US2427928A - Safety device for presses - Google Patents

Description

Sept. 23, 1947. P, N, SHAW 2,427,928

` SAFETY DEVICE' FOR lPRESSES Filed March 15, l1945 SKSheets-Sheet 1 ATTORNEY Sept. 23,1947. P. N. sHAw f 2,427,928

SAFETY DEVICE FOR PRESSES Filed Maron 15. v1945 5 sheets-sheet 2 SAUL N.sHAw

ATTORNEY YJNVENjroR.

sept. 23, 1947. l P. N. SHAWy 2,427,928

SAFETY DEVICE FOR PRESSES Filed March 15, 1945 S'Sheets-Sheet 5 ATTQRNEY Patented Sept. 23, 1947 UNITED STATES PATENT GFFICE 2,427,928 SAFETY DEVICE FOR PRESSES Paul N. Shaw, Shaker Heights, Ohio Application March 15, 1945, Serial No. 582,899

` 11 Claims.

This invention relates generally to safety devices, but has reference more particularly to safety devices which are especially adapted for use in connection with punch presses and the like.

In devices of the general character to which this invention relates, as exemplified in Possons Patent No. 1,417,346, means are provided whereby the hands of a press operator are withdrawn from engagement with the press in timed relation to the movements of the press punch or ram.

It has been found desirable, in connection with various types of press work, to provide means whereby the operator is permitted a greater period of time for the'removal of work from the press and for the placement of work in the press than is permitted by the mechanism shown and described in the aforesaid Possons patent, and the present invention, accordingly, is concerned primarily with the provision of such means.

Another object of the invention is to provide a safety device for pulling a press operators hands away from the press, in which is incorporated means for delaying the operation of such pull- .back means, whereby the operator is permitted additional time for the removal of work from the press and for the placement of the work in the Dress.

A further object of the invention is to provide a device of the character described, which is particularly eiective and desirable for use in connection with presses having a long stroke, such as those used for making munition shells and similar articles.

A still further object of the invention is to provide a device of the character described, in which means are incorporated for varying the point in the ram stroke at which the pull-back means becomes ineffective.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings, forming a, part of this specification, and in which like numerals are employed to designate like parts throughout the same, i

Fig. 1 is a side elevational view, showing a straight side press, having associated therewith a safety device of the character described, having incorporated therein the novel features of the present invention;

Fig. 2 is a view showing a. portion of the mechanism of Fig. 1, on an enlarged scale;

Fig. 3 is a cross-sectional view, taken on the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary side elevation of a portion of Fig. 3;

Fig. 5 is a cross-sectional view, taken on the line 5-5 of Fig. 3;

Fig. 6 is a cross-sectional view, taken on the line 6-6 of Fig. 3;

Fig. 7 is a, cross-sectional view, taken on the line I-1 of Fig. 3;

Fig. 8 is a view similar to Fig. 2, but showing a modied form of the invention;

Fig. 9 is a view of a portion of the mechanism of Fig. 8, as viewed from the right of Fig. 8;

Fig. 10 is a, cross-sectional view, taken on the line IIJ-IIJv of Fig. 9; v

Fig. 11 is a cross-sectional view, taken on the line II-II ofFig. 10;

Fig. 12 is a cross-sectional view, taken on the line I2--I2 of Fig. 10;

Fig. 13 is a cross-sectional view, taken on the line I3-I3 of Fig. 10, and

Fig. 14 is a fragmentary elevation of a portion of Fig. 10, as viewed from the `left of the Fig. 10.

Referring more particularly to Figs. 1 to 7 inclusive, it will be seen that a conventional punch press, for which the present device is adapted, comprises a stationary base I, having a bed or work table 2, on which the work is placed, and the usual reciprocating punch or ram 3, the press being provided, as is generally the case, with a flywheel 4. The reciprocatory movement of the ram 3 is provided for by a crank-arm (not shown).

The safety device, in this case, is supported by a pipe 5 which may be connected to the ceiling of the room in which the press is located, and a pair of tie rods 6, which are connected at one end to the base I of the press, and at their other end to a `coupling 1, which is supported by the pipe 5.

Clamped to the tie-rods 6, adjacent the base of the press is a bracket 8, having rigidly secured therein a cam shaft 9, on the central portion of which is journalled a sleeve I0, to which is keyed a gear II. The gear II is operatively connected to a cam I2 which is also journalled on the shaft 9, the connection being such that rotation of the gear II in either direction causes a correspond-` ing movement of the cam I2 about the shaft 9.

' The cam thereof a non-rotating sheave I3 to which one end of a cable 'I4 is secured, the cable passing about the cam I2 and about a second sheave I5, which is rotatably supported on the tie-rods 6.

The opposite end of the cable is connected to avertically slidable clip I6, to which are connected a pair of flexible members I4', to the ends ofv which are -connected hand straps II, which are adapted to be fitted to the hands of the operator. The cable I4 is normally under such tension as to urge thecam I2 to its rearmost position, as

viewed in Fig. 1, and such tension is effected by- I2 has mounted on an extension;

the connectionis -suchthat as the' rams descends?- its downawrd movement isV communicated to the rack I 8, causing the gear II to be rotated ina'i counterclockwise direction, as viewedin Fig. 1 which, in turn, causes the cam I2 to 'be'rocked in a counterclockwise direction about"theishafl9..y

This causes a pull to be exerted on the cable I4,

II, and insuring that the operators hands will not in anywaybeinjur'edbythe ram or work.

In order to permit the operator agieater period of time forv thefremoval ofworkrom' the press' and'for the placementof workfinithe press,` I have provided a novel operative connection between' the rack' I8 "andthe ram 3 of the press, which connectionY will now be'd'escribed in 'detail` Such connection comprises a' tubular housing I94 having a clevis 20 rigidly connectedA t'oandclos# ing the upper 'endof"th'e"housingijl9, such clevis being connected, as by a pin 2I to thel lower flat end I ofthe rackl y The housing I8 is provided-with'elongatd'slots 221in opposite sides ofthe wall-'thereofgtheseslots forming slideways for stop pins^ 23 which'extend fio'nr'a rod-` 21;'- adjacent thev` kupper end of vsaid rod.' Therod" 2f4`is`slidably'mounted 'ina bronze' Bushing 25"vvl:1ich ig'pinnedorotherwise "secured within the Ahousing -I Sadjacent its lower end.

The-rode24fhas Asecured'toits lower end; as Vby means of acouplin'g 126;"1anextensidnpipe- 2'I,tol the; lower endL of 'which "ai sleeve `28 is connected.' Tle pipe 2-'I has slidably mounted tlf'iL-ireinl 'anV extension rod -2$-,"fto the lower end of whicha; clevis` 3Ufis secured: clevis" 311' Vis -pivotally secured-, as-by a-pinf-:ili'to a post 325, which extends from the ram 3, adjacent the lower end of the latten Y The' rod-29 sfprovided with?\amultplicitylof uniformly spacedllolesfs'l` vs'rhifclr'are adapted' to register fwitlfifpairs" ofsp'acedff holes` 34` in-v thesleve-282fapair-of 'Cotter lkeys -35 ibeingf provided`;2 which Y are adaptedvfon iriserrncnf tnroughr: the aligned hlesfi'rifthe sleeve* 28, andl'rod 29,5`after` the rod has been adjusted relativelyto the sleever 28% The purposefot v'thisfadjuse't'mer'it is to vary the effective length" ofi the tconr'iectionibetw'een the' pins .2t auditif, depending upontneiheightothe pressorrstrokefor theram;

l Havingfthusfdscribedth nirvelfeonnectiorr be: twe 'the :track-"flBiaidthirlmvoffthe press; thel operationV off the connection will fnow "brieybei de'iscriiied: Y i

Whenlthefransalisinf itsluppermost positongfthi pins2f-3 are-f disposediadjacentthe -2 upper 'ends i of thee stoten-2 an the; housingfl 9:: As'ithe-'framfdescendsgthrrcdzd WinSite-caused tosude downil wardly: inrfthef'housingfit; but; thefmcvementiof: tlierod-will not be ccmmunicatddothe fhousing or to tha-rack'y I:8', since the pinsn23fiwil1; merely'y slide downwardly-y inxthe` slots-2 tfortle fullflengthf ofzthesefslots. f i

Thisxdelayi in: movement '"of1 thei housingsI 9:' an'd: rackslraiofds ythe operators desiiiedftime-interval lfor: 4properly -farrangmgffthef work onf the -bed ofthefpiress, while;` at the'samextime; the-oper:-u

thefsafety-device'ismoteffective; during suclr ini-f tial downward movemexiifofithe-ram2 iso-withdraw the.-handsfofathebperator:

When the pins 23 reach the lower end of the slots 22, they come into engagement with the housing I9, and thereafter, with continued downward movement of the ram, the housing I9 is eifecraifiverto`r movefthe rackfilsdowrmardly and therebwoperate the safetyedevicefi theimanner previously described to withdraw the hands of the operator from the press.

Whenthe. ram begins its upward movement,

l*"the" tensioirof the spring I6 is effective to cause thefrack 'IBgshousing I9 and rod 24 to move upwardly as a unit, with the result that the hand strapsl I y'are free-tomove forwardly immediately uponl the inception of such upward movement of the ram. This aordsrthe operator additional time to .pick upand properly placetheA new -piece ofworkiri the press, and is an additional factor, which`-permit`s tl'ieoperationoftlie press Ato be speeded up. l

The upward' movement" of thefrack" l isstopped atv any desired. point by means oi a stop, collar 3`,`fwhi`ch issecured'Qas bylset-'screws 31., to the raCKJIMand-Which abiits'. the bracket S'to determine, the extent of. "upward movement of said rack. v Y

Whl. the. afresaid'delayedfaction ram v-connection rodi is usefull Afor various'types of presses, it'is particular-ly` effective! andi desirable for use. in` connection with presses Vhavingga long stroke, such...asth`ose usedifor: making ,muniticn shells, and'similar articles.. Y

Referring. more pparticularlyn to- Figs.. 8to 14' inclusive, theseures illustrate a modied. form of 'delayed'- actinramconnection. rod,.withlwhich. is incorporatedla trip. release, the ifun'ctionof' which? will .be presently describe4:1.,` Y

- The delayed-action connection in this case, comprises a1 tubulan housing 40T Yuan/111gm a, ,icle'vs 4I, rigidlyconnected ,to'and closing, the -.upper .end ofY housing, sucn'cle'vis beingconnectenh asvby a piri-.f2-i,oA the. -lowen tfend. I ofl'the. rack I'Bfl The housing 40'is provided at one side thereofV withan elongated-.slot 43;: Whichexten'ds. longi tudinally-,of the housingrandshas formed inthe opposite sidgtliereof .Ia series. ofllongitudinally.-

, spacedf'transversely extending recesses-,44,which.

are Auniformly.spaced alongtheshousing.

Mounted fr sliding movement alongithehous, ing-.Ail Aist alwtriprelease headz 45l which may ,be locked. at anytadjusted. position.y alongmhe nous:-A ing .,whichlcorrespondsto Lth'espacing; ofthere-Y cessesM, by extending:r a lock' screw46thi ough\ the head and throughY one oftherecessesJM.A To facilitate vlocking Ottheheadto the housing, the head is'splitV asat. fand thescrew is .threadedly securedto one of the split sectionsftoienablethe head toY be clampedto the housing .in its adiusted position.V` i

Pvotally securedelto tiehead '45,1 asat ASQ isv a lever 49"'having a bracket EULeXtendihgthere-I from in,.one direction,and.armsi5!. and 52ex tending therefromlin the -oppositedirectiona The lever is. fi'irtlier.k providd with. asdwnwardly, extending..por'iziorieiY to. whiclfa .trip.-releasef dogy 5l is secured, as by means oanut 5.5,thedog 54 normally .extendingmhroughltle s1ot43 and .into the space withinfthahousing. The dogd has-.an inclined upper surface 5611Y For the purpose of maintainingfthefdog.5min

its vnormal,position vasashownfinw Eigwl, a pair of tension springs 51 is provided, theses-springs interconnecting-the.. armselandy52 ofthe lever 49 with a pin 58, which extends -fromthe head 15.A

A pull-rod 59 is slidably mountedifor recip-ly rocal movement in the housing 40, bronze bushings 60 being provided to facilitate such movement. Secured to the upper end of the rod 59 is an extension member BI of reduced diameter, having a head 62 of substantially the same diameter as the pull rod and having its lower face `cut away to provide a conical surface 63, the angle of which corresponds to thev inclination of the surface 56 of the dog 54.

The pull-rod 59 corresponds to the rod 24 of the previously-described form of the invention, and has secured to its Alower end a sleeve 64, in which is slidably mounted an extension rod 65, to the lower end of whicha clevis 66 is secured. The clevis S6 is pivotally secured, as by a pin 3|, to a post 32, which extends from the ram 3 adjacent the lower end of the latter.

The rod 65 is provided with a multiplicity of uniformly spaced holes El, which are adapted to register with pairs of spaced holes 68 in the sleeve 54, a pair of Cotter keys 69 being provided, which are adapted for insertion through the aligned holes in the sleeve 64 and rod 65 after the rod has been adjusted relatively to the sleeve 64. The purpose of lthis adjustment is to vary the effective length of the connection rod between the pins 42 and 3|, depending upon the height of the press or stroke of the ram.

Trip release mechanism is provided, which comprises a chain 10, which is connected at one end to the bracket 50, as by means of a pin 1I, and is connected, as by a pin 12 to the lower end of a rod 13. The rod 13 i s secured in any desired position of adjustment in a collar 14, as by meansof a set screw 15, the collar 14 extending from a collar or bracket '16,.which is clamped to one of the tie-rods as by means of a set screw 11.

Having thus described the modified form of connection between the rack I8 and the ram of the press, the operation of the connectionwill now be briefly described.

When the ram is in its uppermost position, the Various parts of the above-described mechanism will be disposed in approximately the position shown in Fig. 8. As the ram descends, the rod 59 will be pulled downwardly, but there will be no lost motion between such rod and the housing 40, since the head 62 of the extension 6I of the rod engages the dog 55, causing the rod and housing to descend as a unit. Consequently the operators hands will be pulled back from the press and out of the danger zone vduring the initial downward movement of the ram.

When the ram has descended to a predetermined point, which is a point at which the chain becomes'taut, the lever 49 will be rocked in a counterclockwise direction, as viewed in Fig. 8, about its pivots 48 and against the tension of the springs 51, thereby withdrawing the dog 54 from engagement with the head S2 of the extension El of the rod 59. Thereafter, the rod 59 will continue to move downwardly with the ram, and during such movement, the housing 40 will be returned to its initial position by the spring I6', so that no pull is exerted on the operators hands.

During this period, therefore, the operators hands are free to approach the press and are in readiness to remove the work piece from the press as soon as the latter has been released by the ram.

During substantially the entire upward movement of the ram, the operators hands are free to take the work out of the press and to place a new work piece in the press. Near the end of such upward movement, the head 62 strikes the dog 54 and cams'the latter away from the housing 40, so as to permit said head to pass the dog and return to its initial position.

The angle of the surfaces 55 and 63 of the dog and head respectively is such as to preclude any tendency, during the downward movement of the head to rock the release lever 49 about its pivots. y

By adjusting the head @5 to various positions along the housing 40, the point at which the release of the rod 59 occurs may be varied to suit various conditions. It is further noted that when the head 45 is in its lower positions, a considerable degree of lost motion between the housing 40 and rod 59 is provided before the head 62 reaches the dog 54 on the downward stroke of the ram. This provides a delayed action of the pull straps at the beginning of the ram stroke, which is desirable for certain types of work, and which is similar to the delayed action described in connection with the rst form of the invention. l

It is to be understood that the forms of my invention herewith shown and described, are to be taken as preferred examples of the same, and thatl various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of my invention, or the scope of the subjoined claims.

Having thus described myinvention. I claim:

l. In combination with a press having a ram, means responsive to the operative stroke of the ram for pulling the press operators hands away from the press, and means for delaying the operation of said pull-back means, said delaying means comprising a tubular housing operatively connected to said pull-back means and a rod operatively connected to said ram, and having a lost-motion connection to said housing.

2. In combination with a press having a ram, means responsive to the operative stroke of the ram for pulling the press operators hands away from the press, and means for delaying the operation of said pull-back means, said delaying means comprising a tubular housing operatively connected to said pull-back means and a rod slidably mounted in said housing and operatively connected to said ram, said rod having a lost-motion connection to said housing.

3. In combination with a press having a ram, means responsive to the operative stroke of the ram for pulling the press operators hands away from the press, and means'for delaying the operation of said pull-back means, said delaying means comprising ya tubular housing having elongated slots in opposite walls thereof, and a rod slidably mounted in said housing and having pins extending into said slots.

4. In combination with a press havin-g a ram, means responsive to the operative stroke of said ram for pulling the operators hands away from the press, said means comprising a tubular housing, a rod slidably mounted in said housing, and a dog maintaining said housing and rod in interlocked engagement, and means for releasing said dog during said stroke of the ram.

5. In combination with a press having a ram, means responsive to the operative stroke of said ram for pulling the press operators hands away from the press, said means comprising a tubular housing, a rod mounted for slidable movement in said housing, a headI adjustably mounted on rod to descend with theram independently` of saidhousng. Y Y

6, In. combination with a press having a ram, and means responsive to the operative stroke of s aidranfi for pulling the pressoperators hands away. from ,the press; said means comprising a tubularA housing, a rod mounted for slidable movementv in said housing, a head rigidly securedA to said housing, and a dog mounted for pivotal movement relatively to saidV housing, said dog being normally interlooked with said, rod, whereby downwardmovement of the rod exerts a direct downward pull on said housing.

7. In combination with a press having a ram, and means 4responsive to the operative stroke of said ram lfor pulling the press operators hands away from ,the press, saidV means comprising a :tubular housing, a rod mounted for slidable movement in said housing, a head rigidly secured to said housing, a dog mounted for pivotal movement relatively to said housing, and spring means normally maintaining said dog in interlocked engagement with saidrod, whereby downward movement of the rod exertsl av direc downward pull on said housing. Y

8. In combination with a press having a ram, and means responsive to the operative stroke of said ram for pulling the press operators hands away from the press, said means comprising a tubular housing, a rod mounted for slidable movement in said housing, a head rigidly secured to said housing, a dog pivotally mounted on said housing, said dogbeingnormally interlocked with said rod, i whereby 'd ownw.ard movement of1 the rod exerts a directv downward pull on said housing, said head being adjustablealong said hous- .lng-

. 9. In combinationwith a press having a ram, means responsive to the operative stroke of the ram for pulling the press-operators hands away from the press, said means comprising members normally interlocked with each; other for movement as a unit, anda dog Vfor maintaining said membersin interlocked engagement, and means for releasing said ydog at a predetermined point during said stroke of the ram, whereby one of said members may move relatively to the other member during the remaining portion of said stroke of said ram,

10. The combination, as defined in claim 9, in which said releasing means eomprises a flexible element having oneend thereof operatively connected to said dos.

11. Theioombination, asv dened in claimV 9, in which said releasingmeans comprises a ehain having one end thereof operatively connected to said dog.

PAUL N. SHAW.

REFERENQES CITED The following references. arefor" record in the file of this patent:

UNITED STATES,4 PATENTS

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