US2559369A - Transfer mechanism - Google Patents

Description

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Mass, a corporation of Massachusetts Application June 18, 1948, Serial No. 33,853

8 Claims.

My present invention relates to a mechanism whereby work pieces to be machined may be transferred in ordered sequence through one or more stations relative to machining units and may be accurately positioned at each station.

This application is a continuation in part of my co-pending application Ser. No. 736,034, filed March 20, 1947.

In the mechanism of my invention work pieces are successively placed in starting position of an initial transfer machine and are then trasferred in successive steps from one position or station of the machine to the next, and to the next machine or to a delivery station without further intervention by the operator except to start or stop the transfer machine or machines and the unit or units associated therewith. Any number of transfer machines and their associated machine units may be arranged in sequence and the work pieces are then transferred automatically from one mechanism to a succeeding mechanism.

Each transfer machine is under the control of the machine unit associated with it so that a work piece is not moved to a working station until the unit, such as a drilling machine, is ready to start the machining operation at that station and is not moved to the next succeedin station until the machine has completed its operation and is ready to receive a succeeding piece.

When transfer mechanisms are arranged in sequence, the starting or loadin station of one mechanism must be vacant before the preceding mechanism is set in operation to deliver a work piece. The operation of each machine is controlled by the next successive machine to permit the transfer of a work piece only when thereceiving station of the successive machine is free to receive it.

It will be apparent, therefore, that no work piece can be moved into a station until the unit at that station is ready to receive it and until the machining operation on a preceding work piece has been completed. The successive transfer machines are thereby timed to the slowest machine although each may itself be otherwise independent.

Inasmuch as each transfer machine is a complete and separate entity, any number of machines may be combined with a corresponding number of units to accomplish any desired number of unit operations and may be readily changed about or adapted to changes in the order or types of units and unit operations.

In assembling a succession of transfer machines it is sufiicient that the work piece may slide or move securely from one to the next.

The units which operate on the work pieces may be of any type, such as a drilling machine, boring machine, planer or shaper or profiler, or a mechanism for turning the work piece to a different position for a succeeding operation, or it may be apparatus for inspecting the work accomplished in preceding units.

The work piece is moved to and through the successive stations of each transfer machine by any suitable propellant, mechanical, electrical, pneumatic, hydraulic, reciprocating or otherwise which moves forwardly from one station to the next at successive controlled intervals. A hydraulically operated reciprocating transfer element having a stroke equal to the distance between the stations is an example of a suitable propellent element.

As a piece arrives at a working station it is located accurately by locating devices, such as pins actuated by a yielding force, such as fluid under pressure, which move into accurately positioned openings or holes in the work piece, or in piece secured to it, when it is in correct position. When the work piece is located in a station by the locating pins it is clamped securely in position by clamping means or plates, preferably actuated by fluid pressure, which hold it throughout the machining operation.

The propellent element may carry a pin, latch or similar mechanism, which engages the work piece on each forward movement from station to station but which is depressed to move underneath a work piece when the element moves reversely.

When hydraulic or pressure fluid is used to actuate the machines it is preferably controlled by valves so arranged that each element of the machine may move only in its proper sequence and timing. Thus the valves are so arranged that the clamping plate is lowered into clamping position only when the locatin pins or elements have moved to locating position.

The transfer element moves in reverse direction when the clamping plate is clamped. As it reaches its rearmost or starting position it then operates a control valve to cause the clamping plate and the locating pin to be retracted, where upon the transfer bar moves forwardly carrying with it the work piece from each station to the next. At the end of its stroke it operates a control valve to permit the locating pin to move to locating position, and when this is accomplished it in turn permits the clamping plate to clamp the work piece in its located position.

These hydraulically operated valve mechanisms insure that each of these movements wiil take place in its proper sequence and only when the preceding operation has been successfully and fully completed.

These hydraulic mechanisms are in turn electrically controlled jointly by the unit or. units associated with the transfer machine and by control switches at the loading stations of the machine and the next succeeding machine. This control circuit releases the hydraulic mechanism to advance a work piece when the unit has completed its operation and withdrawn, when the loading station of the machine is loaded and that of the next succeeding machine isempty. It also comprises a starting switch for the machine actuated by the clamping of the clamping mechanism and a switch actuated by the withdrawal of the locating pins to permit forward movement of the transfer element.

The various features of the invention are illustrated, by way of example, in the accompanying drawings in which- I Fig. I is a diagram in perspective of a machine embodying the invention, details of construction being omitted for the sake of clearness;

Fig. 2 is-awiring diagram of the control system for the machine of Fig. 1;

Fig. 3 is a diagram of a hydraulic or fluid pressure system for the apparatus of Fig. 1';

Fig. 4' is a front view of a machine embodying a preferred form of the invention;

Fig. 5 is an elevation, taken from the right 1 of Fig. 4, of a turnover mechanism and supporting structure.

Fig. 6 is a plan of the mechanism of Fig. 5;

Fig. 7 is a side view of the front end of the machine taken from the. right of Fig. 4;.

Fig. 8 is a side view, taken from the left of Fig. 4 of the front end of the machine of Fig. i;

Fig. 9- is a plan view of a transfer machine, partly broken away to show locatingandclamping mechanisms at the sides;

Fig. 10 is a horizontal section taken at the lever of a supporting bar of a transfer machinehaving, locator pins at the bottom and showing. details of the transfer bar' and actuating mechanisms;

Fig. 11 is a front view of a part of a transfer mechanism of modified form;

Fig. 12 is a side view of a machine showing the actuating mechanisms for the locators of Fig. 10;

Fig. 13 is a plan view of a transfer bar, and Fig. 14 a side view of the bar and of fluid pressure actuating means therefor;

Fig. 15 is a view similar tothat of Fig. 14 of a modified form of transfer bar and actuating mechanism;

Fig. 16 is a plan view of a part of the modifica tion of the transfer bar shown in Fig. 15, and Fig. 1.7 a side view of a modification of transfer bar and fluid pressure actuating means;

Fig. 18 is a front View, partly in section, showing parts of a limit switch operating mechanism;

Fig. 19 is a side view of a part of the. machine illustrated and a form of limit switch mechanism actuated by the transfer bar;

Fig. 20' is a side view of another form of embodiment of the. transfer machine;

Fig. 21 is a front elevation, and Fig. 22 a rear elevation of the machine shown in Fig. 29;

4 Fig. 23 is a side view of a part of a transfer bar and carrier plate for the embodiment of Fig. 20, and Fig. 24 is a diagrammatic plan view showing an arrangement of a train of transfer machines and machining units embodying the invention.

Transfer and timing mechanism In the machine of Fig. I a work piece 25 is placed on a turnover or turn down element 26. The work pieces are illustrated as rectangular blocks but may be of any suitable shape, such as cylinder blocks, gear cases, or other shapes, to bemachined, drilled, etc.

The turnover element has supporting frames 2-? and 2-8 fixed at right angles to each other on a horizontal rock shaft 29 to rotate from the position shown in broken lines to that shown in full lines.

When the work piece is placed on the frame 2'1, in the position shown in broken lines, it opcrates. a control switch 3% whereupon, through the control system illustrated in Fig; 2, an electromagnet 3! is energized to admit fluid through a valve 32 and connecting pipe 33 to one end of a. cylinder and. piston 34 which thereupon act through an arm or other transmission element 35 and rotate the turnover element to upright position, shown in full lines.

The turnover element has a pair of rails 36 and 31 which, in upright or raised position of the element, are in alignment with supporting rails 38 and 39 of the machine. When in this position the work piece actuates a switch 49 which causes a propelling agent to move to a position to engage the work piece for movement on the rails 38 and 39 forwardlyto the station indicated at 4i and then successively to the stations indicated at 42 and 43. This propelling member may be of any suitable mechanism for moving the work piece forwardly at successive intervals.

In the diagrammatic embodiment shown in Fig. 1 the propelling member is a slid-ing transfer bar 44 having pins or latches 4-5, one for each station, including the turn over element, which lower or are depressed to pass beneath the work pieces when the transfer bar moves in reverse direction and then rise to engage the work pieces when the transfer bar moves forwardly and thereby carry them forwardly to the next station.

The transfer barmay be reciprocated forwardly and in reverse by any suitable mechanism. In the embodiment of Fig. 1 it is secured directly to a ram or cylinder 46 slidable on a piston rod 41' and actuated by pressure fluid admitted from a valve 48 through a pipe '19 to move the transfer bar in reverse to starting position and, alternatively, through a pipe 5!! to move it forwardly to the next station. Admission of fluid through the valve 48 to the pipes 49 and 5B is controlled by electromagnets 5i and 52 respectively. When switch 4!! is closed electromagnet E! is energized, fluid is admitted to pipe 49 and the cylinder 56 and transfer bar 44 moves in reverse to starting position. The latches thereupon rise to a position to engage the work pieces at 25, 6|, l2 and 43. Upon admission of fluid through the pipe 50, and release of fluid from pipe 49, as the electromagnet 56 is de-energized and electromagnet 52 is energized, the cylinder and transfer bar move forwardly.

During the reverse movement of the transfer bar work pieces at stations 4! t2 and 6-3 are held in their stations by clamps and locators. These, and the tools of the machine units must be withdrawn before the transfer bar moves forwardly so as to permit the work pieces to advance Without interference. The clamps, indicated at 53, 54 and 55 for the work pieces 4 I, 42 and 43 respectively, are actuated by pressure fluid admitted through a valve 56 to a pipe 51 leading to the upper ends of cylinders 58, 59 and 60 to move the clamps to clamping position or, alternatively, to exhaust fluid through pipe 5'! and admit it through pipe 6! to the lower or opposite end of the cylinder to raise or withdraw the clamp. Admission of pressure fluid to pipe BI is controlled by a limit switch 62 actuated by the transfer mechanism, as it reaches the limit of its reverse movement, to energize an electromagnet 63 of the valve 56 for the admission of fluid to pipe 6|. The clamps thereupon rise or are withdrawn.

As each clamp rises it actuates a limit switch 64. These limit switches are in series and serve to energize an electromagnet 65 of a fluid pressure valve 63 to admit pressure fluid through a pipe 6'! and branch pipes 68, 69 and Hi to one end of a fluid actuated cylinder and piston H for withdrawing the locators.

The locators comprise elements which move transversely of the path of the work pieces in position to locate the work pieces accurately at their respective stations and in precise spacial relation to the machining units. They may be of any suitable form to engage complementary surfaces of the work pieces and, in case a work piece should not be precisely placed by the transfer bar, to shift it to its proper place.

In the embodiment illustrated in Fig. l and in Figs. 4 and '7, the locators comprise pins 12 and i3 slidable in guides or bushings in the frame of the machine and tapered or pointed at the ends projecting toward the work piece to enter corresponding openings in the work piece, or in a plate or member secured thereon, even though the openings be not exactly centered relative to the pins. As the pins move forward into the openings, which they fit closely, the work pieces are brought to precise position. Two locator pins are shown, by way of example, in the accompanying drawings. They may be placed in any convenient position, at the side or bottom of the station as conditions may require.

The several locator pins of each station are secured to and actuated by crank arms I4 and I5 fixed on a rock shaft "is jcurnaled in the frame of the machine and, in turn, rocked by a crank arm 71 and a link 18 connected to the piston of the cylinder H. When fluid is admitted to the cylinder through the pipe 68 the shaft 16 is rotated to withdraw the pins. The work pieces are thereby released to move to the next station and be replaced by a succeeding piece. The drills or other tools of the machining units will also have been withdrawn from the path of the work pieces.

As the rock shaft 15 rotates to withdraw the pins it actuates a control switch to energize the electric control system for advancing the transfer bar 44. This switch may be a double acting switch or one of a pair of switches. In the diagrammatic sketch of Fig. 1 it is a switch 19 actuated by an arm 8i] projecting from the shaft 16. As the switches of the several locators, in series, close they energize the electromagnet 52 0f the valve 48 to admit fluid through pipe 50 to the transfer bar cylinder 46 and exhaust fluid through pipe 49 causing the cylinder and bar to move forwardly provided the receiving station of 6 the next machine BI is free, releasing the contact switch 82.

As the transfer bar reaches the end of its forward movement it trips a limit switch 83. This switch controls a number of electromagnets, one of which is a magnet 84 on the valve 3| to admit fluid through pipe 85 to the cylinder 34 and exhaust it through the pipe 33 thereby swinging or lowering the turnover element to receiving or lowered position. When in lowered position the turnover element trips a limit switch 85 which prevents the transfer bar from moving in reverse until the turnover element is raised.

The limit switch 86 also controls an electromagnet 87 on the locator valve 65 to admit fluid through a pipe 88 and branch pipes 33 to the ends of the cylinders H causing the rock shafts 16 to rotate in a direction to move the locator pins 12 into locating position, fluid being exhausted through the opposite branch pipes 38, pipe 61 and valve 66 to exhaust. In the event that the movement of any of the locator pins should be obstructed, as for example by a work piece being too far from its proper position for the pin to enter the openings, further operation of the machine, and accordingly of all similar machines in series with it, would be blocked. This condition would be indicated by the position of the locator pins or by a suitable signal and could then be readily corrected byshifting the work piece.

Normally the locator pins move in, the rock shaft rotating under the force of the pressure fluid. An arm 9!] on the rock shaft is thereby swung to trip a switch 91 which controls the clamping of the work piece. As the switch 9| is tripped, it energizes an electromagnet 92 which actuates the valve to admit fluid through pipe 57 to the upper ends of the cylinders 58, 59 and 60 and exhaust it through pipes S i. The clamps are thereby forced downwardly into contact with the work pieces at their respective stations. With this arrangement of the locators and clamps the work pieces are accurately positioned before being clamped and are then secured by the clamps for the machining units.

The movement of the clamping mechanism to clamping position serves to energize and start the forward feed of the machining units, such as drills, boring rods, etc. For this purpose a limit .switch 93, one for each clamping mechanism, is

mounted in position to be tripped by the clamping mechanism as it reaches clamping position. The tripping of the switch 93 energizes an electromagnet 94 of a valve 95 controlling the feed of the respective machine unit to advance the drills or other tools.

When each machine unit reaches the limit of its advance movement or completes its machining operation it trips a limit switch 35 on the respective unit which thereupon actuates an electromagnet 91 on the valve $5 to reverse the feed. The switches 93 and 96 may also serve to start and stop a tool rotating motor, a timer being preferably provided in connection with the switch 98 to delay the stopping of the motor during the capabl of co-operation with other machines.

placed to receive work pieces from it or deliver them to it, depending on their position in a series or train of machines. For this purpose the machines in such a series are interconnected as by the switch 82 so that none may operate until the receiving, or initial station of the next is clear or unoccupied and until its receiving or starting station is occupied by a work piece. For example, the machine described above cannot begin its cycle of steps until the starting station of the next machine 8i is clear and until a work piece is placed on the turnover element. In case the work piece moves from one machine to the next without turning, a turnover element is not required for the succeeding machine, nor is it required for the initial machine when the work piece is supplied in upright position. The end machine of the series may be fitted to a take off platform with or without a control switch similar to 82.

As each machine is independently operated any number of them may be arranged in series, it being necessary only that the supporting rails of one be sufficiently aligned with those of the preceding machine to enable a work piece to slide from one to the next.

The various control switches and valve electromagnets of each machine may be arranged in a suitable wiring arrangement independently of adjacent machines except for connection to the switch 82 of the next machine. A simplified wirin diagram for this purpose is illustrated by way of example in Fig. 2. Where two or more circuits are controlled by a single switch, they are shown separated in this diagram but indicated by the same reference numeral to avoid, as much as possible, the crossing of lead wires and complexity that might result therefrom. In practice they may be connected mechanically or by relays as convenience may make desirable.

Wiring system In the diagram of Fig. 2, electric current is supplied from a supply main 99 through a switch I88 either to a lead wire or main Iiil of a manual control system or, as shown, to a main I02 of the automatic control system. From the latter main, current is supplied to a line I03. This line comprises the back limit switches 98 of the machine units, only one being shown in the diaram, which are closed when the units are in full reverse position. In series with the switch 98 is a latched relay switch I04, which may be opened to stop the system but which, in normal operation is closed, and the locator switch QI- which is closed at the start of the cycle. Next in sequence are the clamp limit switch 93, the transfer limit switch 83, and the turn over limit switch 85 all of which are also closed at the start of the cycle. Next in the series of switches is the transfer limit switch 62 which is closed when the transfer mechanism is forward, as at the start of the cycle and the limit switch 82 on the next machine 8! which is closed when the receivin station of this machine is unoccupied and therefore ready to receive a work piece. Followin in the series is the load switch 30, which is closed when the turn over element is loaded and a stop realy I85 which is closed when the machine is operating. When the elements of the machine are in starting position, the starting station of the next machine empty and the starting station, the turn over element, is loaded, all of the switches are closed and the circuit closed through the electromagnet 32 to a return main I06. The valve BI,

therefore, supplies fluid to raise the turn over element, closing switch 40 and releasing limit switch 30.

A branch circuit It! leading from the line I03 in advance of switch 86 is then closed through a normally closed push button switch I98, a branch 8% of switch 86, which is closed when switch 86 is open, and the switch es, which is closed as the turn over element is raised, to the electromagnet 5i and main I95. Valve 48 is thereupon operated to admit fluid through pipe 49 to move the transfer bar M in reverse. As the transfer bar M reaches the limit of its reverse movement it trips limit switch 62.

As limit switch 62 is closed it closes a circuit from the line I63 immediately beyond switch 9-3 through a branch circuit its and electromagnet 63 to main I I15. The valve 56 is then operated to supply fluid through pipe 65 to cylinders 58, 59, SE? to withdraw the clamps 53, 54 and 55. As the clamps are withdrawn they trip switches 54.

As switches fi l, only one being indicated in the diagram, are tripped they close a circuit from line I E93, immediately beyond switch QI, through a branch circuit H0, and normally closed push button HI to electromagnet E5 and then to return main 56. As electromagnet $5 is energized it operates valve 35 to supply fluid to the pipes 6'! and 58 to withdraw the locators which thereupon trip switch I9.

As switch 79 is tripped it closes a circuit from line #53 through branch circuit I I2, push button switch 5 I3, branch relay switch 86 of switch 86, which is closed when switch es is open and is therefore closed at this period, to the switch 82 of the load station of the next machine at I. When this station is empty switch 82 is closed, closing the circuit through electromagnet 52 to main I85. Valve 48 is thereupon operated to supply fluid through pipe 5'6 to move the transfer mechanism forward and trip limit switch 53.

As switch 533 is closed a branch circuit I I4 is closed from the line W3 through the switch branches 62 and d0, which are closed in this branch circuit when they are not tripped, and thence through the electromagnet 84 of valve 3| to the return we. The electromagnet 84 is thereupon energized to admit fluid through the pipe l9 to the cylinder 3-!- and exhaust it through pipe 33. The turn over element then lowers to receiving position, tripping the switch 86 This breaks the circuit through branch circuit ID! to the magnet 5i of valve as and prevents the reverse movement of the transfer bar 44.

From the branch circuit H4 beyond the switches 83, s2 and 4? is an extension H5, in parallel, through a push button I I6, and switches 56, in series only one being shown, which are closed when the clamps are raised or withdrawn to the magnet 87 of valve 66. When the magnet 8'! is energized fluid is admitted through pipe 88 and branches 39, Fig. l, and exhausted through pipe $1 to move the locators into locating position.

As the locators move in they trip switches 9|, one being shown in Fig. 2. Thereupon a circuit is closed from branch I I4 through a side branch II'I through branch switches 86 and 9i, and also switches $3 which are closed when the clamps are out of clamping position, to the electromagnet 92 of valve 58. From the electromagnet 92 the circuit passes to return main I66. Upon energizing the magnet 92 the valve 56 supplies pressure fluid through pipes 57 to upper ends of cylinders 58, 59 and $9 and exhausts it through-

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