US2259576A - Press with dual sliding table - Google Patents

Description

Oct. 21,1941. H. F. MacMlLLlN 2,259,576

PRESS `AND DUAL sLIDING TABLE Filed July 2l, 1937 6 Sheets-Sheet l FHS. 1.

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Oct. 21, 1941. H. F. MacMlLLlN 2,259,576

PRESS AND DUAL SLIDING TABLE Filed July 21, 1937 6 'sheets-sheet 2 Tmc/nm HOWARD EMACM/ LLl/V,

Oct. 21, 1941. H. F. MacMlLLIN PRESS AND DUAL SLIDING TABLE Filed July 2l, 1937 DEE.

6 Sheets-Sheet` 3 .JWM/M1 HOWARD f. Mac MILL/N,

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Oct. 2l, 1941. H. F. MacMlLLIN 2,259,576

PRESS ANDl DUAL SL'IDINCT TABLE Filed July 21, 1937 y 6 shefmwrshen'4` u; In Tn/veuve HOWARD F. MMM/LUN,

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Oct. 21, 1941. H, MacimLLnv` PRESS AND DUAL SLIDING TBLE Filed July 21, 1937 6 Sheets-Sheet 5 SNN HOWARD EMAcM/LLIN,

@MAQ-iw# Oct. 21, 1941. H. F. MacMlLLlN PRESS AND DUAL SLIDING TABLE Filed July 2l, 1957 6 Sheets-Sheet 6 IN. S

A Patented Oct. 21, 1941 mess wrrn D UAL sLmmG TABLE Howard F. AMacMillin, Mount Gilead, Ohio, as

signor to The Hydraulic Press Corp., Inc., Wilmington, Del., a corporation of Delaware Application July 21, 1937, serial No. 154,854

c claims. (ci. o- 11) This invention relates to presses, and in particular, to hydraulic presses including arrangements having movable dies which can be moved into and out of pressing position. y

OneA object of this invention is to provide a press having two or more tables or work-holders, arranged to move in and out of the press alternately so that a pressing operation may be performed on one table or portion o1?l a table while another table or portion of a table is out of the press for the purpose of loading or unloading.

Another object is to provide a press having a V'pair of relatively movable work table units, each unit having at least two work-holding locations, the two units being movable alternately into and out of the press so that one pair of Work-holding locations is in pressing position while the other pair of'work-holding locations is outside the press so that workpieces may be unloaded from or loaded ontothe work-holding locations.

Another object is to provide a press having dual movable tables as described above, wherein. the means for moving the tables is synchronized with the means for moving the press platen or plunger so that the tables are moved only when the press platen is out of its pressing position.

Another object is to provide a press having relatively movable tables, as described above, wherein an electrical control system controls the actionof the main plunger and also controls the action of auxiliary plungersfor moving the work tables in and out. l

Another object is to provide a press having a plurality of relatively movable work tables with hydraulic plungers for moving the work tables into and out of pressing position, together with anA electrical control systemsynchronizing the moving of the tables with the moving of the main plunger or platen so that the Work tables are. moved into or out of pressing position only when tions beneath the press platen. A

Another object is to provide such a control sysplunger is synchronized with the operation of the hydraulic motors for shifting the work tables in such a. manner that the press may .be operated manually by controlling the valves by hand, or C semi-automatically,l wherein the press executes a complete working and return stroke and then comes to a halt, or fully automatically, wherein the press executes an indenite number of working and returnstrokesbefore it is halted by the operator. Y

Another object is to provide an apparatus for rforming articles between forms, wherein the unpressed article is placed in a form in position for pressing and-is pressed while another'unpressed workpiece is placed in` an adjacent form, after which the pressed workpiece is moved out of pressing position while the second unpressed workpiece is moved into pressing position, preferably in response to the cessation of the pressing.

In the drawings: A Figure 1 is a front elevation of one embodiment of the press of this invention.

Figure 2 is a side elevation of the press shown A the work tables and its associated hydraulic motor, taken along the line 4--4 in Figure. 5, and showing the piston cushioning arrangement according to the invention.

Figure 5 is a front elevation of the structure shown in Figure 4.

. Figure 6 is a diagrammatic view showing the positions of the Work tables and the limitl switches when the tables are in one pressing position. l

Figure 7 is a view, similar to Figure 6, but

showing the tables in their opposite or shifted hydraulic circuit for actuating the main or press- 4 tem, wherein the operation of the main pressing positions.

Figure 8 is a diagrammatic view showing the ing plunger.

Figure 9 is a diagrammatic view showing the hydraulic circuit for actuating the table-moving A cylinders.

Figure 10 is an electrical wiring diagram, showing the connections of the various electrical apparatus for controlling the motions ofgthe press and work table motors.

Figure 11 is a simplied wiring diagram of the circuit shown in Figure 10.

, General arrangement i of tables which are movable into and` out of the pressing position, in such a manner that at least one table is beneath the pressing platen when its associated table is outside of the press for loading or unloading purposes. The embodiment shown in the drawings includes a pair of slides having places for two dies on each slide, the two slides lbeing moved by double-acting hydraulic motors controlled bya valve through cross connections in such 'a manner that one of the tables is moved in one direction while the other table is moved in the opposite direction. An electrical control system is provided for shifting the valve so as to control the movement of the tables, and also to synchronize the movement of the tables with the motion of the pressing plunger. With the control circuit of this invention, the pressing plunger cannot complete a pressing stroke until one set of dies is in positionunder the platen and the other set of dies is completely outside the press. The slides or tables are moved by hydraulic motors having a special cushioning arrangement for cushioning the pistons at the opposite ends of their strokes.

Press construction Referring to the drawings in detail, Figure 1 shows a front elevation of a press having a bed or base member i with side members. II rising therefrom, and a top member I2 thereover, the whole being interconnected by strain rods I3 and nuts |4 threaded upon the ends thereof. Mounted upon the top member |2 is asurge tank I5 having means for storing the oil or other working fluid used in the press. The top member I2 also contains a main cylinder I6 (Figure 8) having a main plunger I1 therein and ports I8 and I9 communicating by .conduits 20 and 2| with a control valve 22.

The control valve 22 shown in Figure 3 is of a conventional four-way type well known to those skilled in the art, and includes a casing 23 hav.-

ing a bore 24 with end chambers 25 and 26', a middle chamber 21 and intermediate chambers 28 and 29. 'I'he end chambers 25 and 26 'are interconnected by a passageway 30 having a port valve bore 24 is a valve member 39, having spaced.

heads 40 and 4| thereon. A spring 42 urges the valve member 39 in one direction, whereas a solenoid 43, connected thereto by the links and levers described below, when energized, urges it in the opposite directions The spring 42 is retained in position by a hollow cap 22a secured to the casing 23. The spring 42 is engaged by a collar 44, secured to the valve member 39.

The conduit 32 leads from the passageway 30 and port 3| to the iiuid tank I5.I The conduit 34, however, leads to the main pump 46, from which the suction line 41 leads to the tank I5.. A relief valve 48 is installed in the pressure line 34 from the pump 46, and has an outlet line 49 connected to the exhaust line 32. The solenoid 43 is ,connected tolthe valve member 39 by means of a train of links and levers, including the link 50 interconnecting the solenoid armature 5| with one end of thelever 52. The latter is pivoted 2,259,576 vof a pressing platen associated with a plurality on the shaft 53 which carries an arm 5,4 having a link 55 connecting it to the arm 56 on the shaft 51, the latter also carrying an arm 58 having the link 59 connecting it to the valve rod 39. The other end of the lever 52 is provided with a yoke portion 60, engaged by a collar 6| upon the control rqd 62 of the press (Figure 2). The control rod 62 is mounted for vertical sliding movement in the projections 63 and 64 on .the top 'and bottom members I2 and I0, respectively. 'Ihe lower end of the control rod 62 carries a collar 65, engaged by a yoke 66 upon the end of an arm 61 pivotally mounted upon the shaft 68 and having an operating handle 69 secured thereto for manuallyoperating the valve 22.

Connected to the main plunger I1 is a platen 10 having a plurality of dies 1I and 12, arranged side-by-side and cooperating with mating dies 13 and 14 upon sliding tables 15 and 16. Extending downwardly from each end of each of the tables 15 and 16 is an end member 11 having an aperture '18, through which passes the threaded end 19 of an auxiliary piston rod 80 and secured in position by the nuts 8| and 82 thereon. 'I'he tables 15 and 16 and the table supports 83 and 84 are provided with cooperating guiding ridges and grooves 85 and 86, respectively. The grooves 86 adjoin wear plates 81, secured to the tables 15 and 16 (Figure 4). The table supports 83 and 64 .I

are provided with cylinder bores 88 having outlet ports 89 and 90 and end members 9| with'packings 92 compressed by glands 93. The piston rod 80 is provided with adjustable collars 94 and 95, secured thereto by the set screws 96. The Apiston rod 80 is also provided with a piston head 91 reciprocable within the bore 98 of a sleeve 99, having end closures |00 with restricted fluid ports I0| therein. This construction provides a cushioning action of the piston head 91 as it nears the opposite ends of its stroke. Under these conditions, one of the end closures |00 collides with one of the end members 9|. The piston head 91,

however, continues to move at a reduced rate,

controlled by the rapidity of escape of the uid through the ports IOI. ' I'he table supportsk 83 and 84 are mounted upon the bed I0 of the press. Pressure gauges |02 and |03 are provided on the top member I2 for indicating the pressures obtained in the hydraulic circuits.

The hydraulic circuit for actuating the piston rods 80 and tables 15 and 16 (Figure 9) consists of the cylinders 88. Connected to these tables are the four-way valve |04, similar inconstruction and operation to the four-way valve 22 already described, the relief valve |05, which is likewise similar to the relief valve 46, and the pump |06 for supplying pressure uidl to the cylinders 88. The cylinders 88 for the tables 15 and 16 are cross-connected with the four-way valve |04 in'such amanner that when the pressure iiuid is supplied to one end of one cylinder it is simultaneously supplied to the opposite end of the other cylinder, thereby causing the piston rods 80 to travel simultaneously in opposite directions.

To this end the conduit I 01 runs from the port 90, at the rearward end ofthe left-hand cylinder 88to the four-way valve |04, and a branch line |08 therefrom runs to the forward port 89 of the right-hand hydraulic cylinder 88. Similarly,-

' a line |09 runs-from the forward port89 of the line containing the relief valve |05, runsjto the pump |06, and beyond this the suction line ||2 runs to the surge tank I5. From the fourway valve |04 the discharge lineI I I3 likewise runs to the surge tank I5, and is joined by the dis` charge line ||4 from the relief valve |05.

f The valve member ||5 of the four-way valve |04 is urged in one direction by the coil spring IIB having the collar ||1 secured thereto, and in the opposite direction by the solenoid ||3 when the latter is energized. 'Ihe four-way valve |04 is operated from the amature IIS of the solenoid ||8 (Figure 2) by a 'link |20 connected to one' arm of .the bell-crank |2|, the opposite arm of which is connected tothe valve member ||5.

inwseries, the press cannot be operated electrically until both operators of the press depresstheir respective switches.

When the press is ready to be started, one operator adjusts the selector switches |32 and |33 according to the type of operation desired. If the selector switch |32 is set at the hand position, all control circuits are deenergized so The platen 10 is provided with a projecting por tain switches for controlling the press. A second switch box |26 is mounted upon the rearward side of the press. An indicating light I2 vburns when the circuit is energized.

Electrical circuit The electrical circuit (Figures 10 and 1-1) includes a three-point forward push button switch |28, a two-point' forward push button switch |29', a pair of foot-operated emergency reverse switches |30 and |3|, a two-way hand selector switch |32 and a two-way automatic selector switch |33; also four limit switches |4|, |42, |43 and |44 mounted upon the front and rear of the press bed l0 and actuated by the tables 15 and 1 16 when these reach their opposite extreme p0- sitions (Figures 6, '1 and 10). A fifth limit switch |45 is operated by the collar |24 when the projection or platenlarm |22'r ses the collar |23 and control rod 62 at the end of the return .stroke of the platen 10. A normallyopen pressure switch I 46 is closed when the fluid within vits cylinder |41 reaches 4a predetermined value. This pressure switch cylinder |41 is connectedv to the main cylinder I6 and operated when the pressure within the main cylinder i6 reaches the amount forA which the pressure switch |46 is set.

The electrical circuit alsocontains a two-blade control relay |5I, both of its blades being normally open, a single-blade control relay |52 with a normally open blade, and a two-blade control relay |53, the left-hand blade being normally closed and the right-hand blade normally open.

A single-blade ratchet relay |54 of a conventional type having a normally open blade cooperates with these relays to control the energization of the normally open contacter switches |55 and |56.4 A resistance |51 is included in the circuit of the indicating light (Figure ll) Operation For convenience, let it be assumed that the tables-15 and 16 are each provided with a pair of work locations, respectively designated |58 and |59, |60 and |6| (Figures 6 and 7). If the press is arranged for embossing, this construction enables one pair of workplaces to be pressed Vwhile that the electrical system is completely 'out of operation. Under these conditions the press can be operated, solely by the hand lever 69. The' lelectrical system permits'the press to be operated automatically, infa semi-automatic or a fullautomatic manner. In semi-automatic operation the press platen descends, performs a pressing stroke, returns to its starting positionand halts. It is then necessary for the operator to operate the Aforward switch in order to perform another pressing operation; In full automatic operation, however, the Apress platen performs an indennite number of pressing and return-strokes witho ut halting, until the press is stopped by the operator, such as by depressing one of the footl switches |30 or |3L,"or by throwing the usual line/Switch; u For full automatic operation the operator sets ,the upper selector switch |32 to`fthe automatic position, and the lower selector switch |33 to the full automatic position. Both operators then depress the forwardswitches |28 and |29. The coil ofctlie control relay |5| is then energized from the power line |62 by way of the hand-autou maticfselector 'switch |32, the reverse switches |3| and |30, the forward push button switches |29 vand |28, the control relay coil 5| and the power line |63; When the push buttons |28 and |29 are' released, thecoil of the control relay |5| is heldin an energized, position by a holding circuit bridging these switches through the now closed left-hand switch blade 'of the relay |5|.

With the closingbof .the right-hand switch blade of the control relay |5| thezcontactor switch |55 becomes energized from the power line |62 by way of the now closed right-hand switch blade of the'control relay |5|, the normally'open but now closed limit switches |4| and |44, which are now closed by their respective tables, the full automatic pole of the selector switch |33, the coil of the contactor switch |55, the left-hand `normally closed switch blade 'of the control relay |53 to the. power line "|63, When the blades of the contacter switch |55 close, upon the energization thereof,- the winding of the solenoid 43 is energized from the power lines |62 and |63. This shifts the valve member 39 of the four-way valve-22, causing pressure iiuid to pass from the pressure line 34tothe line4 20, and permitting fluid to be withdrawn through the lines 2| and 32. When thusA supplied with pressure uid the main plunger |1 and platen 1I) start\downward and perform a pressing stroke. When the pressure rises to apredetermined value the pressure fluid within the main cylinder circuit closes the normally open pressure switch |41. This action energizes the coilof the control relay |53 from the power line |62 by way of the pressure switchA |46, the coil of the control relay |53 to the power line |63.

As the control relay |53 closes, it opens its left-handblade and closes its right-hand blade.

A subsequent drop of pressure in the main cylinder circuit, however, while releasing the pressure switch |46 so that it' assumes its normally open position, does not disturb the 'energizatioh of the coiLof the control relay |53 because this is held energized by a holding circuit bridging the pressure switch |46 through the right-hand switch blade, and through the contacts of the normally open but now-closed table limit switches |4| and |44. The energization of the control relay |53 opens its left-hand switch blade and thereby'deenergizes the coil of the contactor switch |55, deenergizing the solenoid 43 and permitting the spring 42 to shift the four-way valve 22 and cause Pressure fluid to be admitted to the line 2|, while permitting the line 20 to become a discharge line connected to the line 32. The main plunger |1 accordingly reverses and starts to move upward on its return stroke.

As the main plunger reaches the top of its return stroke the platen arm |22 lifts the collar I 23 and control rod 62, thereby causing the collar |24 to close the normally open limit switch |45. This action energizes the coil ofthe ratchet relay |54, which energizes or deenergizes the coil of the contactor switch |56, depending upon the position of the ratchet contact of the relay. The energization of the contactor switch |56 causes its normally open blades -to close, thereby energizing the solenoid I I8 and shifting the four-way valve |04. Accordingly, pressure uid is admitted oppositely to the cylinders operating thetables 'l5 and 16 so that these tables move simul-- taneously in` opposite directions. The blanks which the operators have placed upon the exposed work locations thus move into the press, and the other two locations move out with the finished workpieces. The operators remove the flnished workpieces and replace them with other blanks. u

'Ihe shifting of the tables 'l5 and I6 to their opposite positions" releases and opens the table limit switches |4| and |44, and atthe same time engages and closes the limit switches |42 and |43. While the tables are shifting, however, the coil of the control relay |53 becomes deenergized when the previously described holding circuit is broken, thereby closing its normally closed left-hand switch blade and placing the circuit of the coil of the contactor switch |55 4in readiness for reenergization. This reenergization occurs as soon as the limit switches |42 and |43 close through the same circuit as previously described in connection with limit switches |4| and |44. The tables 15 and-16 are now in their reverse positions, and the solenoid 43 is again energized, shifting the control valve` 22 and causing the main plunger |1 and platen 1|| to start downward, executing another forward stroke. In this manner the press executes an indefinite number of working4 strokes, and the tables 15 and 16 shift their positions automatically between pressing strokes. The repeatedcycles of operations continue until the press is halted by the operator, either by depressing the emergency reverse switch |30 or |3|, or by throwing the usual line switch.l

For semi-automatic operation the operator leaves the selector switch |32 at the automatic position, but shifts the selector switch |33 to the semi-automatic position. 'I'he forward push button switches |28 and |29 are now depressed by the operators, thereby reenergizing the coil of the control relay |I, in the manner previously described. 'I'he coil of the control relay |52 is also energized by a circuit completed at the middle contact -of the three-point forward push button switch |28, it being in parallel with the coil of the contactor switch |5| under these conditions. As the control relay |52 has but a single blade, however, it lacks a holding circuit, hence, is immediately deenergized by the opening of any of the push button switches. 'I'he coil of the contactor switch |55 is ,n'ow energized from the power line |62, through the normally open but now in energization by a holding circuit through the left-hand switch blade thereof bridging the normally open contacts of the control relay |52, so -that the energization of the solenoid 43 continues even when the control relay |52 is deenerport.

When the main plunger l1 performs its pressing stroke, the pressurewithin the hydraulic circuit closes the normally open pressure switch |46, thereby energizing the coil of the control relay |53, as before, this energization being 4held` through a holding circuit including the righthand switch blade of the control relay |53. The opening of the normally closed left-hand switch blade thereof deenergizes the .contactor switch |55 and consequently deenergizes the solenoid 43.

The spring 42 then shifts the valve member 39,

reversing the flow of fluid to the main cylinder I6, thereby reversing the travel of the main plunger |1 and causing a return stroke to occur, as before. As the main plunger |1 reaches the top of its return stroke; the platen arm |22 again lifts the control rod 62 and closes the normally open limit switch |45, as before, thereby reenergizing the coil of the ratchet relay |54 and again energizing or deenergizing the contactor switch |56 and solenoid ||8, depending upon the positions of the ratchet relay contacts.

The tables 'I5 and 'I6 again shift their positions, releasing the limit switches |4| and |44 and engaging the limit switches |42 and |43. The consequent opening of the normally open limit switches |4| and |44 again deenergizes the coil of the control relay |53, but the energization of the coil of the contactor switch |55 is not now completed because the deenergization of the control relay |52 has now broken the circuit. The platen arm |22, therefore, moves the control valve 22 into its neutral position, by-passing the discharge of the pump 46 and causing the platen 10 to halt at the top of its return stroke.

It will be understood that I desire to comprehend within my invention such modifications as.

1. In a work-holding device for presses, a supi' port, a plurality of work-holder pairs movably mounted on said support, a hydraulic motor operatively connected to each work-holder pair, a-

source of pressure fluid, hydraulic connections for connecting said source to said motors, and

means for distributing said pressure fluid to said motors and said work-holder pairs so as to cause said motors to move simultaneously in opposite directions.

2. In a work-holding device for presses, a supa plurality of work-holders movably mounted on said support, a hydraulic motor operatively connected to each work-holder, conduits interconnecting one end of one motor with the opposite end of the other motor, a source of pressure fluid connected to said conduits, and means for regulating the ow of fluid from said source to said conduits.

3. In a press, a pressing platen, means for moving said platen, a support, a plurality of Workholder pairs arranged in a single horizontal plane, the work-holders of each pair being positively interconnected and in alignment with each other, and each pair having a hydraulic motor associated therewith, means hydraulically interconnecting said motors for electing synchronous movement thereof in opposite directions, and means responsive to the arrival of said workholders at predetermined positions for initiating the action of said platen-moving means.

4. In a press, a pressing platen, a motor therefor, a support, a plurality of work-holders arranged in a single horizontal plane and movably mounted on said support, hydraulic means operatively interconnecting said work-holders for effecting simultaneous movement thereof in opposite directions so as to bring two work-holders into pressing position while at the same time bringing two other work-holders into unloading position, and means responsive to the arrival of said platen at a predetermined position for actuating said work-holder-moving means to move said work-holders into position for pressing by 4said platen.

v 5. In a press, a pressing platen, a motor therefor, a support, a plurality of work-holder pairs arranged in a single horizontal plane and movably mounted on said support, hydraulically operable plungers respectively connected with said work-holder pairs and hydraulically interconnected for moving said work-holder pairs simul- 'taneously in opposite directions so as to bring land the same plane, the work-holders of each pair being positively connected with each other, two double-acting fluid operable plungers operatively connected with said pairs respectively, conduit means interconnecting one side of one plunger with the opposite side of the other plunger, a fluid source adapted to supply pressure fluid to said conduit for actuating said plungers so as to move their respective workholder pairs simultaneously and in opposite directions, and means for regulating the flow of fluid from said source to said conduit.

HOWARD F. MACMILLIN.

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