US2856876A - Mechanical forming press having a resilient blanket in its supporting structure - Google Patents

Description

M. WATTER MECHANICAL FORMING PRESS HAVING A RESILIENT BLANKET IN ITS SUPPORTING STRUCTURE Filed Jan. 18, 1952 T 2 Sheets-Sheet 1 I INVENTOR. Michael Waiter ,4 TTORNE Y Oct. 21, 1958 M. WATTER, 2,856,876 MECI'IAIIICAL FORMING PRESS HAVING A RESILIENT BLANKET IN ITS SUPPQRTING STRUCTURE Filed Jan. 18, 1952 2 Sheets-Sheet 2 l i n INVEN TOR. Michael Waiter United States Patent MECHANICAL FORMING PRESS HAVING A RE- SILIENT BLANKET IN ITS SUPPORTING STRUC- TURE Michael Watter, Philadelphia, Pa., assignor to The Budd Compan Philadelphia, Pa., a corporation of Pennsylvania Application January 18, 1952, Serial No. 267,140

3 Claims. ((1113-38) The invention relates to an improvement in mechanical presses, and its object is to overcome certain hitherto encountered undesirable and objectionable features.

One of the objects of the invention is to overcome vibrations, noise, and heavy shocks which commonly occur in the operation of mechanically-operated die presses, particularly the large ones.

Another object of the invention is an increase of the range of adjustment of presses and of dies therein so that the adjustment need not be done with the same accuracy as hitherto necessary, and so that minor deviations from the optimum adjustment will not cause dam age or even breakage of parts of dies or press.

The aforesaid objects and other advantages are achieved by supporting directly or indirectly at least one of the dies by the intermediary of a moderately resilient platen or blanket. Such platen being, preferably, a composite material of fabric and rubber as, for instance, available under the proprietary name Fabreeka.

The invention is more fully explained in connection with the following description of several embodiments diagrammatically shown in the attached drawing.

In the drawing:

Fig. 1 is a side elevation of a mechanical press with a set of forming dies mounted therein, certain parts being fragmentarily shown in section approximately along line 11 of Fig. 2;

Fig. 2 is a plan view and section along line 2-2 of Fig. 1;

Fig. 3 is a plan view and section, corresponding to Fig. 2, illustrating the adaptation of the invention to a specific situation to be explained later on; and

Fig. 4 is a fragmentary side elevation, partly in section, corresponding to the lower part of Fig. l and showing another adaptation of the invention to specific conditions.

The press, illustrated in the drawing, comprises a bed or base 1, side members or uprights 2, a crown or top member 3, a crank shaft 4, connecting rods 5, a ram 6, and a bolster 7. Secured to ram 6 is an upper die 8 provided with guide sleeves 9, and mounted on bolster 7 is a lower die 10 provided with guide pins 11 adapted to enter sleeves 9. The press and the die arrangement described so far are conventional.

The novel improvement is represented, in Figs. 1 and 2, by a resilient platen or blanket designated as a whole by numeral 12, which is inserted between bed 1 and bolster 7. The thickness and the resiliency of this blanket are such as to offer the necessary resistance for the proper forming of the workpiece between dies 8 and 16, While providing a shockand vibration-absorbing cushion.

It was found satisfactory to use a material such as Fabreeka, 1 inch thick, which yields about .07 inch or 7 percent under a load of 600 pounds per square inch.

Within certain narrow limits, the platen 12 floatingly supports bolster 7 with lower die 10 and allows lateral adjustment of the lower die 10 relative to the upper die 8 by means of the interengaging pins 11 and sleeves 9.

In order to obtain the desired specific loading of the resilient pad compatible with the objects of the invention, the pad does not extend throughout the opposing surfaces of bed 1 and bolster 7 but is, as shown in Fig- 2, cored out in its mid-region and is for this purpose composed of longitudinal marginal strips 13, transverse end strips 14, and a series of longitudinally spaced intermediate transverse strips 15. If the press bed 1, as assumed in Fig. 2, is provided with ribs, the blanket strips 13 to 15 must be placed on the ribs.

The pad between bed and bolster would, of course, normally reduce the available stroke of a given press. Where this is objectionable, grooves may be cut into bolster and/ or bed at the location of the resilient strips. These grooves (not illustrated) will not objectionably weaken the structure but will have the additional advantage of firmly holding the strips against lateral displacement.

Bed and bolster are held together, as customary, by bolts and nuts (not shown) which extend through holes 16 in the pad. These holes should be oversize, prefer ably about inch. It is recommended that heavy spring washers be used under the head and nut of the bolster bolts so that they will not have a tendency to work out due to the tension being released as the Fabreeka deflects.

For materials such as Fabreeka, it was foundadvantageous to insert a layer of approximately 2 inches and in no case less than 1 inch for die-forming operations. For blanking operations, 1 inch of a Fabreeka type pad was found advantageous. Roughly, it was found that the area of a pad of the Fabreeka type should be calculated so as to give approximately 600 pounds per square inch loading of the pad, based on the rated tonnage of the press.

For installing the pad, bed and base surfaces between which it is to be placed should first be carefully cleaned. Black industrial adhesive cement should then be used to cover the entire upper and lower surfaces of the pad before placing it in position. If several layers of the pad material are used, the layers should also be cemented together with black industrial cement.

Once the pads are installed in the press, the ram adjustment must be made, recognizing the fact that pads will deflect during the work cycle. It should be fully understood that the adjustment of the ram and the outward signs of the forces exerted by a press when used with resilient pad are different from the general experience with presses Without such pad.

For best results, the ram should be adjusted gradually, lowering it until a dimensionally satisfactory stamping is obtained. With pads in place the press should exhibit visibly less vibrations and effort. If that is not the case, it must be assumed that the ram has been lowered excessively and it should be raised to relieve excessive bottoming loads.

Figs. 3 and 4 illustrate two installations of the pads in graduating resiliency in such a way as to assure a true vertical displacement of a die irrespective of asymmetric die loading. The principle is to maintain approximately a loading throughout in such a way that the center of force on the die coincides with the center of resistance of the pad.

The installation illustrated in Fig. 3 employs marginal strips 17 which diminish in width toward the left so that there is less support and, consequently, greater resiliency in the left-hand region than in the right-hand region. This installation is recommended for a die having a greater forming load on the right-hand than on the lefthand, that is: a die with a loading as illustrated for a still further installation in Fig. 4. The transverse strips 18, 19 shown in Fig. 3 may be of the same constant width as shown for the strips 14, 15 in Fig. 2.

Die 20 shown in Fig. 4 is assumed to have the loading distribution diagrammatically illustrated by the dotted arrows 21. The loading is much heavier on the righthand side than on the left-hand side. The pad is correspondingly graduated in its resiliency by being composed of several layers 22, 23, 24 of which the layer 24- only extends over the whole length of bolster 7, Whereas layers 22, 23 terminate short of the right-hand side of bolster 7 and are continued by rigid, such as sheet metal, plates 25, 26 respectively. Here again the composite pad will evidently aflord greater resiliency in the left-hand region, where the forming load of the die is relatively small, than in the right-hand region, where the forming load is relatively high.

At present, it is considered preferable to interpose the resilient blanket between press bed and bolster. The blanket might, however, also be inserted at other places, particularly between bolster 7 and lower die 10, or between ram 6 and upper die 8. Indeed, two or more blankets .01 platens may be employed at different locations of vone press set-up.

While several of the new resilient pad installations have been shown and described, it should be understood that the invention has to be adapted each time to special conditions in regard to the construction and dimension of the presses and of the dies with which it is to be used, without departing from the spirit and the basic features of the invention.

What is claimed is:

1. In a mechanical forming press, a moderately resilient blanket inserted between at least one of the dies and its supporting structure on the press, the relation of the size of the blanket, of its thickness, and of its resiliency in relation to the working pressure of the die being such as to prevent, upon application of the working pressure, major deformation of the blanket and dislocation of the die relative to its supporting structure while permitting self-adjustment of minor deviations from the optimum initial installation of the die without causing damage and breakage of parts of die or press, and as to provide a shock and vibration-absorbing cushion, and in which the resiliency of the blanket is varied over its area approximately inversely to the variation of forming load of the die supported by the blanket.

2. In a mechanical press according to claim 1, in which the area of the blanket is greater in regions of great forming load than in regions of less forming load.

3. In a mechanical press according to claim 1, in which the thickness of the blanket is greater in regions of small forming load than in regions of heavier forming load.

References Cited in the file of this patent UNITED STATES PATENTS 2,009,059 Brennan et al. July 23, 1935 2,248,186 Oeckl July 8, 1941 2,289,524 Smith et al July 14, 1942 2,398,084 Day Apr. 9, 1946 2,411,852 Domine Dec. 3, 1946

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