US3009696A - Compressed air operated suction feeding machine - Google Patents

Description

1961 R. e. COULSON ET AL 3,009,696

COMPRESSED AIR OPERATED SUCTION FEEDING MACHINE Filed April 28, 1958 4 Sheets-Sheet 1 ll 7 I.

Maui-1 IILUGIZTOIEE liGCoulnon/ f1. 6122241 Nov. 21, 1961 R. G. COULSON ET AL 3,009,695

COMPRESSED AIR OPERATED SUCTION FEEDING MACHINE Filed April 28, 1958 4 SheetsSheet 2 Nov. 21, 1961 R. G. COULSON EI'AL 3,009,696

COMPRESSED AIR OPERATED SUCTION FEEDING MACHINE Filed April 28, 1958 4 Sheets-Sheet 3 Nov- 21, 19 1 R. G. COULSON ETAL 3,009,696

COMPRESSED AIR OPERATED SUCTION FEEDING MACHINE Filed April 28, 1958 4 Sheets-Sheet 4 12 1 4 Ii R 1 :29

I I l Z3 Z4 5 1.9

United States Patent 3,009,696 CONIPRESSED AIR OPERATED SUCTION FEEDING MACHINE Ronald G. Coulson and Harold Smedley, Kettering, England, assignors to The British Boot, Shoe and Allied Trades Research Association, Kettering, England Filed Apr. 28, 1958, Ser. No, 731,454 Claims priority, application Great Britain May 1, 1957 12 Claims. (Cl. 271-30) In our British patent application No. 20,506/55 we have described a suction feed device consisting of a constant level device or table for holding workpiece driven upwards by a spring and locked by a brake mechanism coupled to a work holding and transporting device so that the brake is released only when the work holding suction cup is above the stack of workpieces and re-applied to lock the table the moment the work transporting cycle is started thus ensuring a constant level of the top-most workpiece regardless of thickness. In that application we also described a suction feed device in which reduced pressure, applied to a suction cup, serves also to operate pneumatic transport mechanism for moving the cup, constructed so that the mechanism will commence to move the cup from a picking-up position only when the ingress of air into the cup is substantially prevented.

According to the present invention there is provided a pneumatic feed device comprising a suction cup, conneotable to a supply of reduced pressure air, pneumatic transport mechanism operable by compressed air for moving the cup, and valve means responsive to a diminution in pressure in the suction cup to connect the transport mechanism to a compressed air inlet.

The valve means may comprise a spring, gravity or otherwise biassed piston or diaphragm (hereinafter referred to as a piston) coupled to a distribution valve and operating in a cylinderor other chamber connected with the suction cup.

The device preferably comprises a vacuum pump, arranged for operation by compressed air, for supplying the reduced pressure air. This pump is preferably of the ven-turi type, and may be separately connected to the suction cup and valve means.

The invention also consists in a venturi-type vacuum pump arranged for operation by compressed air, constructed as a unit with a valve means comprising a biassed piston or diaphragm coupled to a distribution valve for compressed air and operating in a cylinder connected with the pump so that the distribution valve will be operated by a change in the degree of vacuum generated by the pump, the latter having an air inlet on the reduced pressure side for connection to a suction cup.

The use of compressed air facilitates the incorporation of a pneumatic ram, operable by compressed air, in an arm carrying the suction cup. Such a ram may be used, for example, to advance an article held by the cup when the travel of the arm has been arrested, for presenting the article to a machine. Suitable sequential timing mechanism may be provided for admit-ting air to the ram at the correct stage.

In one convenient arrangement the distribution valve is of the 5-way variety and in the undeflected position of the diaphragm or piston distributes the compressed air to a pneumatic jack whose extension will unlock the brake mechanism permitting the table to rise and bring the topmost workpiece into contact with the suction cup. The action of sealing the suction cup thus brought about effects the displacement of the diaphragm and distributes the compressed air to a main cylinder and exhausting the brake release cylinder at the same time.

The main cylinder then moves and carries out the transport of the work, for example through rack pinion 3,009,696 Patented N ov. 21, 1961 and helical cam mechanism to give a vertical lift followed by an :arcuate swing or a vertical lift followed by a horizontal linear movement, or a combination of these, compressing a main cylinder return spring during this movement.

When the desired release point for the workpiece is reached a pilot valve is operated which effects a movement of a cut-off shuttle valve and cuts off the air supply to the distribution valve and the vacuum generating unit thus permitting the work to be released and the distribution valve to return to normal because of the collapse of the vacuum and thus the main cylinder to exhaust allowing the arm to return to pick-up position over the stack.

When the main piston has returned fully and the pick-up arm is above the stack a second pilot valve is operated and the cut oil shuttle valve flies over switching air on again to the vacuum generating unit and the distributor valve which latter is in the position to distribute air to the brake release jack.

The function of the pilot-operated shuttle valve is to cut off the compressed air at the end of the delivery stroke thus both dropping the workpiece and permitting a return of the main cylinder without waste of compressed air and to switch on the air again when the suction cup is over the stack.

A further on-off air valve, which may be push-button operated, is fitted with an on-latch with a trigger release so that when the constant level platform reaches the uppermost position and is therefore empty the table contacts the trigger and cuts off all air supply until the table is again depressed for loading purposes which can be done by depressing the brake release lever manually, the table being locked in the down position for restacking purposes by releasing the brake lever.

Provision for controlling the speed of the movements is incorporated n the form of a unidirectional throttle valve in the main cylinder supply or exhaust line.

Provision is also made for arresting the swinging arm motion Where desired and signalling for an operation on the held workpiece to be carried out by an external machine the completion of which will release the arm to allow the workpiece to complete its travel.

Further provision is made for extending the swinging arm at the point of arrest by using a pneumatic ram in place of the arm sequenced to extend by the arresting mechanism.

The pneumatic system described can be on continuous automatic feed or one-at-a-time operation when so desired according to positioning of the shuttle valve pilot valves.

The invention is described further with reference to the accompanying drawings, of which- FIGURE 1 is an end elevation of a compressed air operated suction feeding machine,

FIGURE 2 is a part sectional elevation of the machine,

FIGURE 3 is a sectional plan of the machine,

FIGURE 4 is a sectional drawing of a shuttle valve and vacuum generating unit,

FIGURE 5 is a sectional drawing of a push-button on/otf valve,

FIGURE 6 is an elevation of the brake mechanism with pneumatic jack-operated release,

FIGURE 7 is a schematic diagram of the pneumatic circuit for the machine,

FIGURE 8 is a sectional view of an alternative arm for moving the workpiece linearly during its arcuate swing, and

FIGURE 9 is a sectional view of a device for arresting the arcuate swing of the feeding arm where desired.

Referring to FIGURES 1-7, the machine comprises a body casting 1 to which is fitted a lower cover 2 which carries a hollow vertical spindle 3 to which it attached at its lower extremity an arm 4 which carries at its extremity a suction cup array 5. This suction cup array can partially rotate about the axis of arm 4, this rotation being limited by torsional deflection of rubber sleeve 6 one end of which is connected to suction cup array and the other end connected to arm 4.

The upper end of vertical spindle 3 carries a trunnion mounting 7 on which is mounted two rollers 8 and 9. Roller 8 projects through a helical slot in cam drum 10 which is supported in hearings in the top and bottom covers of the body casting. Cam drum 10 carries a gear ring which engages with rack cut in main piston rod 11 which is able to slide in a housing in body 1. The outer trunnion pin roller 9 engages a vertical slot cut in body 1. This vertical slot also connects with annular groove in body 1 so that roller 9 can pass along vertical slot and around annular groove.

At the upper end of body casting 1 is mounted a 5-way diaphragm operated piston valve 12.

The vertical spindle 3 accommodates a return spring 13 which is in contact with the push rod 14 which in turn abuts against the lower face of the body cover.

The piston rod 11 carries a piston head assembly 15 which moves in cylinders 16 which is attached to the body casting 1. The cylinder end cap 17 contains adjustable flow inlet and exhaust valves 18 and 19.

A return spring 20 is housed within the piston rod 11, the outer end of the spring 20 abutting against the end of a spring housing 21.

A pilot valve mounting 22 carrying two spring loaded pilot valves 23 and 24 is mounted on body 1. A finger 25 mounted on a rod 26 freely slides in pilot valve mounting 22 and spring housing 21. The outer end of finger 25 can engage and operate pilot valves 23 and 24 whilst the inner end is housed within a slot in piston rod 11 and can move relative to it. An adjustable stop collar 27 carries a projection which can engage the end of piston rod 11. Mounted on valve 12 is a pilot operated on/off shuttle valve 28 and vacuum generating unit consisting of a jet 29 venturi sleeve 30 housed in body 31.

The aforementioned comprises the compressed air operated suction feed machine which can be mounted on a constant level table device (FIGURE 7) as hereinafter described.

The device comprises a brake for arresting the rise of the table, controlled by a pneumatic jack 32 arranged so as to effect release of brake when extended. The brake unit housing also carries a push button operated on/oif valve 33 which can be latched in the on position 34.

In operation valve 33 is off and the workpiece table is at the top of its stroke and locked in this position by the brake. To load the platform the brake release lever 35 is manually depressed and the table pushed down to accommodate a stack of components which are positioned on the table. The brake lever is then again depressed and the table allowed to rise until the top component of the stack contacts the under side of the suction cups forming part of suction cup array 5. Valve 33 is then opened and compressed air passes through valve to on/ofi shuttle valve 28 via a suitable piping. Since feed arm 4 is at start position under the influence of return springs 13 and 20 pilot valve 23 being operated will operate valve 28 to direct air to the vacuum generating unit 29, 30 and 31 and to the supply side of the 5-way valve 12. This 5-way valve then directs air to brake unit pneumatic jack 32 thus releasing table brake and allowing the stack of components to be pressed firmly into contacts with suction cups 5. Since air is also being supplied to the vacuum generating unit and the consequent reduced pressure is connected by suitable pipes to both the chamber of the diaphragm valve 12 and suction cups 5 obturation of the latter will etfect deflection of the diaphragm in valve 12 permitting main air pressure to be directed to main cylinder 16 by a suitable piping and speed control 18 and permitting brake jack 32 to exhaust to atmosphere thus retracting and locking table. Workpiece which is held in contact with suction cup array 5 by the reduced pressure already referred to is lifted and traversed by the movement of the main cylinder piston, translated by The piston rod 11 pinion cam drum 10, trunnion rollers 8 and 9, shaft 3 and arm 4 to a desired position. At this position piston rod 11 contacts the projection of adjustable stop collar 27 which moves finger 25 by means of rod 26 to which both are rigidly connected. This operates pilot valve 24 which in turn etfects a movement in the shuttle valve thus cutting off air supply at valve 28 to vacuum generating unit 29, 30 and 31 and 5-way valve 12. Thus movement of arm 4 is arrested and workpiece previously held by suction cups is released due to collapse of vacuum which also permits valve 12 to revert to its original position whereby main cylinder can exhaust to atmosphere via speed control valve 19 and exhaust port of 5-way valve 12. Arm 4 then retraces its movement to an original position. When the return motion of the arm 4 is complete, finger 25 is moved by contact with the end of the slot in piston rod 11 and consequently operates pilot valve 23 to reinitiate feeding c cle.

When the last workpiece has been taken from the table, trigger 34 is operated by the table thus closing valve 33, cutting off air supply to the feeding mechanism and placing table under manual control for reloading or restacking purposes.

Referring now to FIGURES 8 and 9, arm 4 is replaceable by an extending arm unit consisting of arm 38 carrying piston 36 sliding in cylinder 37, guided by end cap 40 and returned by spring 39.

The cam drum 10 carries a projection 41 positioned so that it moves in the annular groove in body 1. A detent 44 slides in a housing attached to a clamp ring 42 which embraces the body 1. Detent 44 projects through the slot in body 1 and can engage the projection 41 as the drum 10 rotates. Detent 44 is held in the engage position by spring 45 and peg '43 limits the sliding action of the detent.

Alternative provision for intermediate stopping of the feeding arm can take the form of a retractable stop which can engage the feeding arm, and can be withdrawn to permit the feeding arm to continue its swing when required.

What we claim is:

1. A pneumatic feed device comprising a suction cup, a supply of reduced pressure air connected to said suction cup, a supply of compressed air, pneumatic transport mechanism operable by the compressed air for moving the cup, and valve means responsive to a diminution in pressure in thesuction cup to connect said transport mechanism to said compressed air supply.

2. A device according to claim 1 in which the valve means comprises a biassed piston, a distribution valve coupled thereto, and a chamber connected with the suction cup in which said piston operates.

3. A device according to claim 1 in which the supply of reduced pressure air comprises a vacuum pump, arranged for operation by the compressed air supply for the transport mechanism.

4. A device according to claim 3 in which the vacuum pump is of the venturi type.

5. A device according to claim 4 in which the vacuum pump is separately connected to the suction cup and to the pressure-responsive valve means.

6. A pneumatic transport mechanism control unit comprising a venturi-type vacuum pump arranged for operation by compressed air, a valve means constructed as a unit with the pump and comprising a biassed piston coupled to a distribution valve for compressed air, and a cylinder in which said valve operates connected with the pump so that said distribution valve will be operated by a change in the degree of vacuum generated by the a! pump, the latter having an air inlet on the reduced pressure side for connection to a suction cup.

7. A device according to claim 1 in which an arm is provided to carry the suction cup incorporating a pneumatic ram arranged for operation by the compressed air.

'8. A device according to claim 7 comprising pneumatic means for swinging the arm, means for arresting the swinging motion, and sequential timing mechanism for admitting air to the ram when the swinging motion has been arrested to advance an article held by the cup.

9. A pneumatic feed device comprising a suction cup, a supply of reduced pressure air connected to said suction cup, a supply of compressed air, pneumatic transport mechanism operable by the compressed air for moving the cup, valve means responsive to a diminution in pressure in the suction cup to connect said transport mechanism to said compressed air supply, and an upwardly biassed table for supporting a stack of workpieces, brake mechanism for arresting the upward movement of the table and a pneumatic jack whose extension will unlock the brake mechanism permitting the table to rise and bring the topmost workpiece into contact with the suction cup, in which the distribution valve is of the 5-way 6 variety and in the undeflected position of the piston distributes the compressed air to the pneumatic jack.

10. A device according to claim 9 comprising a pilot valve and a cut-off shuttle valve coupled thereto, arranged to cut ofi the air supply to the distribution Valve and the vacuum generating unit thus permitting the work to be released and the transport mechanism to revert to a starting position by operation of the pilot valve.

11. A device according to claim 10 comprising a second pilot valve mounted for operation, and connected to reverse the shuttle valve, when the suction cup is again over the workpiece stack.

12. A device according to claim 9 incorporating valve means actuated by the table reaching an uppermost position to sever compressed air supply.

References Cited in the file of this patent UNITED STATES PATENTS 2,080,010 Rowlands et al. May 11, 1937 2,200,800 Miller May 14, 1940 2,733,920 Von Hofe et al. Feb. 7, 1956 2,812,061 Pfister Nov. 5, 1957

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