US2504089A - Double-action toggle press - Google Patents

Description

April 1950 F. J. RODE ET AL 2,504,089

-DOUBLE ACTION TOGGLE PRESS 4 Sheets-Sheet 1 Filed Sept. 12, 1946 April '11, 1950 F. J. RODE ET AL 2,504,089

DOUBLE ACT ION TOGGLE PRESS Ffiled Sept. 12, 1946 4 Sheets-Sheet 2 April 11, 1950 F. J. RODE TAL DOUBLE ACTION TOGGLE PRESS Filed Sept. 12, 1946 Nil 4- Sheets-Sheet 5 y M, m, me W w April 11, 1950 F. J. RODE ET AL 2,504,039

DOUBLE ACTION TOGGLE PRESS Filed Sept. 12, 1946 4 Sheets-Sheet 4 Patented Apr. 11, 1950 DOUBLE-ACTION TOGGLE PRESS Fredrich J. Rode and Meredith R. Hatch, Toledo, Ohio, assignors to The Verson Corporation, Toledo, Ohio, a corporation of Delaware Application September 12, 1946, Serial No. 696,390

1 Claim.

The present invention relates to metal blanking and drawing presses and more particularly to a double action mechanical press of the toggle type.

One of the objects of the present invention is to provide a novel double action toggle press so arranged that the workcan more easily be removed from the dies.

Another object is to provide an improved double action toggle press which requires less head room than do presses of conventional type.

Still another object of the present invention is to provide an improved press of the above type in which the major portion of the operating mechanism is arranged in a pit below the bed and in which the driving mechanism is linked to mechanism in the crown for operating a slide by links in such manner that substantially all of the load during the drawing operation is taken by the press tie rod-s rather than by the links.

Yet another object is to provide a novel double action press in which the drawing stroke can be considerably more than half of the blank holder stroke by so arranging the elements that the drawing slide does not have to move the distance of the blank holder stroke before coming in contact with the work. The arrangement of the present invention, therefore, increases the speed and productive capacity of the press.

Yet another object of the present invention is to provide a novel and improved press of the above type from which heavy drawn articles, such as automobile fenders and the like, may be slid directly from the dies without the necessity for raisingv them so as to clear the lower die elements.

An additional object is to provide an improved double action toggle press so arranged that the principal operating mechanism is in the bed or below the bed of the press and in which the blank holder slide moves downwardly into blank holding position while the drawing slide moves upwardly.

Other objects and advantages will become apparent from the following description of a preferred embodiment of our invention which is illustrated in the accompanying drawings.

In the drawings, in which similar characters of reference refer to similar parts throughout the several views:

Fig. 1 is a front view of a double action toggle press embodying the present invention;

Fig. 2 is a view of the left-hand portion of Fig. 1 with portions of the press structure broken away so as more clearly to disclose the operating 2 mechanism. In Fig. 2 the press is shown in the at rest or fully retracted position;

Fig. 3 is similar to Fig. 2 excepting that it shows the press at mid point in its cycle at the completion of the drawing operation; and

Fig. 4 is a graphic representation of the movement of the blank holder and main slide during one cycle of operation;

Presses are known in which mechanical toggle linkage is used for operating a,- blank holder slide in such manner as to cause the blank holder to approach the work rapidly and then remain in a substantially fixed position during the course of the drawing cycle after which the blank holder is rapidly retracted. Usually presses of this type have the entire drive mechanism, including the linkage to the blank holder and the linkage to the drawing slide, in the crown of the press so arranged that both of the linkage mechanisms drive downwardly moving slides.

Presses of the above-described type have certain disadvantages associated with the fact that they require considerable headroom to accommodate the complicated mechanism in the crown of the press. Also, since both the blank holding operation. and the drawing operation take place from above, the die arrangement is usually such that the article at the completion of the draw remains within the lower die element and therefore must be lifted out before it can be removed fromthe press. This removal of the completed article is, therefore, a somewhat time consumi'ng operation since it requires considerable labor, particularly when large articles such as automobile fenders or other major automobile body parts are being fabricated. Also, in transfer presses where anarticle being drawn is automatically moved from station to station during successive strokes of a press, such movement is facilitated if the article can be slid over a fiat surface without the necessity for lifting it to clear the concave die elements.

The press of the present invention is so arranged that the blank holding slide moves downwardly from above so as to clamp the blank in proper working position and to apply the proper pressure while" the drawing slide moves upwardly from beneath, thereby drawing the article in what may be considered as an inverted position as compared with conventional practice. Therefore, after the work slide has been retracted beneath the top surface of the bed of the press at the completion of a cycle of operation, there is nothing above the plane surface of the press to interfere with the removal of the completed article.

Also, our arrangement is such that the major portion of the driving mechanism is located below the bed of the press, thereby permitting the crown to be of less height.

Further, the drive to the blank holder slide is such that action thereof is accomplished by simple links located at the sides of the press, and such that these links carry comparatively low stresses, thereby insuring that the upward pressure produced as a reaction from the blank holder slide will be taken by the crown and the press tie rods rather than by imposing high stresses upon the links. Since it is more feasible to provide rigidity in a press by means of heavy tie rods than by means of heavy links, it is apparent that the action of our press will be smooth throughout the drawing operation inasmuch as there is little tendency toward elongation of the links and resultant changes in the centers of the toggle mechanism during a cycle of operation.

Fig. 4 illustrates one cycle of operation of a typical press of our invention wherein it will be seen that the blank holder moves downwardly during approximately the first 120 degrees of operation of the press and then comes to rest and remains substantially fixed through the following 120 degrees of dwell, this period being followed by rapid retraction of the slide during the last 120 degrees of operation of the cycle. The main plunger or drawing slide first moves downwardly at the beginning of the cycle of operation through a period of approximately 50 degrees and thereafter moves upwardly so as to reach its uppermost point at approximately 220 degrees, this motion being followed by about 1'7 degrees of dwell during which the metal has adequate time in which to flow into position. From approximately 237 degrees to the end of the cycle the main slide is retracted so that the cycle is completed with the main slide below the top of the press bed. The specific figures given above are for the purpose of illustration and, of course, should not be considered as limitative of the invention.

As seen in Fig. 1, the press generally comprises a bed l which supports a pair of side columns I! at each end. The columns in turn support a crown I4, the several units being held together by conventional tie rods l6. These tie rods pass downwardly through the crown and columns and into the bed in a well known manner. Normally a press of this type is installed with the lower portion within a pit so asto bring the die elements to a convenient working level, the press being supported upon its foundation by brackets l8 welded or otherwise suitably secured to the bed and braced by several triangular gussets [9.

A blank holder slide 20 is located between the columns l2 and is guided for movement by means of gibs and gibways 22 which may be of any well known type of construction. The blank holder slide 20 is connected by means of four adjustable knuckles 24 to four connecting rods 26 arranged with two at the front of the press and two at the back thereof in alignment with the front pair, these connecting rods being pivoted by pins 28 to the ends of rocker arms 30, the opposite ends of which are immovably splined or otherwise secured to a pair of transversely extending rock shafts 32. Thus when the rock shafts 32 are moved to such a position that the arms 30 extend straight downwardly so as to bring the pin 28 in dead center alignment between the rock shafts 32 and the knuckles 24, the slide 20 will be in its lowermost position. This position is shown in Figs. 1 and 3. Whenever the rock shafts 32 are rotated out of the above-mentioned position, the pins 28 will be swung upwardly, thereby lifting the slide 20. Substantially the maximum movement in this direction is illustrated in Fig. 2. The drive mechanism comprises an electric motor 34 which continuously rotates a flywheel 36 by a multiple V-belt drive '38. The flywheel 3B is connected to the driven member of a conventional clutch and brake combination, not shown, which when engaged connects the flywheel 36 to a pinion 40. The pinion 40 is meshed with and drives a large gear 42 mounted upon a shaft 44 which also carries a small pinion 46 meshed with a large gear 48. This last gear is mounted upon a suitably journaled shaft 50 which carries a pinion 52 meshed with a low speed main gear 54. Also, there is a reversing pinion, not shown, but "identical with pinion 52, mounted upon the shaft 50 and meshed with a pinion 56 of identical size. This last pinion is similarly meshed with another main gear, not shown but located at the back of the press, which drives substantially a reverse complement of the toggle mechanism, to be described, on the right hand side of the press. This duplication of the toggle mechanism has been eliminated from the drawings, since the overlapping structure in the figures would be confusing. For the sake of simplicity and clarity, only the lefthand mechanism is here described in detail.

The main gear for the left-hand mechanism rotates in a clockwise direction as seen from the front and is provided with a main slide eccentric B0 and a blank holder slide eccentric 62 which are offset with respect to each other in proper position to give the desired co-ordination between the two slides in conjunction with the toggle mechanism, to be described. In general, these eccentrics are so located with respect to each other that when the press is retracted, as seen in Fig. 2, and the blank holder eccentric is approximately at dead center, the main slide eccentric will be approximately 50degrees short of the dead center position. This is for' the purpose of obtaining the staggering of the cycles of the two slides which is apparent from Fig. 4. In other words, the blank holder should be in holding position at the start of the draw. Consequently, the main slide eccentrics are offset so as to reach the most advanced point in their travel just before the blank holder starts to recede.

The main slide eccentric is fitted to a connecting rod 64 which is pivoted at its opposite end by means of a pin 66 to a rocker arm 68. The rocker arm at its opposite end is splined to a shaft 10 which has a second rocker arm I2 located centrally of the press from front to back,

the arm 12 in turn being pivoted by a pin 14 to a link 16, the other end of which is pivoted by a knuckle joint '18 to an adjustment member attached to the main slide 82.

When the press is at the maximum drawing position, as illustrated in Fig. 3, the rotational center of the eccentric 60 is in approximately the dead center position between the shaft 58 and the pivot pin 66. In this position the pivot pin 14 is at approximately the dead center position between the rock shaft 10 and the knuckle joint 18. Because the toggle mechanism just described for operating the main slide involves the use of two toggles in series, so that the linkage moves into such a position that two dead center positions are being approached simultaneously, the action will give the 1.7 degree dwell shown in Fig; 4 for the purpose of permitting the metaltimeto-fiow into position before the pressure isrelea-s'ed.

The blank holder eccentric 62 is fitted to a connecting rod 86 which in turn is pivoted by a pin 88 to a crank arm 90' splined to a shaft 92. This shaft carries a centrally located crank arm 94 arrangedat approximately right angles to the arm 90 and pivoted at its outer end by a pin 96 to a long link 98. By comparing Figs. 2 and 3, it will be seen that rotation of the main gear '54 from approximately the at rest position tethe maximum draw position acts to pull thefarm 90 from a position below and to the left of the shaft 92 to a second position which also below'the shaft 92 and approximately the same distance to the right as the former position is to the left. During this same course of movement, the pin 96 connected to the lower end of the link 98 will be pulled downwardly from a position above and to the left of the shaft 92 to a second position below and to the left of this same shaft. Since this portion of the blank holder operating mechanism involves no toggles which approach dead center position at any point in the stroke, the movement of the link 98 upwardly and downwardly is approximately the same as would be direct action from a crank shaft. In other words, the movement of the link 98 approaches fairly closely to simple harmonic motion and, as will appear presently, this movement of the link is converted by toggle mechanism in the crown so as to cause a rapid approach of the blank holder slide followed by the substantially stationary blank holding portion of the cycle. The effect, therefore, is to place the principal load of the blank holding operation upon the crown and tie rods rather than upon the link 98, whereas if the blank holder slide were pulled downwardly directly by links or pull rods which were operated by toggle mechanism in the base of the press and involved several dead center connections, such pull rods or links would not be feasible of construction since elongation of these members would be a serious problem.

The upper end of the link 98 is pivoted by a pin I to a bell crank type rocker arm I02 journaled upon a shaft I04. A second rocker arm I06 formed integrally with the arm I02 and offset therefrom at an angle of approximately 90 degrees is pivoted at its outer end by a pin I08 to a link I09 connected at its opposite end by a pin III to a. rocking plate IIIl journaled to a fixed pin H2. The plate II 0 also has a second pivotal connection by means of a pin II4 to a link IIB, the opposite end of which is pivoted by pin II8 to a rocker arm I20. This latter arm is splined to the previously referred to rock shaft 32 so that the arms I and move together. The linkage just described is such that when the blank holder is at the mid point in its cycle, the pin 28 is in dead center location between the shaft 32 and the knuckle joint 24. Also, pin I I4 is located at the dead center position between the pin H8 and the stationary shaft II2. Further, the pin I08 is at dead center location between the shaft I04 and the pin III.

Because the linkage arrangement causes three dead center positions to be approached simultaneously, the last element of the series, that is, the slide 20, remains substantially stationary for about 120 degrees of the cycle of operation. In Fig, 3, the pin I08 and the pin II4 have just begun to recede from their dead center positions,

6 since this view is taken at the maximum upward position of the lower slide which is arranged to occur just before the toggle linkage to the blank holder slide issufiicien-tly broken to produce ap preciable movement of the slide 20.

As will be seen from the above description of a preferred embodiment of our invention and further as is apparent from the drawings, we have provided a double action toggle press in which the drive mechanism is incorporated in the portion of the press below the floor level and therefore in an out-of-the-way position, thus permitting the crown of the press to be considerably lower without the necessity for using long highly stressed pull rods. In other words, al though the links 98 transmit motion between the eccentrics at the base of the press and the toggle mechanism in the crown, most of the reduction or stepping down in the speed of operation of the slide is accomplished by comparatively simple toggle mechanism in the crown which requires comparatively little space. Together with this advance we have also provided a compact arrangement for drawing the work upwardly rather than downwardly, thereby providing certain distinct advantages, as have been pointed out previously.

Particular control mechanism for operating the clutch and brake arranged between the flywheel 36 and the pinion 40 has not been illustrated not described, since clutches and brakes and control arrangements therefor are well known to all skilled in this art, such elements being incorporated as a matter of course in all presses. Similarly, counterbalance cylinders for the blank holder slide 20 have not been shown, since it is believed that their illustration would be confusing and would serve no useful purpose inasmuch as counterbalance arrangements for such purposes are well known. Their purpose is simply to counterbalance the weight of the slide so as to take up all of the slack in the drive mechanism, thereby preventing momentary stopping of the slide when it strikes the work. It is apparent also that since the lower slide 82 draws upwardly rather than downwardly, thereby operating against gravity, no counterbalance arrangement for this slide is necessary. This is because all lost motion in the drive mechanism to this slide will automatically be taken up by the weight of the slide operating against the direction of movement rather than with the direction of movement as is the case with downwardly moving slides.

Having described our invention, what we claim as new and useful and desire to secure by Letters Patent of the United States is:

A press comprising a base, a crown, side members for supporting said crown from said base, a main slide in said base, a blank holder slide arranged above said base and between said side members, generally horizontally arranged eccentric and connecting rod means in said base extending toward said side members, operating means connected between said eccentric and connecting rod means and said main slide for driving said main slide from said eccentric and connecting rod means including toggle means adapted to approach dead center simultaneously to produce a dwell in the movement of the main slide at its uppermost position, second generally horizontally arranged eccentric and connecting rod. means in said base extending toward said side members and adapted to operate with said first eccentric and connecting rod means in timed relation thereto, common driving means for both said eccentric and connecting rod means, drive means connected between said second eccentric and connecting rod means and said blank holding slide for operating said blank holding slide from said second eccentric and connecting rod means, the last said drive means including operating links extending from the base of said press to the crown thereof, and toggle mechanism in said crown operated by said links for driving said blank holder slide including toggles in series arranged to approach dead center simultaneously and prior to said first mentioned toggles to produce a dwell in the movement of the blank holder slide at its lowermost position commencing prior to the commencement of the dwell in the movement of the main slide and terminating immediately prior to termination of the dwell in the movement of the main slide.

FREDRICH J. RODE. MEREDITH R. HATCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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