US3015977A

US3015977A - Safety device for punch presses and the like

Info

Publication number: US3015977A
Authority: US
Inventors: Aaron J Stegink; Henry A Wallenstrom
Original assignee: Shwayder Brothers Inc
Current assignee: Shwayder Brothers Inc
Priority date: 1957-09-30
Filing date: 1957-09-30
Publication date: 1962-01-09
Anticipated expiration: 1979-01-09

Description

Jan. 9, 1962 A. J. STEGINK ETAL 3,015,977

SAFETY DEVICE FOR PUNCH PRESSES AND THE LIKE 2 Sheets-Sheet 1 Filed Sept. 50, 1957 INVENTO/PS. AARON J. STEG/NK HE /V/-?Y A. WALLENSTROM A TTOR/VE) Jan. 9, 1962 A. J. STEGINK ETAL 3,015,977

SAFETY DEVICE FOR PUNCH PRESSES AND THE LIKE Filed Sept. 30, 1957 2 Sheets-Sheet 2 /A/VE/V7'0/?$. AARON J. STEG/NK A HENRY 14. WALLE/VSTROM (O BY N 0 I0 (0 76 n ATTORNEY ttes Patented .l'an. 9, 1982 3,015,977 SAFETY DEVHCE FUR PUNCH PRESSEg AND THE LEKE Aaron J. Stegink and Henry A. Wallenstrorn, Denver,

Colo., assignors to Shvvaytler Bros, Inn, Denver, Colo,

a corporation of Colorado Filed dept. 3t), 1957, Ser. No. 686,988 11 Claims. (Cl. 83-6l) This invention relates to safety devices, and more particularly to safety devices which may be utilized in con nection with a punch press or the like, in order to prevent a subsequent operation of the machine in the event that a previous operation has not been satisfactorily performed or completed.

In the operation of punch presses and the like, as in which a strip of material is fed to the press so that successive articles of a particular configuration may be stamped from the strip, particularly when the articles being formed have an irregular shape such as having flanges or angular portions, in the event that the completed article is not ejected and remains in the die, or is only partially ejected, there is obvious danger of damage to the die, punches or other parts used in producing the article, on the next stroke of the punch press. Ordinarily, an operator is required to pay close attention to the operation of the punch press, in order to be able to stop the punch press before damage can occur. However, for relatively high speed operations, the reaction time of the operator may not be sufficient to stop the press before the next stroke, or the failure of an article to be ejected may not be sufliciently quickly observed by the operator. When angles, corners, flanges and the like are formed on the article, a blank of appropriate size may be punched out from the feed strip and pushed into a female die for ultimate formation. A jet of air is a convenient device for ejecting the article, but if the article tends to stick in the die, the air jet may not be able to remove the article. As will be evident, when a previously completed article is in the way, the next succeeding operation has little chance of being successful and a collection of completed or partly completed articles in the die may be the result, With a consequent possibility of damaging the punch ,or die or otherwise interfering seriously with subsequent operations. 7

Among the objects of the present invention are to provide a novel safety device, particularly adapted for use with punch presses and the like; to provide such a safety device which is particularly adapted to be utilized with a punch press in which a completed article is ejected by an air jet or the like; to provide such a safety device which will be effective and certain in operation; to provide such a device which may be utilized in high speed operations; and to provide such a device which is readily applied to conventional types of punch presses and the like.

Additional objects and the novel features of this invention will become apparent from the description which follows, taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of a portion of a punch press equipped with a safety device constructed in accordance with this invention;

PEG. 2 is a vertical cross section of a plate and microphone installation forming a part of the safety device of FIG. 1;

FIG. 3 is a vertical cross section of an alternative plate and microphone installation; and

FIG. 4 is a wiring diagram of the safety device of FIG. 1.

A safety device constructed in accordance with this invention may be utilized inconnection with a conventional type of punch press, such as illustrated in FIG. 1, which includes a bed ill, a reciprocable head 11 and columns 12 and 13 for supporting guides for the head, as well as a conventional drive motor and clutch arrange ment (not shown). In the operation of such a punch press, the motor is normally first turned on, then a solenoid operated clutch is actuated to start the head 11 reciprocating. The head M is ordinarily stopped through the clutch, rather than by stopping the motor, and suitable conventional mechanism is ordinarily employed so that the head will normally be stopped in an upper position. A strip is, from which blanks for the articles to be produced are punched out, is fed intermittently to the punch press from a coil 15, passing between wiping pads l6 supplied with a suitable lubricating oil or the like from a feed cylinder 17, between guide blocks 18 to successive positions above the female die 19, and then through a guide channel 2d. The head 11 may be provided with a die block 21 which carries a series of punches 22, adapted to punch a series of holes in the strip 14, which ultimately appear in the article, on each downward stroke of the head 11. Punches 22 pass through corresponding holes in a plate 23, while this portion of the strip then moves to a position beneath a blanking punch 24, which punches out from the strip 14 a blank having rounded corners, which passes into a transfer mechanism actuated by a cam 25 moved by head 11 into engagement with a cam roller 26 on a lever 27. The transfer mechanism, which is provided with a safety spring 28 moves the blank to a position beneath a male die 29, mounted on head die block 21, which with a cooperating portion of the female die 19 (not shown) may bend up the ends of the blank to form end flanges. Of course, any other desired configuration 0f the article may be obtained in a conventional manner. On die block 21 may also be mounted a trigger 3ft, for actuating a lever 31 to cause a stop finger or pin to permit the strip to be advanced the distance necessary for one blank to be made, each time the head 111 goes back up. Also mounted on the bed it) may be a pair of centering pins 32 which engage holes provided for the purpose in die block 21 to insure that the head 11 is in vertical alignment with the female die 19 as the head comes down. An air valve (not shown) may be mounted in a conventional appropriate position, such as to be opened by a cam each time the head 11 starts back up, while an air hose 33 may extend from the air valve to a nozzle which directs a jet of air, at a position behind the female die 19 in FIG. 1 and therefore is not shown, to eject the completed article. It will be understood, of course, that the punch press shown is only one of many conventional types with which a safety device constructed in accordance with this invention may be utilized.

In accordance with this invention, the safety device includes a plate 35, formed of metal such as steel, placed in a position such that it will be struck by the ejected article immediately, a guide tube 36 preferably being positioned between the nozzle of air hose 33 and plate 35, to insure that the ejected article will strike the plate 35 by traveling through the tube 36. The plate 35 comprises a portion of a microphone assembly and may be constructed in the manner shown in FIG. 2 or in the manner shown in FIG. 3, or in any other suitable manner. Thus, as in FIG. 2, a microphone 37 is mounted on the rear side of plate 35', the latter being supported by a flanged rubber tube 33, which may be formed of other suitable resilient material, so that vibration in the plant will not be transferred to plate 35. Thus, the outer flange of tube 38 may be attached, as by bolts as shown, to the plate 35 at positions spaced from that of microphone 37, while the inner flange of tube 38 may be attached, as by bolts as shown, to the peripheral flange of a supporting bell 39 which is mounted on the end of an arm 40. As in FIG. 1, arm 40 may be adjustably mounted by a pivotal bracket 41 which permits the plate 35 to be disposed at any desired angle, with bracket 41 mounted on a rear arm 42, which is longitudinally adjustable in a supporting bracket 43 suspended by a support 44. As in FIG. 2, the lead wires from the microphone 37 may extend through a cable 45 which conveniently extends through the tube 38 and, as in FIG. 1, upwardly and rearwardly, such as behind column 13, to a control box 46, which may be mounted alongside column 13 or in any other suitable position, such as behind the punch press. From the control box 46, a cable 47 may extend to a switch installed in the electrical line leading to the solenoid controlling the punch press clutch, as will be more clearly evident from FIG. 4, which is described later. The control box 46 may support a dial 48 for adjusting a time delay relay, described later, and a dial 49 for adjusting the sensitivity range of microphone 37. For a purpose described later, a microswitch 50 may be mounted in a suitable position, such as on column 13, to be closed by head 11 on the upstroke and opened on the next downstroke. An off-on switch 51 may also be installed in control box 46, in a position for ready access, while a lamp S2 for indicating that the punch press clutch operating solenoid is energized and a lamp 53 for indicating that the safety device has stopped the punch press, may also be mounted in a suitable position on the control box, such as atop the same, A signal lamp 54 may also be installed on the control box, to indicate that the safety device circuit is energized.

"In the alternative microphone arrangement of FIG. 3, the microphone 37 may be mounted on the rear of a metal plate or disc 55, the periphery of which is attached, as by bolts, to the inner edge of a rubber ring 56, the outer edge of the latter being attached, as by bolts, to an inwardly extending flange 57 of a supporting ring 58, which may be mounted upon a standard or other suitable support so as to place the plate or disc 55 in a position in which it will necessarily be struck by each ejected article. Preferably, the plate 35 of FIGS. 1 and 2 or the disc 55 of FIG. 3 is inclined downwardly and rearwardly, with respect to the direction of movement of the ejected article, so that each article, in turn, may be deflected downwardly into a collection box placed beneath the plate or disc. The disc 55 may be oval, square or rectangular in shape, or have any other desired shape, with the supporting ring 58 preferably having a corresponding shape and the rubber ring 56 also preferably having a corresponding shape. Also, the plate 35 of FIG. 2 may be oval, rectangular or square, rather than circular, or may have any other desired shape.

The microphone 37 is preferably a so-called musical contact microphone, such as the S.K.H. Amperite or any other suitable type which is primarily responsive to certain limited sound frequencies. Since the articles are ejected by the air jet at substantially the same velocity, while the material of plate 35 or disc 55 does not change and the material of the completed article does not change, the sound produced by each article, as it strikes the plate or disc, will produce a sound of substantially the same frequency or within a relatively narrow sound frequency range. Thus, the microphone 37 is preferably selected so that it is more sensitive to sounds within the narrow range of the sound produced by the striking of the successive articles against the

plate

35 or 55. Also, the sensitivity of the microphone 37 may be reduced so that only the sounds produced by articles striking the plate will be sufficient to activate the microphone, irrespective of other sounds produced in the factory. This can be done, since in one installation in which the amount of noise in the factory, due to other punch presses and machines, Was such that one person had to speak in a very loud voice to be head by another, the device operated successfully, indicating that only the sound of the ejected articles striking the

plate

35 or 55 was being picked up by the microphone 37.

In the wiring diagram of FIG. 4, the plate 35 and microphone 37 will be disposed in a position previously described, while the wires 60 and 68', leading from microphone 37 to a plug 61, will be disposed within cable 45 of FIG. 1 and the

lead wires

62 and 63, such as 220 volts, to a solenoid 126 for operating a clutch 127 which controls the punch press in a conventional manner, will be disposed in a conventional position alongside one of the press columns 12 or 13. Other wise, the parts shown in the wiring diagram will be installed in the control box 46, except as indicated. Wire 68 from the microphone 37 may be connected to ground, as shown, while wire 60 may be grounded through a resistor 64 and may also be connected to the grid of a pentode 65, the balancing grids of which may be connected in parallel and to ground through a resistor 66 and a condenser 67 the latter two also being in paral-- lel. The anode of tube 65 may be connected by a wire 68, through a condenser 69, with a variable resistor 70, controlled by dial 49 on the control box 46, the opposite end of resistor 70 being connected to ground and the variable contact 71 thereof being connected to the grid of a triode 72, the cathode of which may be connected to ground through a resistor 66' and a condenser 67, the latter two being in parallel. Tube 65 amplifies the signal given by microphone 37, while tube 72 contr-ols the sensitivity of the circuit to the sound produced, being advanced for relatively light articles and retarded for relatively heavy articles. The anode of tube 72 may be connected to the primary winding 73 of a transformer, one end of the secondary winding 74 of which is connected through a resistor 75 to the grid of a thyraton tube 76, the anode of which is connected to the coil of a relay 77. The opposite end of transformer secondary 74 is connected to a variable contact 78 of a variable resistor 79, connected across heater 80 of tube 76.

Movable contact 81 of relay 77, connected to lead 63 by a wire 82, is normally closed, but when open, will break the circuit to a time delay relay 83, which has been energized by the closing of microswitch 50 by the head 11 as it moves upwardly. The fixed contact of relay 77 may be connected to the coil of relay 83 by a wire 84, the opposite end of the relay coil being connected by a wire 85 with lead 62 and microswitch 50 conveniently being interposed therein. Lamp 52 is conveniently connected across wires 82 and 85 to indicate that the clutch actuating solenoid 126 is energized. A safety relay 86, when energized, is adapted to open a switch 87 in lead 63, to deenergize the solenoid 126 actuating clutch 127 and simultaneously close a switch 88 to cause lamp 53 to light, the latter being connected across the

leads

62 and 63 through switch 88, to indicate that the safety relay has operated. The coil of relay 86 is conveniently connected by a wire 89 with lead 62 and by a wire 90, through normally closed contact 91 of time delay relay 83, with lead 63. As will be evident, since the microswitch 50 is automatically closed by head 11 as it moves on the up stroke, the time delay relay 83 will automatically open its contact 91 to deenergize the safety relay 86, after a predetermined period of time, corresponding to the time necessary for the head 11 to reach the top of its stroke, unless the relay 77 is energized by a signal from microphone 37, indicating that the article produced on the previous down stroke has been successfully ejected by the air jet.

In the circuit diagram of FIG. 4, the various contacts and switches are shown with the punch press operating, the connection to the punch press solenoid being at the upper ends of

wires

62 and 63, as shown in FIG. 4. A normally open starting switch 92 may be connected between wire and lead 63, through a wire 93, as shown, so that switch 92 may be momentarily closed to energize relay 86, switch 87 previously being open, so that relay 86 will close switch 87 and wire 90, through normally closed contact 91, will maintain relay 86 energized and switch 87 closed, after starting switch 92 has been released. A manually operated stop switch 94 is conveniently interposed in line 63, while a microswitch 95 may be installed in a wire 96 leading from the opposite side of relay 77. Time delay relay 83 may be so constructed that it will open switch 95 each time a signal is received through opening of contact 81, to clear the tube circuit, in preparation for the next operation of the punch press, so that tube 76 will not continue conducting.

Power for the tube circuit may be supplied from

leads

97 and 98 to a transformer having a primary winding 99 and a secondary winding 100, one side of the latter being connected to ground and the other side through a resistor 101 with a silicone rectifier 102, the connection therebetween also being connected to a grounded condenser 103. The opposite side of rectifier 102 may be connected to a resistor 104, the opposite sides of which may be connected to grounded

condensers

105 and 106. From resistor 104, current is supplied through a wire 107 to a junction with a wire 108 and a three-contact variable resistor 109. One contact 110 of the latter is connected with the opposite end of transformer winding 73, the second contact 111 is connected to the opposite end of the coil of relay 77 through wire 96, and the third contact 112 is connected to the plate or cathode of thyraton tube 76. From wire 108, resistors 113 and 114 are connected in series with wire 68 between the anode of tube 65 and condenser 69, while the connection between resistors 113 and 114 is connected to a grounded condenser 115. One terminal of a resistor 116 may be connected to Wire 1055, while the opposite terminal is connected with the' plate of amplifying tube 65 and may also be connected to a grounded condenser 117. Primary winding 99 of the transformer also induces current in another secondary winding 118, which supplies the heater 119 of each of

tubes

65 and 72 through

wires

120 and 121, such as at 6.3 volts, while a second transformer, supplied by leads 97' and 98' and having a primary winding 122 and a secondary winding 123, may supply current, as also at 6.3 volts, to the heater S for the tube 76 through a wire 124, with the opposite side of each of heater 80 and secondary winding 123 being grounded, as shown. Lamp 54 may also be connected between Wire 12 1 and ground.

it will be understood, of course, that the above-described circuit is exemplary only and that various other circuits adapted to accomplish the same or a similar purpose may be used. Also, if the microphone 37 responds to noises other than those produced by the ejected article striking the plate 35' or 55, a filtering circuit may be incorporated, to filter out signals which are not caused by the article striking the plate. The various resistors, condensers, etc., may have suitable values, although in one installation the resistor 64 was 1 megohm, 0.5 watt; resistors 66 and 66' were 250 ohms, 0.5 watt; resistor 70 was 1.0 megohm, resistor 75 was 100,000 ohms, 0.5 watt; variable resistor 79 was 5,000 ohms; resistors 101 and 104 were 1,000 ohms, 1.0 watt; resistor 109' was 50,000 ohms, 50 watts; resistors 113 and 114 were 220,000 ohms, 0.5 watt; and resistor 116 was 1 megohm, 0.5 watt. Similarly,

condensers

67, 67' and 115 were microfarads;

condensers

103 and 105 were 40 microfarads;

condensers

69 and 106 were 0.05 microfarad; and condenser 117 was 0.1 microfarad.

From the foregoing, it will be evident that a safety device constructed in accordance with this invention fulfills to a marked degree the requirements and objects hereinbefore set forth. The device is readily installed, since it requires no substantial change in a conventional punch press, but operates swiftly and accurately to stop the punch press in the event that a completed article is not ejected. The metal plate, against which the ejected article strikes, when supported in a flexible or resilient microphone. nents of this invention are the timedelay device which manner, will permit a microphone attached on the rear is controlled by the head of the punch press or the like on the withdrawal stroke and adevice such as a relay which iscontrolled by amicrophone for rendering inoperative the time delay device when ,a signal is produced -by the microphone caused by the ejected article striking the resiliently supported plate.

The time delay device will, of course,.automatically stop the punch press after a predetermined interval of time, unless the device actuated through the microphone deactivates the time delay device. Thus, the device of this invention is certain in operation,-since if the microphone circuit for some reason should become inoperative, the punch press will be automatically stopped before it begins another stroke. All that is necessary to install the device of this invention is to position the microphone plate properly and to install the safety relay switch in the circuit which controls ,the operation of the head of the punch press or :thelike. Also, mounting of-the microswitch or other'device for actuating the time delay device, as on the column of the punch press or the like, is relatively simple. The device is also particularly adapted to be used in connection with high speed operations, since the distance which the ejected article must travel to strike the microphone plate is relatively small and the signal produced by the microphone is transmitted through the electrical circuit to the time delay device almost instantaneously. Thus, the signal has ample time to produce an operative result before the head of the punch press or the like is ready to begin another stroke.

Although a preferred embodiment of this invention has been illustrated and described, as well as certain alternative embodiments, it will be understood that other embodiments may exist and various changes may be made therein, all without departing from the spirit and scope of this invention.

What is claimed is:

1. A safety device for punch presses and the like, in which a completed article is forcibly ejected, comprising a plate mounted in a position to be struck by a completed article upon ejection; means mounted on said plate and responsive to the sound produced by the article striking said plate; and means controlled through said sound responsive means for preventing further operation of said punch press prior to the production of the next article in the event that said sound responsive means is not activated by a sound corresponding to that of an ejected article striking said plate.

2. A safety device as defined in claim 1, wherein said plate is resiliently mounted.

3. A safety device as defined in claim 2, wherein said plate is disposed at an angle to the path of movement of and ejected article, so as to deflect the completed articles to a point of collection.

4. A safety device as defined in claim 2, including a hollow, elongated guide member disposed between said plate and the point of ejection of said articles and mounted i111 a position to guide ejected articles in striking said p ate.

5. A safety device as defined in claim 1, including means for automatically stopping said punch press or the like following the production of one article and before the production of the next article; and means controlled through said sound responsive means for deactivating said automatic means upon the activation of said sound responsive means by an article striking said plate.

6. A safety device as defined in claim 5, including time delay means for interrupting the operation of said automatic means for a predetermined period of time.

7. A safety device as defined in claim 1, in which said plate is a flat plate of metal; which includes a tubular member formed of resilient material and having a flange at one end attached to said plate and a flange at the op posite end attached to a support, said support being adjustable to different angular, vertical and horizontal posi- 'fiange; and said sound responsive means includes a micro phone attached to the side of said plate opposite the side against which ejected articles strike.

9. A safety device for a punch press having a reciprocating head and male and female dies, said punch press being adapted to produce articles having angular portions, from a flat strip of material fed to a position for operation thereon by said dies, said punch press being provided with air jet means for ejecting completed articles, comprising a plate mounted at an angle to deflect completed articles downwardly and in a position to be struck by a completed article when ejected; a guide tube disposed between the point of ejection of said article and said plate; a switch adapted to be closed on the return stroke of the head of said punch press after completion of an article; a time delay relay energized upon closing of said switch and adapted, after a predetermined period of time, to terminate the movement of said punch press head; a microphone mounted on the side of said plate opposite the side struck by said completed article; a relay for deactivating said time delay relay; and an electrical circuit including said microphone, an amplifying tube and a thyratron tube, for energizing said deactivating relay upon a signal produced by said microphone when a completed article strikes said plate.

10. A safety device, as defined in claim 9, including means for adjusting the amplification of the signal produced by said microphone.

11. A safety 'device for punch presses and the like, in which a completed article is forcibly ejected, comprising a plate mounted in a. position to be struck by a completed article upon ejection; means mounted on said plate and responsive to the impat of an article striking said plate; means for automatically stopping said punch press or the like following the production of one article and before the production of the next article; and means controlled through said impact responsive means for deactivating said automatic means upon the activation of said impact responsive means by an article striking said plate.

References Cited in the file of this patent UNITED STATES PATENTS 1,241,257 Wurts et a1 Sept. 25, 1917 1,734,732 Kranz Nov. 5, 1929 2,337,132 Shaw Dec. 21, 1943 2,391,882 Conn Jan. 1, 1946 2,416,595 Reynolds Feb. 25, 1947