Method And Apparatus For Necking And Flanging Can Bodies

Abstract

A cylindrical can body is positioned between axially aligned necking and flanging dies which are forced together so that the dies force the can body ends completely into and onto the dies to neck and flange the can body ends. The dies are then pulled apart, with the can body being first clamped to the flanging die to pull the necked end of the can body from the necking die. The can body is gripped and held between its ends to allow the flanging die to be then pulled off the flanged end of the can body.

Description

BACKGROUND OF THE INVENTION

This invention relates to the manufacture of "three-piece" metal cans, i.e., cans having a can body made from a rectangular sheet of metal rolled into a cylinder with the edges being joined by a soldered lap extending the length of the cylinder, and two can ends which are thereafter secured to the can body by rolling operations.

In recent years it has been found desirable to form a cylindrical neck of reduced diameter on one end of the can body. In subsequent operations a can end of reduced diameter is fitted to the necked end of the can body and secured thereto by a rolling operation which forms an end rim of a diameter less than the diameter of the can body. The other end of the can body is flanged outwardly, a normal sized can end being then fitted thereto, the edges of the can end and can body flange being rolled to form a rim whose internal diameter is just slightly greater than the reduced-diameter rim of the necked end. Such construction enables a slightly smaller can end to be used on one end of the can, resulting in substantial material savings when great numbers of cans are produced. Further, such construction enables the filled cans to be stacked on top of each other with the reduced-diameter end rim of one can nested in the normal-diameter end of the necked can. This nesting is advantageous in stores wherein cans are stacked on open shelves and also in manufacturing operations wherein two cans are to be joined together and merchandised as a single unit.

In typical can body-forming machines, a can body gripper grips the exterior of a can between its ends and holds the can in axial alignment with a pair of end-forming dies, the dies being forced onto the end of the can to produce the desired shape on the can end. After forming, the dies are pulled off the can ends so that the can body is free to be moved to the next station of operations. In machines wherein the same operation is performed at both ends of the can, i.e., if the can body is double-flanged or double-necked, little difficulty is experienced in stripping the dies from the can ends, since the pull exerted by one retracting die on the can body is balanced by the opposite pull exerted on the can body by the oppositely retracting die. Even if there is some small unbalance in forces on the can body as the dies are pulled therefrom, the can body gripper can hold the can body against axial movement. However, a severe problem exists if it is desired to simultaneously neck one end of a can body while flanging the other end. With a typical end-flanging die there is very little frictional resistance between the flanging die and the flanged can end thereon, and accordingly very little force is required to hold the can against axial movement as the flanging die is stripped therefrom. On the other hand, when a can body end is forced into a necking die and a cylindrical neck is formed thereon there is a considerable amount of frictional engagement between the necked end and necking die and a substantial force will be required to strip the necked end from the die. Forces in the order of 25 pounds pull are often encountered in stripping necking dies from cans. When both ends are necked, the high extraction force of one die is balanced by the extraction force of the other die. If one end is necked and the other end is flanged, the extraction of the flanging die provides substantially no pull to the can to hold the can against movement with the necking die as the necking die is retracted. As a consequence, substantially the entire force on the can body to hold it against axial movement with the retracting necking die must be provided by the can gripper. Since the can gripper forces radially inwardly on the unsupported middle of the can, application of sufficient force to the gripper to hold the can as the necking die is stripped therefrom will result in a buckling of the can body.

SUMMARY OF THE INVENTION

The main object of the invention is to provide an end-forming machine for can bodies suitable for high-speed, high-capacity operation, e.g., in order of 600 can per minute, wherein one end of a can body is necked and the other end is flanged and wherein the can body is firmly gripped, without danger of deformation thereof, as the can body is stripped from the necking die.

This object is achieved by forming an outwardly projecting flange on one end of the can body as the other end is being necked, and by then clamping the flanged end of the can firmly to the flanging die adjacent the flange. Since the can body end is fully backed and supported by the pilot portion of the flanging die, the clamping force on the can end can be very substantial without fear of damage or deformation to the can body. With the can body so held, the dies are forced apart to strip the can body from the Thus, for this stripping operation, the grip on the can body is, in effect, shifted from the can body gripper to the flanging die. After the can body has been stripped from the necking die, either completely or sufficiently so that little force is required on the can to hold it against final stripping, the can body is unclamped from the flanging die, the can is held by the can body gripper and the flanging die is stripped from the flanged end. With both dies stripped from the can, the can body is free to be discharged from the can body gripper.

Other objects and advantages will become apparent in the course of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings forming a part of this application and in which like parts are designated by like reference numerals throughout the same,

FIG. 1 is a longitudinal sectional view of a multi-head turret machine for flanging and necking a can body, with only one of the heads of the machine being shown;

FIG. 2 is a longitudinal sectional view of the necking die of FIG. 1, illustrating the relation of the elements thereof prior to insertion of the necking die onto the end of a can body;

FIG. 3 is a view as in FIG. 2, showing the relation of the necking die elements when the die is fully inserted into a can body end;

FIG. 4 is a transverse sectional view of the can body gripper of FIG. 1;

FIG. 5 is a longitudinal sectional view of the flanging die of FIG. 1;

FIG. 6 is a view, partly in section, of the flanging die, taken on line 5--5 of FIG. 5;

FIG. 7 is a chart illustrating the time sequence of operation of the necking die, can body gripper and flanging die of FIG. 1;

FIG. 8 is a generally diagrammatic illustration of the machine, showing can entry and discharge and the position of the head at various stages of the necking and flanging operations.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, and in particular to FIG. 1 thereof, wherein one head of a multi-head turret-type machine is shown, the machine 10 comprises opposed bell housing members 11 and 12 each mounted in stationary relation to a suitable platform by conventional means (not shown). A hollow drive shaft 13 extends axially through the stationary bell housings, the shaft being rotatably journaled at either end in bronze bushings 14, and having a drive gear 15 keyed to one end thereof so that the shaft may be rotated in the bell housings by means of a conventional drive source (not shown).

Fixed to shaft 13, within bell housing 11, is a support member 16 having spaced-apart yokes 17 and 18 thereon to support the necking die shaft 19 for axial sliding movement therein, the axis of shaft 19 being parallel to the axis of drive shaft 13. Necking die shaft 19 is square, or otherwise non-circular, in cross section and yokes 17 and 18 are correspondingly shaped so that the necking die cannot rotate about its axis in the yokes. The end of necking die shaft 19 towards the center of the machine comprises a necking die holder 20 which carries the necking die 21 thereon. Secured to the other end of necking die shaft 19 is a cam follower roller 22 which rolls in cam track 23 formed in the outer surface of cam ring 24 which is fixed to bell housing 11. The cam ring 24 extends completely around shaft 13, so that as the main drive shaft 13 rotates in the housing, roller 22 will be moved along the stationary cam track 23, with the side walls of the track acting upon roller 22 to impart the desired reciprocal axial movement to the necking die shaft 19.

A corresponding flanging die shaft 26 is disposed inside bell housing 12 and is mounted in yokes 27 and 28 for axial movement as cam follower roller 29 is moved along stationary cam track 30. The end of flanging die shaft 26 towards the center of the machine comprises a die holder 31 which has flanging die 32 secured thereto, flanging die 32 and necking die 21 being coaxial. Flanging die holder 31 also has can body clamps 33 mounted thereon.

Secured to main drive shaft 13, centrally thereof, is a can body gripper 34, adapted to grip and hold a can body 35 between and in coaxial relation to the necking and flanging dies.

Air under pressure for operation of the necking die, flanging die clamps and can body gripper is supplied to the machine as follows. Low pressure air from air source 36 passes through a rotating union 37 at the drive end of the machine and into conduit 38 within drive shaft 13. Conduit 38 extends through an opening in the drive shaft up to valve 39. Conduit 40 then continues from valve 39 back within drive shaft 13, conduit 40 being brought out and attached to passage 41 in base 42 of the can body gripper 34 which leads to the piston cylinder 43 in base 42. Valve 39 is a conventional two-way valve having a depressible valve operator 44 actuated by screw 45 mounted for axial movement on necking die shaft 19. When valve operator 44 is depressed, FIG. 1, valve 39 connects conduits 38 and 40 so that low-pressure air is delivered to the can body gripper 34. When the necking die shaft 19 has moved slightly to the left and screw 45 has moved therewith to relesase valve operator 44, valve 39 will close conduit 38 to flow therethrough and will open conduit 40 to atmospheres so that air pressure in the can body gripper will then be vented.

High-pressure air from source 45 is delivered through rotating union 46 at the free end of the machine and into conduit 47 within drive shaft 13, through tee connection 48, and conduit 49 to valve 50. A flexible conduit 51 extends from valve 50 to necking die shaft 19, conduit 51 being then connected to the internal passage 52 which extends to the necking die 21. Valve 50 on plate 53, which is fixed to drive shaft 13, has a cam follower roller 54 thereon for actuation of valve 50, roller 54 being in rolling engagement with cam surface 55 on the cam ring 56 fixed to bell housing 11. Valve 50 and the actuator therefore are conventional; when roller 54 is allowed by cam surface 55 to move outwardly, valve 50 connects conduits 49 and 51 so that high-pressure air is delivered to the necking die. When cam surface 55 forces roller 54 inwardly, valve 50 is actuated to close off conduit 49 and to vent conduit 51 to atmosphere.

Similarly, high-pressure air is delivered from the tee connection 48 through conduit 59 to valve 60 and then by flexible conduit 61 to the internal passage 62 in th flanging die shaft 26. In like manner, the interengagement of cam follower roller 63 and cam surface 64 will operate valve 60 to either connect conduits 59 and 61, or to shut off conduit 59 and ven conduit 61 to atmosphere.

Although the necking die may be of any construction which will form a reduced-diameter neck on a can body end, preferably the necking die 21 is of the type more fully shown and described in my copending application, Ser. No. 320,895, filed Jan. 4, 1973 and entitled "Pilot Construction for Necking Die Assembly", the description of which is incorporated herein by reference.

In brief, necking die 21 comprises an outer die member 70 having an inwardly facing cylindrical die surface 71 approximately the same diameter as the outside diameter of can 35, an inwardly tapered die surface 72 which forms the shoulder on the can body and a reduced-diameter cylindrical die surface 73 which forms the cylindrical reduced-diameter neck on the can body. As a can body end is forced into the die, the can body end will engage and slide along the inwardly tapered surface 72 and be deformed inwardly thereby, the can end then coming into engagment with the shoulder 74 on the internal polit 75. Continued insertion of the can body into the die causes pilot 75 to be pushed axially within the die assembly, against the force of spring 76, with the cylindrical, reduced-diameter neck on the can being formed between die surface 73 and the outer surface 77 of the pilot segments 78 carried by the pilot (FIG. 3). As the can body and necking die are then pulled apart, the pilot 75 is forced back to its original position (FIG. 2) by spring 76 to assist in the initial stripping of the cam from the die.

Necking die 21 is securely mounted on necking die holder 20 by screw 79, pin 80 being used to prevent rotation of die 21 on the die holder. Air under pressure from necking die shaft passage 52 passes through the axial passage through mounting screw 79 and to the interior of the flexible sleeve 81. When this sleeve is pressurized, it forces all of the pilot segments 78 outwardly to provide a firm support for the can body end as it is being necked while allowing one or more of the die segments to yield inwardly as the can lap 82 is inserted into the die assembly.

Referring now to FIGS. 1 and 4, the can body gripper 34 includes a radially extending web 85 secured to the can body gripper base 42, on which are mounted two gripper arms 86 and 87, gripper arm 86 being rigidly mounted on web 85 while gripper arm 87 is pivotally mounted thereon for rotation about the axis of pivot pin 88. Piston 89, slidable in bore 90 in base 42, is outwardly biased by spring 91 and engages pivotal gripper arm 87 to force it in a counterclockwise direction (FIG. 4) so that the arcuate surfaces 86a and 87a of the gripper arms will grip a can body 35 therebetween. Piston 92, in cylinder 43, is engageable with the pivotal gripper arm 87 on the other side of pivot pin 88. When air under pressure is introduced through conduit 40 and base passage 41 into cylinder 43, piston 92 will be forced outwardly, causing the gripper arm 87 to pivot in a clockwise direction against the bias of spring 91 and thus release the grip on the can. In addition, as the gripper arm 87 moves in a clockwise direction, the edge 87b of the arcuate gripper surface 87a will move outwardly, away from the axis of drive shaft 13, to eject the can body 35 from the gripper arms.

Referring now to FIGS. 5 and 6, the flanging die 32 comprises an outer, inwardly tapered guide surface 101, a cylindrical, outwardly facing pilot surface 102 of a diameter substantially equal to but very slightly less than the inner diameter of the can body 35, and an outwardly curved flanging surface 103. The flanging die 32 is received within die shoe 104, the latter having a shoulder 105 at the end of the flanging surface 103 to limit the relative movement of a can body end onto the flanging die. Die shoe 104 in turn rests against core 106, and the entire flanging die assembly is secured to flanging die holder 31 by means of screw 107. Core 106 is longitudinally slotted, at 108 and 109, to receive clamp arms 110 therein, each clamp arm being pivotally mounted between its ends on core 106 by pivot pin 111, and provided with a clamp shoe 112 on one end thereof. Each clamp shoe has an arcuate clamping surface 113 of a curvature complementary to the outer surface of the can body being flanged, the clamp shoe being adapted to engage the can body adjacent the flange formed thereon and to clamp the can body firmly to the cylindircal pilot surface 102 of the flanging die. Each clamp arm is biased outwardly by spring 114 the clamp arms having sufficient pivotal movement about pins 111 so that the clamp surfaces 113 can move outwardly beyond the die shoe shoulder 105. Core 106 is radially bored at 116 and 117 to receive pistons 118 therein, each piston being engageable with a clamp arm on the side of pivot pin 111 opposite to spring 114. Screw 107 is provided with an axial passage 119 and lateral ports 120 so that air under pressure can pass from the internal passage 61 of flanging die shaft 26 through screw 107 and be exerted against the inner surfaces of pistons 118. When air under pressure is exerted against the pistons, they will move the clamp arms against the bias of springs 114 so that the clamping surfaces 113 move into clamping engagement with a can body on the flanging die. Release of air pressure will then allow springs 114 to pivot the clamp shoes 112 away from the flanging die. Preferably, the clamping surfaces 113 are made of a plastic material, such as Delrin, so that the can body will not be scratched or marred by the clamping surfaces.

OPERATION

The operation of the machine is best described with reference to FIGS. 7 and 8. a rotating can entrance make-up conveyor 125, having a plurality of magnetic can-holding pockets 126 equal in number to the number of heads on machine 10 and rotating in synchronism therewith, brings a can 35 into registration with can body gripper 34 when the latter is at position A, approximately 15.degree. before vertical. At this time, and as shown in FIG. 7, the necking and flanging dies have been moved by cam follower rollers 22 and 20 to their fully retracted positions, as shown in FIG. 1. With the necking die retracted, valve 40 has been actuated to supply air under pressure to the can body gripper 34 so that the pivotal arm has been moved to open, or ungripped, position. Cam surface 55 has caused cam follower roller 56 to actuate valve 50 so that high-pressure air is present in the necking die pilot 75, forcing the pilot segments 78 outwardly. Cam surface 64 has caused cam follower roller 63 to actuate valve 60 to vent the flanging die core allowing the springs 114 to maintain the clamp shoes 112 outwardly from the flanging die. As the main shaft 13 and the make-up conveyor 125 continue to rotate, stationary stripper arm 127 strips the cam body from pocket 126, the can body being held in the can body gripper by the spring-pressed can retainer 128.

When the can body has reached position B, cam tracks 23 and 30 begin to move the necking and flanging dies simultaneously towards each other. At position C, the necking die shaft has moved sufficiently far to allow valve 40 to vent the can body gripper cylinder 43, in turn allowing spring 91 to move gripper arm 87 into gripping engagement with the can body so that the can body is held in axial alignment with the necking and flanging dies.

At position D the necking flanging dies have been brought sufficiently close together so that one end of the can body starts into the necking die and the flanging die starts into the other end of the can body. At position E, one end of the can body is at the beginning of the inwardly tapered die surface 72 of the necking die while the other end of the can body is at the beginning of the outwardly tapered die surface 103 of the flanging die.

During the travel from positions E to F, the can body ends are simultaneously outwardly flanged and inwardly shouldered, with the force on the can body exerted by the flanging die being balanced by the force imposed on the can by the shouldering portion of the necking operation. At position F, the flanged end has come into engagement with shoulder 105 of the flanging die shoe 104 and the inwardly shouldered has come into engagement with shoulder 74 of the necking die pilot 75. At this point, the flanging die cam track 30 stops forward movement of the flanging die and holds the flanging die against axial movement. Also, at position F, cam surface 64 causes valve 60 to be actuated to supply air under pressure to pistons 118, causing the flanging die clamps to clamp firmly against the flanged can body.

During travel from position F to G, the necking die continues to move inwardly to form the cylindrical reduced-diameter neck on the can body. During this time axial thrust on the can body imposed by the necking die is fully opposed by the stationary flanging die, and no thrust is imposed on the can body gripper 34.

From G to H, the necking die dwells and at H begins to be retracted by its cam track 23, and to be pulled from the necked end of the can. Although the necking die pilot is biased by spring 76, and the air pressure in the pilot, to its original position which will aid in stripping the necked end of the can body from the necking die, considerable pull will be exerted on the can by the retracting necking die. This pull, however is fully opposed by the stationary flanging die which has the opposite end of the can body firmly clamped thereoto. As a consequence, there is no resultant axial force between the can body and the can body gripper 34 during this stripping operation from the necking die.

At position I, the necking die pilot is in its original outward position relative to the necking die assembly, and cam surface 55 causes valve 50 to be actuated to vent the necking die pilot, allowing the pilot segments to collapse inwardly. The necking die continues to retract, with the flanged end still being clamped to the flanging die until position J is reached wherein no part of the necked can is in engagement with the outer necking die 70. At this point, th air pressure on the flanging die pistons 118 is vented, allowing springs 114 to move the clamps to their outer position. Also, retraction of the flanging die is started.

Such pull as is exerted on the can body by the final stripping of the necked end from the collapsed necking die pilot is opposed by the pull exerted on the can body by stripping the flanging die therefrom. However, neither pull is of any great magnitude and little force is requred to be exerted on the can body by the can body gripper even if these pulling forces are unbalanced.

At positions K and L, respectively, the necking and flanging dies have been stripped from can body, the dies continuing to retract until they reach their original positions at position N.

Shortly before that and at position M, the necking die shaft causes screw 45 carried thereby to engage valve actuator 44, to supply air under pressure to the can body gripper. The force of the air on piston 92 kicks pivotal arm 87 to open position, ejecting the necked and flanged can body downwardly and outwardly to can chute 129.

At some subsequent position P, valve 50 is again actuated to pressure the interior of the necking die pilot. The elements are then carried back to piston A to pick up the next can body for the next cycle of operation.

Claims

Having thus described by invention, I claim:

1. Apparatus for simultaneously necking and flanging a can body comprising:

a necking die holder and flanging die holder mounted for movement towards and away from each other,

necking die means for forming a reduced-diameter neck on the end of a can body when a can body end is forced thereinto, said necking die means being carried by said necking die holder for movement therewith,

a flanging die carried by said flanging die holder, said flanging die having a cylindrical pilot portion adapted to be inserted into the end of a can body and an outwardly curved die surface at the end of said pilot portion for flaring the end of a can body to form an outwardly projecting end flange thereon, said necking die means and said flanging die being coaxial and spaced from each other,

means for gripping the exterior of a can body between the ends thereof and for holding said can body coaxial with said necking die means and said flanging die means,

means for forcing said necking die holder and flanging die holders towards and way from each other,

can body clamp means having clamp surface thereon,

means mounting said can body clamp on said flanging die holder for movement therewith, and for movement thereon whereby said clamp surface of said clamp moves towards and away from engagement with said cylindrical pilot portion of said flanging die adjacent the outwardly curved die surface thereof, means for forcing said clamp surface towards said cylindrical portion of said flanging die and for moving said clamp surface away therefrom.

2. Apparatus as set forth in claim 1 wherein said can body clamp means has two clamp surfaces diametrically opposite to each other relative to the axis of said flanging die, each clamp surface having an arcuate surface thereon, the curvature of said surfaces being complementary to the cylindrical pilot portion of said flanging die.

3. Apparatus as set forth in claim 2 wherein said clamp surfaces are made of plastic material.

4. Apparatus as set forth in claim 1, wherein said means for moving said clamp surface of said can body clamp away from the pilot portion of said flanging die comprises a spring and wherein said means for forcing said clamp surface of said can body clamp towards said pilot surface includes a piston engageable with said can body clamp and a controllable source of fluid under pressure for forcing said piston in a direction to move said can body clamp against the bias of said spring.

5. A method of necking one end of a can body with a necking die which forms a shoulder and reduced-diameter cylindrical neck on the end of a can body and flanging the other end of the can body with a flanging die which forms an outwardly extending flange on the end of a can body, the method comprising:

inserting the flanging die partially in one end of a can body and inserting the other end of the can body partially into the necking die,

forcing the dies relatively towards each other to insert the flanging die completely into the can body and to insert the can body completely into the necking die,

clamping the can body to the flanging die adjacent the flange formed on the can body,

forcing the dies relatively apart while maintaining the can body clamped to the flanging die during at least the intial stripping of the necked end of the can body from the necking die and then unclamping the can body from the flanging die,

gripping the exterior of the can body between its ends while relatively moving the gripped can and flanging die axially apart.

6. A method as set forth in claim 5 and further including holding said can body against axial movement during initial insertion of the flanging die in one end of the can body and initial insertion of the other end of the can body into the necking die, moving both of said dies towards each other to form the flange and shoulder simultaneously on the can body ends, holding said flanging die against axial movement after the can body has been flanged and moving said necking die axially towards said flanging die to form the neck on said can body, holding said flanging die against axial movement until the flanged can body end is unclamped therefrom and holding the can body against axial movement as the flanging die is moved axially therefrom.