Expansible drive shaft tool mechanism

An expansible drive shaft tool mechanism is disclosed in which mutually cooperating parallel drive shafts carry tool elements that can be shifted into and locked by shaft expansion in any of selected positions along such drive shafts. Applied hydraulic pressure in a sealed chamber causes outward expansion of a flexible outer sleeve member on each such shaft to grip the tool elements. An inner sleeve member closely encircled by the outer sleeve member and joined in sealed relationship therewith at opposite end portions forms the radially thin elongated annular sealed chamber into which the pressurized hydraulic fluid is forced by the action of a plunger type hydraulic pressure source housed inside the inner sleeve member cavity. Actuation of the hydraulic pressure source plunger passing through a cylindrical fluid take-up chamber by longitudinal displacement is effected by means of a pneumatic piston energizable through a connecting line including a low pressure rotary seal or union. Hydraulic fluid that may leak past a primary seal along the plunger is taken up in the seal chamber which, of cylindrical form, incorporates a sliding piston or seal element contacting the plunger and cavity wall and urged by a return spring to exert pressure on such accumulating hydraulic fluid tending to return it to the hydraulic cylinder. Such seal chamber including the spring-returned seal element is thus available to take up leakage of hydraulic fluid seeping past the primary seal, whether caused by operating pressure or by thermal expansion of fluid in the system, and to urge the fluid back through a check valve when the pressure drops again.

BACKGROUND OF INVENTION 
This invention relates to an improved expansible drive shaft rotary tool 
system and more particularly to hydraulically actuated expansible multiple 
drive shafts and associated variably positioned tools mounted on the drive 
shafts. The invention is herein illustratively described by reference to 
the presently preferred embodiment thereof; however, it will be recognized 
that certain modifications and changes therein with respect to details may 
be made without departing from the essential features involved. 
The drive shaft mechanism comprising the present invention is applicable 
for example to supporting and rotatively driving sets of rotary male and 
female creasing wheels used in forming the fold lines for corrugated board 
box panels and the like. Precise positioning and continued mutual registry 
of the cooperating sets of creasing wheels is therefore desirable together 
with the ability to quickly and easily change their positions for 
different job requirements. Numerous other tool positioning applications 
also exist in industry wherein the invention may be applied to advantage 
such as cutters, grinders and many others. 
It is not new in the art to employ expansible drive shafts to maintain 
rotary tools in any of selected operating positions along a shaft. For 
example, Warren et al. U.S. Pat. No. 3,173,325 discloses one such proposal 
wherein the support shafts for the tools are hollow to accommodate 
hydraulic fluid variably pressurizable to control the degree of expansion 
of the shaft wall and thereby the holding force exerted on the surrounding 
tools. Floating bearings are necessary in that case due to endwise 
expansion of the shaft accompanying its lateral bulging or expansion to 
hold the tools. 
Wyllie et al. U.S. Pat. No. 3,166,013 represents another patent disclosing 
an expansible shaft in this case for supporting a tubular printing 
cylinder or for varying the tension or driving force on a web of paper. In 
that example grooves or channels in the base cylinder surface closely 
surrounded by the expansion sleeve communicate fluid to the various areas 
within the sleeve to effect its expansion with the printing tube centered 
on the shaft in order to hold the printing tube in place when fluid 
pressure is increased within the grooves. 
In addition hydraulically expansible mandrels pressurized by internal 
piston-cylinder units have been proposed heretofore as mounting supports 
for individual tools, examples being U.S. Pat. Nos. to Atherholt, Sr., 
2,971,765; Better et al., 2,963,298; and Sturgis, 2,938,347. 
An object of the present invention is to provide a quick-acting, compact, 
lightweight, and leak-proof hydraulically actuatable expansible shaft 
mechanism that can be made as long as desired and of any desired diameter, 
while requiring minimum volumetric space in its expansion chamber, 
pressure source cylinder and connecting passages. 
Another and related objective is to provide such a mechanism substantially 
devoid of tool position shifting caused by shaft elongation when the 
shaft's pressure chamber is pressurized, yet which does not sacrifice 
expansion sleeve flexibility in achieving this result. Thus, support 
bearings for the shaft may be conventional (i.e., need not be of the 
"floating" type) to accommodate endwise shifts, and precise positioning of 
tool elements along the shaft, whether established manually or by 
automatic positioning mechanisms, will be maintained during shaft 
expansion to grip and lock such tool elements in place. 
In addition it is an object of the invention to incorporate compact and 
effective hydraulic fluid take-up and make-up provisions in such a shaft 
mechanism that not only reduces the chance of exterior leakage of 
hydraulic fluid under the high internal pressures used (e.g., up to 3,000 
psi, for example) but that also serves as a source of make-up fluid to 
replace fluid seeping past the primary seal associated with the hydraulic 
plunger pressurization device should any such exterior leakage occur. In 
addition such make-up device provides a means to accommodate changes in 
total hydraulic fluid volumetric containment requirements caused by 
substantial temperature variations expanding or contracting the 
incompressible hydraulic fluid. 
A more specific object hereof is to devise such a shaft mechanism wherein 
maximum effective shaft diameter expansion may be achieved by 
pressurization within the expansion chamber of the shaft without causing 
attendant and commensurate lengthening of the shaft and without incurring 
problems of shaft eccentricity affecting axial alignment of the rotary 
tool elements mounted on the shaft. 
Still another object is a shaft mechanism of the described type employing a 
combined pneumatic and hydraulic pressurization apparatus avoiding the 
usual problems with rotary high pressure seals that must contain the fluid 
against leakage at high rotational shaft speeds such as 500 rpm or more. 
With the improved mechanism all of the hydraulic system is contained with 
the rotary shaft. 
BRIEF DESCRIPTION OF INVENTION 
As herein disclosed the invention employs an expansible elongated shaft 
that is mounted on longitudinally spaced bearings between which the one or 
more rotary tool elements slidably surrounding and mounted on the shaft 
may be adjustably positioned. The shaft comprises an elongated flexible 
(i.e., thin walled) and resiliently expansible cylindrical outer sleeve 
member and an associated cylindrical sleeve member closely surrounded by 
the outer sleeve member and forming a fluid-tight rigid joint therewith at 
longitudinally spaced points. An elongated, radially thin, annular, 
fluid-filled sealed chamber is thereby formed between the two sleeve 
members and is connected to a variable pressure hydraulic source 
selectively operable to vary the pressure of fluid within such chamber and 
thereby the holding force exerted on the surrounding tool elements 
effected by outer sleeve expansion. Because of the configuration of the 
sleeve members forming the radially thin sealed chamber and the mechanical 
interconnection of these sleeve members at the ends of such chamber, any 
longitudinal expansion force exerted by hydraulic piston effect endwise on 
the outer sleeve member tending to displace the tools from their assigned 
positions has rather minimal effect. Likewise avoided is the problem of 
bearing stresses caused by shaft lengthening under the hydraulic pressure 
used to effect shaft diameter expansion. 
The low volumetric fluid capacity requirement of the sealed chamber permits 
use of a relatively small and compact hydraulic source unit to vary the 
pressure within that chamber and permits convenient housing of such a 
pressure source, cantilevered endwise into the hollow interior of the 
inner sleeve member of the shaft. A pressurizing plunger passing through a 
cylindrical seal cavity is connected externally to a pneumatic piston. The 
area of the pneumatic piston is significantly greater than the area of the 
pressurizing plunger. The pneumatic piston of large diameter can thus be 
supplied with operating pressure of relatively low magnitude in the 
connecting hose. 
A sliding seal element in sealing contact with the plunger and surrounding 
wall of the cylindrical seal chamber is backed by a return spring and 
thereby yieldably accommodates varying amounts of hydraulic fluid seeping 
into the seal cylinder, and tends to return that fluid back to the 
hydraulic pressure cylinder and associated passages leading into the shaft 
chamber through a check valve when pressure is reduced therein. 
Moreover because of the very low volume of hydraulic fluid required to fill 
the sealed chamber, the shortness of the passages leading to that chamber 
from the hydraulic plunger cylinder pressure source due to the location of 
the latter within the adjacent ends of the expansion shaft, it is possible 
to release and lock the tool elements on the expansible shaft with very 
little time lag and with a small energy requirement. 
These and other features, objects and advantages of the invention will 
become evident to a person skilled in this art based on the following 
description of the illustrative embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
With reference to the drawing, shafts 10 and 12 are or may be substantially 
identical in construction as are the hydraulic pressure sources therein 
and the means for actuating the same. Consequently, only the details of 
shaft 12 are depicted in the illustration by sectioning and detailing of 
parts therein, and only these will be described in detail hereinafter. 
Elongated shaft 12 is rotatively supported at its ends by bearings 14 and 
16 which may be a conventional type of ball bearing or roller bearing. 
Between the bearings the shaft comprises an elongated resiliently 
expansible cylindrical outer thin-wall sleeve member 18 and a cylindrical 
inner hollow sleeve member 20 closely encircled or surrounded by the outer 
sleeve member. These coaxially extending sleeve members are suitably 
joined at their ends, as by welding them together or to shaft end "plugs" 
or heads 22 and 24 to form a fluid-tight joint between the sleeve members. 
Due to the close spacing between the sleeve members in a radial sense they 
thereby define a radially thin elongated annular (fluid filled) sealed 
chamber 26 that extends the full coextending length of the sleeve members. 
This chamber is radially thin preferably of the order of a few percent in 
radial "thickness" of its average diameter. At one end, the chamber is 
placed in communication with a hydraulic pressure cylinder 28. Cylinder 28 
is mounted on a web or disk 30 joined to or part of the shaft plug 24 and 
projecting cantilevered into the hollow interior of the inner sleeve 
member 20 as shown. Radial flow passages 32 place the sealed chamber 26 in 
fluid communication with the interior of the hydraulic pressure cylinder 
28. A hydraulic plunger 34 coaxial with the cylinder 28 extends from the 
cylinder 28 past a primary fluid seal 50. The plunger rod 34 can thus be 
inserted to varying degrees into the interior of the cylinder 28 so as to 
displace hydraulic fluid therein and thereby produce variable increase of 
hydraulic pressure communicated to the sealed chamber 26. 
Plunger 34 extends axially from the cylinder 28 to connect with pneumatic 
piston 36 of substantially larger diameter than plunger 34. Piston 36 is 
received in pneumatic cylinder 38 also mounted on the shaft 12 and 
rotatable therewith. A rotary pneumatic seal or union 40 is connected to 
the pneumatic cylinder 38 so as to deliver air under pressure to the 
latter from a hose 42 leading to a stationary external pneumatic pressure 
source (not shown). Thus by selective pressurization of the relatively 
large-diameter air cylinder 38 varying pressure changes may be developed 
in the hydraulic cylinder 28 of much higher magnitudes for application to 
the sealed chamber 26, thereby to expand the outer sleeve 18 into contact 
under varying pressures with the tool elements T thereon. 
In passing from the hydraulic cylinder 28 to the air cylinder 38 the 
plunger 34 passes through a seal chamber 44 coaxial with the plunger and 
containing a sliding seal element 46 that makes sealing contact with both 
the plunger and the inner wall of the cylinder. A helical spring 48 
interposed between the sealing element 46 and one end wall of the sealing 
chamber 44 urges the sealing element in the direction toward the hydraulic 
cylinder 28. A check valve 53 connects this small spring pressurized 
chamber 55 with the main sealed chamber 26. Thus should there be any 
leakage of hydraulic fluid from the hydraulic cylinder past the plunger 
and the primary seal 50 associated with the plunger at the entrance to the 
hydraulic cylinder that leakage will be taken up in the variable space 
provided in the seal chamber 55 by yieldable positioning of the sealing 
element 46 therein. Upon release of pneumatic pressure in cylinder 38 and 
return of plunger 34, the oil leaked under pressure from chamber 26 is 
returned to chamber 26 through check valve 53. 
In the illustration a check valve 52 is mounted in a radial passage 54 
leading into the chamber 55 to permit supply of hydraulic fluid to the 
latter and thereby through valve 53 to the sealed chamber 26. Normally 
this valve 52 is closed, however, and the system including the various 
chambers and passages within the expansible shaft and its associated 
pressurization means represents a self-contained system. Leakage is to be 
avoided and pressure changes accompanying expansion and contraction of the 
hydraulic fluid due to temperature effects should also be accommodated and 
avoided so as to not interfere with ease of positioning of the tool 
elements T along the shaft when the actuating pressure therewithin is 
removed. A pressure of about 30 lbs./sq. in., more or less, is exerted by 
the spring 48 on the sliding seal element 46. By illustrator's license in 
the drawing, the element 46 is shown in full body in position adjacent the 
cylinder 28 with the spring 48 extended, and is shown in half in a 
retracted position with the spring 48 fully compressed. 
In operation the hydraulic passages and chambers within the shaft system 
are initially filled through the plugs 56 and are preferably filled to the 
point that all the air is bled out of the expansion chamber 26 and 
connecting passages. The chamber 55 is then filled through valve 52 until 
the spring on floating piston 46 is compressed. 
With the fluid system at minimum pressure (i.e. the plunger 34 retracted), 
the tool element T may be shifted to the desired operating positions along 
the shaft quite readily, this being done either manually or by mechanical 
devices. For instance a computer controlled stepping motor device may be 
used to selectively position the elements T along the shafts 10 and 12 
suiting the requirements of a particularl job to be done. Thereupon 
pneumatic pressure delivered through conduit 42 and rotary seal 40 into 
the lefthand end of pneumatic cylinder 38 causes the piston 36 to move to 
the right which thereby forces the hydraulic plunger 34 into the cylinder 
28 to increase the hydraulic pressure within the expansion chamber 26. 
Such increase of pressure causes the flexible outer sleeve 18 to flex or 
bulge outwardly into simultaneous forcible engagement with the tool 
elements T to lock the tool elements in position. Because of the 
flexibility of the sleeve 26, all of the tool elements are effectively 
locked regardless of their proximity to the shaft end plugs 22 and 24. 
When it is desired to reposition the tool elements T, air pressure exerted 
on the piston 36 is removed permitting resilient recoil of the stressed 
sleeves 18 and 20 to expel pressurized fluid from the chamber 26. Pressure 
in the chamber drops and the tool elements can then be readily shifted to 
new positions. 
Having thus described the preferred embodiment of the invention, it will be 
appreciated that various changes and modifications of detail may be made 
without departing from the essentials involved. These essentials, 
including the novel combinations comprising the invention, are set forth 
in the claims that follow: