US1893187A - Cushioning mechanism for power hammers - Google Patents

Description

Jan. 3, URBANEK ET L CUSHIONING MECHANISM FOR POWER HAMMERS Filed May l0, 1928 JIJ/1 U5 Urlo@ nek Patented Jan. 3, 1933 UNITED STATES aUiIus URRANEK, orvimvvn, AUSTRIA, AND ARTHUR scHNEIDuR,` or DussRrDoRr,

'Y 1 y GERMANY Y PATENT .o1-*FICE cusmolvnv'crv MEcHANrsM roR :POWER- HAMMRRS Application filed Hay 10, 1928, Serial No. 276,577, and in Austria May 31, 1927'.-` f

'.This invention relates to a hydraulic brak forthe tup rod of drop hammers. v Drop hammers are known in which the tup rod, forexample, board, toothed rack, piston rod together -with the piston and the like are movable relative to the tup, and in which the momentum of the rod laccumulated during the drop is dissipated byfa brake. Drop hammers arefurther known in which the momentum ofthe rod movablerelatively to the tup is acciunulated in a steam 4orairchest of the tup cylinder, and in which the upward movement of the rod is checked by a hydraulic brake in the tup, which brake is only effectiv duringsaid upward movement.

Both of these constructions have disadvantages. The first mentioned construction leads by the use of elastic driving medium such as, for example, steam, compressed air or the like to undesired high relative speeds between 'rod and tup causing the carrier owing to its violent stoppage to be adversely eected, whilst the ,last mentioned construction requires a very long path of retardation which mechanically -is unsatisfactory.' v

The present invention consists in an appropriate combination of features of both constructions, in which a double hydraulic brake is employed, one braking action being chiefly eective during the downward movement o-f the tup, whilst the other is'eifective during the upward movement.

The invention is illustrated in the accomanying drawing in which the figure is a ragmentary vertical sectional view of one form of the invention.

A hydraulic cylinder 2 is arranged in the l tup l and contains disc pistons 4 and 5 of a plunger piston 3. The tup rod of any desired construction, for example, a piston rod is ixedly connected to the plunger 3. In the drawing the piston is illustrated in its highest position. In this position the tup is supported by means of the cylinder cover on a collar 6 formed on the plunger piston 3. Ports 9 are formed in the piston 4 for the free passage of the braking liquid as a plate 7 for controlling them is held by a spring 8 in its highest position.

The illustrated position of the piston remains unchanged-during the fall of thetup. When the tup delivers its blow and Vis retarded, then the piston moves downward and the braking fluid is 4introduced around the piston 5 and alsothrough and around the piston 4. As in the usual distance of drop, the speed of the tup `end is about 6.5 metres perv second, and the liquid is forced at a great speed up through the ports 9. yIf thefplate valve 7 were displaced on its seat against the 60 piston 4, then Vsimultaneously it 4would be fo-rced upwardly at a great. speed Aand thereby -receive injury by forceful Contact with the collar 6 or other limiting arrangement. This danger is avoided however by holding the plate valve 7 olf its seat against the pistony 4 by means of the spring 8, thereby rendering the raising of the valve by the liquid unnecessary.

The breaking liquid in its passage round and through the pistons is considerably throttled, so thatthe necessary super-pressure for retardation of the rod and dissipation ofv energy is produced.

The liquid displacedby the plunger piston 3 passes through holes 10 into the air reservoir provided in the interior of said piston.

In order to keep the braking force approxi-` mately constant in spite of the vdecreasing speed of the rod the lower part of the cylinder. is reduced, so that the outlet cross section for theliquid displaced bythe piston 5 constantly decreases. The rod therefore will from the moment of the blowjmake an approximately uniformly retarded movement until it comes to rest. y Y

As soon ,as the 4operation of the tup takes place, the braking liquid will pass downwardly through the ports 9, and close the valve by overcoming the tension of the spring which is made only slightly more than the weight of the valve. Grooves l1 are provided in the cylinder wall for the overiow. As these grooves however are o-f small cross section the piston 4 upon its upward movement is met` with a .powerful resistance, and can only assume a small relative speedagainst the tup. As,-moreover, the grooves merge out at the top, gentlecontact of the co-llar 6 with lthe 100 cylinder cover is ensured.

Upon the upward movement of the rod the lower piston 5 is non-eective, because the large cross section liberated by it cannot produce any preceptible throttling effect during the small upward speed of the rod.

According as the plunger' piston' 3 ascends, so does the braking liquid return from the air reservoir into the brake cylinder 2.

Then the rod drops there is no need lfor the piston e to fit completely tight owing to its great speed, but it is well for it to do so upon ascent because only then will the relative movement of the rod against the tup be able to be regulated by thelongitudinal profile of the grooves ll, or the cross-section of holes l5 orl grooves 16 and so forth.

Y Ve claim: Y j

' l. A cushioning device, comprising a chamber containing a liquid, a plunger movable in said chamber and having a cavity communicating with said chamber, said chamber presenting a steadily decreasing Cross sectional area to the plunger in its downward movement, said plunger comprising two-iiange-like projections dividing the chamber into three sections, the upper projection having ducts to establish communication between the two upper sections and a check valve for said ducts.

2. A cushioning device, comprising a chamber containing a liquid, a plunger movable in said chamber and having a cavity communicating with said chamber, there being ducts to establish communication between the cavity and the end section of the chamber, a collar on said plunger tovlimit the' upward movement thereof within the chamber,said chamber presenting a steadily decreasing cross sectional area to the plunger in its downward movement, said plunger comprising two ydisc shaped projecting flanges dividing the chamber into three sections, the upper. iiange having ducts to lestablish communication between the two upper i sections, and ai check valve for said last mentioned ducts, said check valve comprising a resiliently supported disc adapted to seal said ducts.

3. A'cushioning device, comprising a liquid containing chamber having an upper cylindrical portion of reduced cross sectional area, a lower conical portion of reduced cross sectional area and a mid-portion having grooves in itsV wall, a plunger movable in said chamber and having a cavity communicating with said chamber, said chamber presenting a steadily decreasing cross sectional area to the plunger in its downward movement, said plunger comprising two flange-like projections dividing the chamber into three sections, the upper projection having ducts yto establish communication between the two upper sections, anda check valve for said ducts.

4. A cushioning device, comprising a liquid containing chamber having an upper cylindrical portion of reduced cross sectional area., a lower conical portion of reduced cross sectional area and a mid-section having grooves in its wall, a plunger movable in said chamber and having a cavity communicating with said chamber, there being ducts to establish` communication between the cavity and the mid-section of the chamber, avcollar on said plunger to limit the upward Inovement thereof within the chamber, said chamber presenting .av steadily decreasing cross sectional area to the plunger in its downward movement, said plunger comprising two disc shaped projecting iianges dividing the chamber into three sections, the-upper flange having ducts to establish commu-v nication between the two: upper sections, and a check valve for said llast mentioned ducts', said check valve comprising a resiliently supported disc adapted to'seal said ducts.

5.' A cushioning` device for power hammers, Vcomprising a liquid containing cham!- ber, a plunger movable-finl said chamber and having a cavity communicating with'.- the chamber, said chamber presenting a steadily decreasing cross sectional area to theplunger in-its upward. andi in its-'downward movement, said plunger comprising two flangelike projections dividing the `chamber into three sections, the upper projection having ducts to establish communication between the' upper and mid-chamber sections, and -a check valve to seal saidducts.

Signed at Vienna, Austria, this-'20th day- Of April, 1928;- Y

n J. URBANEK. Signed at Cologne, Germany, this 25thdayv ofl April, 1928. ARTHUR SCHNEIDER.

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