US3881606A

US3881606A - Sliding nest feeding apparatus

Info

Publication number: US3881606A
Application number: US390578A
Authority: US
Inventors: Ross P Swinehart
Original assignee: WISCO IND Inc
Current assignee: WISCO IND Inc
Priority date: 1973-08-22
Filing date: 1973-08-22
Publication date: 1975-05-06
Anticipated expiration: 1992-05-06

Abstract

A feeding apparatus for a punch press or other similar machine, which utilizes a movable nest to convey a workpiece into the working area of the machine. Vertical support for the workpiece is provided by slide plates which extend from a loading position to the working area. The nest is supported and moved by a carriage and drive system located beneath the slide plates, and which attaches to the nest through a narrow slot in the plates. The movement of the nest and the actuation of the punch press are controlled automatically by a control unit, so that the machine operator need only load the nest in its loading position and depress the run switch of the punch press. A fully automatic mode is also provided. Barriers may be provided between the loading position and the working area through which the locating nest and workpiece are permitted to pass, but which will prevent the insertion of the operator''s hand into the working area of the machine.

Description

United States Patent 1 Swinehart 14 1 May 6,1975

[ SLIDING NEST FEEDING APPARATUS [75] Inventor: Ross P. Swinehart, Oregon, Wis.

[73] Assignee: Wisco Industries, Inc., Oregon, Wis. [22] Filed: Aug. 22, 1973 [21] Appl. No.: 390,578

[56] References Cited UNITED STATES PATENTS 2,881,834 4/1959 83/437 3,155,241 11/1964 Suofy......... 2l4/l BB 3,552,180 1/1971 Hall et a1. 214/1 BBX Primary Examiner-Willie G. Abercrombie Attorney, Agent, or Firm-Theodore J. Long; John M. Winter; Harry C, Engstrom [5 7 1 ABSTRACT A feeding apparatus for a punch press or other similar machine, which utilizes a movable nest to convey a workpiece into the working area of the machine. Vertical support for the workpiece is provided by slide plates which extend from a loading position to the working area. The nest is supported and moved by a carriage and drive system located beneath the slide plates, and which attaches to the nest through a narrow slot in the plates. The movement of the nest and the actuation of the punch press are controlled automatically by a control unit, so that the machine operator need only load the nest in its loading position and depress the run switch of the punch press. A fully automatic mode is also provided. Barriers may be provided between the loading position and the working area through which the locating nest and workpiece are permitted to pass, but which will prevent the insertion of the operator's hand into the working area of the machine.

7 Claims, 7 Drawing Figures PXTENTELHM sams 3.881.606

SHEET 2 0r 5 Fig. I)

FIIEHTEB HAY 6 I975 SHEET 30F 5 RHENTEUHAY 6 i975 SHEU l 8F 5 SLIDING NEST FEEDING APPARATUS BACKGROUND OF THE INVENTION l. Field of the Invention This invention pertains to a device for feeding workpieces to the work area of a punch press or similar machine.

2. Description of the Prior Art Despite the obvious dangers inherent in the manual feeding of punch presses and similar machines, manual feeding has been the general practice. Automated feeding devices have been developed for situations where operations are being performed on large production quantities of workpieces suitable for mechanical feeding. Such automated feeding devices have tended to be ill-adapted or prohibitively expensive for short production runs or for handling workpieces with shapes which are not readily susceptible to mechanical feeding. Thus, manual feeding of punch presses and other simi lar machines has persisted because of its economy and adaptability.

When a punch press is to be manually fed it is common practice to affix a locating nest to the upper surface of the lower die. The locating nest generally comprises a flat piece of metal with a portion cut out to fit the outline of the particular workpiece being worked on. The machine operator places the workpiece by hand in the cut out portion of the nest, which is adapted to locate and restrain horizontal movement of the workpiece during the pressing operation. Usually the workpiece must be supported from below by the lower die so that the workpiece will be properly shaped when it is pressed between the upper and lower dies.

Experience has shown that any feeding system which requires or permits the operator to place one or both of his hands in the point of operation of a press, which has been defined as the area of the press where material is actually positioned, and work is being performed (hereinafter sometimes referred to as the "work area). is inherently dangerous and represents a substantial safety hazard. Recent federal safety regulations promulgated under the Occupational Safety and Health Act of I970 (OSHA) greatly restrict hand feeding of presses, unless the point of operation opening is onefourth inch or less.

A guard or stationary barrier which physically prevents entry of the hands between the dies is the most positive protection for the operator, but in the past, use of such guards has usually been impossible or impractical unless the workpieces have been readily susceptible to mechanical feeding. Accordingly, two common safety devices have been utilized which, though not preventing entry of the operators hands into the press work area, do attempt to insure that the operators hands will be removed from the work area before operation of ram or the slide of the press. One such device comprises dual hand controls which must both be pressed by the operator substantially simultaneously to cause the press to cycle. The other device includes cables physically attached to the operators hands or amts which will pull the operators hands out of the work area during initial movement of the press slide. Frequently a combination of both such devices will be employed. Nevertheless, operators have displayed great ingenuity in circumventing the protective operation of such devices. In addition, such devices can substantially reduce the production speed of a hand fed press.

Various devices have also been designed to feed the workpiece into the work area from a remote area. This eliminates the need for the operator to place his hands in the die area, and barriers may be placed around the die area to positively prevent his doing so. The operation of these feeding devices generally involves mechanical grasping of the workpiece and placement in the locating nest in the die area, in an operation analogous to manual feeding. These devices are often bulky and unsuited to small presses. Such devices also may not meet OSHA regulations when an operator is utilized to place workpieces in the feeding device, since the moving parts of the feeding device may themselves present a hazard to the operator.

SUMMARY OF THE INVENTION l have invented a compact sliding nest feeding apparatus adapted to be used with existing presses and dies. My sliding nest feeding apparatus eliminates the need for an operator to place his hands in the work area as well as presenting no hazard to the operator from its own moving parts. My invention also increases the productivity of a human operator over conventional manual feeding.

My sliding nest feeding apparatus utilizes a movable locating nest, rather than a nest affixed to the lower die of a punch press or similar machine as is conventional. The nest is mounted for movement between a loading position outside the work area of a machine and a working position within the work area. The nest restrains horizontal motion of the workpiece contained therein, while vertical support is provided to the workpiece by slide plates which extend from the loading position to the work area (eg. the lower die), and on which the workpiece is slidably supported. The nest is moved by a carriage which rides beneath the slide plates and extends up through a narrow slot in the plates to attach to the nest. The slot, which runs longitudinally toward the working position of the machine, is one-fourth inch or less in width to prevent an adult human finger from being inserted therein, and thus meets OSHA safety standards.

The carriage is mounted by precision bearings riding on a pair of longitudinally extending bars, and is moved by a pneumatic drive system. The pneumatic drive system is operated by a control unit which is interconnected with the controls of the press or other machine with which the sliding nest feed is being used. On command from the machine, by depressing the punch press Run buttons, the control unit of the sliding nest feeding apparatus causes the nest to move from its remote loading position to a working position within the work area of the machine, actuates the machine when the nest is precisely located in its working position, and causes the nest to move back to its loading position when the machine has completed its operations on the workpiece contained within the nest. The sliding nest feeding apparatus also operates in a continuous mode wherein the nest continuously cycles between the working and loading positions, and dwells for a selected period of time in the loading position to permit the operator to hand load a workpiece into the nest.

Barriers, or guards, may be employed to enhance the safety of my sliding nest feeding apparatus by enclosing the work area of the punch press. Because of the low profile of the nest which moves into the work area, the opening in the barrier through which the nest and workpiece passes need only be as high as the workpiece. The restricted opening in the barrier and the distance between the barrier and the work area of the press prevent the operator from inserting his hand into the work area.

Further objects, features and advantages of my invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings showing a preferred embodiment of a sliding nest feeding apparatus exemplifying the principles of my invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a perspective view of my sliding nest feeding apparatus shown in combination with a punch press.

FIG. 2 is a perspective view of the nest feed unit of my sliding nest feeding apparatus.

FIG. 3 is a top plan view of the nest feed unit with the upper slide plates removed to expose the internal parts of the unit.

FIG. 4 is a perspective view of the nest feed unit, with the upper slide plates removed and a portion of the frame broken away to expose the internal parts of the unit.

FIG. 5 is a front elevation view of the control unit portion of my sliding nest feeding apparatus.

FIG. 6 is a top plan view of the nest feed unit shown mounted adjacent to a schematically illustrated punch press lower die.

FIG. 7 is a schematic view of the electrical and pneumatic systems of my sliding nest feeding apparatus shown as inter-connected with the electrical system of a conventional punch press.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to the drawings wherein like numerals refer to like parts throughout the several views, a preferred embodiment of my sliding nest feeding apparatus is shown generally at 10 in FIG. 1. The feeding apparatus 10 is composed of two basic units, a nest feed unit 11 and a control unit 12. The nest feed unit 11 and the control unit 12 are both attached to a punch press shown generally at 13 in FIG. 1. While the operation of my sliding nest feeding apparatus will be described in connection with a punch press of the type shown, the feeding apparatus is adaptable for use with any similar machine requiring precise positioning of a workpiece in a work area.

The punch press 13 is of conventional design, having a stationary bed I4 with a lower die 14a mounted on it, and a slide 15 with an upper die 15a mounted on the bottom of the slide in opposing relation to the lower die. The slide 15 is capable of reciprocating motion toward and away from the bed 14, and the slide is guided in a definite path by the frame 13a of the press 13. The area above the upper surface of the lower die 14a generally comprises the work area of the punch press, which is the area that must be avoided by the operator during operation of the press 13.

Normal operation of the press commences with placement of a workpiece in the proper working position on the lower die 14a. The upper die 15a and the slide 15 descend from their upper position to their lower position to press the workpiece between the upper and lower dies, and then ascend back to their upper position to await the loading of another workpiece. The press may automatically eject the finished workpiece, or the workpiece may be removed manually, as desired. The press work cycle described above is initiated by depressing a pair of push buttons 16 which are the Run switches of the press. For safety reasons, the internal circuitry of the press requires that the two push buttons 16 be depressed at approximately the same time in order to initiate the press cycle. This safety feature is well known in the art, and is incorporated in many punch presses in an attempt to ensure that the machine operator has his hands out of the die area when the press cycle is initiated. My sliding nest feeding apparatus, however, permits control of the press by any other appropriate type of activating means, such as a foot switch 16a, since the safety of the operator does not depend on his use of both hands to activate the press. The push buttons 16 and auxiliary foot switch 16a comprise switch means which are electrically connected to a control box 17 containing most of the electrical controls for the press. For ease of description, the operation of the press will hereafter be described with reference to the push buttons 16, but it is understood that the foot switch 16a is interchangeable therewith. A primary power line 18 provides a source of electrical power to the control box 17, and it is preferable for the proper operation of my sliding nest feeding apparatus 10 that standard volt r.m.s. A.C. power be provided.

The means by which mechanical power is supplied by the press 13 to reciprocate the slide 15 is typical of mechanical presses, although my sliding nest feeding apparatus can be employed with presses having other means for supplying mechanical power. The mechanical power means of the press 13 has a crankshaft 19, the end of which extends from the press body as shown in FIG. 1, and which makes one complete revolution each time the press goes through a work cycle. The crankshaft 19 is engaged with the slide 15 of the press 13 in such a manner that revolution of the crankshaft causes reciprocation of the upper die 15a. A solenoid operated clutch (not shown) is activated by the push buttons 16 to engage the crankshaft 19 with a mechanical power unit of any suitable and appropriate type. The power unit employed in the embodiment shown in FIG. 1 consists of an electric motor 13b driving a flywheel (not shown) within housing 13c.

My feeding apparatus employs a locating nest 20 in which the workpiece is placed by the operator, but the nest 20 is attached to the nest feed unit 11, rather than to the lower die 14a as is done in conventional manual feeding. The nest 20 is similar in construction to the nests used in manual feeding, and as shown for illustrative purposes in FIGS. 1 and 6, the nest 20 is made of a flat piece of metal with a cut out portion therein generally conforming to the outline of the workpiece. Other nest configurations may be appropriately employed, and examples of these alternative configurations will be subsequently described.

Referring to FIG. 2, the nest feed unit 11 has a frame 21 which has mounted on the upper side thereof two flat metal

slide support plates

22a and 22b which together form a planar upper support surface 22 to provide upper support plate means for slidably supporting a workpiece placed on the nest feed unit. The

slide plates

22a and 22b are fixedly attached to the frame 21 by screws 23 and are spaced a short distance apart to define a longitudinal slot 24. The slot 24 is preferably no greater than one-fourth inch in width to conform to OSHA safety regulations and general safety considerations. The frame 21, which is preferably made of a strong, lightweight magnesium-aluminum alloy, rests on a spacer shim block 25 which is placed between the frame 21 and the stationary bed 14 of the press 13, the frame being firmly attached to the bed 14 by bolts 26a which pass through appropriate holes 26 in the frame and threadingly attach to the bed. The purpose of the shim block 25 is to position the support surface 22 in substantially the same plane as the upper surface of the lower die 14a; thus the dimensions of the shim block 25 will be determined as necessary to achieve the proper spacing.

As shown in FIG. 2, a nest carrier plate 27 is attached above the support surface 22 to a carrier bar 28a by bolts 29. The carrier bar 280 extends up through the slot 24 and is attached below the support surface 22 to a carriage upper body 2817 by bolts 30, as shown in FIG. 4. The carrier plate 27 is adapted to mount the particular nest configuration being used, and as illustratively shown in the drawings, the carrier plate 27 has a broadened front portion 270 which extends transverse to the slot 24 and has a number of holes 27b therein. The front portion 27a is preferably spaced a sufficient distance above the support surface 22 to allow the nest to be attached to the underside of the carrier plate front portion 27a by screws passing through the holes 27b.

As best shown in FIGS. 3 and 4, a main support bar 31 and a parallel side support bar 32 extend longitudinally parallel to and below the support surface 22 and are fixedly attached to the frame 24. The

bars

31 and 32 are preferably round and of un iform cross sectional diameter throughout their lengths. A precision main support bearing 33 is mounted on the main support bar 31 and a precision side support bearing 34 is mounted on the side support bar 32. The

bearings

33 and 34 are selected to ride on the

bars

31 and 32 with little friction and with very low tolerances. The carriage upper body 28b fits over the

bearings

33 and 34 and a carriage lower body 280 is fitted on the bearings from beneath and firmly attached to the carriage upper body 28b by screws 35. The carriage lower body 280, the carriage upper body 28b, the carrier bar 280 and the

bearings

33 and 34 form a carriage 28 which is free to move in a longitudinal direction on the

bars

31 and 32 between the front end 210 and the back end 21b of the frame 21. The lateral spacing of the

bars

31 and 32 and the low tolerances of the

bearings

33 and 34 prevents any rotational or other non-longitudinal motion of the carriage 28 on the support bars 31 and 32. The carriage 28 and the carrier plate 27 thus provide a means for supporting and carrying the locating nest 20 for precise longitudinal motion above and parallel to the support surface 22.

As best seen in FIG. 3, a pneumatic cylinder 36 is longitudinally attached to the frame 21 below the support surface 22, and a piston 37 (not shown in FIG. 3) is movably contained within the cylinder 36 to divide the cylinder into two substantially airtight compartments.

Flexible cables

38a and 38b are respectively attached to the opposite sides of the piston 37 and extend out of the cylinder 36 through air tight seals, around pulleys 39a and 39b respectively which are mounted to the frame 21 at opposite ends of the cylinder and proximate to the frame, and are attached to the opposed sides of a bracket 40 which is mounted on the carriage 28. Air or other suitable gas may be selectively supplied under pressure to pneumatic couplers 41a and 4112 which communicate with the interior of the cylinder 36 at the respective ends thereof. Air or other gas introduced under pressure to one of the couplers with the other coupler at atmospheric pressure produces a dif ferential pressure on the piston 37 which tends to move the piston away from the source of air pressure, and because the carriage 28 is connected to the piston through the

cables

38a and 38b, the carriage also tends to move, but in a direction opposite to the direction of motion of the piston. The arrangement of the pneumatic cylinder 36, piston 37 and

cables

38a and 38b allows the carriage 28 to move over its full longitudinal travel between a first position wherein the carriage is abutting the back end 21b of the frame 21, and a second position wherein the carriage is abutting the front end 21a of the frame. The cylinder and the pulleys 39a and 39b require no more longitudinal space than that required to accommodate the carriage 28 between the extremes of its travel.

A normally open front limit switch 42 and a normally open back limit switch 43 are attached to the frame 21 near the front end 210 and the back end 21b respectively, as shown in FIG. 3. A front limit switch trip 44 and a back limit switch trip 45 are adjustably attached to the carriage 28 in position to trip respectively the switch 42 or the switch 43 when the carriage is at the extremes of its travel. Conducting wires 46 electrically connect the limit switch 42 to a socket 48, and similar conducting wires 47 connect the limit switch 43 to the socket 48 which extends through the frame 21 and allows electrical connections to be made to the limit switches 42 and 43 from outside the nest feed unit 11.

A metal base plate 49 is attached to the bottom of the frame 21 to prevent the intrusion of any foreign object into the interior of the nest feed unit 11 from below, and to protect the operator from the internal moving parts of the nest feed unit.

As shown in FIG. 1, an electrical control line 50 connects the control unit 12 to the socket 48 on the nest feed unit 11. Pneumatic lines 51a and 51b run from the control unit 12 to the couplers 41a and 41b, respectively, on the nest feed unit. A pneumatic supply line 52 supplies air under pressure from a shop compressor or other standard source of air pressure to the control unit 12. The press control box 17 is connected to the control unit 12 by an electrical control line 53.

In addition to the basic nest feed unit 11 and the control unit 12, my sliding nest feeding apparatus has a normally open limit switch 54 mounted on the press 13 near the end of the press crankshaft 19 that extends from the press body. A cam 55 is mounted on the end of the crankshaft 19, and is positioned to contact and close the limit switch 54 as the slide 15 and upper die 15a are ascending toward their upper position and the work cycle of the press 13 is being completed. A connecting line 56 electrically connects the limit switch 54 to the control unit 12. The limit switch 54 is preferably closed before the slide 15 reaches its upper position to insure that the slide will not be stopped before the limit switch is closed.

As shown in FIG. 5 the control unit 12 has a housing 57 which surrounds and protects the controls contained therein. A three-position selector switch assembly 58 is mounted on one side of the housing 57 and is used to select the mode in which the sliding nest feed will be operating. The three modes selectable by the switch assembly 58 are the single cycle mode, the continuous mode, and the off mode wherein the sliding nest feed is disengaged. The operation of the sliding nest feeding apparatus in these three modes will be subsequently discussed. A selector dial 59 is mounted on the same side of the housing 57 as the selector switch assembly 58, and is used to set the length of time that the nest 20 will dwell in the loading position as will be subsequently explained. An electrically actuated pneumatic control valve 60 distributes air under pressure, supplied by the air supply line 52, to the pneumatic lines 51a or 51b as determined by the control unit 12. Air coming into the control unit 12 under pressure from line 52 is preferably passed through an air filter 61, an air pressure regulator 62, and a mist oiler 63, before passing through a line 64 to the pneumatic valve 60. The mist oiler 63 introduces a fine oil mist into the compressed air which helps to lubricate the moving parts of the pneumatic valve 60 and the cylinder 36 and piston 37 in the nest feed unit 11. The pneumatic control valve 60, air filter 61, air pressure regulator 62, mist oiler 63, cylinder 36 and piston 37, and associated cables 38, pulleys 39 and air lines 51 are all of known, conventional construction, and together provide a means for driving the carriage 28 over its longitudinal travel in response to an electrical signal.

Referring to FIG. 6, the nest feed unit 11 is shown mounted next to the schematically illustrated lower die 14a of the press in horizontally spaced relation. The nest feed unit must usually be spaced horizontally from the lower die because of the shape of the die 14a, and to allow proper placement of the nest 20 over the working position of the die. To provide vertical support for the workpiece between the nest feed unit 11 and the lower die 140, an extension slide support plate 65 is attached to the frame 21 by screws 66 and extends from the support surface 22 to the die 14a. The upper surface of the extension plate 65 is in the same plane as the upper surface of the lower die 14a and the support surface 22.

The locating nest 20 is illustrated in FIG. 6 at the two extremes of its travel; the position of the nest 20 shown in solid lines is the fully retracted loading position of the nest above the support surface 22 wherein the carriage 28 supporting the nest is in its first position abutting the back end 21b, while the position of the nest shown in dashed lines is the working position of the nest above the lower die 14a wherein the carriage is in its second position abutting the front end 21a. The machine operator places the workpiece in the nest 20 at its loading position. Upon actuation of the sliding nest feeding apparatus the nest pushes the workpiece inwardly toward the working position above the die 14a. The nest prevents horizontal motion of the workpiece in a direction transverse to the longitudinal motion of the nest, and prevents any horizontal motion of the workpiece once the workpiece is in the working position. The precision construction of my invention has, in a commercial embodiment, allowed placement of the workpiece to within 2 mils (2/ i000 inch) of its desired working position. Vertical support is provided to the workpiece over its travel from the loading position to the working position consecutively by the support surface 22, the extension plate 65, and the surface of the lower die 14a.

The means for controlling the operation of the press 13, the feeding apparatus 10 and the functional interconnections between the press 13, the control unit 12, and the nest feed unit 11, are illustrated by FIG. 7, which is a simplified schematic view of the electrical and pneumatic portions of the sliding nest feeding apparatus and the press. The nest feed unit is shown generally at 11 within the broken line, the control unit is shown generally at 12 within the broken line, and the press is shown generally at 13 within the broken line.

When the selector switch assembly 58 is in its first position or off mode, as shown in FIG. 7, the feeding apparatus 10 is completely disengaged electrically from the press 13 since a direct connection is made between the

conductors

53a and 53b, and between the

conductors

53c and 53d. This allows the press 13 to operate as it originally did before addition of the feeding apparatus 10. The press circuitry shown at 13 within the broken line is for illustrative purposes only, and the basic functional units of the press circuitry are shown in block form, and are representative of the circuitry used in presses, which is well known in the art. However, my sliding nest feeding apparatus 10 is designed to function, with minor modifications if necessary, with any press which is activated by electrical circuitry, and it is understood that my invention does not depend on the particular circuitry utilized by the press.

The clutch of the press 13 is operated magnetically by a slide actuator solenoid 67 which forms a part of the mechanical power means of the press 13. As long as electrical power is supplied to the solenoid 67 the clutch will be engaged and the slide 15 and the upper die will reciprocate. Removal of electrical power from the solenoid 67 allows the clutch to automatically disengage and the upper die to cease its motion. Electrical power is supplied to the press 13 by ac. power lines 18a and 18b where, for descriptive purposes, the conductor 180 will be considered the high or incoming line and the conductor 18b the ground or return line. The conductor 18a is connected by a conductor 68 to the push button switches 16 (or alternatively to foot switch as shown in FIG. 1) wherein circuitry internal to the push button switches requires that the two push buttons be depressed at approximately the same time in order to allow a completed circuit through the switches 16. Current flowing through the closed push button switches 16 is passed to the anti-repeat circuitry 69, shown generally as a block in FIG. 7, by the

conductors

53d and 53c, and thence to the clutch solenoid 67 by the

conductors

53b and 53a, and back to the return line 18b by a conductor 70. The anti-repeat circuitry 69 is well known and is required by OSHA regulations to be included in the slide actuator circuitry in all two-hand control presses wherein the slide is intended to make a single stroke upon actuation of the press. The anti-repeat circuitry 69 allows current to flow from the push buttons 16 to the clutch solenoid 67 only long enough for a single stroke of the slide 15 to be completed. Thereafter the anti-repeat circuitry 69 will not allow current to flow to the solenoid 67 until the push buttons 16 are released and again depressed. Thus when the push buttons 16 are closed, the slide 15 will make one stroke and return to its upper position to allow reloading of a workpiece on the lower die 14a.

The nest feed unit is shown schematically at 11 within the broken line in FIG. 7. Motion of the piston 37 within the cylinder 36 results in motion of the carriage 28 because of the

cables

38a and 38b connecting the piston and carriage. When the carriage 28 is at the extremes of its travel it depresses and closes either limit switch 42 or limit switch 43, depending on whether the carriage is stopped at its second position at the front end 210, or at its first position at the back end 21b of the frame, respectively. The switch 42 and the switch 43 are electrically connected to the control unit by the

conductors

50a and 50b and the

conductors

50c and 50d, respectively.

Referring to FIG. 7, the commercially available pneumatic valve within the control unit 12 is shown schematically at 60 within the broken line for illustrative purposes. The pneumatic control valve 60 has an air valve assembly 71 which is composed of a valve body 71a and a center spool 71b which rides within the valve body. The spool 71b will be stable in one of two positions: either supplying air under pressure to pneumatic line 51a, or to pneumatic line 51b, with the other line being open to atmospheric pressure. A forward travel actuator solenoid 72, when activated, attracts the spool 71b to the illustrated position where air under pressure from supply line 52 is being directed to the pneumatic line 510. A return travel actuator solenoid 73, when activated, will attract the spool 71b to the alternate position where air under pressure from the supply line 52 is being directed to the pneumatic line 51b. A conductor 74 electrically connects one side of the solenoid 73 to the switch 58f of the selector switch assembly 58, while the other side of the solenoid 73 is connected to the conductor 56a which comes from the limit switch 54. A time delay circuit 75 is electrically connected to one side of the solenoid 72 while the other side of the solenoid is connected to the conductor 50c coming from the limit switch 43. The commercially available time delay circuit 75 acts essentially as an open switch for a period of time after voltage is impressed across it and then becomes a closed switch for as long as current continues to be supplied to it. A variable resistor 750 within the circuit 75 allows the period of time that the time delay circuit 75 is non-conducting to be varied. The resistance of the resistor 75a is adjusted by use of the selector dial 59 shown in FIG. mounted on the exterior of the control unit housing 57. The time delay circuit 75 is connected by the conductor 76 to the conductor 74.

The control unit 12 also contains a relay 77 which consists of a normally open switch 77a and an electromagnet 77b which closes the switch 77a when acti vated. A conductor 78 connects one side of the switch 77a and the electromagnet 77b to the conductor 50b. The other side of the electromagnet is connected by a conductor 79 to the conductor 76. A conductor 80 connects the other side of the switch 770 to the switch 58g of the selector switch assembly 58. The switch 58g is connected by a conductor 81 to the conductor 50d.

The switch assembly 58 is a seven pole ganged switch having three positions corresponding to the three modes of the sliding nest feed. With the selector switch assembly 58 in the off mode, position one, the conductor 53b is connected to the conductor 53a through the switches 58a and 58b; and the conductor 53d is connected to the conductor 53c through the

switches

58d and 580. The other switches are open. With the selector switch assembly 58 in the single cycle mode, position two, the conductor 53a is connected through the switch 58a to the conductor 50b; the conductor 53b is connected through the switch 58b to the conductor 50d; the conductor 530 is connected through the switch 580 and the switch 58a to the conductor 53d; the conductor 53c is connected through the switch 58c to the conductor 56b; the conductor 53f is connected through the switch 58f to the conductor 74; and the conductor is connected through the switch 583 to the conductor 81. With the selector switch assembly 58 in the continuous mode, position three, the conductor 53a is connected through the switch 58a and the switch 58b to the conductor 53b; the conductor 53c is connected through the switch 58c to the conductor 50b; the conductor 53d is connected through the switch 58d to the conductor 50d; the conductor 53e is connected through the switch 58:? to the conductor 56b, the conductor 53f is connected through the switch 58f to the conductor 74; and the switch 580 is an open circuit so no connection is made between the

conductors

80 and 81.

As previously described, the operation of the press 13 is not affected by the presence of my sliding nest feeding apparatus 10 when the selector switch assembly 58 is in the off position, or off mode. The operation of the feeding apparatus when in the single cycle and continuous modes will now be described with reference to FIGS. 6 and 7.

With the sliding nest feeding apparatus 10 in the single cycle mode, the machine operator manually places a workpiece in the locating nest 20 when the nest is in the fully retracted loading position illustrated by solid lines in FIG. 6. The operator then depresses and closes the push button switches 16 (or the foot switch This completes a first circuit from the power line 18a to the limit switch 43 which is closed by the carriage 28 when the nest 20 is in the loading position and from the limit switch 43 to the return power line 1812 through the air valve solenoid 72 and the time delay circuit 75. The time delay circuit 75 is set to conduct after a short period of time, which then allows the control signal current to pass through the forward travel actuator solenoid 72 and thereby causes the valve 71 to direct air under pressure to the line 51a. Since the line 51b is open to the atmosphere, this causes a differential pressure to exist across the piston 37. The piston 37 is thereby forced toward the other end of the cylinder 36, and the carriage 28 correspondingly moves the attached nest 20 toward its working position illustrated by broken lines in FIG. 6. The movement of the carriage is stopped by the frame front end 21a, and at that point the limit switch 42 is closed by the carriage. This completes a second circuit from the power line through the push button switches 16, the anti-repeat circuitry 69, the switch 42, the solenoid 67 and back to the return line 18b. The slide actuator clutch solenoid 67 is thereby activated by the control signal current and the slide 15 and upper die 15a begin their previously described reciprocation cycle. The relay electromagnet 77b is also activated and the switch 770 is closed. This condition of the relay 77 remains in effect as long as the push button switches 16 remain closed, and insures that electrical power will be provided through the switch 770 to the solenoid 67 even if the switch 42 is opened before the work cycle is completed.

After the die 15a has engaged and withdrawn from the workpiece and the ascending slide 15 nears its uppermost position, the limit switch 54 is closed by the cam 55 and a third circuit is completed from the power line 180 through the switch S4 to the return travel actuator solenoid 73 and back to the return line 18b. Activation of the solenoid 73 by the control signal current causes the valve 71 to direct air under pressure to the line 51b to move the carriage 28 rearwardly. The carriage 28 eventually stops against the frame back end 21b with the nest 20 in its loading position, and the switch 43 is again closed. However, the air valve solenoid 72 is not activated because the anti-repeat circuitry has become an open circuit and remains open until the push button switches 16 are opened. When the slide 15 reaches a point proximate to its upper position the anti-repeat circuitry 69 becomes an open circuit which deactivates the clutch solenoid 67 to thereby disengage the clutch and stop the motion of the slide. Opening of the push button switches 16 causes the antirepeat circuitry to close and thus enable the press 13 and the sliding nest feeding apparatus to begin a new cycle when the push button switches are again closed.

With the sliding nest feeding apparatus 10 in the continuous mode, the nest 20 is repeatedly moved between the loading position and the working position as long as the Run switch means are depressed by the machine operator. In this mode. a single push button or a foot switch 16a would be employed to activate the press and feeding apparatus The nest 20 is set to dwell for a desired period of time in the loading position to allow the operator or an automatic loading device to load a workpiece in the nest.

In the continuous mode, power is continuously supplied to the

conductors

50d and 56b. When the nest 20 reaches its loading position the switch 43 is closed by the carriage 28. This activates the forward travel actuator solenoid 72 after a dwell period determined by the time delay circuit 75 to initiate movement of the nest 20 toward its working position. When the nest 20 reaches the working position the switch 42 is closed by the carriage 28 to activate the clutch solenoid 67 and cause the press slide and upper die 15a to reciprocate. As the slide 15 and upper die 15 return to their upper position the limit switch 54 is closed by the cam 55 to activate the return travel actuator solenoid 73 and thus cause the nest to move back to its loading position. Current to the anti-repeat circuitry 69 is cut off as soon as the switch 42 is opened by the rearward movement of the carriage 28, since in the continuous mode the connection between the

conductors

80 and 81 is broken by the switch 58g and there is no bypass circuit through the relay switch 77a around the switch 42 to supply the anti-repeat circuit. The anti-repeat cir cuit 69 is thus ready to conduct current to the solenoid 67 as soon as current is supplied to it. The cycle repeats when the nest reaches the loading position and the switch 43 is again closed by carriage 28.

Ejection of the finished workpiece from the nest 20 may he performed automatically by means associated with the punch press. or manually by the operator in both the single stroke or continuous modes. If the machine ejects automatically, the workpiece is ejected from the die area and the operator simply inserts another workpiece into the nest 20 on the next cycle. Otherwise the finished workpiece returns to the loading position with the nest 20, where the operator must remove it before inserting another workpiece into the nest.

To provide the maximum safety for the operator of the press 13, the entire work area of the press may be blocked off to the operator by guard barriers which meet OSHA safety standards. Such guards are shown in FIG. 1 attached to the press. and include a left side barrier 82a and a right side barrier 82b. A barrier 83 is placed between the loading position of the nest and the work area of the press 13 and is attached by bolts 84 to a bar 820 connecting the left and

right side barriers

82a and 82b. The barrier 83, which is preferably made of transparent plexiglass to allow an unobstructed view of the work area, has a cut-out portion 830 which is shaped to allow the nest 20 with a workpiece therein to pass through, but is not large enough to allow the operator to place his hands in the work area between the upper and lower dies.

It is apparent that my sliding nest feed may be used with various nest configurations other than that shown in the drawings and described herein for illustrative purposes. For example, the nest could be composed of a stationary portion affixed to the lower die 14a, and a movable portion attached to the carriage 28 which pushes the workpiece from the loading position to the working position where the workpiece would be precisely located between the stationary and movable nest portions. The nest could also consist of stationary rails leading to the working position and a nest portion attached to the carriage 28 which pushes the workpiece between the rails to a stop mounted on the lower die 140. Any nest configuration which transfers a work piece from a loading position, and precisely locates the workpiece in a working position can be used with my invention.

It is understood that my invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces all such modified forms thereof as come within the scope of the following claims.

1 claim:

1. Feeding appartus for engaging a locating nest which horizontally locates a workpiece in a working position within the work area of a press, and for transferring the locating nest between the working position and a loading position remote from said work area, said feeding apparatus comprising:

a. a frame attachable to said press;

b. support plate means attached to the upper side of said frame for slidably supporting a workpiece within said locating nest between said loading position and said work area, said support plate means having a longitudinal slot therein;

c. at least one longitudinally extending support member mounted to said frame beneath said support plate means;

d. a carriage having a lower portion located beneath said support plate means and slidably attached to said support member for longitudinal motion of said carriage, and having an upper portion extending through said slot and above said support plate means to engage and support said locating nest above said support plate means; and

e. drive means for driving said carriage between a first position wherein said locating nest is in said loading position, and a second position wherein said locating nest is in said working position.

2. The feeding apparatus specified in claim 1 wherein the width of said slot is no greater than one-fourth of an inch.

3. The feeding apparatus specified in claim 1 wherein a pair of longitudinally extending parallel bars are mounted to said frame beneath said support plate means, and wherein said carriage includes bearings slidably mounted on said parallel bars to permit longitudinal movement of said carriage and to substantially prevent non-longitudinal movement of said carriage.

4. The feeding apparatus specified in claim I wherein said drive means includes:

a. a pneumatic cylinder attached to said frame;

b. a piston movable within said cylinder;

c. means for connecting said piston to said carriage whereby movement of said piston will cause movement of said carriage; and

(1. control valve means for supplying air under pressure to said cylinder, including forward travel actuator means for causing said control valve means to direct air under pressure to one end of said cylinder to cause said piston to drive said carriage from said first position to said second position when said forward travel actuator means is supplied with electrical power, said control valve means also including return travel actuator means for causing said control valve means to direct air under pressure to the other end of said cylinder to cause said piston to drive said carriage from said second position to said first position when electrical power is supplied to said return travel actuator means.

5. The feeding apparatus specified in claim 4 including electrical control means for directing electrical power to said forward travel actuator means to thereby move said locating nest from said loading position to said working position, for directing electrical power to said machine to initiate the work cycle of said machine when said locating nest is in said working position, and for directing electrical power to said return travel actuator means after said machine has performed its work on said workpiece to thereby move said locating nest back to said loading position.

6. The feeding apparatus specified in claim I wherein said drive means comprises:

a. a pneumatic cylinder;

b. a piston movable longitudinally within said cylin der;

c. means for connecting said piston to said carriage whereby movement of said piston will cause corresponding movement of said carriage; and

d. means for selectively adjusting the differential pressure across said piston to produce motion of said carrier means between said first position and said second position.

7. The feeding apparatus specified in claim 1 including means for controlling said drive means to cause movement of said carriage from said first position to said second position, and movement of said carriage back to said first position after work has been performed when said carriage is in said second position.

Claims

1. Feeding appartus for engaging a locating nest which horizontally locates a workpiece in a working position within the work area of a press, and for transferring the locating nest between the working position and a loading position remote from said work area, said feeding apparatus comprising: a. a frame attachable to said press; b. support plate means attached to the upper side of said frame for slidably supporting a workpiece within said locating nest between said loading position and said work area, said support plate means having a longitudinal slot therein; c. at least one longitudinally extending support member mounted to said frame beneath said support plate means; d. a carriage having a lower portion located beneath said support plate means and slidably attached to said support member for longitudinal motion of said carriage, and having an upper portion extending through said slot and above said support plate means to engage and support said locating nest above said support plate means; and e. drive means for driving said carriage between a first position wherein said locatiNg nest is in said loading position, and a second position wherein said locating nest is in said working position.

4. The feeding apparatus specified in claim 1 wherein said drive means includes: a. a pneumatic cylinder attached to said frame; b. a piston movable within said cylinder; c. means for connecting said piston to said carriage whereby movement of said piston will cause movement of said carriage; and d. control valve means for supplying air under pressure to said cylinder, including forward travel actuator means for causing said control valve means to direct air under pressure to one end of said cylinder to cause said piston to drive said carriage from said first position to said second position when said forward travel actuator means is supplied with electrical power, said control valve means also including return travel actuator means for causing said control valve means to direct air under pressure to the other end of said cylinder to cause said piston to drive said carriage from said second position to said first position when electrical power is supplied to said return travel actuator means.

6. The feeding apparatus specified in claim 1 wherein said drive means comprises: a. a pneumatic cylinder; b. a piston movable longitudinally within said cylinder; c. means for connecting said piston to said carriage whereby movement of said piston will cause corresponding movement of said carriage; and d. means for selectively adjusting the differential pressure across said piston to produce motion of said carrier means between said first position and said second position.