US2992580A

US2992580A - Two-stage holding magnet for presses and the like

Info

Publication number: US2992580A
Application number: US604507A
Authority: US
Inventors: Stolk William; Jr Edward E Judge
Original assignee: MACH TOOL ELECTRIC CORP
Current assignee: MACH TOOL ELECTRIC CORP; MACHINE TOOL ELECTRIC Corp
Priority date: 1956-08-16
Filing date: 1956-08-16
Publication date: 1961-07-18
Anticipated expiration: 1978-07-18

Description

July 18, 1961 w. STOLK ETAL TWOSTAGE HOLDING MAGNET FOR PRESSES AND THE LIKE Filed Aug. 16, 1956 2 Sheets-Sheet 1 w s m R J 5 0 y T Mm M vm m 1 W55 v No r. MM/ W n W Y 5 July 18, 1961 w. STOLK ETAL TWO-STAGE HOLDING MAGNET FOR PRESSES AND THE LIKE Filed Aug. 16, 1956 2 Sheets-Sheet 2 5 h M E TKO m w I 5 0 MN W I 0 E United States Patent 2,992,580 V TWO-STAGE HOLDING MAGNET FOR PRESSES AND THE LIKE William Stolk and Edward E. Judge, Jr., Lansing, M1ch.,

assignors to Machine Tool Electric Corporation, Lansing, Mich., a corporation of Michigan Filed Aug. 16, 1956, Ser. No. 604,507 12 Claims. (Cl. 83-136) The present invention relates to an improved magnetic two-stage or dual acting holding unit for industrial presses and the like, which is employed in the handling and disposal of scrap material left in the blanking out of pieces from an advancing strip of magnetic metal stock.

It has been been proposed to employ magnetic holding means in association with the moving die of a metal punching or stamping press for the purpose of retaining the stock from which a blank is struck out and of disposing of this scrap in a suitable receptacle. Electromagnetically energized units are employed for this purpose; however, it has been found that residual magnetism prevents the expeditious discharge of the scrap to the receptacle, the magnetic holding unit acting in the manner of a permanent magnet. Other types of provisions for stripping and discharging the scrap material, as by an air blast, mechanical stripping and handling means, and the like, are relatively cumbersome and expensive.

It is therefore a general object of the invention to provide a two-stage or dual acting holding unit for the purpose described, in which a primary electromagnet is energized as the moving die of the press punches a part from a strip of ferrous metal, the magnet engaging and retaining the scrap left as the punched piece drops to a suitable receiver, the primary magnet being de-energized following this; and in which auxiliary electromagnetically operated means of the improved unit then acts mechanically to discharge the scrap into a suitable receptacle Which has been advanced into receiving position in the meantime.

Another object is to provide an improved dual acting electromagnetic scrap holding and handling unit of the type described, featuring a primary holding electromagnet and an associated electromagnetic stripper acting in the manner of a solenoid to discharge the scrap in a positive fashion, in which the electromagnetic provisions are mounted in a very compact manner for installation in a set along an edge of the reciprocating die of a press.

Another object of the invention is to provide an improvement in punching or stamping presses having in combination therewith a dual acting magnetic holding unit, or a set of such units, as described.

Yet another object is to provide an improved method of handling and stripping scrap stock as an incident in an industrial stamping operation.

The foregoing as well as other objects will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a fragmentary view in vertical section through an improved electromagentic holding unit according to the invention, this view being in section along a broken line corresponding to the line 11 of FIG. 2, and showing in a general way the manner of attaching it to a press member; I

FIGS. 2 and 3 are, respectively, top and bottom plan views of the unit; 7

FIG. 4 is a fragmentary perspective view, schematic in nature, illustrating operations in the improved scrap holding and handling method;

, FIG. 5 is a schematic fragmentary view in end elevation of the structure of FIG. 4,.only'a single holding unit of a set being shown;

FIG. 6 is a wiring diagram. for the electromagnetic holding apparatus; and

FIG. 7 is a fragmentary plan view conventionally illustrating successive steps in the performance of the method.

Referring first to FIGS. 1, 2 and 3, there is illustrated therein a dual acting electromagnetic holding unit 10 according to the invention, as operatively applied to a vertically acting die member 11 of a conventional punch press, a set of units 10 being disposed along an edge of the die beneath which a sheet or strip of magnetic metal stock is successively advanced as blanks are punched from the stock by a die (not shown) on the member 11, and in horizontally offset relation to such die and a blank punched from the stock. Further reference, in general, to the press and its operation in relation to the proposed method of holding and handling scrap pieces will be hereinafter made.

The unit 10 includes a lower magnet housing 12 having a lower face substantially flush with that of die member 11, and an annular space 13 receiving an electromagnet coil 14, the housing 12 being of magnetizable material and constituting the electromagnet core. A flange 15 extends radially outwardly from the housing 12 about a portion of its periphery (FIGS. 2 and 3) and is apertured to receive bolts 16 by which the unit 10 is secured on the die member 11 in horizontally or laterally offset relation to a die (not shown) carried by that member, i.e., laterally or transversely of the direction of axial movement of such die, and of a blank B punched by the latter.

The annular coil receiving space 13 is closed off at its bottom by a centrally apertured spacer disk 17 of insulating material, held in place by a split retaining ring 18, and the housing member 12 is provided with an upper opening 19 to this space for the accommodation of wiring (not shown) for the coil 14.

=Diametrically opposed bores 20 are for-med through the central core member of the housing 12, on either side of the axis thereof, for the reception of like ejector or stripper pins 21, whose slightly enlarged heads 22 project upwardly into the central circular recess 23 of an insulating spacer disk 24. This disk is secured on the housing 12 by circumferentially spaced screws 25. As illustrated in FIG. 1, the bottoms of stripper pins 21 are in their inoperative, withdrawn position at least substantially flush or upwardly within the lower face of die member 11 and magnet housing 12.

The reference numeral 26 generally designates a solenoid housing of cylindrical outline, substantially coextensive in diameter with the spacer 24 and electromagnet housing 12, and the housing 26 is secured in relation to those parts by screws 27 connecting the solenoid housing 26 to the insulating spacer disk 24.

The inner wall 28 of solenoid housing 26 is cylindrical, and the lower, radially flanged base of a fixed tubular solenoid core plate 29 is fitted in the interior of the housing 26. A further tubular, axially movable solenoid core 30 is spaced above the axial sleeve portion 31 of the member 29, in axial alignment therewith, and the core 30 slides axially in the radially flanged insulating spool 32 of a solenoid whose coil 33 is housed between the spool flanges. A smallpin 34 prevents rotation of the stationary core plate 29 in reference to the spacer 24 therebeneath. Rotation of the movable core 30 is prevented by "a radially extending pin 35 in the top wall of solenoid housing 26, the pin extending into an axial groove or slot 36 at the top of the core 30, which core projects through the top wall of the housing.

'j The axial bore 37 of core 30 adjustably receives the stem of an elongated plunger 39 provided with an enlarged tappet plate 40 at its lower end, which plate is received in the central opening 23 of spacer 24. A threaded upper portion 41 of the plunger stem threadedly engages an upper, reduced diameter portion of the bore 37, and is provided with a kerf or slot 42 to receive an adjusting tool. Thus, upon rotation of the stem plunger 39 in relation to core 30 the stroke of plunger tappet 40, and the stripper pins 21 actuated thereby, may be adjusted. A capstan type lock nut 43 is applied to the plunger above the tubular core 30.

An electrical connector or fitting 44 leads to solenoid wiring space 45 within the housing 26, which has a lateral access opening 46 normally closed by an arcuate plate 47. An insulating guide and spacer ring 48 slidably receives the core 30 inwardly of the wiring space 45.

It is believed that the operation of the improved magnet unit will appear from the foregoing description. As the die member 11 and stripper housing 12 descend to engage the sheet metal blank, the stripper pins 21, in also engaging the sheet, will be elevated and withdrawn within the housing, since the solenoid coil 33 is de-energized at this time. Upon electrical energization of the coil 14, as through the circuit appearing in FIG. 6, the magnetic scrap material will be attracted to and held on the magnet housing 12, as the part or piece punched by a die on the die member 11 is discharged to a suitable receiver. Upon interposition of a scrap receiver beneath the die member and subsequent de-energization of electro-magnet coil 14 and energization of the solenoid coil 33, the core 30 will be projected downwardly, carrying the stem 39 and its tappet plate 40, and thus causing the stripper pins 21 to be projected a short distance of, say, A inch, out of the bottom of the housing 12. The scrap is thus ejected in a positive fashion from the previously magnetized housing 12. These operations are appropriately coordinated with the press die stroke, as by limit switch means, such as are shown in FIG. 6, as will be hereinafter referred to.

FIGS. 4, and 7 show in the most general way the mode of mounting a set of, say, six of the dual acting electromagnet units shown in FIGS. 1, 2 and 3 on and along an edge of the moving die member 11 of a punch press whose fixed base is designated 50, the remainder of the press body being designated 51. All of the parts are quited conventional. The reference numeral 52 represents a strip of blank material advancing endwise through the press, as viewed in FIG. 5; while a reciprocable scrap receiver pan is conventionally shown and designated 53.

Referring to FIG. 7, a blank B is punched from the stock 52 at each operation of the die member 11, which also severs the stock between the punched out margin and the sides of the stock, as at 54. Dotted line portions of FIG. 7 represent a series of blank punching and scrap holding relationships corresponding to those shown in solid line, but perform subsequently at the same working station.

As shown in FIGS. 5, 6 and 7, the sequence of operations in accordance with the new method is as follows: the stock 52 is advanced beneath the die member 11 in the usual fashion, the member 11 descends to blank the piece B, which falls into a receptacle in the lower press body 50, and the electromagnet coil 14 is coincidentally energized by a limit switch, causing the severed scrap piece (55 in FIG. 7) to be attracted to and held by the housing 12 of the set of electromagnetic units 10 arranged along the face of the die. The die member 11 then raises to its starting position, carrying with it the scrap 55, whereupon the scrap receiver, tray or pan 53 is projected laterally beneath the die member. Solenoid coil 33 of the unit 10 is now energized by limit switch means, simultaneously with the de-energization of the electromagnet coil 14, causing the stripper pins 21 to be projected downwardly as above described. They en gage the scrap piece 55 and kick it off the magnet housing '12 into the receiver 53, which is then reversed in movement and extracted from beneath the die member '11. The above sequence of operations then repeats.

Referring to the schematic diagram of FIG. 6, the wiring arrangement is believed self-explanatory, in the main. A step-down transformer 56 having an adjustable secondary tap is supplied from an appropriate external alternating current line source, and is connected to the input terminals of a rectifier 57, from the output terminals of which a rectified DC. potential of, say, 24 volts is thus taken, and an overload fuse 58 is placed in one of the rectifier output leads. The electromagnet coil 14 and the solenoid coil 33 0f the unit 10 are paralleled across the output leads, each in series with the contact of a control relay. The relays are respectively designated 6t) and 61, with the series connected contacts designated by corresponding reference numerals.

Relays

60, 61 for the electromagnet and solenoid coils 14-, 33, respectively, are alternating current relays and are connected in parallel across the AC. supply leads 62 of the system in the interlock arrangement shown. Thus, a limit switch 63, mounted on the die member 11 and closed momentarily on the down stroke of the latter, near the bottom of the stroke, is shunted by a contact of the magnet coil relay 60, with a further limit switch 64 in series. The limit switch 64 is mounted on the scrap receiver 53, being actuated when the receiver is underneath the die member 11. Switch 64 has two contacts, one of which de-energizes the electromagnet coil circuit and the other of which energizes the solenoid coil circuit, being connected in series across the leads 62 with the coil of solenoid control relay 61.

What We claim as our invention is:

1. An electromagnetic unit of the type described, comprising an electromagnet housing receiving a coil and having means to mount the housing to an outer side portion of a moving part, in lateral reference to the direction of movement of the latter, a solenoid housing fixedly mounted in superposed relation to said electromagnet housing, an annular, non-magnetic spacer between said housings, a solenoid coil in said solenoid housing, a core movable axially in said solenoid housing in response to energization of its coil, said core projecting into said spacer, and a stripping member movable axially in said electromagnet housing and projecting into said spacer at one end, said stripping member being actuated by said core upon energization of said solenoid coil to project at its opposite end from said electromagnet housing, said electromagnet housing and part having parallel exposed work engaging surfaces in substantially flush, side-by-side relation to one another.

2. An electromagnetic unit of the type described, comprising an electromagnet housing receiving a coil and having means to mount the housing to an outer side portion of a moving part, in lateral reference to the direction of movement of the latter, a solenoid housing fixedly mounted in superposed relation to said electromagnet housing, an annular, non-magnetic spacer between said housings, a solenoid coil in said solenoid housing, a core movable axially in said solenoid housing in response to energization of its coil, said core projecting into said spacer, a stripping member movable axially in said electromagnet housing and projecting into said spacer at one end, said stripping member being actuated by said core upon energization of said solenoid coil to project at its opposite end from said electromagnet housing, and means for adjusting the actuating stroke of said stripping member, said electromagnet housing and part having parallel exposed work engaging surfaces in substantially flush, side-by-side relation to one another.

3. An electromagnetic unit of the type described, comprising an electromagnet housing receiving a coil and having means to mount the housing to an outer side portion of a moving part, in lateral reference to the direction of movement of the latter, a solenoid housing fixedly m 4 AAA mounted in superposed relation to said electromagnet housing, an annular, non-magnetic spacer between said housings, a solenoid coil in said solenoid housing, a core movable axially in said solenoid housing in response to energization of its coil, said core having a plunger threadedly engaged thereon and projecting into said spacer, and a stripping member movable axially in said electromagnet housing and projecting into said spacer at one end, said stripping member being actuated by said plunger upon energization of said solenoid coil to project at its opposite end from said electromagnet housing, said electromagnet housing and part having parallel exposed work engaging surfaces in substantially flush, side-by-side relation to one another.

4. A dual acting, electromagnetic handling unit for sheet metal blanking presses and the like, comprising an electromagnet having a core presenting a flat Work holding surface of substantial area movable to engage with a sheet to be blanked, a stripper mounted for movement in said core in the direction in which said surface moves to engage the sheet, a solenoid housing in superposed relation to said core, said stripper having an actuating plunger core received in said solenoid housing, a solenoid coil in said housing' surrounding said plunger core in encircling relation to the latter and effective upon energization to project said plunger core and stripper axially, said stripper being received substantially wholly within said first named core when not so projected and extending substantially outwardly of said surface of the latter when so projected, and an electrical circuit including means to periodically energize said solenoid coil in timed relation to the engagement of said first named core surface with a sheet and cause said stripper to eject said sheet from said first named core.

5. A dual acting, electromagnetic handling unit for sheet metal blanking presses and the like, comprising an electrically energized electromagnet having a magnetizable core presenting a flat work holding surface of substantial area movable to engage with a sheet to be blanked, a stripper mounted for movement in said core in the direction in which said surface moves to engage the sheet, a coil operatively arranged relative to said core to magnetize the latter upon energization of said coil, a solenoid housing in superposed relation to said core, a non-magnetic spacer interposed between and secured to said core and housing, said stripper having an actuating plunger core and being received through said spacer into said solenoid housing, a solenoid coil in said housing surrounding said plunger core and effective upon energization to project said plunger core and stripper axially, said stripper being received substantially wholly within said electromagnet core when not so projected and extending substantially outwardly, of said surface of the latter when so projected, and an electrical circuit including means electrically connected to said respective coils to energize the same in alternation, whereby to alternately cause said electromagnet core to grip and hold a sheet upon energization and to cause said stripper to eject said sheet from said first named core upon energization of said solenoid coil.

6. An electromagnetic unit for use in association with a press in the blanking of pieces from sheet stock and the handling of the blanked stock, comprising an electromagnet housing, an electrically energizable electromagnetcoil in said housing, said housing having means to mount the same to a moving part of the press, and having a bottom surface adapted to be disposed, as so mounted, in flush relation to a bottom surface of said press part, a solenoid housing fixedly mounted in superposed relation to said electromagnet housing and having an electrically energizable solenoid coil therein, and stripping means movable in said housings and having a stock engaging portion which is projected beneath the bottom surface of said electromagnet housing to disengage the stock from the latter by and upon energization of said solenoid coil, said stock engaging portion being movable upon engagement of said press part and electromagnet housing with said sheet stock into a position not to project substantially beneath said bottom surface of the electromagnet housing, and means to electrically energize said coils.

7. An electromagnetic unit for use in association with a press in the blanking of pieces from sheet stock and the handling of the blanked stock, comprising an electromagnet housing, an electrically energizable electromagnet coil in said housing, said housing having means to mount the same to a moving part of the press and having a bottom surface adapted to be disposed, as so mounted, in flush relation to a bottom surface of said press part, a solenoid housing fixedly mounted in superposed relation to said electromagnet housing and having an electrical-1y energizable solenoid coil therein, a solenoid core movable in said solenoid housing coaxially of said solenoid coil and actuable by the latter in response to energization of the last named coil, a stripping member movable in said electromagnet housing coaxially of said core and actuable by said core to project the stripping member beneath said bottom surface of said electromagnet housing, said stripping member being movable upwardly upon engagement of said press part and electromagnet housing with said sheet stock into a position in which it does not project substantially beneath said bottom surface of the electromagnet housing, and means to electrically energize said coils.

8. An electromagnetic unit for use in association with a press in the blanking of pieces from sheet stock and the handling of the blanked stock, comprising an electromagnet housing, an electrically energizable electromagnet coil in said housing, said housing having means to mount the same to an outer side portion of a moving part of the press, and being shaped to be in flush relation to said side portion as so mounted, said housing having a bottom surface adapted to be disposed as so mounted in flush relation to a bottom surface of said press part, a solenoid housing fixedly mounted in superposed relation to said electromagnet housing and having an electrically energizable solenoid coil therein, a solenoid coil movable in said solenoid housing coaxially of said solenoid coil and actuable by the latter in response to energization of the last named coil, a stripping member movable in said electromagnet housing coaxially of said core and actuable by said core to project the stripping member beneath said bottom surface of said electromagnet housing, said stripping member being movable upwardly upon engagement of said press part and electromagnet housing with said sheet stock into a position in which it does not project substantially beneath said bottom surface of the electromagnet housing, and means to electrically energize said coils in alternation and in timed relation to the movement of said press part to initially attract the sheet stock \from which a part has been blanked to said bottom surface of the electromagnet housing and subsequently strip the same from said electromagnet housing.

9. An electromagnetic unit for use in association with a press in the blanking of pieces from sheet stock and the handling of the blanked stock, comprising an electromagnet housing, an electrically energizable electromagnet coil in said housing, said housing having means to mount the same to a moving part of the press and having a bottom surface adapted to be disposed as so mounted in flush relation to a bottom surface of said press part, a solenoid housing fixedly mounted superposed relation to said electromagnet housing and having an electrically energizable solenoid coil therein, a solenoid core movable in said solenoid housing coaxially of said solenoid coil and actuable by the latter in response to energization of the last named coil, an annular, nonmagnetic spacer interposed between said housings, said core projecting axially into said spacer, a stripping member movable in said electromagnet housing coaxially of said core and extending axially into said spacer for actuation by said core to project the stripping member beneath said bottom surface of said electromagnet housing, said stripping member being movable upwardly upon engagement of said press part and electromagnet housing with said sheet stock into a position in which it does not project substantially beneath said bottom surface of the electromagnet housing, and means to electrically energize said coils in alternation and in timed relation to the movement of said press part to initially attract the sheet stock from which a part has been blanked to said bottom surface of the electromagnet housing and subsequently strip the same from said electromagnet housing.

10. An electromagnetic unit for use in association with a press in the blanking of pieces from sheet stock and the handling of the blanked stock, comprising an electromagnet housing, an electrically energizable electromagnet coil in said housing, said housing having means to mount the same to an outer side portion of a moving part of the press, and being shaped to be in flush relation to said side portion as so mounted, said housing having a bottom surface adapted to be disposed as so mounted in llush relation to a bottom surface of said press part, a solenoid housing fixedly mounted in superposed relation to said electromagnet housing and having an electrically energizable solenoid coil therein, a solenoid core movable in said solenoid housing coaxially of said solenoid coil and actuable by the latter in response to energization of the last named coil, an annular, non-magnetic spacer interposed between said housings, said core projecting axially into said spacer, a stripping member movable in said electromagnet housing coaxially of said core and extending axially into said spacer for actuation by said core to project the stripping member beneath said bottom surface of said electromagnet housing, said stripping member being movable upwardly upon engagement of said press part and electromagnet housing with said sheet stock into a position in which it does not project substantially beneath said bottom surface of the electromagnet housing, and means to electrically energize said coils in alternation and in timed relation to the movement of said press part to initially attract the sheet stock from which a part has been blanked to said bottom surface of the electromagnet housing and subsequently strip the same from said electromagnet housing.

11. The combination with a press for the blanking of pieces from sheet stock, of an electromagnet unit for the handling of the blanked stock, said unit comprising an electromagnet housing, an electrically energizable electromagnet coil in said housing, said housing having means to mount the same to a moving part of the press and having a bottom surface adapted to be disposed as so mounted in flush relation to a bottom surface of said press part, a solenoid housing fixedly mounted in superposed relation to said electromagnet housing and having an electrically energizable solenoid coil therein, a solenoid core movable in said solenoid housing coaxially of said solenoid coil and actuable by the latter in response to energization of the last named coil, a stripping member movable in said electromagnet housing coaxially of said core and actuable by said core to project the stripping member beneath said bottom surface of said electromagnet housing, said stripping member being movable upwardly upon engagement of said press part and electromagnet housing with said sheet stock into a position in which it does not project substantially beneath said bottom surface of the electromagnet housing, and means to electrically energize said coils.

12. The combination with a press for the blanking of pieces from sheet stock, of an electromagnet unit for the handling of the blanked stock, said unit comprising an electromagnet housing, an electrically energizable electromagnet coil in said housing, said housing having means to mount the same to an outer side portion of a moving part of the press, and being shaped to be in flush relation to said side portion as so mounted, said housing having a bottom surface adapted to. be disposed as so mounted in flush relation to a bottom surface of said press part, a solenoid housing fixedly mounted in superposed relation to said electromagnet housing and having an electrically energizable solenoid coil therein, a solenoid core movable in said solenoid housing coaxially of said solenoid coil and actuable by the latter in response to energization of the last named coil, an annular, non-magnetic spacer interposed between said housings, said core projecting axially into said spacer, a stripping member movable in said electromagnet housing coaxially of said core and extending axially into said spacer for actuation by said core to project the stripping member beneath said bottom surface of said electromagnet housing, said stripping member being movable upwardly upon engagement of said press part and electromagnet housing with said sheet stock into a position in which it does not project substantially beneath said bottom surface of the electromagnet housing, and means to electrically energize said coils in alternation and in timed relation to the movement of said press part to initially attract the sheet stock from which a part has been blanked to said bottom surface of the electromagnet housing and subsequently strip the same from said electromagnet housing.

References Cited in the file of this patent UNITED STATES PATENTS Re. 11,710 Robinson Jan. 24, 1899 599,228 Du Brul Feb. 15, 1898 907,690 Harbeck Dec. 22, 1908 1,128,036 Paulero Feb. 9, 1915 2,346,719 Aske Apr. 18, 1944 2,359,048 Monroe Sept. 26, 1944 2,675,718 Finney Apr. 20, 1954