PRESS FEED DRIVE

CROSS-REFERENCE TO RELATED APPLICATION

[1] This application claims the benefit under 35 U. S. C, § 119 (e) of the earlier filing date of U.S. Provisional Application Serial Number 61/024,874 filed on January 30, 2008, the contents of which are hereby incorporated by reference.

FIELD OF INVENTION

[2] The present invention relates generally to press feeds for feeding stock material into a stamping press and more particularly to a drive for a feed roll of a press feed.

BACKGROUND OF THE INVENTION

[3] A press feed is often used in connection with an automatic stamping press to feed coiled stock material into the press. A common method of feeding the stock material into the press is through a pair of feed rolls which apply friction to the material, and rotate in a cooperative manner in opposite directions to feed the stock into the press.

[4] Examples of press feeds can be found in commonly assigned U.S. Patent Nos . 7,287,678; 5,915,293; 5,884,542; 5,868,296; 5,808,465; 5,755,370; 5,720,421; 5,181,642; 4,487,352; 4,449,658; 4,434,924; 4,375,759; 4,316,569; 4,138,913; 4,133,216; RE29,795 and 3,977,589 the disclosures of which are incorporated by reference herein.

[5] In a typical press feed, one or more of the feed rolls is driven by an electric motor. The feed rolls are typically of multi-diameter construction, a large diameter section for frictional engagement with the material and a smaller diameter section for supporting the feed roll in anti-friction bearings. The electric motor is attached to the small diameter section of the feed roll either directly, with a coupling, through a reducing gear drive, or through a belt and pulley arrangement . The electric motor is typically a synchronous motor capable of accurate indexing operation. Typical synchronous motors include brush- type permanent magnet motors, brushless permanent magnet motors, stepper motors, and switched reluctance motors.

[6] Such press feed configurations are well suited for the feeding of narrow stock materials but are disadvantageous for the feeding of wide stock materials, especially when operating at high index rates .

[7] In order to accommodate the feeding of wide stock materials with a typical press feed, the overall length of the feed rolls must be increased. In this case, either the length of the large diameter section of the feed roll must be increased, resulting in excessively high rotational inertias, or the length of the smaller diameter section of the feed roll must be increased, resulting in lower torsional and radial stiffness of the feed roll shaft. In either case, the performance of the feed unit is reduced.

[8] Therefore a need exists for a press feed apparatus having minimal rotational inertia while providing high torsional and radial stiffness.

SUMMARY OF THE INVENTION

[9] In one general aspect, this application discloses a press feed apparatus for intermittently advancing stock material to a press. According to various embodiments, the press feed apparatus includes a frame; a motor for indexing operation, the motor including an output shaft having first and second ends. The output shaft includes first and second output shaft pulleys on the first and second ends, respectively, of the output shaft for rotation therewith. The press feed apparatus further includes a second output shaft pulley on the second end of the output shaft for rotation therewith; a first feed roll rotatively mounted to the frame, the first feed roll having first and second ends; a first feed roll pulley on the first end of the first roll for rotation therewith; a second feed roll pulley on the second end of the first roll for rotation therewith; a first synchronous timing belt disposed about the first output shaft pulley and the first feed roll pulley; a second synchronous timing belt disposed about the second output shaft pulley and the second feed roll pulley, the first and second timing belts applying a drive force from the motor to the first feed roll through the first and second feed roll pulleys; and a second feed roll rotatively mounted to the frame and cooperating with the first feed roll to intermittently advance stock material therebetween. According to an embodiment, the motor is a permanent magnet servo motor. According to another embodiment the motor is a stepper motor. According to another embodiment, the motor is a hydraulic motor. According to another embodiment, the first and second output shaft pulleys are integral with the motor output shaft.

[10] The press feed apparatus disclosed in this application has minimal rotational inertia while providing high torsional and radial stiffness.

BRIEF DESCRIPTION OF THE DRAWINGS

[11] For the present invention to be clearly understood and readily practiced, the present invention will be described in conjunction with the following figure, wherein like reference characters designate the same or similar elements, which figure is incorporated into and constitutes a part of the specification, wherein:

[12] FIG. 1 is perspective view of the press feed apparatus according to a preferred embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[13] It is to be understood that the figure and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the invention, while eliminating, for purposes of clarity, other elements that may be well known. Those of ordinary skill in the art will recognize that other elements are desirable and/or required in order to implement the invention. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. The detailed description will be provided hereinbelow with reference to the attached drawing .

[14] Referring to FIG. 1, there is illustrated a preferred embodiment of the press feed apparatus of the present invention, generally designated by the numeral 10, for

feeding stock material 12 to a power operated press (not illustrated) , such as, for example, a press for stamping, punching, cutting, or the like. Press feed apparatus 10 includes first and second feed rolls 14, 16 rotatively mounted within a suitable housing frame 18. First feed roll 14, the lower of the two feed rolls in this embodiment, includes a central large diameter portion 20 for frictional engagement with the stock material 12 and first and second smaller diameter portions 22, 24 at each end thereof. The smaller diameter end portions 22, 24 support first feed roll 14 in anti-friction bearings 26 mounted in frame 18. First and second feed roll pulleys 28, 30 are mounted on first and second smaller diameter portions 22, 24, respectively, for rotation therewith.

[15] A drive force is applied to first feed roll 14, which cooperates with second feed roll 16 to apply motive force to the stock material 12 passing between the feed rolls 14, 16. The drive force applied to first feed roll 14 is provided by a motor 32 having an output shaft 34. Motor 32 is preferably a synchronous motor capable of accurate indexing operation at a high cycle rate to intermittently advance stock material to a press . Motor 32 is preferably an electric permanent magnet servo motor but could also be a stepper motor or a hydraulic motor. Output shaft 34 is disposed in parallel with first and second feed rolls 14, 16 and is rotatively supported in frame 18 by anti-friction bearings (not shown) . The output shaft 34 includes first and second end portions 42, 44 each having an output shaft pulley 46, 48 mounted thereon.

[16] First and second synchronous timing belts 50, 52 are arranged such that each timing belt 50, 52 operatively passes over an output shaft pulley 46, 48 and a corresponding feed roll pulley 28, 30. In a preferred embodiment, the feed roll pulleys 28, 30 include splines or teeth 54, the output shaft pulleys 46, 48 include splines or teeth 56 and the timing belts 50, 52 include corresponding integral teeth 58. The drive force is transferred from motor 32 through output shaft 34, output shaft pulleys 46, 48, synchronous timing belts 50, 52 and feed roll pulleys 28, 30 to first feed roll 14.

[17] By using two or more timing belts 50 and 52, the diameters of feed roll pulleys 28 and 30 can be kept smaller than the diameter of the central large diameter portion 20 of the first feed roll 14 eliminating any interference with the stock material 12 while maintaining a short large diameter portion 20 of the first feed roll 14 thereby minimizing the rotational inertia of the feed system. The use of two or more timing belts 50 and 52 additionally provides high torsional stiffness as it relates to the coupling of the motor to the feed roll . Furthermore the close proximity of the feed roll pulleys 28 and 30 to the central large diameter portion 20 of the feed roll 14 minimizes the length of the smaller diameter end portions 22 and 24 of feed roll 14 providing high torsional stiffness as well as high axial stiffness of feed roll 14.

[18] Nothing in the above description is meant to limit the present invention to any specific materials, geometry, or orientation of elements. Many part/orientation substitutions are contemplated within the scope of the

present invention and will be apparent to those skilled in the art. For example, it should be apparent to one of skilled in the art that the feed roll pulleys 28, 30 and the output shaft pulleys 46, 48 may or may not be integral with their corresponding structure. The embodiments described herein were presented by way of example only and should not be used to limit the scope of the invention.

[19] Although the invention has been described in terms of particular embodiments in an application, one of ordinary skill in the art, in light of the teachings herein, can generate additional embodiments and modifications without departing from the spirit of, or exceeding the scope of, the claimed invention. For example, the drive of the present invention is not limited to a pair of belts but could include more than two belts. Accordingly, it is understood that the drawings and the descriptions herein are proffered only to facilitate comprehension of the invention and should not be construed to limit the scope thereof .