US3911811A

US3911811A - Machine frame, especially for presses

Info

Publication number: US3911811A
Application number: US515089A
Authority: US
Inventors: Rune G Adolfsson
Original assignee: Carbox AB
Current assignee: Carbox AB
Priority date: 1973-10-18
Filing date: 1974-10-15
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14
Also published as: FR2248151B3; SU548440A1; DE2449256A1; JPS50112868A; SE377071B; SE7314161L; FR2248151A1

Abstract

A machine frame, particularly for presses, including an elongated beam which is adapted to act upon a workpiece, and at least one biassing winding arranged to generate forces tending to keep the beam compressed in its longitudinal direction, thereby resisting deformational forces applied to the beam.

Description

[4 1 Oct. 14, 1975 United States Patent [191 Adolfsson MACHINE FRAME, ESPECIALLY FOR 44 11 an 00 O0 1..

Von Platen.........

PRESSES Inventor:

3,687,066 8/ 1972 Von Platen et a]. 3,800,695 100/214 4/1974 Jonsson et a1.

[73] Assignee:

Primary ExaminerBilly J. Wilhite [22] Filed:

Attorney, Agent, or Firm-Flynn & Frishauf Foreign Application Priority Data Oct. 18, 1973 ABSTRACT Sweden............................ 73141616 A machine frame, particularly for presses, including Int Cl 2 100/ an elongated beam which is adapted to act upon a workpiece, and at least one biassing winding arranged [58] Field of Search...... 100/214, 295; 72/455, 465,

to generate forces tending to keep the beam com- 72/389 pressed in its longitudinal direction, thereby resisting deformational forces applied to the beam.

15 Claims, 4 Drawing Figures 1,384,498 Thomas 100/295 US. Patent Oct. 14, 1975 Sheet 1 of3 3,911,811

U.S. Patent 0a. 14, 1975 Sheet 2 of 3 3,911,811

US. Patent Oct. 14, 1975 Sheet 3 of3 3,911,811

1 MACHINE FRANIE, ESPECIALLY FOR PRESSES The present invention relates to a machine frame which is especially adapted for presses and comprises an elongated beam which, in the operation of the machine, by direct or indirect contact with a workpiece subjects the latter to a pressure for the purpose of deforming it. This pressure will naturally generate reactional forces affecting the beam. If the length of the beam is great in relation to its cross-section, the reactional forces will tend to deform into concave shape the surface of the beam facing the workpiece. This applies generally but, in order to simplify the following description of the invention, it is here presumed that the contact surfaces of the workpiece and the beam are rectilinear in the longitudinal direction of the beam.

The deformation problem above referred to is accentuated when, for some reason, it is not possible to increase the cross-sectional area of the beam in order to make the beam sufficiently resistant against bending loads. A typical example of that situation is found when sheet metal blanks are pressed into tubular form, an operation normally carried out in several steps. During the final steps, when the gap between the two longitudinal edges which are to be seamed together for formation of a tubular cross-section, it often happens that the tube completely surrounds the press beam. As is easily understood, the lateral dimension of the beam will accordingly decide the minimum diameter of the tube which can be manufactured in the machine. In other words, if the width of the beam can be limited, the operational range of the machine is correspondingly increased. However, it has not so far been possible in that way to attack the corresponding problem, since a reduced cross-sectional area of the beam has by necessity resulted in deteriorated strength properties, particularly in terms of resistance against bending loads. In this connection it should be observed that even if the workpiece would not put any restriction on the crosssectional dimensions of the beam so that it would from that point of view be possible to reach sufficient rigidness by giving the beam a large cross-sectional area, such a solution of the problem would still have several significant drawbacks. The most substantial disadvantage is that if the strength of the beam is increased in that way, the increased weight and dimensions of the beam result in increased manufacturing costs for the beam proper. Secondly, it becomes more bulky and, thirdly, the increased dimensions and weight of the beam entails that the dimensions also of the other components of the machine frame must be correspondingly increased. This is especially true in respect of the hydraulic cylinders or other means used for moving the beam towards and from the workpiece. It is also realized that in such a situation the power consumption of the machine is increased.

SUMMARY OF THE INVENTION The main object of the invention is to eliminate or substantially to reduce the above discussed shortcomings of the prior art machine frames by providing a frame the beam of which is highly resistant against deformational forces without having significantly increased dimensions. According to the main characteristic of the invention this apparently contradictory requirement has been realized in the way that the beam is provided with at least one biasing winding adapted to generate forces tending to maintain the adjacent portions of the beam under compression in the longitudinal direction of the beam.

BRIEF DESCRIPTION OF THE DRAWINGS Some embodiments of the invention will now be described in greater detail, reference being made to the accompanying drawing in which:

FIG. 1 is a perspective view showing a portal press designed according to the present invention and including a movable upper beam provided with a biasing winding;

FIG. 2 is a cross-sectional perspective view illustrating a beam according to a first embodiment of the invention, the beam being provided with one winding;

FIG. 3 corresponds to FIG. 2 but illustrates an embodiment according to which the beam features two biasing windings; and

FIG. 4 is a part-sectional elevation showing a beam designed according to a third embodiment and consisting of a plurality of pivotably interconnected sections which in the longitudinal direction of the beam are held together by two biasing windings.

DETAILED DESCRIPTION OF THE DRAWINGS The portal press illustrated in FIG. 1 has a framework comprising of two end frames bridged by a lower stationary beam and an upper movable beam. Each end frame comprises an upper substantially semicircular yoke 1 and a lower such yoke 2 interconnected by a pair of vertical columns 3 and 4, respectively. The substantially rectangular frame formed by those components is surrounded by a biasing winding 5 which could be of any suitable or known construction and normally consists of a bobbin surrounded by a great number of turns of steel wires biased under tension. The working table 6 of the machine is formed by the heavy lower beam which is of rectangular cross-section and the ends of which are supported on the bottom, substantially crescent-shaped yokes 2 of each of the side frames. Reference numeral 7 designates the top beam which can be raised and lowered relatively the stationary bottom beam by means of two doubleacting

hydraulic cylinders

8 and 9 which accordingly operate between the top surface of the upper beam 7 and the bottom surfaces of the end frame upper yokes l.

The machine above described does so far correspond to the prior art. However, in accordance with the teaching of the present invention, the upper beam 7 carries two upwardly directed

projections

10 and 11, preferably integral with the beam proper and surrounded by a biasing "winding 12 which, in principle, can be of the same design as windings 5. Numeral 13 refers to a hydraulic cylinder extending along the minor axis of the essentially oval winding 12. The operation of that cylinder will be described below.

As seen from FIG. 1, the distance between the two end frames of the press is large, meaning that when the press is used for treating a workpiece positioned in the gap between its two beams the latter will be subjected to reactional forces tending to deform their surfaces facing the workpiece into concave shape. This tendency is no big problem as far as the lower beam 6 is concerned because, since it is not movable but stationary and could easily be given heavy dimensions. Moreover, it is possible to support it from below by means of a number of intermediary legs 14-16. However, as

has been explained above, it is not possible to apply the same principle of construction as far as the top beam is concerned as such a solution of the problem would entail a plurality of disadvantages. With the aid of winding 12 it is, however, according to the basic idea underlying this invention, possible in the unloaded state of beam 7 to deform it so that its bottom surface assumes a convex shape. When, during the operation of the press, the beam 7 is then subjected to the reactional forces generated by the workpiece and accordingly oriented in the opposite direction, the final result will be that the two deformation-generating force systems cancel each other, so that the bottom surface of beam 7 will be located in an uncurved horizontal plane. It should be understood that the reference here to the bottom surface of the upper beam has been made only in order to clarify the operation and that in many applications it would be more pertinent instead to refer to the contact surface of a die or other tool carried by beam 7. Hydraulic cylinder 13 affords a possibility continuously to adjust the selected biasing of winding 12 so that the required compensation can be matched to different loading conditions.

FIG. 2 shows the detailed structure of beam 7 as above described. Numeral l7 refers to the tensionbiased wires making up winding 12, whereas numeral 18 refers to a downwardly projecting flange carried by beam 7 and, according to the illustrated embodiment, forming the active upper tool of the press.

In FIG. 3 components having a direct counterpart in FIG. 2 have been identified by the same reference numerals. The difference over FIG. 2 is that beam 7 has been provided with two biasing windings by the addition of a lower such winding 19. The following advantages of that design are especially worth mentioning. The major advantage resides in that, starting from a given initial deformation of the beam, it can be subjected to greater total compressional forces in its longitudinal direction. This is due to the well-known fact that the compression strength of the material is substantially greater than its bending strength. The practical advantage is that the cross-sectional area of the beam can be decreased, resulting in a relatively slender and light-weight beam configuration. Another advantage accompanying the use of double-biasing windings as shown in FIG. 3 is that it affords additional possibilities to control the deformation of the beam. According to this embodiment of the invention there is an option between providing both windings with control means corresponding to hydraulic cylinder 13 or, if the loading conditions will not vary during the lifetime of the press, to use a stronger biasing of the wires in the top winding 12 than that applied to the wires of the bottom winding 19. When the beam is then subjected to the load generated by the workpiece it is, as was the case according to the embodiment first described, possible to establish inside the beam a layer N which can be considered neutral, maybe not from a strictly scientific point of view but as far as deformation is concerned.

It is to be observed that the fact that a beam featuring a top and a bottom biasing winding as illustrated in FIG. 3 is permanently subjected to compressional loads in its longitudinal direction results in additional advantages. Thus, FIG. 4 illustrates how this condition makes it possible to divide the beam into a plurality of axially spaced

adjacent sections

20, 21, 22, and 23. The two

end sections

20 and 23 are identical and the same applies to all of the

intermediary sections

21, 22 etcetera. The end surface of each section facing an adjacent section has an arcuate recess 24. Two such opposite recesses do accordingly form a groove which houses a pivot 25. As is directly apparent from FIG. 4, the individual sections have a limited freedom of movement around those pivots. Such pivoting action occurs upon deformation of beam 7. This takes place in two stages. The first stage corresponds to the initial deformation of the beam due to the influence of the biased windings. The second deformation takes .place in response to the load to which the beam is subjected in the operation of the machine. As has been explained above, the present invention makes it possible during that second stage to have the loadgenerated deformation compensating the initial one so that the net result will be that the longitudinal axis of the beam is rectilinear during the active cycle of the machine. The corresponding advantages in terms of increased dimensional accuracy of the workpiece etc. should be obvious to any one skilled in the art. Another positive effect resulting from the sectional design of the beam is that it becomes possible, by means of only two standardized components, end sections and intermediary sections, to compose beams of arbitrary length so that different applications can be matched. From a strength point of view the material in the intermediary sections is used in an optimal way if those sections are given a tubular cross-section.

In the practical working of the invention it is possible in several respects to deviate from the embodiments here described for the purpose of illustrating the basic idea. By way of example it can be mentioned that the movable beam can be provided with more than two biased windings arranged according to other patterns than those here illustrated. In accordance with still another aspect of the invention the top surface of the beam has several projections arranged stepwise at different levels, biasing windings being mounted in each such level. It should also be understood that other means than hydraulic cylinders can be relied upon for the purpose of controlling the biasing effect of the windings, e.g., wedges. It is also manifest that the other portions of the frame can be modified within the scope of the invention. Finally, it should be underlined that the term beam as used in this specification should be interpreted in a descriptive and not in a limiting sense. The only substantial requirement in the working of the invention is that by means of at least one biased winding the deformation caused by the reactional forces exerted by the workpiece can be compensated for. Further, as has been explained above, if at least one such winding is mounted on opposite sides of the neutral layer of the beam the latter can be completely protected from internal tensional forces. This has two major beneficial results, on the one hand an increased fatigue strength and on the other a possibility to use beams of more slender and light-weight construction. In accordance with a special characteristic of the invention the beam is also provided with means sensing its deformation and comprising a signal transmitter. As soon as a measurable deviation from the rectilinear form of the beam has been detected, that transmitter supplies a control signal which is fed back to means controlling the magnitude of the tensional biasing force. Stated in other words, the bias in one or more of the windings can in this way be modified in response to that control signal so that the deformation trend is counteracted. In this way one can achieve that the active bottom surface of the beam or of its tool, respectively, automatically and continuously maintains its desired shape.

The invention is generally applicable in machines comprising beams or similar components subjected to high deformational forces. However, it is of particular interest in presses used for bending metal sheet material because in those machines the distance between the two end frames can be very great. By virtue of the present invention the press can operate according to the folding principle rather than the roller bending principle which is particularly advantageous in the treatment of metal plates of high thickness or high strength. Since the invention has made it possible, in the production of plate tubes, to carry on the folding of the tube blank up to a stage where the gap between the two longitudinal edges has been reduced to such an extent that removal of the workpiece by a movement perpendicular to the longitudinal axis of the beam is no longer possible, there is in such applications often a need to extract the workpiece out from its beamsurrounding position. This may be accomplished in the way that one of the two end frames of the machine is made tiltable. That solution is, however, known per se and does not consequently form any part of the present invention.

What is claimed is:

l. A machine frame for imparting treatment forces to a workpiece comprising:

workpiece receiving means (6) for receiving a workpiece; an elongate beam (7) spaced from said receiving means (6);

means (8, 9) for moving said elongate beam (7) relative to said workpiece receiving means (6) to apply said treatment forces to a workpiece located between said elongate beam (7) and said workpiece receiving means (6), said elongate beam which, when acting upon a workpiece under treatment in the maching being subjected to reactional forces tending to deform said elongate beam (7); and

at least one biasing winding means (12) coupled to said elongate beam (7 and arranged to generate forces tending to keep said elongate beam (7) compressed in its longitudinal direction.

2. A machine frame according to claim 1, wherein said elongate beam (7) comprises a plurality of longitudinally spaced sections (-23).

3. A machine frame according to claim 2, wherein said elongate beam (7) includes pivot means (24, pivotally connecting said sections (20-23) together.

4. A machine frame according to claim 2, wherein said sections (20-23) are of tubular cross-section.

5. A machine frame according to claim 1, wherein said at least one biasing winding means includes two biasing windings (12, 19) spaced around the longitudinal axis of said elongate beam (7).

6. A machine frame according to claim 5, wherein said elongate beam (7) comprises a plurality of longitudinally spaced sections (20-23).

7. A machine frame according to claim 6, wherein said elongate beam (7) includes pivot means (24,25) pivotally connecting said sections (20-23) together.

8. A machine frame according to claim 6, wherein said sections (20-23) are of tubular cross-section.

9. A machine frame according to claim 1, wherein each said at least one biasing winding means exhibits biasing forces so that in the unloaded state of said elongate beam (7) the elongate beam (7) exhibits a deformation tending to compensate for the deformation to which it is subjected in response to the reactional forces exerted by the workpiece during the operation of the machine.

10. A machine frame according to claim 1, wherein said at least one biasing winding means includes means (13) for controlling the magnitude of the biasing force thereof.

1 1. A machine frame according to claim 10, wherein said at least one biasing winding means includes a generally oval shaped biasing winding mounted on a surface of said elongate beam (7) and having an open transverse area, and wherein said means for controlling the magnitude of the biasing force includes means (13) coupled to said biasing winding for varying the effective transverse dimension thereof, thereby varying the biasing force.

12. A machine frame according to claim 11, wherein said means for controlling the magnitude of the biasing force of said at least one biasing winding means includes hydraulic cylinder means (13) connected across a transverse dimension of said biasing winding means.

13. A machine frame according to claim 11, wherein said elongate beam (7 includes first and second abuttment members (10, 11) said biasing windings being mounted between said abuttment members and in tension.

14. A machine frame according to claim 1, wherein said elongate beam (7) includes first and second abuttment members (10,11) extending therefrom and spaced apart in the longitudinal direction of said elongate beam; and wherein said at least one biasing winding means includes at least one biasing winding wound in tension around said spaced abuttment members.

15. A machine frame according to claim 13 wherein said at least one biasing winding means is generally oval in shape, and includes means for controlling the effective transverse dimension of said generally oval shape for controlling the magnitude of the biasing forces generated by said at least biasing winding means.

Claims

1. A machine frame for imparting treatment forces to a workpiece comprising: workpiece receiving means (6) for receiving a workpiece; an elongate beam (7) spaced from said receiving means (6); means (8, 9) for moving said elongate beam (7) relative to said workpiece receiving means (6) to apply said treatment forces to a workpiece located between said elongate beam (7) and said workpiece receiving means (6), said elongate beam which, when acting upon a workpiece under treatment in the maching being subjected to reactional forces tending to deform said elongate beam (7); and at least one biasing winding means (12) coupled to said elongate beam (7) and arranged to generate forces tending to keep said elongate beam (7) compressed in its longitudinal direction.

2. A machine frame according to claim 1, wherein said elongate beam (7) comprises a plurality of longitudinally spaced sections (20-23).

3. A machine frame according to claim 2, wherein said elongate beam (7) includes pivot means (24, 25) pivotally connecting said sections (20-23) together.

11. A machine frame according to claim 10, wherein said at least one biasing winding means includes a generally oval shaped biasing winding mounted on a surface of said elongate beam (7) and having an open transverse area, and wherein said means for controlling the magnitude of the biasing force includes means (13) coupled to said biasing winding for varying the effective transverse dimension thereof, thereby varying the biasing force.

13. A machine frame according to claim 11, wherein said elongate beam (7) includes first and second abuttment members (10, 11) said biasing windings being mounted between said abuttment members and in tension.