US2722276A

US2722276A - Feed control mechanism for punch presses

Info

Publication number: US2722276A
Authority: US
Inventors: Benjamin F Revelle
Original assignee: Missouri Automatic Control Corp
Current assignee: Missouri Automatic Control Corp
Priority date: 1949-10-15
Filing date: 1949-10-15
Publication date: 1955-11-01
Anticipated expiration: 1972-11-01

Description

Nov. 1, 1955 B. F. REVELLE 2,722,276

FEED CONTROL MECHANISM FOR PUNCH PRESSES Filed Oct. 15, 1949 2 Sheets-Sheet l B. F. REVELLE 2 Sheets-Sheet 2 Nov. l, 1955 FEED CONTROL MECHANISM FOR PUNCH PRESSES Filed Oct. 15, 1949 Unite States Patent Otice 2,722,276 Patented Nov. 1, 1955 FEED CONTROL MECHANISM FR PUNCH PRESSES Benjamin F. Revelle, St. Louis, Mo., assigner to Missouri Automatic Control Corporation, St. Louis, Mo., a corporation of Missouri Application October 15, 1949, Serial No. 121,568

1 Claim. (Cl. 164-89) This invention relates generally to stock feeding mechanisms for power driven punch presses or the like and more particularly to control means for the automatic operation of such mechanisms.

Heretofore in automatic feed mechanisms for punch presses, it has been customary to privide a reciprocating member carried on the press ram and arranged to engage the feed mechanism on the downward stroke of the ram, thereby to release the feed rolls and to stop feeding just before the die engages the work. With this arrangement feeding must occur partially on the upstroke of the ram and partially on the downstroke of the ram after the press has been tripped. Such an arrangement is shown and described in the patents to J. Wittek, No. 1,796,417, issued March 31, 1931, and No. 1,867,343, issued July 12, 1932.

It has been found desirable to provide means whereby all feeding of stock may be caused to occur on the return or upstroke of the press ram prior to top dead center so that in event scrap or completed work becomes lodged in the die so as to prevent the proper feeding of stock for the succeeding stroke, such improper feeding may be detected prior to the tripping of the press so that tripping of the press may be prevented and damage to the die avoided. It is particularly important to insure that proper feeding has occurred before permitting the press to be tripped when complicated and costly progressive dies are in use.

This invention has for its primary object the provision of a control system for the automatic operation of punch presses whereby feeding of stock is coordinated with the operation of the press in such manner that all feeding is caused to occur on the return or upstroke of the press ram prior to upper dead center and whereby tripping of the press is caused to occur, or permitted to occur, only if the stock has been fed to the correct position during the upstroke of the ram.

A further object is the provision of an actuating means for tripping the punch press and control means sensitive to the position of the stock being fed for controlling the actuating means whereby the press is tripped only when the stock is fed to the correct position.

A further object is to provide a lluid pressure operated actuater for controlling the operation of the feed mechanism, a remote control valve for controlling the operation of the actuator, and eccentric means rotating with the press crank shaft and adjustable with respect thereto, for operating the control valve.

Further objects and advantages will become apparent when reading the following description in connection with the accompanying drawings, in which:

Fig. l is a schematic view showing the pertinent parts of a power driven punch press together with a stock feeding device and a control system constructed in accordance with the present invention;

Fig. 2 is a side elevation of a conventional punch press showing the drive for the feed device, the control valve for controlling the operation of the feed device and a earn 2 mounted on the crank shaft for operating the control valve;

Fig. 3 is an enlarged side view of the feed device shown in Fig. 1; and v Fig. 4 is a sectional view of the feed device taken on line 4-4 of Fig. 3.

Referring to the drawings, a conventional power drive'n punch press is generally indicated at 10 in Fig. 2. The press has a frame 11, and a crank shaft 12 having an eccentric 13, which imparts reciprocating motion to a ram 14. The ram 14 carries a die holder 15 in which is mounted a male die 16. Mounted concentrically with the crank shaft at one end is a ily wheel 17 driven by suitable power means, not shown, through a belt 18. There is a conventional single revolution type trippable clutch indicated at 19 for connecting the fly wheel and crank shaft having a trip arm 20, which when rotated in a clockwise direction causes the clutch mechanism to be tripped thereby engaging the y wheel and crank shaft for one revolution of the crank shaft in a manner well understood in the art. The press further includes an operating stage 21, on which is mounted a die shoe 22 rigidly attached thereto as by screws 23. A female die mounted on the die shoe 22 for cooperation with the die 16 is indicated at 24.

At the right side of the press bed or operating stage 21 in Fig.' l, is a stock feeding device generally indicated at 25. The feed device 25 is shown in detail in Figs. 3 and 4 and comprises a pair of parallel horizontal frame members 26, which are shown as integral extensions of the die shoe 22. Iournalled in the frame members 26 is a shaft 27 on which is mounted for rotation therewith a lower feed roll 28. Arranged above the shaft 27 is a shaft 29, on which is mounted for rotation therewith an upper cooperating feed roll 30. The upper shaft-29 is journalled in a pair of bearings 31 which are arranged to slide vertically in the frame members 26, as indicated at 32 in Fig. 3, so that the feed rolls 28 and 30 may be moved toward and away from each other. The slidable bearings 31 are urged downward by a pair of relatively strong springs 33 which are retained in cap members 34 attached to the top of the frame members 26 by screws 35. The'feed rolls are therefore normally in contact with each other.

Mounted on shaft 27 for rotation therewith is a bevel gear 36, which meshes with a bevel gear 37, mounted on one end of a countershaft 38 for rotation therewith.

The countershaft 38 is suitably journalled in the die,

shoe 22 and has mounted on its other end for rotation therewith, a sprocket wheel 39. There is also a sprocket wheel 40 mounted on thecrank shaft 12 for rotation therewith and there is a roller chain 41 connecting

sprockets

39 and 40. The lower feed roll 28 is thus driven by the press crank shaft 12. The upper feed roll shaft 29 is driven by the lower shaft 27 through a pair

lof spur gears

42 and 43 which are keyed to the ends of shafts. The feed rolls are thereby driven in unison.

On the front frame member 26 of the feed device there is pvotally mounted at 44, a bell crank having an arm 45 provided with a slotted hole 46 at its free end through which one end of the upper feed roll shaft 29 projects. The other arm 47 of the bell crank is pvotally connected at its free end to a pneumatic actuator generally indicated at 48, see Fig. l. The actuator 48 is illustrated as a reciprocating pneumatic motor having a piston 49, a cylinder 50 and a connecting rod 51 to which arm 47 is pvotally connected at 52. As the piston 51 moves toward the left, the bell crank is rotated counterclockwise and the arm 45 lifts the upper feed roll against the pressure of springs 33 thereby separating the feed rolls and stopping the feeding of stock. A reel of strip stock is indicated at 53 in Fig. 1 and is shown mounted on `supports 54 attached to the press frame. The strip stock is also shown extending through the feed rolls and between the dies.

For the operation of the pneumatic feed actuator 48, compressed air is supplied from a suitable source through a main air line 56, to a surge tank 57 and thence alternately to the opposite ends of the actuator `cylinder V through a common air line 58, a 4-way pressure .operated valve generally indicated at 59, .and the

branch lines

60 and 61. The 4-way valve 59 is of conventional design having a normal returned position in which air is admitted from line 58 through line 60 to the right side of cylinder 50 and exhausted through line 61 and an exhaust ,port 62, and having an .actuated position Ain which air is admitted from line 5S through line 61 to the left side of cylinder 50 and air is exhausted :through line 60. In the first or normal position of the valve it will be seen that the bell crank is rotated counterclockwise forcing the feed rolls apart to interrupt feeding and in the second or actuated position the lbell crank is rotated clockwise moving the feed rolls together thereby to engage the stock and .effect feeding. The action of the actuator in this direction is augmented by the springs 33.

The 4-way valve 59 is provided with a pnuematic actuator 63 associated therewith and to which compressed air is supplied through an air line 64. The actuator 63 is under the control of a quick acting blowvalve generally indicated at 65, interposed in line 64. The blow-valve has an operating arm 66 arranged to be engaged by a cam 67 which is adjustably `attached to the end of crank shaft 12 in any suitable manner as by a screw 67a. When the arm 66 is engaged by the cam 67, the blow-valve is opened, admitting air to the actuator 63 and causing the 4-way valve to be actuated to the position in which compressed air is admitted to the left side of cylinder 50 thereby permitting the feed rolls to come together and effect feeding of stock. When the cam leaves the arm 66 the blow-valve closes and the 4-way valve returns to its normal position in which compressed air is admitted to the right side of cylinder 50 causing the feed rolls to be separated and feeding to be interrupted.

For the operation of the press clutch 19, there is provided an actuator generally indicated at 68. Actuator 68 is also illustrated as being a reciprocating type pneumatic motor having a piston 69, a cylinder 70 and a connecting rod 71 which is pivotally connected to the trip arm 20. The actuator 68 is operated in a tripping direction only by compressed air, the return of the actuator and the trip arm 20 being effected by suitable biasing means such as the spring 71a. Compressed air is supplied to the actuator 68 through an air line 72 in which is interposed a pilot valve generally indicated at 73. The pilot valve 73 is normally closed and is operated to an open position by a pneumatically operated actuator 74 associated therewith. Compressed airis supplied to the pilot valve .actuator 74 through an air line 75 in which is interposed a solenoid valve 76 having a winding 77, which when energized causes the -valve to open admitting air to the pilot valve actuator 74 and causing the pilot valve to open. When the pilot valve 73 is opened, compressed air is supplied to the clutch actuator resulting in the tripping of the clutch. When de-energized the solenoid valve closes permitting the .pilot valve to close and the actuator 68 to return to its normal position.

An energizing circuit for the solenoid winding 77 is provided which includes a voltage step-down transformer 78, a lead 79, the winding 77, and a lead 80. Input to the transformer 78 is supplied from a commercial source through the

leads

83 and 84. Interposed lin the lead 184 is a sensitive switching device generally indicated at "85, see Fig. l. The switch 85 may be provided with any suitable operating buttonor lever as indicated at "86 and the switch is .positioned adjacent the dies .in such manner that its actuation in a direction to close the circuit is caused by the final slight movement of the stock, as it approaches the correct position in the die for the succeeding work stroke.

There is a manual switch 87 interposed in the lead 84 whereby the solenoid circuit may be controlled manually and there is also a normally closed manual or foot operated valve 87 interposed in the air line 75 for the control thereof, whereby the press may be operated manually in connection with the safety feature provided by the cooperation of switch 85 and solenoid 76.

The blow-valve operating cam 67 is adjustably positioned so that the blow-valve is opened and feeding of stock is started on the upstroke of the ram as soon as the nished part is ejected. The dwell on the cam 67 determines, of course, the portion of the upstroke of the ram during which feeding occurs. Cams having varying lengths of dwell may be substituted to increase or decrease that portion of the upstroke during which stock is fed, thereby to accommodate various set-ups in -which various portions of the upstroke must occurbefore nish work can be ejected and before feeding may be begun. To obtain the length of feed required during the available upstroke a sprocket 39 having the correct number of teeth is selected.

In operation, the

rolls

28 and 30 being normally separated when there is a supply of compressed air, the stock is inserted between the feed rolls and fed to the correct position between the dies by hand. A conventional stock stop or locating pin, not shown, being employed to correctly position the stock in the die. As the stock is moved to the correct position, the sensitive switch 85 is closed causing energization of the solenoid valve 76 thereby causing it to open and thereby causing the pilot valve I4 to open and the actuator 68 to trip the clutch 19 provided the foot valve 88 is opened. As soon as the dies part, that portion of the stock or finished work as the case may be which has engaged the switch 85, is moved either by ejection or by the feed mechanism out of engagement with the switch thus permitting the solenoid valve to close andthe trip clutch to return to a cocked position. if correct feeding is accomplished on the succeeding upstroke, the switch will again be closed and the press may be tripped. If the stock has not been fed to the correct position the switch 85 will not be closed and the `press `will not be tripped even though `the .foot valve 87 may be opened. The foot valve 87 may be held open by any suitable means for continuous automatic operation of the press.

Obviously the actuator 48 may be an electromagnet and the control valve 65 a switching device operated by the cam 67. Likewise the clutch operating cylinder 68 may be a solenoid. The foregoing description and accompanying drawings are intended to be illustrative and not limiting, the scope of the invention being set `forth in the appended claim.

I claim:

In a power driven punch press for high speed operation on flexible strip stock, a frame, a crankshaft journalled in the frame, a reciprocating member driven `through a downward working stroke and an upward return stroke by said crankshaft, a continuously driven y Wheel, a single revolution, self-releasing, self-cooking, trip-type clutch which when tripped connects the crankshaft as it approaches top dead center to the fly wheel for one revolution, a strip stock feeding device including a pair of continuously driven feed rollers, which feed rollers are movable toward each other to effect stock feeding `and movable `apart to cease feeding of stock, said rollers being normally held apart in a non-feeding position, means for moving said rollers to a feeding .position shortly after the start of the return stroke of said reciprocating member, for holding said `feed rollers Ain a feeding position during part of the return stroke of said .reciprocating member, and for returning said rollers to a non-feeding position prior to the completion of the return stroke of said reciprocating member and consequently before said crankshaft reaches top dead center, said means including an operating lever carried by said frame and a cam rotating with said crankshaft and having a surface for engaging said lever, said cam surface having such angular relationship with said crankshaft that said lever is engaged thereby only during the return stroke of said reciprocating member, and means for tripping said clutch when the feeding of stock has been accomplished, which means includes a sensitive control element mounted along the path of the stock being fed and being arranged to be engaged by the stock when it has been fed to the correct position.

References Cited in the le of this patent UNITED STATES PATENTS Colley Aug. 23, 1887 Stevens Feb. 28, 1922 Batch et al. Aug. 14, 1923 Neuhengen Ian. 29, 1924 Kurkowski July 1, 1924 Crane et al. Aug. 1, 1939 Tetlaff Nov. 4, 1941 Candee et al. Dec. 30, 1941 FOREIGN PATENTS Australia Nov. 7, 1946