US2776481A

US2776481A - Pressure-fluid operated tool

Info

Publication number: US2776481A
Application number: US595709A
Authority: US
Inventors: Walter E Northcutt
Original assignee: HK Porter Inc
Current assignee: HK Porter Inc
Priority date: 1956-07-03
Filing date: 1956-07-03
Publication date: 1957-01-08
Anticipated expiration: 1974-01-08

Description

Jan. 8, 1957 w. E. NoRTHcUTT 2,776,481

PRESSURE-FLUID OPERTED TOOL Filed July 5, 1956 .MMI

wird.

2,7 7 6 ,481 .Patented:Jansfsiwsv 2,716,481 `lfPRESSURE:Front optimum TooL WaltenEl ANorthcutt,Melrose,.Mass.,. assignor to H. K.

' Porter, Inc.; Somerville, Mass., a corporation of Massa- `cllusetts .,fApplicationtIuly'S; 41956,l Serial\No."595,709

. c4C1aims. (CL :t0-+180) This finve'ntion':y relates ftohydraulically operated tools .'.slich'as those used for; Ec'utting'ste'el l bars` and other heavy ,-work beyond the-range fof 4hand-operated tools, the 'object tb'eing .'to provide-"an improved"constructionlforlsuchA a :toolf/whereinameans' are'provid'edflto `prevent entryinto the mechanism of foreign particles with resulting-wear or deterioration of the tool. For instance, in steel mills such tools are use'dfforttrimming'steel rod after hot rolling, and there is alwaysscale on the rod which is being cut. As each cut is made small particles of scale are broken away and fall into the opening between the blades and if they are drawn into the bearing surfaces between the moving parts, they may cause cutting or galling, so that the ram of the tool will stick or the bearings be enlarged until side movement is excessive and the blades will no longer be in alignment. l

My invention will be well understood by reference to the following description of the illustrative embodiment thereof shown for example in the accompanying drawings, wherein:

Fig. l is a perspective of the tool;

Fig. 2 is a view chiey in longitudinal section on a larger scale; and

Figs. 3 and 4 are diagrammatic details, unrealistic as to the dimensions shown.

The tool herein shown is a portable tool in the sense that it may be brought to the work and may be in part positioned or guided by hand and its cutting cycle is under manual control.

Referring now to the drawings, and more particularly to Fig. 2, the cutting elements of the tool are supported by a C-frame having a fixed cutter 12 mounted on one arm of the C, while the other arm is provided with a guiding and bearing surface herein formed by a liner or bushing 14 for the ram 16 of the hydraulic mechanism on the distal end of which is mounted a cooperating tool 1S the edge of which, when the ram is moved to the left from the position of Fig. 2, cooperates with the edge of the cutter 12 for severing the work.

The C-frarne 10 is herein at least eifectively integral with a head 19 closing the left-hand end of a cylinder 20, in which reciprocates a single acting piston 22, the ram 16 in this instance being the piston rod. A head 24 closes the right-hand end of the cylinder and forms a working chamber to which hydraulic fluid may be admitted through the nipple 26 from the flexible conduit 28, Fig. l, leading to a source of supply. When the fluid is so admitted the piston 22 moves to the left on the power stroke and on the exhaust stroke it is returned by the compression springs 30 interposed between the piston and the head 19. An orienting pin 32 on the piston enters a hole 34 in the head 19 to orient the parts.

Referring to Fig. l in the tool shown a ring 36 surrounds the cylinder and provides means for suspending the tool by a flexible connection from an overhead point. A handle 38 mounted von the nipple 26 provides for steering the tool and a trigger 40 on the handle controls the operation of the hydraulic mechanism. These detrails are here describedbecause illustratdin"Fig, 1,""but they are 'ofno importance tothe invention andarenot shown in Fig. 2.

"The" headl 1191 at^the`left`of 'thefc'ylinder' denes with fthe piston a chamber of variablesize. -AThe head Yis packed withian O-ring2'42,' but 'on movementof the piston to the right air may enter'this chamber through. an inwardly opening valve 44'loadedby a"'lightspring. `Ascreen a46- and iilter"48-outwardlyl of 'the'valve prevent foreign 10" particles from entering withthe` air.

I Onthe 'exhauststroke' bf thejme'chanismwhen the.' piston moves to the `right a"'charge`of air Vis drawn rinto the chamber. On the return stroke ythe valve is closed,'fthe `16 andthe-bshing'f 14. "No clearance is'shown' between these lparts 'in'vv Fig. 2 because that would' be misleading.

The'control-of this' chargebf air is effected by what is ina sense a packing 50, -although installed reverselyto 'itheusualvmannergand vwhichfunctions also as a'yielding valve. This ring is shown with some exaggeration most clearly in Figs. 3 and 4, and is generally of channel shap'e section with a base 52 and outwardly aring yielding lips 54 and 56. The ring may be molded from plastic material of suitable resiliency. I have found nylon to be suitable. I believe also that certain silicone rubbers would serve, but have not fully tested them under conditions of use. Tetrafluorethylene is another possibility. This ring may be installed in a suitable groove in the ram 16 with the lips projecting axially outwardly toward the distal or free end of the ram which carries the tool 18. In Figs. 3 and 4 the clearance between the ram and the cylinder is much exaggerated. In practice the radial thickness of the base 52 of the ring may be somewhat smaller than the nominal clearance between the bottom of its groove and the liner, say two to live thousandths of an inch. On the other hand the lips may be so molded that the distance between them is slightly greater than this nominal clearance, again say two to ve thousandths of an inch, and therefore they are under a slight compression in Fig. 3. When the ram is moving toward the right, due to spring pressure, and is exhausting the hydraulic lluid to the right of piston 22 the lip 56 bears on the liner 14 and slides over it with a wiping action as shown in Fig. 3. This lip not only is a mechanical barrier against the entry of foreign matter past it, but also serves as a Valve, due to the higher pressure outside the tool tending to spread the lips of the wiper. It may be noted that as the piston 22 moves to the right it creates an enlarging volume with a pressure below atmospheric. The reduced pressure within the tool chamber allows outside atmospheric pressure to unseat the ball valve 44 until equilibrium of pressures is established, at which point ball valve 44 closes.

Now as the piston moves toward the left the valve 44 is closed and pressure begins to build up in the chamber as its volume decreases. In the initial stage of the movement the lip 56 will retain the position shown in Fig. 3 and act as a mechanical wiper or squeegee moving on the liner 14. As pressure builds up however it may ileX inwardly to the position diagrammed in Fig. 4, permitting ow of air outwardly, and the web portion S2 of the ring may move downwardly to the bottom of its groove, increasing the clearance for air escape past the ring. This stream of air tlows outwardly between the bearing surfaces and around the blade 18, lessening the possibility of scale working in between the former.

I am aware that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and I therefore desire the present embodiment to be considered in all respects as illustrative and not restrictive, as is in fact clear in several matters from the description itself. Reference is to be had to the appended claims to indicate those principles of the invention exemplified by the particular embodiment described and which I desire to secure by Letters Patent.

I claim:

1. A pressure-fluid operated tool comprising a cylinder having a piston therein, a ram carried by the piston having a tool mounted thereon, a closure head for the cylinder through which the ram passes defining within the cylinder an air receiving chamber, guiding means for the ram, an inwardly opening valve for admitting air to the chamber on the exhaust stroke of the piston and yieldable means p providing for discharge of entrapped air from the chamber over the guiding surfaces on the power stroke of the piston.

2. A pressure-Huid operated tool comprising a cylinder having a piston therein, a tool-carrying member carried by the piston, a closure head for the cylinder through which said member passes defining within the cylinder an air receiving chamber, means associated with the head providing an elongated external bearing for said member, a tool on the end of said member and packing means between said member and bearing having a resiliently ilexible axially outwardly extending lip which bears on one of them during the exhaust stroke to exclude passage of air to the chamber during the exhaust stroke and yields to permit passage of air over the bearing surfaces during the power stroke.

3. A pressure-fluid operated tool comprising a cylinder having a piston therein, a ram carried by the piston having a tool at its distal end a bearing in which the ram slides, a packing ring between ram and bearing having a lip extending axially outwardly and resiliently yieldable radially inwardly, means controlled by movement of the piston for drawing in a charge of air on one stroke of the piston and means for releasing it to the bearing surfaces at the inward side of the lip on the other stroke.

4. A tool comprising a frame having a pair of cooperating cutters mounted thereon one being mounted on a ram to move to and from the other, the frame having a bearing for supporting and guiding the ram, a packing between bearing and ram adjacent the tool normally biased to exclude passage of air therethrough from the tool side but yieldable to pressure from the other side, pressure-duid operated means for reciprocating the ram, and means operated thereby for discharging air under pressure to the bearing surfaces at said other side of the packing.

No references cited.