US2507556A - Driving mechanism of mobile platens in presses - Google Patents

Description

DRIVING MECHANISM OF MOBILE PLATENS IN PRESSES Filed April 16, 1946 H. 'BOBST May 16, 1950* 2 Sheets-Sheet 1 fnyendar f/E/VR! B0557" fldorneys May 16, 1950 H. BoBsT DRIVING MECHANISM OF MOBILE PLATENS IN PRESSES 2 Sheets-Sheet 2 F'iled April 16, 1946 Patented May 16, 1950 DRIVING MECHANISM OF MOBILE PLATENS IN PRESSES Henri Bobst, Lausanne, Switzerland Application April 16, 1946, Serial No. 662,589 In Switzerland April 18, 1945 3 Claims.

The object of the present invention is a driving mechanism for a press having a movable lower platen and a fixed upper platen.

This mechanism is characterized by the fact that four pairs of toggle levers driving the platen are disposed each at one corner of a rectangle inside which is placed a crank shaft carrying two groups of opposed connecting rods, the latter being adapted to act on the toggle levers by moving simultaneously the knuckle joints connecting each pair of levers.

The annexed drawing shows an embodiment of a mechanism of this type, given by way of example and illustrates moreover an accessory improvement which is made possible by the proposed construction, and which is for this reason directly dependent therefrom.

Fig. 1 is a partial vertical cross section of a platen press of which the mechanism according to the present invention drives the lower platen.

Fig. 2 is a similar vertical cross section, at

' right angles to the plane of Fig. 1.

Fig. 3 refers to the aforementioned accessory improvement.

Figs. 4 and 5 show how the means controlling the transport of the blanks worked by the press are placed in relation to the new mechanism described.

The press shown in Fig. 1 consists of the frame work in three parts I, 2 and 3, of which the L middle part I constitutes the standard and supports the upper fixed counter-platen 4 and guides the movable lower platen 5.

This latter is supported at its four corners by four pairs of toggle levers of which two pairs marked 5 and l are to be seen in Fig. 1. They form the limits of a rectangle which, in the example given, is practically square, and they rest on a foundation 8 of the similarly rectangular shape.

The knuckle joints connecting each pair of toggle levers are caught each by one of the four connecting rods 9, ill, H and 12, divided in two groups and opposed two by two on each side of the central toothed wheel !3 of the crank shaft It.

The crank shaft is placed inside the rectangle limited by the toggle levers, and forms in the described example, a cross shaped figure with the driving shaft 15 carrying the endless screw it and driven from outside by means of the coupling fly-wheel ii.

The aforementioned members operate very simply:

The fly-wheel ll turning with the shaft 15, the endless screw l6 drives the toothed wheel [3 of 2 the crank shaft M, the rotation of which constrains the pairs of connecting rods 9, ID and ll, l2, to drive the knuckle joints of the toggle levers periodically towards the exterior, repelling them simultaneously and thus raising the movable platen 5 to execute the pressing stroke.

Various important advantages are obtained by the foregoing arrangement:

The thrusts on the connecting rods repelling the toggle levers are practically balanced. As a result, the different parts of the frame do not share the driving effort of the toggle levers as is the case in driving mechanisms using an outside crank, between the gear box of which and the press per se there is generally considerable reaction stress. The guides for the movable platen may be reduced to a simple slide I8, guided by a die l9, as the lateral stress is very small. The thrusts due to the working of the platen are absorbed by the press itself. Construction becomes less expensive and the reduced space necessitated by the mechanism obviates dismantling of the machine for transport, its middle part I being easily transported as a whole. Lubrication is also simplified.

Figs. 1 and 3 show moreover that the construction makes it possible to enclose easily the movable parts of the press inside a casing protecting them against introduction of impurities and of dust arising from the work carried out, particularly when the press is used to cut out cardboard.

The frame I shutting in the mechanism on two sides, it suffices to provide the sheet- iron plates 20 and 2! to close it on the other two sides. These plates, attached at their lower part to the foundation 8, extend upwards and are applied along the movable platen 5, against which they rest by means of the shoes 22 in leather, felt, etc. providing an effective seal.

The result is that the space containing the toggle levers, the connecting rods, the crank shaft, 2, part of the driving shaft and the gears, forms a practically closed space and that, as a result of the successive upward and downward strokes of the movable platen constituting the ceiling of said space, there will be a tendency to have therein alternatively a vacuum and a plenum.

The plate 2| being provided with an air supply valve 23, with or without a filter, and the plate 28 with a discharge valve 24, the whole will be ventilated in the sense that at each ascent of the platen 5, fresh and/or filtered air will enter the space occupied by the elements of the driving mechanism, and that at each descent of the platen, this air will be expelled the slight plenum resulting therefrom preventing dust infiltration through the seals 22. The discharge valve could even be dispensed with and the air would escape by the joints seals 22.

This circulation of air of course also serves to cool the whole mechanism.

It would naturally be possible to add a pump to the whole, constantly sending air into the above mentioned space so as to create a plenum independent of the movements of the platen 5.

In presses working at high speed, great rigidity is necessary between the driving of the movable platen and the feed mechanism of the worked blanks. That is to say, it would be advantageous to establish a short connection by large dimensioned pieces.

In the example shown, it has been assumed that sheets of cardboard were transported by gripper bars such as 25, conducted between the chains 26, driven by the shaft 21.

It is obvious that the distance between the crank shaft 14 and the shaft 27 is very short and easily adaptable to a direct connection of the drive mechanism of the toggle levers to that of the chains. This drive is here carried out by the crank cam 28 placed at the end of the crank shaft [4 (Fig. 2) and according to Figs. 4 and 5.

A connecting rod 29 articulated to the nob of the crank oscillates the toothed segment 30 thereby imparting a to and fro movement to the pinion 3! of the shaft 21, a coupling gear or clutch 35 actuated by the cam 28 and the rod 32 of the fork 33 limits the movement of the shaft 21 in the direction of the arrow 34 of Fig. 4.

The drawing clearly indicates the rigidity of this connection, reduced to its simplest form and using only short and large dimensioned parts.

It may be added that to regulate the pressure exerted by the toggle levers, it is advisable to rest these latter on the foundation '8 by means of keys such as 35 (see Fig. l), for example wedge shaped and adjustable as to position.

What I claim is:

1. In a press having a fixed upper platen and a rectangular movable lower platen, a set of toggles connected to each corner of and beneath the lower platen, a crank-shaft located in the substantially rectangular space between said sets of toggles and having four cranks arranged in 0pposed pairs and a gear in the center thereof, a pitman connecting each said crank to one of said sets of toggles, a common frame having closed vertical end and side walls for supporting said crank-shaft and toggles and enclosing at least 4. the lower portion of said toggles, a drive shaft penetrating from outside said frame into said space and operatively connected to said gear, a casing resting on said common frame and having vertical end and side walls extending the walls of said frame, said casing enclosing all the upper portion of said toggles and at least part of said lower platen and engaging frictionally the side faces of said lower platen, a chain shaft, a direct driving connection between said crank shaft and said chain shaft, endless chains driven by said chain shaft, and gripper bars connected to said chains for conveying work pieces to the press.

2. A press according to claim 1 wherein said direct driving connection comprises a crank nob rotatable with said crank-shaft, a connecting rod actuated by said nob, a toothed segment connected to and oscillatable by said rod about an axis parallel to said chain shaft, a gear on said chain shaft engaging said segment, a clutch interposed between said gear and chain shaft, and a cam on said crank-shaft controlling engagement of said clutch in one direction of oscillation of said segment and disengagement thereof in the other direction.

3. A press according to claim 2 including a cam-follower leaning on said cam, a rod rotatable with said cam-follower, and a crank on said rod connected to a movable part of said clutch, whereby rotation of said rod in response to actuation of said cam-follower by said cam will disengage said clutch in one direction of rotation of said rod and engage it in the other direction.

HENRI BOBST.

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

UNITED STATES PATENTS Number Name Date 215,872 Bowdoin May 27, 1879 239,475 Exley Mar. 29, 1881 247,613 Carson Sept. 27, 1881 395,857 Taylor Jan. 8, 1889 423,064 Littlejohn Mar. 11, 1890 511,785 Melvin Jan. 2, 1894 783,342 Wilfrey Feb. 21, 1905 1,110,977 Welch Sept. 15, 1914 1,485,546 Affelder Mar. 4, 1924 1,584,230 Knight May 11, 1926 1,926,576 Beatty Sept. 12, 1933 2,081,175 Friden May 25, 1937 2,413,554 Evers Dec. 31, 1946 2,425,040 Luehrs Aug. 5, 1947

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