.

If the stop block 16 is to be raised, the main ram 14 is driven to its bottom position with the adjustment screws 58 bottomed against the rod ends of the air cylinders 72. On the work sizing head 15, the final expander plate 56 now nests into the recessed cavity or channel 51 in the stripper plate 50, bottoming against the upper surface of the latter. Approximately 1 inch of guide rods 59 and 60 will now be exposed between the enlarged stop nuts 61 and its lower surface of the stripper plate 50. The stripper plate locks 64 engage with the lateral lock extensions of the stop block 16. A wedge tool (not shown) then is fitted about the guide rods 59 and 60, between the stripper plate 50 and the enlarged stop nuts 61. These wedge tools prevent the guide rods 59 and 60 from passing through the stripper plate 50 and raising the final expander plate 56. The latter therefore will not engage and release the stripper plate locks 64. Accordingly, when the stripper plate 50 is raised, the stop block 16 is simultaneously raised since it is locked to the stripper plate 50 by the stripper plate locks 64. When raised to the desired position, the threaded screws 70 are tightened to engage the friction plate locks 68, to lock the stop block 16 in this position. The wedge tools are removed, and the stripper plate locks 64 are released when engaged by the final expander plate 56.

The air cylinders 72 are extended by the action of the mechanically actuated air valve 76, as soon as the stripper plate locks 64 are disengaged. The threaded screws 58 then are threadably raised or lowered by a measured amount exactly equal to the raising or lowering of stop block 16 so that the ends thereof will seat atop the pistons 74, and the work sizing head 15 is supported in spaced relationship from the top of the coils stacked on the nest tooling plate 17, to prevent the coils from being prematurely sized.

Next, tooling parts corresponding in number and pattern to the coils to be formed are assembled with their respective retainer plates. For example, hairpin nests 24 are placed in the nest retainer plate 17, final expanders 63 are affixed with the final expander tooling plate 38, expander rods 22 are affixed within the rod tooling plate 21, and strippers 23 are affixed within the stripper tooling plate 49.

In addition, coil retaining and reinforcing fixtures are removably attached to the expander frame. A row of shoulder bolts arranged vertically and equally spaced into a pair of plates affixed to the front faces of alignment plates 28 and 29 serve to retain these fixtures. Each fixture is hooked over a pair of bolt heads. The number and dimensions of these backup fixtures is governed by the capacity of the expander 10. One or more fixtures is employed dependent upon the dimensions of the coil to be expanded. Each fixture has a hinged "door" 110 so that a coil may be rapidly inserted and removed.

Each of these fixtures also has an adjustment allowing for different front-to-back (fin depth) dimensions in addition to adjustable side supports for coil width.

For a coil of given dimensions, it is pre-determined the quantity and size of fixture (or fixtures) to employ as determined by the height of the coil. The fixture is located on the expander's frame as required and the depth and width adjustments are made to the fixture (or fixtures) as the corresponding dimensions of the coil dictate.

Following installation of the proper quantity and pattern of tooling parts and installation and adjustment of the coil backup fixtures, the coil is placed into the expander 10 with the backup fixture door 110 open. It is nested firmly into the nests 24 and the backup fixture doors 110 are then closed.

Upon operating the main cylinder 18, its piston 19 is extended which action, in turn, lowers the main ram guide carriage 20. The latter is guided by means of the guide rollers 42 and the inner guide tracks 30 and 30' on the frame members 25 and 26. The main ram 14 being integrally affixed to the main ram guide carriage 20 likewise is lowered, and the expander rods 22 slidably pass through the rod alignment tooling plates 48, the final expander plate 56, the final expander tooling plate 62, the final expanders 63, the stripper plate 50, the stripper tooling plate 49 and the strippers 23, into the ends of the tubular members of the coils. As the expander rods 22 are forced into and through the tubular members, the latter are radially expanded by balls or bullet-shaped tips affixed to the ends of the expander rods 22 to unite them with the fins of the coils, in the generally well-known manner. As indicated above, the main cylinder 18 is operated with a "push-type" hydraulic cylinder action and a regenerative control to achieve maximum ram speed during the major portion of the ram cylinder stroke.

As the main ram guide carriage 20 and the main ram 14 are lowered, the rod alignment plates 43 and 44 stack up atop the work sizing head 15, as illustrated in FIG. 4. The support rods 45 and 46 which normally support them merely slide through these plates and extend vertically upwardly, as illustrated.

As the main ram 14 starts to lower, the work sizing head 15 also is lowered until the ends of the threaded screws 58 seat atop the pistons 74. These pistons 74 support the work sizing head 15, while the tubular members of the coil are being expanded by the expander rods 22. At the end of the stroke of the main ram 14, the ram plate 35 of the main ram 14 engages the tops of the height adjustment screws 58 and forces work sizing head 15 down, overcoming the air pressure of cylinders 72 until the final expanders 63 come in contact with the tube ends of the tubular members of the coil. The combined resistance caused by sizing of the tube ends of the tubular members by the final expanders 63 and the coil length sizing by the strippers 23 causes an increase in hydraulic pressure in line 88 to the main ram cylinder 18. This increase is detected by the pressure switch 93 which then switches the hydraulic cycle to a non-regenerative cycle so that maximum tonnage is exerted.

When the threaded screws 58 are forcibly urged downwardly to the point that the work sizing head 15 engages and operates the mechanically operated air valve 76, the air cylinders 72 are operated to retract their pistons 74. The work sizing head 15 now is lowered without the resistance previously provided by the air cylinders 72, to engage the strippers 23 with the coil being formed, and the final expanders 63 with the tube ends so as to "bell" these ends and perform the final coil length sizing operation. When the work sizing head 15 seats atop the stop block 16, the sizing operation is completed, and the operation of the main cylinder 18 is reversed so as to retract its piston 19.

At the time that the work sizing head 15 seats atop the stop block 16, the stripper plate locks 64 are engaged. The work sizing head 15 therefore is locked and held in the final sizing position until the expander rods 22 are withdrawn from the tubular members of the coils. At this time, the ram plate 35 of the main ram 14 engages the enlarged stop nuts 61 on the upper ends of the guide rods 59 and 60. These shafts then are physically raised which action, in turn, raises the final expander plate 56 which is affixed to them. The final expander plate 56 upon being raised, engages and releases the stripper plate locks 64. When the enlarged stop nuts 61 on the lower ends of the guide rods 59 and 60 engage the stripper plate 50 of the work sizing head 15, the whole work sizing head is raised. When the main ram reaches its vertical upper limit, as determined by a limit switch (not shown) which is actuated when the work sizing head is raised a set distance above the stop block 16, the cycle is completed, and the formed coil can be removed.

From the above description, it can be seen that the construction and operation of the expander 10 is such that its overall height can be substantially reduced, in comparison to conventional vertical expanders of the same capacity. This reduction approaches a 30 percent reduction, and results primarily from the fact that the main cylinder 18 is offset from the main ram 14, rather than being aligned atop the main ram as has been the standard practice in the past. This offset relationship is accomplished by affixing the main ram 14 to the upper end of a main ram guide carriage which is slidably engaged and guided between the two alignment plates 28 and 29 of the expander 10, and by affixing the piston 19 of the main cylinder 18 to the carriage cross frame 41 as the lower end of the main ram guide carriage 20. The length of the main ram guide carriage 20 is substantially equal to the length of the piston 19 of the main cylinder 18, so that the main ram 14 is vertically lowered the same distance it would be lowered if the main cylinder is affixed atop the main ram. Therefore, the height of the vertical expander 10 can be reduced an amount substantially corresponding to the length of its main cylinder or piston.

This construction and operation furthermore permits the main cylinder 18 to be vertically mounted in a fashion such that a "push-type" hydraulic cycle with a regenerative control on the initial portion of the expander cycle can be used, thus operating with a faster main ram velocity, as previously explained. This construction, with the "push-type" hydraulic cycle will also generate greater tonnage on the power stroke than a "pull-type" hydraulic cycle, with the same cylinder bore and system pressure since the piston rod area does not subtract from the piston area.

The mechanical design of the expander 10 also provides a substantial improvement over most vertical expanders. The main ram guide carriage 20, the work sizing head 15 and the stop block 16 all being carried by the vertical frame members 25 and 26 provides for better guiding and alignment of the working surfaces of the expander 10.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and certain changes may be made in the above construction. Accordingly, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

Now that the invention has been described, what is claimed as new and desired to be secured by Letters Patent is:

1. Tube expansion apparatus for forming articles such as cooling coils and the like for air conditioners and other heat exchange apparatus of expansion rods for radially expanding the tubular members thereof, a work sizing head including a final plate supporting a plurality of final expanders for finally sizing said articles, and a stripper support member supporting a plurality of strippers to hold said coil while retracting said expansion rods, and a main cylinder having a piston for raising and lowering said main ram, said final plate and said stripper support member to extend said expansion rods into said tubular members to radially expand them and to engage said final expanders with said articles to size said articles and to engage said strippers for retracting said expansion rods, the improvement comprising a pair of parallel, spaced-apart frame members, a main ram guide carriage of a length substantially corresponding to that of said main cylinder slidably disposed between and guided by said frame members as it is raised and lowered, said main ram being fixedly secured to the upper end of said main ram guide carriage, said main cylinder being vertically supported between said frame members rearwardly of said main ram with its piston extending downwardly and affixed to the lower end of said main ram guide carriage, said piston upon being extended from said main cylinder lowering said main ram guide carriage and hence said main ram affixed to it, said final plate and said stripper support member being slidably supported upon said frame members beneath said main ram and raised and lowered by said main ram as it is raised and lowered.

2. The tube expansion apparatus of claim 1, further including a push-type hydraulic cycle with a regenerative control for said main cylinder.

3. The tube expansion apparatus of claim 1, wherein said pair of frame members have inner guide tracks, said main ram guide carriage being slidably engaged with said inner guide tracks so as to be guided and aligned thereby.

4. The tube expansion apparatus of claim 3, wherein said main ram guide carriage has roller guide means at the upper and lower ends thereof which engage the opposite sides of said inner guide tracks to guide and align said main ram guide carriage.

5. The tube expansion apparatus of claim 3, wherein said main ram guide carriage further has brass slide pads at the upper and lower ends thereof which engage the inward edges of said inner guide tracks to guide and align said main ram carriage.

6. The tube expansion apparatus of claim 3, wherein said pair of frame members further have outer guide tracks, said final plate and said stripper support member being slidably engaged with said outer guide tracks so as to be guided and aligned thereby.

7. The tube expansion apparatus of claim 6, wherein said final plate and said stripper support member have roller guide means thereon which engage the opposite sides of said outer guide tracks and brass slides thereon to engage the outward edges of said outer guide tracks to guide and align said final plate and said stripper support member.

8. The tube expansion apparatus of claim 1, further including a pair of air cylinders having pistons, a pair of coil height adjustment screws coupled to said final plate and vertically disposed so that the lower ends thereof are engageable with respective ones of said pistons, said pistons normally being extended and engaged by the ends of said coil height adjustment screws to support said final plate and said stripper support member to prevent the final plate from engaging said articles and prematurely sizing them and to prevent said stripper support member from engaging and crushing said coil.

9. The tube expansion apparatus of claim 8, further including control means for operating said air cylinders to retract their pistons when said final plate is forcibly urged downwardly by said main ram to a predetermined position.

10. The tube expansion apparatus of claim 9, wherein said control means comprises mechanical air valve means physically operated by said final plate.

11. The tube expansion apparatus of claim 1, further including a stop block which is releasably locked to said pair of frame members beneath said work sizing head, said work sizing head having a final plate lock on each of the opposite sides thereof which lockingly engage with said stop block when said work sizing head is seatingly engaged atop said stop block, said final plate locks preventing said work sizing head from being raised before said expansion rods are withdrawn from said tubular members, and lock release means for releasing said final plate locks when said expansion rods have been withdrawn.

12. The tube expansion apparatus of claim 11, wherein said lock release means are coupled to and operated by said main ram to physically engage and to release said final plate locks when said main ram is vertically raised to a position where said expander rods are withdrawn from said tubular members.

13. The tube expansion apparatus of claim 11, further including a pair of guide rods affixed to said main ram and to said work sizing head, said work sizing head normally being hangingly supported by said main ram by means of said guide rods said lock release means being fixedly secured to said guide, rods and operated thereby to release said final plate locks when said guide rods are physically raised by said main ram.