US3079823A

US3079823A - Off-set ejector for punch dies

Info

Publication number: US3079823A
Application number: US746880A
Authority: US
Inventors: Paul R Ekstrom
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-07-07
Filing date: 1958-07-07
Publication date: 1963-03-05
Anticipated expiration: 1980-03-05

Description

3,ti7,823 (EFF-SET EIlECTQR FOR PUNCH DES Paul R. Ekstrom, 1326 Ciinton Ave, Alameda, Calif. Filed July 7, 1158, Ser. No. 746,889 11 Claims. er. 83-111) The present invention relates to devices for displacing work from a die preparatory to inserting a new piece of work.

Punch dies are presently used for forming openings in small flat metal parts. This part to be punched is positioned on a metal die block havin. openings corresponding to the openings which are to be formed in the metal part. Metal punches of the same size as the die openings are forced against the other side of the part to cut out and remove a slug of metal from the part to be punched.

Removal of the slug is efiected through slug ports which pass through the metal die and are tapered outwardly from the die opening.

The metal part is held in place in the desired relation to the die opening by a metal gate secured to the upper surface of the die in surrounding relation to the metal part, so as to prevent sidewise movement of the part relative to the die.

With the metal part nesting in the recess formed by the gate and the die, it is rather difiicult to remove after the punching operation. Consequently, some type of ejecting means for pushing the part up out of its nested position must be provided.

Such ejector means may consist of a pin passing through the die to a point underneath the metal part. The pin is arranged to push the part up out of its nested position upon actuation of the pin, as by an air cylinder.

Usually, the air cylinder is formed within the die block concentric to the pin opening and the air piston and pin are turned from a single piece of metal.

While the pin is extended by means of air pressure, furnished to the opposite side of the air piston, it is commonly retracted by the force of gravity alone.

The described construction creates two serious problems. Firstly, the bores for the pin and piston must be concentric, and the in and piston must also be concentric. This creates machining problems.

Secondly, when the part is small or there are a number of openings to be punched, the ejector pin must be positioned rather close to the die opening. f necessity, the air piston must have a considerably larger diameter than the ejector pin. Due to the concentricity of the pin and piston, it is often difiicult, if not impossible to locate the ejector pin.

The present invention contemplates an ejector means for punch dies in which the pin and piston may be non concentric, that is the pin and piston may be eccentric with relation to each other.

Accordingly, it is a principal object of the present invention to provide a punch die ejector construction in which the ejector pin is mounted on the piston for selective adjustment to any desired degree of eccentricity.

Another object of the present invention is to provide an ejector in which the'ejector pin may be positioned close to the punch die opening without interfering with the slug passages. V i

A still further object of the present invention is to provide an ejector which will operate when the die is in a position other than horizontal by reason of a positive displacement of the pin from its retracted to extended position and return.

It is additionally proposed to provide an ejector of the character described which is retracted by means of a spring, and in which the parts are proportioned to pre- Sydlih g Patented Friar. 5, 19%3 M vent full compression of the spring, thus making for a longer life under repeated use.

Other objects and features of advantage of my invention will become apparent from a consideration of the following description, and of the drawing forming a part of this application.

in the drawing:

FIGURE 1 is a perspective view of an ejector for punch dies constructed in accordance with the present invention and shown partially in cross-section to reveal internal details.

FIGURE 2 is a perspective view similar to that of FIG- URE l but illustrating a modified form of ejector.

FIGURE 3 is a cross-sectional view on an enlarged scale through the air piston of FIGURE 2.

The ejector for a punch die of the present invention consists essentially of a cylindrical chamber 6 formed in a die block 7 and having a cylindrical piston 8 mounte for axial reciprocation in the chamber 6.

An ejector pin 9 of smaller diameter is carried by the piston for reciprocating movement therewith and is slida- -bly engaged in a bore 11 which is axially parallel with the chamber 6 and extends to a point underlying a portion of the Work 12 mounted in the die.

As here shown, the die block 7 consists of a hardened die member 13 formed with die openings 14 and mounted upon a backing block 15. The work 12 is held in position over the die opening 14 by a suitable gate member 17 indicated by the phantom lines in FIGURES l and 2.

Outwardly tapering passages 18 extend through the die block 7 from the die opening 14.

In accordance with the present invention, the ejector pin 9 and the piston 8 may be eccentric to each other. This will permit the ejector pin bore 11 to be positioned more closely to the die openings lid than would be possible where the pin and piston are concentric.

In the form of my invention illustrated in FIGURE 1, the piston 3 is ofcup-shape, and provides an upstanding cylindrical wall 19 and a fiat internal floor 21.

The ejector pin 9 is provided with an enlarged fiattened head 22 slidable over the floor 21 to any desired degree of eccentricity.

The ejector pin 9 is biased toward its retracted position by a spring 23 coiled around the pin and compressed between the head 22 and the upper end 24 of the chamber 6.

After the punching operation is completed, the ejector pin 9 is moved upwardly by the force of compressed air supplied to the lower end of piston 8 through a conduit 26. The spring 23 provides a positive return of the piston and ejector pin to retracted position when the air pressure is removed from conduit 26, thus permitting the ejector to be used in any position.

As a feature of the invention, the spring 23 cannot be overstressed. This is accomplished by proportioning the Walls 19 and the spring 23 so that the upper edge of the wall will contact the upper end 24- of the chamber 6 before the spring is fully compressed. This is important in insuring that the spring does not break through many cycles of operation.

The form of ejector illustrated in FIGURE 1 is somewhat limited in that the ejector pin cannot be adjusted so that its edge coincides with the edge of the piston 8. Thus, the edge of the chamber 6 will always be closer to the slug opening 13 than the ejector pin will be.

Under certain conditions of use it is desirable to locate the ejector pin at the edge of the chamber. The form of my invention illustrated in FIGURES 2 and 3 of the drawing makes such positioning possible.

In this form of the invention, the piston 8 is solid and is formed with a diametrically arranged groove 31 in its upper end. The ejector pin 9 has an enlarged lower end 32 which engages in an undercut portion 33 of the v groove 31.

The return spring 23is compressed between the lower end 34 of a bore 36 formed in the piston 8 and the upper end 24 of the chamber 6.

The spring 23 'is proportioned so that .it will not be fully compressed when the upper end 37- of the piston contacts the upper end 24 of the chamber 6. This will prevent over-stressing of the spring 'andigive it a much longer life than would otherwise be obtained.

Preferably, a guide sleeve 38 is slidablyamountedin the bore 36 in surrounding relation to' the 'spring23 to keep the spring'aligne'd with the bore 36. This assures that the spring cannot become misalignedand broken ofi when the air pressure is applied to the piston.

In adapting the ejector of the present-invention to a punch die, the die opening 14 and slug passages 18 are machined in the die block. The chamber 6 is then bored in the backing block and the conduit 26 installed.

The bore 11 for the ejector pinjis then formed in the die face in a suitable position, it being noted that 'it is only necessary for the die' bore to open through the upper end 24 of the chamberfi at any position relative to the axis of the chamber.

With. this construction, no. attempt need be madeto make the bore 11 concentric with the chamber 6, the adjustable feature of the ejector pin on the piston 8-automatically accommodating to. whatever eccentricity is encountered. i

Fromthe foregoing, it .will be apparentthatI have provided anv ejector for punch dies which is simple to machine'and to install and which is self-accommodating to various degrees of eccentricity between the piston and the ejector pin.

I .claim:

1. An ejector for a punch. die, having a slug opening therethrough, comprising a cylindrical chamber formed in said die-in laterally spaced relation to the slug opening, a bore of reduced, diameter formed in said die and hav-' ing an axis in parallel spaced relationto the axis of said chamber and opening to said chamber and to a point underlying a portion of the work to be mounted in said die, a cylindrical piston mounted for axial reciprocation in said chamber toward and away from said bore, an ejector pin carried by: said piston for reciprocating movement therewith and slidably engaged in s'aid bor e; and means mounting the pin with respect to the cy'linder to provide lateral movement of the pin relative to the piston, conduit. means in said die adapted for selectively connecting a sourcehof .fluid under pressure to said chamber for urging said piston toward said bore whereby said pin will eject the work from said die, and means eifeetive on releaseof the actuating pressure to" cause". retrograde rnovementof the ejector unit.

2. An ejector for. a punch die as described in claim 1 wherein said pin is floatingly mounted on said. piston for displacement radially thereof so as to adapt the pin and piston to chambers'and bores positioned 'with 'ditferent degrees of relative eccentricity.

3. ,An ejector unit as defined in claim 1 wherein said piston is of cup shape providing? a flatinte'rnal mamas said ejector pin is formed .withauenlarge'd flattenedfhead slidable over said floor. i M

4.,An ejevcllorrunit as defined in claim 3 wherein said retrograde causing means comprises .a"coil spring iicit cling said ejector -'.pin' iandproportionedfforbearing against said flattened head and the end of said chamber adjacent said borey 5. An ejector unit ,for dies-having. a cylindricalchamher and an eccentric ejector bore, comprising a cylindrical piston formed for reciprocation insaid chamber, said piston having an end formed with a transverse undercut slot, an ejector pin having a shoe portion at one end formed for sliding engagement in said slot and having its opposite endformed forsliding engagement in said bore, and spring means on said piston for urging the latter to retracted position in said chamber,

6. An ejector unit as definedin claim 5 wherein said spring means includes a helical spring mounted in a bore in said piston for compression between thebottom of said. bore and the confrontingend.of-saidchamber.

7. An ejector unit as defined in claim 6 wherein'said spring is proportioned sothat it will be less than fully compressedwhen saidpiston engages .the end of said chamber.

8. An ejector unit as defined in claim- 7 wherein a tubular member is slidably mountedjin said bore in said piston, and in surrounding relationto said-spring soas to provide a guidefor retaining -said spring concentric to said bore in said piston.

9. In a punch.die-machine, a die block formed with a punch hole adapted to cooperate with-a punchmember and an outwardly taperedslug opening extending from said punchhole through-said die blockgrsaid die block being formedwith a cylindrical chamberadapted for selective connection to.a sourceof fluid under pressure and an. ejector bore of. smaller diameter than said chamber and having an axis parallel to and-spaeed froni the axis of said cylindrical chamber -wherebysaid bore maybe formed inclose proximity -to said punch hole without interference. between. said chamber 'andsaid slug opening, a cylindrical piston mounted for axial reciprocation in said chamber and having an end'facing saidbore formedwith ,a transverseundercut slot,-an eject'or pin axially re:

ciprocable insaid ejector bore and havinga shoe portion at one .end formed for sliding engagement in said slot whereby said ejector pin may be positioned with any de sired degree ofieccentricit y to said piston, and'sprihg means compressed between said piston and the'end of said chamber, said spring meansbeingresiliently compressible.,to,a1lo,w said. piston rise in said chamber when fluid under; pressure. is admittedthereto and being sufiicientlystrong to retract said pistonin said chamber when the fluid under pressure is released from the chamber.

10. A punch die machine as 'defined in claim 9 whe1'ein ,said pistontisnformed with an axially parallel cylingf drical recess, and said'spring means includes a helical spring mounted .in said cylindrical recess and extending therefrom to bearfagainst theend of saidcham ber containingsaidejector bore 1l.:,A punch die. machineas defined inv claim 10 wherein :a .tubular. member is slidably mounted in said cylindrical recessin said piston and in surrounding relation to said spring so as to provide a guide for retaining said spring. in alignment with'said cylindrical recess, said spring being proportioned so that itwill beless than fully compressed.when said piston engages theend ofsaid chamber to limit the stroke of said "ejector References. Cited .in' the fileof this-patent

Claims

1. AN EJECTOR FOR A PUNCH DIE HAVING A SLUG OPENING THERETHROUGH, COMPRISING A CYLINDRICAL CHAMBER FORMED IN SAID DIE IN LATERALLY SPACED RELATION TO THE SLUG OPENING, A BORE OF REDUCED DIAMETER FORMED IN SAID DIE AND HAVING AN AXIS IN PARALLEL SPACED RELATION TO THE AXIS OF SAID CHAMBER AND OPENING TO SAID CHAMBER AND TO A POINT UNDERLYING A PORTION OF THE WORK TO BE MOUNTED IN SAID DIE, A CYLINDRICAL PISTON MOUNTED FOR AXIAL RECIPROCATION IN SAID CHAMBER TOWARD AND AWAY FROM SAID BORE, AN EJECTOR PIN CARRIED BY SAID PISTON FOR RECIPROCATING MOVE-