Patent Application
20120048907
This invention relates to apparatus for feeding a strip of thin sheet metal from a supply coil into die set tooling within a reciprocating press, for example, tooling as disclosed in applicant's U.S. Pat. No. 5,857,374 for the high speed production of aluminum can shells. Various types of sheet metal feeding equipment or apparatus are disclosed in U.S. Pat. No. 2,025,418, No. 3,177,749, No. 4,138,913, No. 4,489,872, No. 4,561,581, No. 4,953,808, No. 5,501,412, No. 5,833,105, No. 5,451,011 and No. 5,622,330. When feeding a thin sheet of metal or aluminum strip into tooling within a single action or double action press, as disclosed in above mentioned U.S. Pat. No. 5,857,374, it is very desirable for the strip to be fed from a supply coil and indexed into tooling within the press at a high rate of speed in order for the press to operate at a high production speed, for example, 400 strokes per minute.
It is also desirable for the strip to be accurately and smoothly advanced into the tooling without any vibration or whipping of the strip in order to obtain higher speed feeding and also minimize overfeeding of the metal strip. It is further desirable to provide for quickly separating the strip feeding apparatus from the press to minimize down time of the press for maintenance of the press and/or tooling or replacement of the tooling. While the above identified patents disclose different forms of apparatus for receiving a web or strip of material or sheet metal strip from a supply coil and advancing the strip in successive steps into a reciprocating press, the different apparatus do not provide all of the desirable advantages mentioned above and especially high speed, precision and dependable advancement of the strip into a reciprocating press from which higher speed production is desired.
The present invention is directed to an improved system for high speed and precision advancement of a thin sheet metal strip from a supply coil into a reciprocating press. In general, the system includes a frame supporting a pinch roll adjacent a feed roll driven by variable speed drive. The rolls are positioned to receive the strip from a supply coil and direct the strip upwardly between horizontally spaced inner and outer vertical guide members or parallel spaced rods where the strip is formed by a retractable threader cap into an inverted U-shaped and continuously moving vertical loop. Loop sensors are positioned adjacent the vertical guide members and detect the top of the loop in the strip between the guide members, and the sensors precisely control the variable speed drive. From the vertical guide members, the strip is directed by inner and outer guide members or spaced rods into a pinch roll adjacent an index roll driven by a servo motor controlled in response to operation of the press. The index roll and adjacent pinch roll may be supported by the frame and direct the strip horizontally into the press. Preferably, the frame is releasably connected to the press by locators on the press, and the frame is supported by a set of vibration isolation units mounted on a base stand supported by air film casters. When the frame is released from the press, the entire system, including the frame and support stand may be quickly removed from the press for servicing of the press and/or die set tooling or replacement of the tooling.
Other features and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.
Referring to
The side plates 34 are also connected by a horizontal platform or plate 38 which supports a pair of pivotal arms 42 connected to corresponding fluid or air cylinders 44. A pinch roll 46 extends between the arms 42 and opposes an adjacent feed roll 48 driven by variable speed drive motor 50. From the chute 18, the strip S is directed upwardly by curved inside guide members in the form of parallel spaced cylindrical rods 52 and into the nip 54 between the feed roll 48 and the adjacent pinch roll 46. The strip S is fed upwardly or vertically between parallel spaced outer vertical guide members in the form of parallel spaced stainless steel cylindrical rods 55 supported by horizontal cross members 58 and 59 of the frame 20.
A strip threader cap 65, in the form of parallel spaced semi-circular rods, is supported for pivotal movement by a shaft 67 between a strip curving or threading position (
When the threader cap 65 is pivoted to its retracted position, the curved loop 75 is free to move upwardly above the guide rods 73 and between the outer vertical guide rods 55. The floating top of the loop is detected or sensed by a pair of opposing vertical loop control sensors 78 supported by cross members connected to vertical members 82 of the frame 20. The sensors 78 control the variable speed drive motor 50 for the feed roll 48 so that the free flowing loop 75 always stays between the vertical guide rods 55. Suitable sensors are produced by Allen-Bradley and Banner Engineering Corp. The vertical members 82 of the frame 20 are supported by vertical side plates 84 of the frame and are rigidly connected by the cross members 58 and 59 (
After the sheet metal strip S is directed downwardly between the vertical outer guide rods 55 from the loop 75, the strip S is directed between parallel spaced curved outer guide members or rods 85 and parallel spaced curved inner guide rods 86 which are continuations of the downwardly projections of the curved guide rods 73. The upper portions of the curved rods 85 and 86 are supported by horizontal cross members 88 and 89 of the frame 20. The lower end portions of the curved guide rods 85 and 86 are supported by vertical cross plates 92 and 94 of the frame 20 and are positioned so that the strip S is directed horizontally between an index roll 98 and an adjacent pinch roll 99. The index roll 98 is supported by end brackets or plates 103 secured to the vertical cross plate 94 of the frame 20, and the index roll 98 is driven by an electrical servo motor 105 (
The upper pinch roll 99 is supported by vertical arms or end plates 107 pivotally supported by corresponding shafts 109 which, in turn, are supported by end blocks mounted on the upper cross plate 92. Fluid or air cylinders 112 are also supported by the plate 92 and have piston rods 114 connected to pivot the arms or end plates 107 to control the downward pressure of the pinch roll 99 against the index roll 98. From the rolls 98 and 99, the strip S is directed horizontally into the press 15 on a guide and support plate 115 projecting from the press. However, the assembly of the index roll 98, pinch roll 99 and motor 105 may be supported by brackets mounted on the press.
As shown in
As shown in
When the system 10 is positioned for feeding or indexing the sheet metal strip S into the press, the frame 20 is rigidly and positively connected to the press 15 by a set of connector pins 134 each secured to a pair of end brackets 136 welded to the plates 103. The pins 134 are received within corresponding U-shaped recesses or cavities 138 formed within the top of a pair of connector arms 140 projecting from the press 15 under the pins 134. When the air casters 130 are supplied with pressurized air, the stand 120 and strip feeder system 10 are slightly elevated, and the pins 134 are lifted from the cavities 138 so that the stand 120 and system 10 are free to be conveniently and quickly moved away from the press 15.
Referring to
The components of the strip feeding system 10′ are substantially the same as the components of the system 10 and are identified with the same reference numbers but with the addition of prime marks. In the embodiment of
As also shown in
From the drawings and the above description, it is apparent that a stock or strip feeding system constructed in accordance with the invention provides desirable features and advantages. More specifically, the vertical inverted loop system works with the variable speed feed roll and the servo driven index roll to provide the more consistent and smooth loop control and avoid whipping of the strip forming the loop, especially when the metal strip is very thin, for example, under 0.010 inch. The vertical loop control sensors 78 also provide for a very accurate loop control height so that the weight of the inverted U-shaped loop portion of the strip S between the vertical guide members or rods 55 cooperates with the feed roll 48 and the index roll 98 to assure a smooth and precise incremental advancement of the strip S into the press in response to operation of the press. The more accurate and precise feed advance or indexing of the strip S into the press enables a reduction or minimizing the feed distance or progression which results in a material cost savings for each stroke of the press.
As mentioned above, the strip feeding system 10 or 10′ also permits an increase in production speed of the press, for example, from 400 strokes per minute to over 500 strokes per minute. The smooth high speed precision advance or indexing of the strip S into the press also provides for using thinner sheet metal stock or strip material which further contributes to cost reduction. The use of the feed and index rolls to engage only a center portion of the strip in combination with the vertical loop system provides for feeding the strip into the press without the need for side or edge guides for the strip and eliminates friction produced by edge guides. The center feeding and indexing of the strip also accommodates strip material with some camber while maintaining accuracy and high speed without jams of the system. In addition, the vibration isolation mounts 118 also cooperate to provide smooth feeding and indexing of the strip during high speed operation of the press and without pulling on the strip. The air flotation pads 130 on the lower base stand 120 further provide for easy and quick removal of the strip feeding system 10 from the press to provide convenient access to the press and/or die set tooling for servicing or replacement of the die set tooling. As another important advantage, the upward vertical loop system 10 or 10′ eliminates the need for the index roll 98 to pull on or lift the strip, and the system further provides for minimizing the floor space required for precision high speed feeding a sheet metal strip into a reciprocating press.
While the forms of a strip feeding system herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms, and that changes may be made therein without departing from the scope and spirit of the invention as defined in the appended claims.
