US3742714A

US3742714A - Pressure system for expanding shafts

Info

Publication number: US3742714A
Authority: US
Inventors: C Thomas
Original assignee: Koppers Co Inc
Current assignee: United Container Machinery Group Inc
Priority date: 1971-10-22
Filing date: 1971-10-22
Publication date: 1973-07-03
Anticipated expiration: 1990-07-03
Also published as: GB1391979A; JPS525116B2; NL7213550A; FR2157648A5; JPS4890989A; DE2250508A1

Abstract

A pressure system for expanding one or both of a pair of coaxially mounted rotatable shafts to secure a plurality of tool elements at preselected locations along the length of the shafts; the pressure system uses a rotary union connected to the end of the expandable shaft through which fluid pressure flows to the shaft, a control valve by which fluid pressure may be maintained and then released from the shaft, a reservoir for receiving the fluid from the shaft when it is contracted, and a pressure supply device which supplies the necessary pressure to the fluid to expand the shaft sufficiently to secure the tool elements on the shaft. The pressure system is preferably hydraulic in nature and is normally used in conjunction with a plurality of pairs of coaxially mounted rotatable shafts where each of the pairs of shafts are spaced circumferentially equidistant about a central common axis enabling a selected pair to be rotated into a workpiece engaging position.

Description

United States Patent 1 Thomas Assignee:

Filed:

PRESSURE SYSTEM FOR EXPANDING SHAFT S Inventor: Charles E. Thomas, Reisterstown,

Oct. 22, 1971 Appl. No.: 191,725

References Cited UNITED STATES PATENTS 10/1941 Ernst et a1. 60/52 HF Warren et al 83/665 X Koppers Company, Inc., Pittsburgh,

[451 July 3, 1973' Primary E.raminer- Edgar Geoghegan Attorney-Boyce CQ Dent, Oscar B. Brumback et a1.

[57] ABSTRACT A pressure system for expanding one or both of a pair of coaxially mounted rotatable shafts to secure a plurality of tool elements at preselected locations along the length of the shafts; the pressure system uses a rotary union connected to the end of the expandable shaft through which fluid pressure flows to the shaft, a control valve by which fluid pressure may be maintained and then released from the shaft, a reservoir for receiving thefluid from the shaft when it is contracted, and a pressure supply device which supplies the necessary pressure to the fluid to expand the shaft sufficiently to secure the tool elements on the shaft. The pressure sys-'- tem is preferably hydraulic in nature and is normally used in conjunction with a plurality of pairs of coaxially mounted rotatable shafts where each of the pairs of shafts are spaced circumferentially equidistant about a central common axis enabling a selected pair to be rotated into a workpiece engaging position. 1

7 Claims, 1 Drawing Figure PRESSURE SYSTEM FOR EXPANDING SHAFTS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to cutting with axially shiftable tool pairs and more particularly to the locking of tool elements along the length'of an expandable shaft utilizing a fluid pressure system.

2. Description of the Prior Art Several types of expandable shafts or mechanisms are known, such as shown in U.S. Pat. Nos. 3,166,013, 3,130,978, 2,971,765, and 2,963,298.

All of the aforementioned patents have one thing in common, and that is they show an expandable outer surface of some type to lock tool elements securely thereon and they utilize fluid pressure to'expand the such surfaces.

However, they generally require manual connection of a pressure supply to expand the surfaces and separate means for relieving the pressure to unlock the elements. Furthermore, in the event of fluid leakage during operation, the tool elements may shift along the expandable member causing damage to the tools or workpieces; at least, it is necessary to stop the work being performed to reexpand the member, which results in lost work time.

In the prior art devices the fluid is either selfcontained or supplied by a noncontinuous running device. This results in the situation that should a leak or seepage develop, substantial production time is lost while the operation is stopped in order to repressurize the expandable devices. Furthermore, should a leak or seepage develop, the tool elements willhave a tendency to slip causing the workpiece to be malformed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a continuously operable pressure supply system that will overcome the aforementioned disadvantages and others. Thus, the necessary pressure is mainp are adapted for selectivepositioning about the comtained to keep the expandable device expanded even if v a leak or seepage occurs, causing no loss in production time since the operation need not be stopped to repressurize.

This is generally accomplished by connecting a union means to the end of an expandable shaft through which fluid pressure passes to expand the shaft; a valve means is connected to the union means for conducting fluid pressure to the shaft and for relieving fluid pressure from the shaft upon contraction of the shaft; a continuously operable pressure supply means connected to the valve means for supplying fluid pressure through the .valve and the union means to expand the shaft an amount sufficient to secure tool elements thereon; and a reservoir means connected between the valve means and the pressure supply means for receiving fluid from the shaft upon contraction and for replenishing the fluid to the pressure supply means.

The system can be used on only a single shaft of a pair of shafts but preferably both shafts are expandable, in which case, asecond union means is connected to the second shaft to simultaneously receive fluid pressure from the pressure supply means.

It is even more advantageous to have the system supply the necessary fluid pressure to a plurality of pairs of shafts that are spaced circumferen'tially equidistant about a central common axis, where each of the pairs 'mon axis in alignment with a workpiece engageable with the tool elements. To accomplish this, another union means in coaxial alignment with the central common axis is connected to each valve means which is connected to each pair of shafts by way of union means for supplying fluid pressure to each pair of shafts to sufficiently expand the shafts to secure the tool elements thereon.

BRIEF DESCRIPTION OF THE DRAWINGS The above and further objects and novel features of the invention will appear more fully from the following detailed description when the same is read in connection with the accompanying drawing. It is to be expressly understood, however, that the drawing is not intended as a definition of the invention but is for the purpose of illustration only.

In the drawing wherein like parts are marked alike:

The lone FIGURE is a digrammatic illustration of the pressure system of the present invention showing its application to a plurality of expandable members of various types.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention generally comprises a pressure system 10 for expanding the periphery of a first shaft 12 of a pair 13 of coaxially mounted

rotatable shafts

12 and 14 to secure tool elements 16 surrounding the first shaft 12 at selected locations along its length.

Briefly, shaft 12 includes a union means 18 connected to one end through which fluid pressure passes toan inner cavity 20 of shaft 12. A valve means 22 is connected to the union means 18 for conducting the fluid pressure to shaft 12 and then to release the fluid pressure to contract shaft 12. A reservoir means 24 is connected to the valve means 22 for receiving the fluid pressure from shaft 12 upon contraction thereof. A

continuously operating pressure supply means 26 is connected to the valve means 22 for continuously supplying fluid pressure through the valve means 22 and the union means 18 to expand shaft 12 a sufficient amount to secure the tool elements 16 thereon. The reservoir means 24 is connected to the supply means 26 for returning fluid from the system to replenish the supply of fluid in the supply means 26.

In another mode of operation, both

shafts

12 and 14 are expandable so that similar tool elements 16 can be secured to the periphery of both

shafts

12 and 14 for cooperatively operating on a workpiece 15 passing therebetween. A second union means 28 is connected to the end of shaft 14 and to valve means 22 for supplying sufficient fluid pressure to shaft 14 to secure tool elements 16 along its length.

Pressure system 10 can also be used for expanding the periphery of the first shaft of several similar pairs of shafts l3 and 31 to secure tool elements 16 surrounding the shafts at selected locations therealong'. The pairs of shafts l3 and 31 are preferably spaced circumferentially equidistant about a common axis 34 so that each pair of shafts l3 and 31 can be rotated about In this mode ofoperation, another union means 36 is I coaxially aligned with the common central axis 34 and is connected to each valve means 22 for directing fluid pressure to each union means 18 through each valve means 22 thereby providing fluid pressure to the shafts to expand them a sufficient amount to secure tool elements l6 thereon.

Preferably each shaft of the pairs of shafts l3 and 31 is expandable for securing similar cooperating tool elements 16 along the length of each shaft.

If desired, two pairs (second pair omitted for clarity) of expandable shafts can be operated adjacent to each other on the same leg of frame 38 thereby permitting two dissimilar operations to be performed simultaneously on workpiece 15.

More specifically, the present invention is illustrated in connection with a slitter-scorer machine for slitting, triming, and scoring a moving web of solid or corrugated paperboard. It can also be utilized in connection with other machines, for example, slotting machines which cut slots in individual blanks of solid or corrugated paperboard.

The embodiment shown in the drawing illustrates a slitter-scorer having 3 work stations each having a pair of cooperating coaxially aligned shafts which may be selectively positioned for operating on a moving web. As illustrated, the uppermost pair of shafts is shown in the position for operating on the web 15. Each station is rotatable about a central common, axis 34 to place the desired station into the operating position.

Although each station is shown as including only a single pair of shafts, it should be understood that each station may have additional pairs of shafts in alignment with the first pair upon which are mounted tool elements for performing various types of operations upon the web.

The present invention can also be used with a single work station mounted on a non-rotatable support, (not shown) or it can be used with two work stations (not shown), where the work stations are diametrically opposite one another mounted upon a support rotatable about a central common axis to place work stations into the operating position. It can also be used with three operating stations, two of which are shown in the drawing are spaced circumferentially equidistant about a central common axis mounted on a support that enables a selected station to be rotated into the operating position.

The uppermost station shows one construction of the shafts in which one or both of the

shafts

12 and 14 of the pair 13 are hollow. The second station shows the preferred construction in which one or both of the

shafts

32 and 33 of the pair 31 include a solid cylindrical core 44 surrounded by a tubular shell 30 forming an annular space 50 between the outer periphery of the core and the inner periphery of the shell.

The principles used in expanding hollow shafts by fluid pressure to secure tool elements thereon are utilized in the present invention in the following manner.

As shown in the first pair of shafts 13, a hollow shaft 12 is sealed at both ends by

journals

40 and 42 of which at least one journal 40 has an inner cavity 41 to conduct fluid and fluid pressure to an inner cavity 20 of the shaft. The

journals

40 and 42 of shaft 12 are supported in bearings 17 in generally triangular side frames 38 permitting the shaft and journals to berotated by a conventional drive means (not shown). Shaft 12 is constructed of suitable material, such as steel, to not only withstand fluid pressures from 2,000 to 3,000 pounds per square inch (p.s.i.) when expanded, but rigid enough not to flex or deform beyond acceptable limits when a workpiece 15 passes between tool elements 16 on shaft 12 and a similar shaft 14 coaxially mounted for cooperation with shaft 12 thereby forming a pair of cause of fluid pressure. In this construction, shaft 33 7 includes a solid cylindrical body or core 44 and a cylindrical tubular shell 30 surrounding the peripheral surface of thecore. Core 44 contains a fluid passage 46 extending within the length of the core with a plurality of fluid passages 48 perpendicularly connecting the axial fluid passage 46 to the outer periphery of the core. The tubular shell 30 is secured to the core by end plates 52, such as by welding, to form a fluid-tight structural connection to increase the cross-sectional area of the shaft and reduce the area against which fluid pressure tends to axially expand the shaft. An annular space 50 is provided between the outer periphery of core 44 and the inner periphery of tubular shell 30 by the proportions of these two elements. For example, with a shell having an outer diameter of about 7% inches, an inner diameter of 6% inches, and about 96 inches long, the outer diameter of the core 44 should be about 5% inches in diameter to provide an annular space 50 about /4 inch radially around the core. These dimensions can be easily varied depending on the actual application. This enables fluid and fluid pressure to flow through fluid passage 46 and fluid passages 48 to the inner cavity 50 for expanding the tubular shell 30. The extension of core 44 beyond the end of shell 30 form journals 35 supported in bearings 17 in side frames 38 to permit rotation of the shaft 33.

The preferred arrangement of shafts for slitting and scoring operations is to assemble the pairs of shafts between a pair of identical triple-leg frames 38 with corresponding pairs of legs L1, L2 and L3 each comprising a single workstation. Each workstation includes a pair of coaxially mounted

rotatable shafts

13 or 31, and, if desired, a second pair of coaxially mounted rotatable shafts adjacent to the first pair for performing two dissimilar operations simultaneously upon workpiece 15, (second pair omitted for clarity). Each of the three workstations on frames 38 is spaced circumferentially equidistant about a central common axis 34. The axis may be a pivot shaft 74 which is mounted between supports 54 at both ends of the shaft 74 (only the righthand support 54 is shown for clarity) which enables a selected workstation to be rotated to the operating position in the conventional manner.

To expand and contract the expandable shafts in each workstation, an external continuously operating pressure system l0'of the present invention is utilized. The system 10 includes single

rotary unions

18 and 28 which are attached to

journals

40 and 35 of the pairs of

expandable shafts

13 and 31, thus permitting the introduction of sufficient fluid F to create the necessary fluid pressure in the

inner cavities

20 and 50 from the stationary elements of the system to the rotating elements. If more than two workstations are used and more than a single pair of expandable shafts per workstation is to be expanded, separate single rotary unions l8 and 28 are utilized on each expandable shaft.

- A valve means 22 is connected to each

single rotary union

18 and 28 by a conduit 56, which is connected between the inlet port 19 of the unions and the outlet port 21 of the valve. vValve 22 is preferably a conventional four-way hand operated valve. When valve 22 is placed in a locked position, fluid F flows through the valve, through conduit 56, through unions l8 and 28, through

journals

40 and 35 and into

inner cavities

20 and 50 of eachof the pairs of

shafts

13 and 31 to expand the shafts a sufficient amount to secure tool elements 16 along the length of each expandable shaft. To

contract each shaft, the'handle 23 of valve 22 is rotated to an unlocked position allowing fluid to flow out of the

inner cavities

20 and 50 of each pair of shafts l3 and 31 to relieve the fluid pressure. If more than two workstations are utilized, a separate valve 22 is used in connection with each workstation. If more than one pair of expandable shafts is utilized in each workstation, valve 22 is connected by conduit 56 from the valves single outlet port 21 to each single rotary union l8 and 28, thus permitting the simultaneous expansion and contraction of all shafts when the valve is placed in the locked or unlocked position. However, if desired, a valve 22 may be provided for each shaft of the pairs so that each shaft may be selectively expanded.

If only one workstation is used, then a reservoir means 24 is connected directly to the valve means 22 by conduit 58. Conduit 58 is connected between a relief port 25 of valve 22 and the inlet port 27 on the reservoir. By placing valve 22 in an unlocked position pressure is released from each pair of

shafts

13 and 31 which enables fluid to flow to the reservoir 24 where it is contained.

A continuously operating pressure supply means 26, and more preferably, a conventional air to hydraulic intensifier pump, is connected to an air supply (not shown) by conduit 62 which is connected to an air inlet port 61 on the pump for supplying sufficient air pressure to activate piston 68. Conduit 64 is connected to an air outlet port 63 of pump 26 to return used air to the air supply system or to atmosphere. On the fluid side of pump 26, conduit 66 is connected directly between a fluid outlet port 65 of the pump and the fluid inlet port 53 of valve 22 for supplying sufficient fluid pressure to the expandable shafts of a single workstation by reciprocation of piston 70. Conduit 60 is connected between a fluid inlet port 67 of pump 26 and a fluid outlet port 29 of reservoir 24 for replenishing the system with fluid F. Preferably, the continuously operating pressure supply means 26 utilizes a dual piston pneumatic pump 26 which balances 40 to 60 psi air pressure on one piston 68 against 2,000 to 3,000 psi hydraulic pressure on a smaller piston 70 mechanically connected to piston 68. Thus a quiet, efficient, pressure amplifier is obtained and the balancing feature of pump 26 automatically makes up any system pressure loss. If sufficient air pressure is not available, an alternate power source utilizing a conventional electric motor/- pump system can be used.

The fluid used inthe pressure system should be in the nature ofa non-compressible medium, such as hydraulic oil,. for supplying a substantially instantaneous pressure from the pump 26 through the system to the

inner cavities

20 and 50 of each pair of expandable shafts l3 and 31 and to another pair (omitted for clarity) on legs L3 for expanding the outer periphery of each shaft a. sufficient amount to simultaneously secure the tool elements 16 along the length of each shaft.

When the pressure system is used in conjunction with two or more workstations rotatable about a central common axis 34, a different construction than the one described above is used between pump 26 and valves 22. This construction includes a central common axis 34, which preferably comprises pivot shaft 74, with the frames 38 secured thereto. The pivot shaft 74 is rotatably supported at each end by a bearing 55 in supports 54 (only one support shown for clarity), so that the shaft 74 may be rotated to place the desired workstation in its operating position.

A manifold 72, or similar device, is formed on one end of the pivot shaft 74 inboard of the left hand frame 54 (not shown) and is constructed with a central passage therein (not shown) with a plurality of other passages (not shown) connected perpendicular to the central passage and extending to the outer periphery of the manifold to form inlet ports 37 and outlet ports 39.

A conduit 76 connects the outlet port 39 of manifold 72 to the inlet port 53 of valve 33 and conduit 78 connects the outlet port 25 of valve 22 to the inlet port 37 of manifold 72; thus, fluid F flows through manifold 72 to each of the valves 22 positioned between manifold 72 and each workstation.

Another union means 36, preferably a conventional dual rotary union, is connected in coaxial alignment to manifold 72 for supplying fluid F through the manifold 72 to each expandable pair of

shafts

13 and 31 in each workstation and will maintain fluid pressure in the shafts when the workstations are rotated about their central common axis 34 to place them in either of their operating or non-operating positions. An inlet port 43 in union 36 is connected to conduit 66 which is connected to the fluid outlet port 65 of pump 26 for supplying sufficient fluid F to the expandable shafts. The outlet port 45 of union 36 is connected to the inlet port 27 of reservoir 24 for receiving fluid upon contractio of the expandable shafts.

Since the principle of the present invention is based on the desirability of supplying a continuous and constant pressure to each expandable shaft, a check valve 80 is preferably placed in conduit 76 between valve 22 and manifold 72 with the direction of fluid flow toward the valve, to prevent pressure fluctuations, or pressure loss due to transient action, that may be cause by the operation of valve 22.

A conventional pressure gauge 82 is preferably connected to conduit 66 by conduit between pump 26 and union 36 for monitoring the fluid pressure pro duced by the pump.

A conventional pressure switch 84 is also preferably connected to conduit 66 by conduit 92 between pump 26 and union 36 for shutting down the drive means (not shown) to the shafts should the fluid pressure drop below the necessary pressure sufficient to maintain the tool elements 16 in a secured position on the expandable shafts, for example more than 500 psi. below desired pressure. The purpose of the pressure switch 84 is to prevent continued scoring and slitting operations on workpiece 15 if the tool elements 16 become unlocked because of a loss of fluid pressure.

A conventional pressure relief valve 86 isipreferably connected betweenconduits 58 and 66 by conduits94 and 96 for releasing fluid from the pressure system to the reservoir 24 should pressure exceed that which is sufficient to expand the expandable shafts. This valve prevents a possible rupture due to excessive pressure in the system.

A conventional fluid filter 88 may also be connected to conduit 60 between the reservoir 24 and pump 26 to maintain fluid F flowing through the system in a substantially foreign particle-free condition.

In operation, assuming the pair of shafts 13 on leg Ll of frame 38 has previously been expanded thereby securing tool elements 16 along the length of each

shaft

12 and 14, leg L2 of frames 38 are pivoted to the nonoperating position with legs L1 in the operating position with tool elements 16 on the pair of shafts 13 operating on the moving web 15. In this position of the workstations, the machine operator can rotate handle 23 of valve 22 on leg L2 to the unlocked position causing the pair of shafts 31 to contract by allowing the pressure on fluid F to be relieved from

shafts

32 and 33, through journals 35, through unions l8 and 28, through valve 22, through manifold 72, through union 36, and to reservoir 24. The machine operator can now position the unsecured tool elements 16 along the length of each

expandable shaft

32 and 33 to their desired locations. Subsequent rotation of handle 23 of valve 22 to the locked position causes fluid pressure, generated by applying 40 to 60 p.s.i. air pressure to piston 68 of pump 26 causing a pressure of 2,000 to 3,000 p.s.i. to be imparted to fluid F by piston 70, to be transmitted from pump 26 through union 36, manifold 72, valve 22,

unions

18 and 28, journals 35, passages 46 and 48 in core 44, and into the annular space 50 between the outer periphery of core 44 and the inner periphery of shell 30. The pressure of fluid F acts uniformly and simultaneously over the entire inner periphery of shell 30 causing shell 30 to expand a sufficient amount to secure all tool elements 16 simultaneously on the outer periphery of shell 30.

Once the desired operation is completed on workpiece by

expandable shafts

12 and 14 on leg L1, frames 38 are rotated about central common axis 34 until legs L2 are located in the operating position. The tool elements 16 on

expandable shafts

32 and 33 of legs L2 are now ready to perform their operation on workpiece 15. Then the tool elements on the legs in the nonoperating position may be repositioned.

Although the pressure system described herein is preferred, another arrangement can be used in which fluid pressure is introduced into the inner cavities through one end of the shaft and relieved through the opposite end. In this case, another rotary union would be needed on the relief end; the control valve would be connected the the latter union to relieve the pressure. In addition, the reservoir would be connected to the relief valve and to the pressure supply means.

Of course, either arrangement may be used to expand a single shaft to secure tool elements thereon.

Accordingly, the invention having been described in its best embodiment and mode of operation, that which is desired to be claimed by Letters Patent is:

l. A pressure system for expanding and contracting the periphery of at least one of a pair of coaxially mounted rotatable shafts to secure tool elements surrounding said one shaft at selected locations therealong, comprising:

a union means connected to an end of said one shaft through which fluid passes to an inner cavity of said one shaft;

said one shaft including an annular member extending through said inner cavity and forming an annular space between said-annular member and the inner periphery of said one shaft for receiving fluid pressure from said union means;

a selectively operable valve means connected to said union means for conducting fluid pressure to said union means;

a fluid pressure supply means connected to said valve means for supplying fluid pressure to said one shaft through said valve means and said union means to expand said one shaft an amount sufficient to secure said tool elements thereon and a reservoir means connected between said one shaft and said supply means for receiving fluid released from said inner cavity upon contraction of said one shaft and for replenishing the supply of fluid to said supply means.

2. The pressure system of claim 1 further including a second union means connected to an end of a second shaft of said pair and to said valve means through which fluid passes to an inner cavity of said second shaft for expanding the periphery thereof an amount sufficient to secure tool elements surrounding said second shaft thereon.

3. A pressure system for expanding the periphery of at least one shaft of each of a plurality of pairs of coaxially mounted rotatable shafts to secure tool elements surrounding said one shafts at selected locations therealong, said plurality of pairs of shafts spaced circumferentially substantially equiditant about a central common axis, each of said pairs movable about said common axis for alignment with a workpiece engageable with said tool elements, comprising:

a first union means connected to an end of each of said one shafts through which fluid passes to an inner cavity of each of said one shafts;

each of said one shafts including an annular member extending through each of said inner cavities and forming an annular space between each of said annular members and the inner periphery of each of said one shafts for receiving fluid pressure from each of said first union means;

a valve means for each of said union means and connected thereto for conducting fluid pressure to each of said union means;

a second union means in coaxial alignment with said central axis and connected to each of said valve means for directing fluid pressure to each of said first union means through each of said valve means thereby providing said fluid pressure to said one shafts;

a fluid pressure supply means connected to said second union means for supplying fluid pressure to each of said one shafts through said second union means and through each of said valve means and each of said first union means to expand each of said one shafts an amount sufficient to secure said tool elements thereon; and reservoir means connected between said second union means and said supply means for receiving fluid released from each of said one shafts upon contraction thereof and for replenishing the supply of fluid to said supply means.

4. The pressure system of claim 3 further including a third union means connected to an end of each of said second shafts of said pairs and to each of said valve means through which fluid passes to an inner cavity of each of. said second shafts for expanding the periphery thereof an amount-sufficient to secure tool elements surrounding each of said second shafts thereon.

5. The pressure system of claim 1 wherein said fluid comprises a hydraulic medium for supplying uniform and substantially instantaneous pressure against the inner periphery of said one shaft to expand the outer periphery of said one shaft uniformly and thereby secure all of said tool elements simultaneously thereon.

6. The pressure system of claim 3 wherein said fluidtool elements in a secured position on said one shaft.

Claims

1. A pressure system for expanding and contracting the periphery of at least one of a pair of coaxially mounted rotatable shafts to secure tool elements surrounding said one shaft at selected locations therealong, comprising: a union means connected to an end of said one shaft through which fluid passes to an inner cavity of said one shaft; said one shaft including an annular member extending through said inner cavity and forming an annular space between said annular member and the inner periphery of said one shaft for receiving fluid pressure from said union means; a selectively operable valve means connected to said union means for conducting fluid pressure to said union means; a fluid pressure supply means connected to said valve means for supplying fluid pressure to said one shaft through said valve means and said union means to expand said one shaft an amount sufficient to secure said tool elements thereon; and a reservoir means connected between said one shaft and said supply means for receiving fluid released from said inner cavity upon contraction of said one shaft and for replenishing the supply of fluid to said supply means.

3. A pressure system for expanding the periphery of at least one shaft of each of a plurality of pairs of coaxially mounted rotatable shafts to secure tool elements surrounding said one shafts at selected locations therealong, said plurality of pairs of shafts spaced circumferentially substantially equiditant about a central common axis, each of said pairs movable about said common axis for alignment with a workpiece engageable with said tool elements, comprising: a first union means connected to an end of each of said one shafts through which fluid passes to an inner cavity of each of said one shafts; each of said one shafts including an annular member extending through each of said inner cavities and forming an annular space between each of said annular members and the inner periphery of each of said one shafts for receiving fluid pressure from each of said first union means; a valve means for each of said union means and connected thereto for conducting fluid pressure to each of said union means; a second union means in coaxial alignment with said central axis and connected to each of said valve means for directing fluid pressure to each of said first union means through each of said valve means thereby providing said fluid pressure to said one shafts; a fluid pressuRe supply means connected to said second union means for supplying fluid pressure to each of said one shafts through said second union means and through each of said valve means and each of said first union means to expand each of said one shafts an amount sufficient to secure said tool elements thereon; and a reservoir means connected between said second union means and said supply means for receiving fluid released from each of said one shafts upon contraction thereof and for replenishing the supply of fluid to said supply means.

4. The pressure system of claim 3 further including a third union means connected to an end of each of said second shafts of said pairs and to each of said valve means through which fluid passes to an inner cavity of each of said second shafts for expanding the periphery thereof an amount sufficient to secure tool elements surrounding each of said second shafts thereon.

6. The pressure system of claim 3 wherein said fluid comprises a hydraulic medium for supplying uniform and substantially instantaneous pressure against the inner periphery of each of said one shafts to expand the outer periphery of each of said one shafts uniformly and thereby secure all of said tool elements simultaneously thereon.

7. The pressure system of claim 1 including a fluid pressure switch for shutting down a drive means for said shafts when said fluid pressure in said system falls below a minimum pressure sufficient to maintain said tool elements in a secured position on said one shaft.