US3719091A

US3719091A - Press with overhead drive

Info

Publication number: US3719091A
Application number: US00016535A
Authority: US
Inventors: M Drummer; R Riegert; M Wolfgang; W Munch
Original assignee: L Schuler GmbH
Current assignee: L Schuler GmbH
Priority date: 1969-03-04
Filing date: 1970-03-04
Publication date: 1973-03-06
Anticipated expiration: 1990-03-06
Also published as: FR2034648A1; GB1245726A; DE1910850B2; DE1910850A1

Abstract

In a press, particularly a transfer press, having a multi-point drive to the ram from pairs of crank wheels, the crank wheels in each pair are arranged coaxially in oppositely rotating pairs and are connected to spaced points on the ram by mirror image linkages which may be a simple connecting rods or compound linkages. In a transfer press, each tool may be mounted on a separate ram provided with such a drive.

Description

United States Patent Drummer et al.

14 1 March 6, 1973 PRESS WITH OVERHEAD DRIVE [75] inventors: Max Drummer, Heiningen; Micheal Wolfgang, Goppingen; Werner Munch, Goppingen; Rupert Riegert, Goppingen, all of Germany [73] Assignee: L. Schuler GmbH, Goppingen, Germany [22] Filed: March 4, 1970 [2]] Appl. No.: 16,535

[30] Foreign Application Priority Data March 4, 1969 Germany ..P 19 10 850.0

[52] US. Cl ..74/44 [51] Int. Cl ..Fl6h 21/22 [58] Field of Search ..74/44 [56] References Cited UNITED STATES PATENTS 1,813,087 7/1931 Sandage ..74/44 3,315,596 4/1967 Peters ..'......74/44 2,550,063 4/ l 951 Johansen 1,391,036 9 1921 Yates ..74/44 Primary Examiner-Milton Kaufman Assistant ExaminerWesley S. Ratliff, Jr. AttorneyCraig, Antonelli and Hill [57] ABSTRACT 13 Claims, 3 Drawing Figures PRESS WITII OVERHEAD DRIVE The invention relates to presses having overhead drives, and more particularly but not exclusively transfer presses in which the workpieces are moved progressively along the longitudinal axis of the press, the drive to the press ram being of the mechanical multi-point type in which power is transmitted through driving pinions to crank wheels disposed in pairs and a connecting member pivoted to the ram is journalled eccentrically on each crank wheel.

In known presses of this type, the pairs of crank wheels lie in a single plane with toothed rims in engagement, one of the crank wheels of each pair being driven by means of a driving pinion. The ram is normally reciprocated by means of either one or two pairs of crank wheels and associated connecting rods, providing a two-point or a four-point drive respectively. In these multi-point drives it is known for the crank wheel axis to be disposed transversely in relation to the longitudinal axis of the press, that is to say, in the case of transfer presses, transversely in relation to the flow of workpieces through the press. This arrangement has the disadvantage that the maximum dimension of the ram along the longitudinal axis of the press is limited by the diameter of the meshing crank wheels, since no substantial offset is possible between the crank wheel axis and the axis of articulation of the connecting rod on the ram. Offset here means the horizontal distance between the pivotal axis of the connection between the connecting member and the ram and the axis of the associated crank wheel. Since with a multi-point drive the connecting members should be connected to the ram as close as possible to the edges of the ram, that is to say, close to the lateral guides provided for the ram in the press frame, it is found that in many known presses of this kind the crank wheels must project substantially beyond the ends of the ram, thus necessitating a large and unwieldy head piece on the press to house the ram drive, and an enlargement of the area occupied by the press. In addition the press becomes top-heavy and is seriously affected by the vibration it generates. If for the purpose of achieving a greater ram length, while retaining an acceptable degree of offset of the ram drive, the crank wheels are spaced from one another without increasing their diameter and are connected together by intermediate gearing, the cost of manufacture is considerably increased, since intermediate gearing of this type must be designed for the heavy shock loads imposed during operation of such presses. In addition, the mass of the top part of the press is still further increased and thus the response of the press to vibration is still further impaired. The increased vibration amplitudes that result may lead to failures in operation and to increased tool wear. For presses with longitudinal shaft drive, that is to say in which the drive shaft and hence the axes of the crank wheels extend parallel to the longitudinal axis of the press, similar problems arise in relation to the size of the headpiece of the press and the resulting detrimental consequences. The size of the headpiece also gives rise to difficulties in transport and assembly, since headpieces must normally be prefabricated and not be cast, or welded and machined, at the installation site.

Both with transversely and with longitudinally disposed crank wheel axes, each pair of crank wheels situated in one plane are rotated in opposite directions, since their toothed rims (usually) mesh with one another, and in the case of a four point drive with two pair of crank wheels mounted in parallel, those crank wheels which are coaxially disposed are rotated in the same direction. The coaxially disposed crank wheels must be driven in the same direction of rotation because the articulation axes of the two associated members connecting them to the ram are always offset in the same direction and by the same distance in relation to the crank wheel axes. Rotation of the coaxial crank wheels in opposite directions is not possible with this arrangement.

In order to solve the vibration problem, it would be theoretically possible to provide a bottom drive instead of an overhead drive. This arrangement however is completely impracticable in the case of transfer presses, since the necessary connecting rods would block access to the press rams on both sides. A press ram should however whenever possible be accessible from all four sides, namely from two oppositely situated sides for workpiece transport, and from the other two sides for the purpose ofinspection and tool changing.

The primary object of the invention is to provide a multi-point overhead ram drive for a press which is light and compact.

According to the invention, a press has a ram vertically reciprocable in a frame and a drive to said ram supported in said frame above said ram, said drive comprising a drive pinion drivingly connected with at least one pair of crank wheels, and connecting elements eccentrically pivotally connected to said crank wheels and pivotally connected at spaced points to said ram, wherein each pair of crank wheels is disposed coaxially, and the driving connection of each wheel of the pair with the drive pinion is such that they rotate in opposite directions. A substantial advantage of the invention is that the head piece of the press can be made with about half the volume previously required, with correspondingly reduced weight and space requirements. For this reason along the response of the entire press to vibration is substantially improved, since the natural frequency of vibration is higher and the amplitude of the vibrations occurring is thus smaller. In addition, the raising of the natural frequency makes it easier to arrange for the frequency of the exciting forces applied by the drive to be situated well away from the resonant frequencies of the press. A further advantage in reducing vibration arises from the fact that since the coaxial crank wheels rotate in opposite directions, and the movements of the associated connecting members are equal and opposite, the out of balance forces generated by them during operation of the press are largely cancelled. The reduced size of the headpiece of the press makes it possible for the overall dimensions of the entire press frame to be made smaller and facilitates the transport and assembly of the press. Presses according to the invention also require less material.

In one embodiment of the invention the connecting members are connected to the ram with equal and opposite offset. Given a correct choice of the direction of rotation of the crank wheels, such an arrangement provides the advantage that the upward movement of the ram is accelerated and the downward movement of the ram retarded.

This arrangement is particularly suitable for a fourpoint ram drive comprising two pairs of crank wheels. It may however also be advantageously employed in a two-point ram drive.

Known transfer presses have a single ram, on the lower side of which the individual tools, beneath which the workpiece passes in succession, are fastened. The individual tools are not always equal in height and the distance between their working plane and the fastening plane of the tools is not always the same. These tools must therefore be fastened on the ram at different distances from the bottom surface of the latter. At the same time the tools must be adjusted with an accuracy of fractions of a millimeter and the various tools in a transfer press tool set must be adjusted very accurately in relation to one another. The time required for tool setting when tools have to be changed in transfer presses is therefore extremely long.

In order to obviate this disadvantage, a transfer press according to a further feature of the invention has a plurality of rams disposed in line parallel to the direction of movement of workpieces through the press, each ram being provided with a separate drive and having a separate adjusting device by which the height of the ram relative to its point of connection to the connecting members may be altered. By this means it is possible with the aid of the ram adjusting devices'to adjust the height at which the tools are fastened on the rams very accurately. The ram adjusting devices may be known automatically controlled devices by which the pivotal connections by means of which the bottom end of the connecting members are articulated to the ram can be moved very gradually upwards or downwards in the ram by a certain amount. Fine adjustment of the tools can therefore be effected with the aid of the ram adjusting devices, and it is no longer necessary for the individual tools to be fastened at different distances on the lower side of the ram. This is of particular advantage when two or more tools are fastened to a single ram and must therefore be adjusted very accurately in relation to one another, because the fitting of the tools need not be adjusted accurately in relation to the tools fastened to other rams, since this latter adjustment can be effected by the ram adjusting means.

A press of this kind having a plurality of rams can be constructed at an economically acceptable cost if the drives are constructed in accordance with the invention and the head of the press therefore requires correspondingly little space. The crank wheels of the individual rams are advantageously driven by a longitudinal shaft extending parallel to the longitudinal axis of the press.

The connecting members between the crank wheels and the ram may be of various constructions. In one embodiment of the invention the connecting members are in the form of simple connecting rods. A drive of relatively simple construction is obtained in this manner. By selecting a certain offset between the pivotal axis of the connection between the rod and the ram and the crank wheel axis a desired retardation of the downward movement and acceleration of the upward movement of the ram may be obtained. The motion of the ram thus may be varied slightly from simple harmonic without offsetting the crank wheels relative to the ram. In order to increase the deviation from simple harmonic motion, as is frequently desirable, two component connecting members may be provided. In this embodiment each connecting member comprises a connecting rod pivotally connected at one end to the ram and at the other end to a lever eccentrically journalled on the associated crank wheel, the movement of the lever being controlled by a link. By selection of the length ratios of the connecting rod and the lever and selection of the point at which the link acts on the lever, as well as by applying a drive to the link, a wide range of variation in the motion of the ram can be achieved.

In one arrangement the lever is in the form of a twoarmed lever, one arm of which is connected to the connecting rod while the other arm is connected to one end of the link. The other end of the link may be pivotally connected to the press frame. In this way a robust drive of relatively simple construction is achieved, the motion of the ram being capable of variation within wide limits by suitable selection of the dimensions and interconnections of the various parts.

The two-armed lever may be in the form of a triangular plate journalled on an eccentric carried by the associated crank wheel, the lever arms being formed by two apices of the plate.

By the addition of other linkage elements the movement of the ram can be further modified; for example, a drawing press drive known in itself may be provided.

Two embodiments of the invention are described with reference to the accompanying drawings, in which:

FIG. 1 is an end view of the upper part ofa press with the end cover and bearing plate of the headpiece removed,

FIG. 2 is a section on the line II-II in FIG. 1, and

FIG. 3 a diagrammatic end view of the upper part of a press according to the invention showing an alternative form of drive.

Referring to FIGS. 1 and 2 a ram 2 is mounted in a frame 1 of a press. Parallel to the longitudinal axis of the press is a main drive shaft 3, which carries a pinion 4 and is driven by a drive motor (not shown). Between the drive motor and the main drive shaft 3, a coupling and braking device (likewise not shown) is incorporated in the drive train. Together with other shafts, which will be referred to below, the main drive shaft 3 is journalled in bearing plates 7 and 8, which in turn are carried by the machine frame 1. The pinion 4 meshes with a first intermediate gear 5, which in turn meshes with a second intermediate gear 6, so that the two intermediate gears rotate in opposite directions. The two intermediate gears and the pinion 3 are situated in the same plane. An intermediate pinion 9 and 10 respectively is rigidly connected to each of the two

intermediate gears

5 and 6. The two intermediate pinions 9 and 10 are situated on opposite sides of the two

intermediate gears

5 and 6. Together with its intermediate pinion 9 the first intermediate gear 5 is mounted by means ofa shaft 11, and the second intermediate gear 6 together with its intermediate pinion 10 is mounted by means of a shaft 12 in the bearing plates 7 and 8. A crank wheel 13 meshes with the intermediate pinion 9 and a crank wheel 14 with the intermediate pinion 10.'

The crank wheel 13 is mounted for rotation on a shaft 15 in the bearing plate 7 and the crank wheel 14 on a shaft 16 in the bearing plate 8. The two crank wheels are disposed coaxially and rotate in opposite directions. On each of the crank wheels there is disposed an eccentrically situated crank pin 17, on which connecting

rods

18 and 19 respectively are journalled. The other ends of the connecting

rods

18 and 19 are pivotally connected to the ram 2. As can be seen clearly from FIG. 1, the width of the upper part of the press is substantially smaller than in the case of a pair of crank wheels disposed in the same plane. Through the horizontal offset of the pivotal axes of the connecting

rods

18 and 19 on the ram 2, in relation to the axes of the two crank

wheels

13 and 14 respectively, and given correct selection of the direction of rotation, a retarded downward movement and an accelerated upward movement of the ram 2 is obtained. The motion of the ram thus departs from simple harmonic. The crank

wheels

13 and 14 may be provided with eccentrics in place of the crank pins 17. As shown in FIG. 2, the press may include a plurality of rams each having a drive.

A much greater deviation of the motion of the ram from simple harmonic may be obtained with the embodiment illustrated in FIG. 3. For the sake of simplification of the drawing those parts already described with reference to FIGS. 1 and 2 and bearing the references 3 to 12, that is to say the drive to the two crank wheels, are omitted. Two crank wheels 21 and 22 provided with

eccentrics

24 and 25 in place of crank pins are mounted for rotation on a stationary common shaft 23. A two-armed lever 26 is journalled on the eccentric 24 and a two-armed lever 27 is journalled on the eccentric 25, both levers having the form of triangular plates, two apices of each of which form lever arms. To one lever arm of the two-armed lever 26 is fastened by means of a pivot 28 one end of a connecting rod 29 the other end of which is pivotally secured to the ram 2. In mirror-image symmetry to the connection to the two-armed lever 26, one arm of the two-armed lever 27 is secured by means of a pivot 30 to one end of a connecting rod 31, the other end of the rod 31 being pivoted to the ram 2. A link 32, one end of which is pivotally mounted on a pin 33 secured to the press frame, is pivotally connected to theother lever arm of the two-armed lever 26. In mirror-image symmetry thereto one end of a link 34 is pivotally connected to the other arm of the two-armed lever 27, the other end being pivotally mounted on a pin 35 secured to the press frame. The resulting linkage connecting the wheels 21 and 22 respectively to the ram 2, causes a modification of the motion of the ram 2 which is adjustable within wide limits by varying the dimensions of the components of the linkage.

In a variant of the embodiment of FIG. 3, the

links

32 and 34 may be connected to the

pivots

28 and 30 instead of to the other lever arms.

It will be understood that the invention is not restricted to the exemplary embodiments illustrated, but that variations thereof are possible without departing from the scope of the invention.

What we claim is:

1. A press comprising a plurality of rams disposed in line, each ram being vertically reciprocal in a frame, and a separate drive to each of said rams being supported in said frame above said respective ram, said drive comprising a drive pinion drivingly connected with at least one pair of crank wheels, and connecting elements eccentrically pivotally connected to said crank wheels and pivotally connected at spaced points to said ram, wherein each pair of crank wheels is disposed coaxially, the driving connection of each wheel of the pair with the drive pinion is such that they rotate in opposite directions, and the connecting elements being connected to the ram with equal and opposite horizontal offset relative to the axis of their associated crank wheels. 1

2. A press according to claim 1, wherein the drive pinions of each drive are carried by a main drive shaft parallel to the line of rams.

3. A press having a ram vertically reciprocal in a frame, and a drive to said ram supported-in said frame above said ram, said drive comprising a drive pinion drivingly connected with at least one pair of crank wheels, and connecting elements eccentrically pivotally connected to said crank wheels and pivotally connected at spaced points to said ram, wherein each pair of crank wheels is disposed coaxially, the driving connection of each wheel of the pair with the drive pinion is such that they rotate in opposite directions, and the connecting elements being connected to the ram with equal and opposite horizontal offset relative to the axis of their associated crank wheels, each connecting element comprising a connecting rod pivotally connected at one end to the ram and at the other end to a lever eccentrically journalled on the associated crank wheel, a link being provided to control the movement of the lever.

4. A press according to claim 3, wherein the lever is a two-armed lever, one arm of which is pivotally connected to the connecting rod, and the other to one end of the constraining link. 7

5. A press according to claim 4, wherein the other end of the constraining link is pivotally connected to the press frame.

6. A press having a ram vertically reciprocal in a frame, and a drive to said ram supported in said frame above said ram, said drive comprising a drive pinion drivingly connected with at least one pair of crank wheels, and connecting elements eccentrically pivotally connected to said crank wheels and pivotally connected at spaced points to said ram, wherein each pair of crank wheels is disposed coaxially, and the driving connection of each wheel of the pair with the drive pinion is such that they rotate in opposite directions, each connecting element comprising a connecting rod pivotally connected at one end to the ram and at the other end to a lever eccentrically journalled on the associated crank wheel, a link being provided to control the movement of the lever, the lever being a two-armed lever in the form of a generally triangular plate journalled on an eccentric carried by the associated crank wheel, its arm being formed by two of the apices of the plate, one arm of which is pivotally connected to the connecting rod, and the other to one of the constraining link.

7. A press according to claim 1, wherein each ram is provided with means to adjust its vertical position relative to its points of connection with the connecting elements.

8. A press with overhead drive, especially a transfer press in which work pieces are moved in the longitudinal direction of the press, the press having a ram with a mechanical multipoint drive, said drive comprising a drive pinion drivingly connected to at least one pair of crank wheels, two connecting members being pivotally connected to said ram and eccentrically pivotally connected to respective ones of said pair of crank wheels, said pair of crank wheels being disposed coaxially and each wheel of said pair of crank wheels being driven in opposite directions, the axes of the pivotal connections of the two connecting members at the ram extending parallel to the axis of the crank wheels and to one another and being offset in mutually opposite directions with respect to the axis of the crank wheels and with respect to parallel regarding the direction of motion of the ram.

9. A press according to claim 8, wherein each connecting member is provided with a joint between the crank wheel and the ram, a connecting rod being connected between the joint and the ram and a lever being connected between the joint and the crank wheel, and a guide arm engaging said lever.

10. A press according to claim 8, wherein the connecting members are connecting rods extending between the pivotal connections to-the ram and the pivotal connections to the crank wheels.

11. A press having a plurality of rams disposed in line, each ram being vertically reciprocal in a frame, and a separate drive to each of said rams being supported in said frame above said respective ram, said drive comprising a drive pinion drivingly connected with at least one pair of crank wheels, and connecting elements eccentrically pivotally connected to said crank wheels and pivotally connected at spaced points to said ram, wherein each pair of crank wheels is disposed coaxially, and the driving connection of each wheel of the pair with the drive pinion is such that they rotate in opposite directions.

12. A press according to claim 11, wherein each ram is provided with means to adjust its vertical position relative to its points of connection with the connecting elements.

13. A press according to claim 12, wherein the drive pinions of each drive are carried by a main drive shaft parallel to the line of rams.

s' w w s a

Claims

1. A press comprising a plurality of rams disposed in line, each ram being vertically reciprocal in a frame, and a separate drive to each of said rams being supported in said frame above said respective ram, said drive comprising a drive pinion drivingly connected with at least one pair of crank wheels, and connecting elements eccentrically pivotally connected to said crank wheels and pivotally connected at spaced points to said ram, wherein each pair of crank wheels is disposed coaxially, the driving connection of each wheel of the pair with the drive pinion is such that they rotate in opposite directions, and the connecting elements being connected to the ram with equal and opposite horizontal offset relative to the axis of their associated crank wheels.

3. A press having a ram vertically reciprocal in a frame, and a drive to said ram supported in said frame above said ram, said drive comprising a drive pinion drivingly connected with at least one pair of crank wheels, and connecting elements eccentrically pivotally connected to said crank wheels and pivotally connected at spaced points to said ram, wherein each pair of crank wheels is disposed coaxially, the driving connection of each wheel of the pair with the drive pinion is such that they rotate in opposite directions, and the connecting elements being connected to the ram with equal and opposite horizontal offset relative to the axis of their associated crank wheels, each connecting element comprising a connecting rod pivotally connected at one end to the ram and at the other end to a lever eccentrically journalled on the associated crank wheel, a link being provided to control the movement of the lever.

4. A press according to claim 3, wherein the lever is a two-armed lever, one arm of which is pivotally connected to the connecting rod, and the other to one end of the constraining link.

10. A press according to claim 8, wherein the connecting members are connecting rods extending between the pivotal connections to the ram and the pivotal connections to the crank wheels.