Metal deforming – By plural tool-couples – With means to feed work between plural tool stations
Reexamination Certificate
1999-11-10
2001-05-01
Crane, Daniel C. (Department: 3725)
Metal deforming
By plural tool-couples
With means to feed work between plural tool stations
C072S405100, C072S405010, C198S621100
Reexamination Certificate
active
06223582
ABSTRACT:
BACKGROUND OF THE INVENTION
This application claims priority of DE 198 51 745.9, filed Nov. 10, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a transfer system, particularly for the transfer of workpieces between successive machining stations, such as press stages of large-piece transfer presses.
As a rule, a transfer system, which extends along the entire length of the press and moves the individual workpieces in synchronism, carries out the piece transport from one press stage to another. Such a known transfer system is described, for example, in DE 41 43 099 A1. This transfer system has two transfer rails which extend along the length of the press and on which carriages are disposed. Two carriages respectively carry a cross traverse between one another which is provided with suction spiders for receiving workpieces. For carrying out the transfer step from one press stage to another, the carriages are connected by a linkage with a cam drive which is connected with the main drive of the press. A lifting and lowering movement is superimposed on the back-and-forth movement of the transfer rails achieved in this manner. This lifting and lowering movement is achieved in that the rails are lifted and lowered as a whole.
Such a transfer system synchronously moves the suction traverses connected with a cam drive. Correspondingly, the participating tools must open and close simultaneously.
In contrast, WO 93/00185, discloses a transfer system which has transfer modules between individual press stages. The transfer modules can be controlled independently of one another. Each transfer module has two driving units which are applied on the right and the left to a respective suction traverse. The driving units contain a lifting unit, which is stationarily disposed, and an advancing unit, which is lifted and lowered by the lifting unit. The advancing unit contains a motor which drives the suction bridge by way of a planetary gear combined with a double crank. In this case, the backlash of the planetary gear is added to a possible bearing play between the individual interlinked cranks which finally adds up to an unreliable positioning existing at the suction bridge.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a modular workpiece transfer system which permits a high positioning speed and a good positioning precision.
This object has been achieved by a transfer system which has a transfer system for the transport and the positioning of workpieces, comprising a controllable workpiece holding device configured to be set up for temporarily coupling a workpiece to a carrier device, a lever mechanism configuration to hold with an output and guide the workpiece holding device with its output and guides it on an at least two-dimensional transfer curve, and at least two drive units which are connected by way of the lever mechanism with the workpiece holding device and of which one of the drive units is arranged in a stationary manner and the other of the drive units is arranged in a movable manner as an intermediate member in the lever mechanism.
The transfer system according to the invention uses a lever mechanism for guiding and positioning a workpiece holding device. This lever mechanism determines the actual position and the movement of the workpiece holding device by the interaction of at least two levers. One of the levers is connected at its one end with the other lever which, in addition, is guided at a point spaced away from the connection point. This double guidance or support results in a relatively high positioning precision and the influence of bearing plays or hinge clearances is largely repressed.
It has been found to be advantageous for the dynamics (transport speed) as well as for the positioning precision to provide two preferably separately controllable drive units, of which one is stationarily disposed and the other is integrated in the lever mechanism or is directly connected with it. The stationary drive can be configured to be stable and high-powered without its weight impairing the dynamics of the transfer system. As a result of the solid construction of the concerned stationary drive unit, however precision advantages can be achieved.
The integration of the moved drive into the lever mechanism or the connection to the latter preferably takes place at a point of the lever mechanism which carries out only slow movements. Therefore, the transposition of the driving movement to the desired transfer curve is carried out by the lever mechanism. As the result of the integration of the moved drive in the lever mechanism or the direct connection to the latter, the transposition of the driving movement can be achieved with little play which, in turn, results in a good positioning precision.
The lever mechanism preferably has a swivel arm which is connected with the carrier device at one end, is connected, at a connection point spaced away therefrom, with a driving device and is connected at another point with a guiding device. The lever arm or swivel arm is therefore supported twice, which results in a precise guidance.
Preferably, one connection point is used for the positioning of the swivel arm, with the lever position being defined in at least two directions and one degree of freedom (swivelling axis). The other connection point is preferably constructed as a guide with two degrees of freedom. This means that the lever in this case is disposed to be displaceable and swivellable, for example, in one direction.
Although, in principle, other configurations are within the scope of the present invention, it is found to be advantageous in many embodiments for the inoperative drive unit to be a linear drive and, for the moved-along drive unit to be a swivel drive. The linear unit may operate, for example, by way of a ball screw spindle with a high gear reduction and cause only a lifting or lowering of the workpiece holding device. The swivel drive may, for example, be connected with a swivellably disposed guide rod which, in turn, is connected with the swivel arm. The connection may be formed by an articulation.
As required, the swivel drive may also be arranged in a stationarily inoperative manner and may impart the desired swivelling movement to the guide rod connected with the swivel arm or to the swivel arm itself. A vertical adjustment of the workpiece holding device will then be caused by a length adjustment of the swivel arm by a telescopic drive which is moved along.
The lever mechanism is preferably completely arranged in a plane which is aligned parallel to the plane defined by the transfer curve, that is, in most cases, vertically. This has the significant advantage that, when the transfer stroke is carried out, the individual elements of the lever mechanism do not pass through laterally projecting movements. In the inoperative or intermediate position during the work of the individual press stages, the elements of the lever mechanism can remain in a very space-saving manner between the press stages in the parking position.
During the operation of the transfer system, that is, when a transport stroke is carried out, the swivel arm or the lever mechanism guides the workpiece holding device, for example, the suction bridge also in a space-saving manner. Thus, while the press erection surface is minimal, maximal space is available for the individual press stages. Finally, this is achieved in that all articulation axes and swivel axes of the lever mechanism extend transversely to the transport direction and horizontally or at least at a right angle with respect to the plane described by the transfer curve.
REFERENCES:
patent: 4024959 (1977-05-01), Gruner
patent: 4487409 (1984-12-01), Orii
patent: 4585389 (1986-04-01), Watanabe
patent: 5140839 (1992-08-01), Bruns
patent: 5267463 (1993-12-01), Doyama
patent: 5899108 (1999-05-01), Hofele
patent: 5970763 (1999-10-01), Takayama
Dangelmayr Andreas
Eltze Jürgen
Hofele Hans
Thudium Karl
Crane Daniel C.
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Schuler Pressen GmbH & Co.
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