US2754117A

US2754117A - Strip feeding apparatus

Info

Publication number: US2754117A
Application number: US26505A
Authority: US
Inventors: Edwin I Ghormley
Original assignee: ALUMINUM GOODS Manufacturing Co
Current assignee: ALUMINUM GOODS MANUFACTURING Co
Priority date: 1948-05-12
Filing date: 1948-05-12
Publication date: 1956-07-10
Anticipated expiration: 1973-07-10

Description

y 10, 1956 E. l. GHORMLEY STRIP FEEDING APPARATUS United States Patent STRIP FEEDING APPARATUS Edwin I. Ghormley, Dayton, Ohio, assignor, by mesne assignments, to Aluminum Goods Manufacturing Company, Manitowoc, Wis., a corporation of New Jersey Application May 12, 1948, Serial No. 26,505- 12 Claims. (Cl. 271-25) This invention relates to apparatus for the intermittent advancement of strip stock, for example the feeding of a continuous strip of sheet metal to a punch press or the like.

The invention has especial although not limited application to a punch press installation wherein pieces of sheet metal are cut and initially formed from strip stock mechanically fed in step-by-step fashion to the press.

A principal object of the invention is accurately to present uniform lengths of the strip to the press in order that a minimum of material will be lost as scrap.

Feeding apparatus, for use as described, heretofore has suffered from a lack of precision resulting in the supply of irregular strip lengths to the press and consequent heavy scrap loss of material. Contributory causes have been the difliculties inherent in handling and moving sheet metal and the demand for high speed production, requiring a quick acting feed mechanism. As the speed of action increased, the problem of exactly correlating the motion of the strip stock to the motion of the feed devices correspondingly became greater, it being necessary to overcome the initial inertia of the strip without slippage and to inhibit independent sliding of the strip under its own momentum when released by the feed devices. These requirements, to which may be added the frequent need for avoiding defacement of the material in areas acted upon by the press, have not been met in a satisfactory manner by known strip feed apparatus.

Another object of the invention is to obtain increased control over the advancement of the strip through the provision of means operating under the control of and in timed relation to the feed devices for holding the strip against advancement relative to the feed devices.

A further object is to enable quick and accurate intermittent feed of strip material by a simple and efiective mechanism, particularly suited for the handling of relatively wide strip stocka related object in this respect being to avoid marking or defacement by utilizing only narrow edge portions of the strip for engagement with the feed devices.

In carrying out the objects of the invention, there has been evolved a practical embodiment thereof comprising a reciprocable feed device including spaced cam shaped pawls moving into gripping engagement with the strip in response to motion of the feed device in one direction and moving out of such engagement upon interruption of the motion of the feed device in said one direction, and further comprising supplemental spaced pawls movable by said feed device concomitantly with release of the first pawls into gripping engagement with the strip.

Other objects and structural details of the invention will appear from the following description when read in connection with the accompanying drawings, wherein:

Fi l is a top plan view of a strip feeding apparatus constructed in accordance with the present invention and showing the feed device at the end of its strip advancement stroke.

Fig. 2 is a view in irregular longitudinal section, taken substantially along the line 22 of Fig. 1;

Fig. 3 is an end view of the apparatus, looking from the right hand end as viewed in Fig. 1; and

Fig. 4 is a view in longitudinal section, enlarged with respect to Figs. 1, 2 and 3, and taken substantially along the line 44 of Fig. 1, but showing the feed device at the start of the strip advancement stroke.

Referring to the drawings, in its illustrated embodiment the strip feed apparatus of the invention is shown mounted upon a frame or base 10. In general, the apparatus contitutes a unit separate from the punch press or other machine with which it is used, although the base 10 may be attached directly to the body of the press.

The strip material upon which the apparatus acts is included in the several views of the drawings, in broken lines in Fig. 1 and in full lines in Figs. 2, 3 and 4. The strip is indicated at 11, and, as may be seen, is a continuous sheet of relatively thin metal of the type used in forming kitchen utensils and similar thin walled devices.

The base 10 comprises a central longitudinal rib portion 12 and a top flanged portion 13. At one end of the base is a broad, transverse wall 14 extending above the flanged portion 13 and below the bottom of the rib portion 12. The downwardly projecting portion of the wall 14 is adapted for attachment of the base to the selected mounting, while the upwardly projecting portion of the wall provides a support for the work strip 11 and for strip gripping devices hereinafter to be described. Mounted on the flange 13 of the base 10, axially of the base, is an actuating cylinder 15. The opposite ends of the cylinder 15 have a screw threaded connection in closure plates 16 and 17 (see Fig. 4). The plates 16 and 17 are secured to the flange 13, as by bolts 18, and in addition provide a suport and slideway for the strip 11. The plate 17 additionally receives a pair of

guide rods

19 and 21 at the one ends thereof, the opposite ends of the rods being screw threaded into the upwardly projecting portion of the base wall 14. The

rods

19 and 21 are spaced from one another on opposite sides of the longitudinal axis of the cylinder 15 and are rigidly mounted in the plate 17 by a screw threaded connection supplemented by lock nuts 22.

Within the cylinder 15 a piston 23 is reciprocably mounted. Connected to the piston 23 is a rod 24 which extends through an axial opening in end plate 17 and into the space between the

rods

19 and 21. Mounted on the projecting end of rod 24 is a member 25 slidably mounted upon the flange 13 and formed with spaced openings through which the

rods

19 and 24 are passed. The member 25, accordingly, is reciprocable with the piston 23 and is guided in such motion by its bearing upon flange 13 and by the

rods

19 and 21. The member 25 has the shape of a rectangular block and extends transversely beyond the side edges of the base flange 13 to a length approximately coincident with the length of the base wall 14. Theupper edge of the member is arranged to engage and support the under side of the strip 11 in cooperation with the wall 14. At its opposite ends, the member 25 has rigidly secured thereto upstanding arms 26 arranged to embrace and to guide the side edges of the strip 11. On the inner surface of each arm 26 is mounted a cam or pawl 27, each pawl being pivotally attached to an arm 26 as by a stud screw 23. The pawls 27 are sector shaped with the pivot represented by the screw 28 passed through the ends of relatively smaller area. The pawls are suspended from their pivot with their fan-like ends of larger area in overlying relation to the member 25 and to respective side edges of the strip 11, which is passed between the member 25 and the pawls 27. The bottom edge of each pawl 27 adjacent the strip is cam-shaped in such wise that the length of the pawl measured from the pivot 28 is greater along the leading or right-hand side edge as viewed in Fig. 4 than along the rear or left-hand side edge. The arrangement accordingly is such that for a given guage of strip stock rocking motion of the pawls in a clockwise direction as viewed in Fig. 4 is limited by reason of contact with the strip 11, whereas comparatively free counterclockwise motion of the pawls relative to the strip 11 is permitted.

The pawls 27 are interconnected by a cross-bar 29 cccentrically placed so as to urge the pawls normally in a clockwise direction for engagement with the strip 11. The engaging edges of the pawls may be serrated as shown for better gripping action.

Referring to the end wall 14 of the base 10, the upwardly projecting portion thereof is formed, as may be seen in Fig. 3, with upstanding end arms 31 which are in embracing and guiding relation to the strip 11. On the inner surface of each arm 31 is mounted a pawl or lever 32, the pawls being pivotally connected to the arms 31 by stud screws 33. The pawls 32 have a somewhat square shape with the pivot screws 33 passed through a lower corner thereof. One side edge 34 of each pawl 32 overlies the wall 14 and the strip supported thereon. Another side edge 35 of each pawl 32 slopes rearwardly beyond the confines of the arms 31 and is arranged in the path of movement of a corresponding arm 26 on the member 25. Under the influence of pressure applied by the arms 26, the pawls 32 are urged in a clockwise direction as viewed in the drawings to press the edges 34 into gripping engagement with the strip. The pawls 32 are interconnected by a cross-bar 36 eccentrically placed to urge the pawls in a clockwise direction or in a direction normally to engage the edges 34 with the strip. The surface 34 of the pawls 32 may be notched as shown for better gripping contact with the strip.

Extending longitudinally through spaced points in the upstanding portion of base wall 14 is a pair of bolts 37 (Figs. 3 and 4) provided as stops for member 25. The bolts 37 are screw threaded into the wall 14 and project through the wall a greater or lesser distance in accordance With the rotative adjustment thereof. A lock nut 38 is provided to hold each bolt in any selected position of adjustment.

The member 25, in conjunction with the arms 26 and pawls 27 mounted thereon, constitutes a gripping device for intermittent advancement of the strip 11. The pawls 32, in conjunction with supporting arms 31 and end wall 14, constitute a second gripping device for retaining the strip against independent relative movement, as will be seen. The member 25 is reciprocated by motion of the piston 23 Within cylinder 15, the member being connected to the piston through rod 24. Piston 23 may be caused to move within cylinder by any conventional means, for example by air pressure admitted through a port 39 in end plate 17 and a port 41 in end plate 16. It will be understand that the pressure fluid is alternately supplied to and exhausted from the opposite ends of the cylinder 15 by Way of

ports

39 and 41 and that this control may be effected through a four-way valve or like device under automatic or manual control. It is believed sufiicient for the present purposes to understand that the piston 23 is, under the influence of supplied pressure fluid, moved rapidly from end to end ofthe cylinder to eflect quick strokes ofthe member in strip advancement and return directions.

According to the operation of the apparatus, the strip 11 initially is arranged by hand in overlying contacting relation to the cylinder end plates 16 and 17, the reciprocable member 25 and the end wall 14. The strip so arranged is, as previously mentioned, embraced between the arms 26 and the arms 31 and lies beneath the gripping portions of the

pawls

27 and 32 and in position to be contacted thereby. The leading end of the strip 11 projects beyond the end wall 14 toward orupon the bed of'the punch press, a fragment of which is schematically indicated at 42 in Fig. 2. The parts initially assume the position shown in Fig. 4 wherein the piston 23 is retracted within the cylinder 15, and the member 25 occupies its extreme left hand position representing the end of the return stroke or start of the strip advancement stroke. At this time the pawl arms 27 engage the strip 11 adjacent the respective side edges thereof. The pawl arms 32 likewise engage the strip 11 by reason of the weight of the eccentrically placed cross-bar 36, out effect no gripping engagement thereof and do not offer material resistance to the advance of the strip 11.

Upon admission of pressure fluid to the left hand end of cylinder 15 through port 41 and a simultaneous connection of the right hand end of the cylinder to exhaust through port 39, piston 23 moves in a forward or rightward direction within the cylinder. By reason of its connection to piston 23 through rod 24, the member 25 partakes of such motion, carrying with it the arms 26 and pawls 27. At the start of such motion the pawls 27 rock upon the strip 11, but the cam edges on the bottoms of the pawls ahnost immediately cause a wedging or gripping of the strip 11 between the supporting member 25 and the pawls 27. Continued motion of the member 25 and its associated parts accordingly is accompanied by a pulling or advancement of the strip 11 in the direction of the arrow shown in Fig. 4. Motion of the member 25 and strip 11 continues until the piston 23 reaches its limit of motion in cylinder 15 or until interrupted by contact of the member 25 with the stops 37. Preferably the length of the strip advancement stroke is defined by the stops 37 and at a time before the supply of pressure fluid through port 41 is discontinued. Greater precision of movement thus is possible and the presence of a briefly continued pressure at the end of the stroke inhibits rebounding and ensures the application of a firm holding force upon the pawls 32. The action of the piston 23 within cylinder 15 and, therefore, of the member 25, is rapid and the interruption of such motion by contact of the member 25 with bolts 37 is a sudden and summary action, as a result of which the pawls 27 tend to swing by their momentum in a counterclockwise direction out of gripping relation with the strip 11. The strip 11 likewise has a tendency toward continued ad- Vance, but accurate positioning thereof in accordance with the well defined limits of movement of the member 25 is provided for through the pawls 32. The stop bolts 37 are so adjusted with respect to the sloping abutment surfaces 35 of the arms 32, that contact of the arms 26 with the abutment surfaces 35 takes place substantially simultaneously with interruption of the motion of member 25 by stops 37. The impact pressure delivered by the arms 26 to the pawls 32 in this manner rocks the pawls 32 to gripping engagement with the strip 11, the pawls 32 thus becoming effective at the same time the strip is released from gripping contact with the feed pawls 27. Independent sliding movement of the strip resulting in an irregular positioning of the strip upon the punch press bed thus is prevented. This is the position of the parts and phase of the operation illustrated in Fig. 2.

The return stroke of the parts is initiated by a reversal of the pressure fluid supply and exhaust connections to the cylinder 15, and it will be understood that control of the supply of pressure fluid may be related to the operation of the punch press so that the member 25 of the gripping device is retracted or moved through its return stroke while the press is acting upon the portion of the strip just previously fed and so that the strip advancement stroke takes place during the motion of the punch press head away from and toward the bed. Duringthe return stroke the shorter length of the pawls 27 are presented to the strip 11 so that the pawls move along the strip out of or in lightly contacting relation theretoback to the starting position of Fig. 4. lnterruptionofthe return stroke as member 25 arrives at its starting position tends to produce a clockwise swinging motion of the arm 27, which thereby rock in a direction to move the longer lengths thereof into contact with the strip 11. But slight motion or the member 25, therefore, is required at the start of the next strip advancement stroke to effect a gripping relation between the pawls 27 and strip 11. Motion of the arms 26 away from the abutment surfaces 35 of the pawls 32 releases the strip from gripping engagement with the pawls 32, so that it is free again to advance with the pawls 27 and member 25.

Means may be provided for limiting the independent rocking motion of the

arms

27 and 32, occurring respectively at the end of and at the sart of the strip advancement stroke. In the illustrated apparatus, pins 43 are set in the arms 26 for limiting the pawls 27 and similar pins 44 are set in the arms 31 for limiting motion of the pawls 32.

What is claimed is:

1. A step-by-step strip feeding device, comprising first and second spaced supports for the strip, said first support being movable toward and from said second support, first and second pawls respectively pivotally carried by said supports in overlying relation to the strip, said first pawl having a cam surface in engagement with the strip arranged in cooperation with said first support to grip the strip in response to motion of said first support toward said second support and arranged to release the strip in response to opposite motion of said first support, said second pawl having a surface in engagement with the strip and arranged in cooperation with said second support to grip the strip in response to pressure applied to said second pawl in one direction, and means on said first support for applying pressure to said second pawl in said one direction at a predetermined point in the motion of said first support toward said second support.

2. A step-by-step strip feeding device according to claim 1, characterized in that sair second pawl is formed with a cam surface for contact with the strip and with a surface for contact with said first supporting member, said pawl being urged by said member in a direction to press said cam surface against the strip.

3. A step-by-step strip feeding apparatus, comprising a reciprocable first gripping device in the form of a strip supporting member and a cam pivotally mounted in overlying relation to said supporting member and to the strip thereon, a second gripping device in the path of reciprocation of said first device and including a strip supporting member and a cam pivotally mounted in overlying relation to the supporting member and to the strip thereon, the cam of said first device engaging the strip and rocking to gripping relation therewith in response to motion of said first device toward said second device, and the cam of said second device presenting a portion for contact with said first device and arranged to be rocked thereby into gripping engagement with the strip.

4. A step-by-step strip feeding device according to claim 3, characterized by means for interrupting motion of said first support toward said second support concomitantly with the application of gripping pressure to said second pawl.

5. A step-by-step strip feeding device, comprising first and second spaced supporting members presenting abutment surfaces for contact with one side of the strip, said first member being movable toward and from said second member, a first pawl pivotally carried by said first supporting member in overlying relation to the abutment surface thereon and formed with a cam edge for contact with the opposite side of the strip, said pawl acting to grip and to advance the strip in response to movement of said first supporting member toward said second supporting member and to release the strip in response to return motion of said first supporting member, and a second pawl pivotally carried by said second supporting member in overlying relation to the opposite side of the strip and movable by said first supporting member into gripping engagement with the strip.

6. A step-by-step' strip feeding apparatus, comprising a gripping device reciprocable through strip advancement and return strokes, said device including a strip supporting member and a cam pivotally mounted in overlying relation to said supporting member and to the strip thereon, said cam engaging the strip and rocking to gripping relation therewith in response to motion of said device in a strip advancement direction, means for interrupting the motion of said device in a strip advancement direction in response to which action said cam tends to rock out of gripping relation with the strip, and means operable by said device concomitantly with interruption of motion of said device in a strip advancement direction to apply a gripping and holding pressure to the strip.

7. A step-by-step strip feeding apparatus according to claim 6, characterized in that said last named means comprises a pawl arranged to be urged into gripping engagement with the strip by contact of said gripping device therewith and released from such engagement by withdrawal of said device on its return stroke.

8. Apparatus for the intermittent advancement of metal strip stock and the like, comprising a base, a gripping device mounted on said base for reciprocable motion through strip advancement and return strokes, said device including a supporting member disposed transversely beneath the strip and further including a pair of spaced cams pivotally mounted in overlying relation to said supporting member and respectively adjacent the said edges of the strip, said cams engaging the strip and rocking into and out of gripping relation therewith respectively in response to motion of said device in a strip advancement direction and in a return direction, and a second gripping device mounted on said base in the path of reciprocation of said first device for preventing continuedadvancement of the strip following its release by said first gripping device, said second device comprising a transverse strip supporting member and overlying pawls arranged as the cams on said first device and operable by said first device to move into gripping engagement with the strip.

9. Apparatus according to claim 8, characterized by eccentrically placed cross bars respectively engaging said cams and said pawls and urging said cams and said pawls to contact with the strip.

10. Apparatus for the intermittent advancement of metal strip stock and the like, comprising a base, a gripping device mounted on said base for reciprocable motion through strip advancement and return strokes, said device including a supporting member disposed transversely beneath the strip and further including a pair of spaced cams pivotally mounted in overlying relation to said supporting member and respectively adjacent the side edges of the strip, said cams engaging the strip and rocking into gripping relation therewith in response to motion of said device in a strip advancement direction, means for interrupting the motion of said device in a strip advancement direction, said cams tending as a result of such action to rock out of gripping relation with the strip, and means operable by impact pressure delivered by said gripping device for gripping and holding the strip from continuing advancement following release of said cams.

11. A step-by-step strip feeding device, comprising first and second spaced supporting members presenting abutment surface for contact with one side of the strip, said first member being movable toward and from said second member, a first pawl pivotally carried by said first supporting member in overlying relation to the abutment surface thereon and formed with a cam edge for contact with the opposite side of the strip, said pawl acting to grip and to advance the strip in response to movement of said first supporting member toward said a '7 second supporting member :and to release the strip-in response to return motion of said first supporting member, and a second pawl pivotally carried by said second supporting member in overlying relation to the opposite side of the strip and movable by said first supporting member into gripping engagement with the strip, said second ,pawl having a cam surface to engage the strip and an abutment portion engaged by the said first supporting member, said earn surface and said abutment portion being on substantially opposite sides of the pivot for said second pawl.

12, Apparatus for the intermittent advancement of metal strip stock and the like, comprising a gripping and feeding device reciprocable through strip advancement and return strokes, and a .stripadvancement arresting device operated by impact pressure delivered by said gripping-and'feedingrdeviee adjacent to the end of its strip advancement stroke.

References Cited in the file of this patent UNITED STATES PATENTS 723,400 MacKenzi Mar. 24, 1903 1,124,577 Allen Jan. 12, 1915 1,220,574 Waltz Mar. 27, 1917 1,693,728 Rainsford Dec. 4, 1928 1,749,505 Pierce Mar. 4, 1930 2,096,073 Spencer Oct. 19, 1937