Can Body Making Machine

Abstract

A can body making machine wherein a previously formed cup is wall-ironed and domed and then trimmed. The wall-ironing punch is actuated by an electric motor which drives a barrel cam. The primary ram, carrying the ironing punch is moved by a follower cooperating with a first track in the barrel cam. The secondary ram carrying a stripper punch is actuated by a follower cooperating with a second track in the barrel cam. The stripper punch telescopes within the ironing punch. The cam tracks are configured for a dwell of both punches at their fully retracted position to permit loading, and then to provide a constant speed movement of the two punches as a unit to engage a preformed cup and force it through wall-ironing tool pack and into a doming die. Upon completion of the doming operation the first track serves to quickly retract the ironing punch, while the second track holds the stripper punch stationary, to strip the formed can from the ironing punch, and thereafter returns the stripper punch quickly to its starting position. An indexing pocket conveyor transports the formed cans individually to a trimmer. A gravity chute feeds the preformed cups to the wall-ironing punch, and means are provided to re-round the cups for entry thereinto of the ironing punch.

Description

BRIEF SUMMARY OF THE INVENTION

In the manufacture of beverage cans, the industry has, to a great extent, gone to the two-piece can, wherein one piece includes the cylindrical wall and one end wall integral therewith, and the other piece is the other end wall which is attached after filling. In the manufacture of the first above-mentioned piece, one of the procedures includes the preforming of a cup having relatively thick walls and being relatively shallow. This may be accomplished by drawing or by impact extrusion. Regardless of how the cup has been formed, it is necessary to wall-iron it. For this operation the cup is entered by a punch element, and is forced thereby through a wall-ironing tool pack which may consist of one or more ironing rings. In this operation the wall thickness is reduced to the required final dimension, and the wall length is increased to somewhat more than the required final length. A bottom forming, or doming operation is then performed on the integral end, and finally the free end of the formed can is trimmed to the required length.

Wall ironing presses have, in the past, been either hydraulic presses or mechanical crank presses. Both types of presses entail certain disadvantages. While a uniform punch speed is essential for good wall ironing, and while hydraulic presses provide such uniform speed, they are too slow in operation for modern high speed production requirements. Crank presses on the other hand can be operated at high speeds, but they do not provide the uniform punch speed through the wall-ironing tool pack. Furthermore, mechanical presses must have an excessively long stroke to afford ample time for loading a new cup into position for wall-ironing. (Reference here is to back stroke after the formed can has been stripped from the punch.)

It is therefore the primary object of this invention to provide a press which combines uniform speed for the punch, high operating speed, and reduced stroke length. Ancillary to the above object, is the provision of a mechanical press, wherein the movement of the punch is produced by a cam and follower, with the cam rotating at constant speed continuously, and the cam groove being configured to provide the constant speed working stroke, a quick-return stroke, and appropriate dwells.

Another object of the invention is to provide for correct entry of the punch into the preformed cup, by providing a re-rounding arrangement in connection with the cup feed to insure that cups which may not be truly cylindrical will be brought to cylindrical shape to permit easy entry of the punch thereinto.

Yet another object of the invention is to increase still further the speed of production of can bodies, by incorporating a trimmer into the machine, and providing a special conveyor to transport formed cans, one by one, from the forming operation to the trimmer, without danger of jamming which would be likely to result from the fact that, after wall-ironing, the can bodies are of varying lengths.

Still another object of the invention resides in operating all elements thereof, including the cup feed, wall-ironing and doming, stripping, conveying to the trimmer, and the trimmer, in timed relation to each other, from a single source of motive power.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING

FIG. 1 is an isometric view of a machine according to the present invention.

FIG. 2 is a view partly in cross section on an enlarged scale taken axially of the machine.

FIG. 3 is an elevational view on a very much enlarged scale of the cup feeding and re-rounding mechanism; and

FIG. 4 is a greatly enlarged cross sectional view of the punches and doming die.

DETAILED DESCRIPTION

Basically the machine comprises the frame 10 and a conventional trimming machine generally indicated at 11 has been mechanically married to the forming machine with the advantages resulting therefrom which will be described in more detail hereinafter. A primary ram is shown at 12 and a secondary ram at 13. These rams slide in common guides indicated at 14. Each of these rams has a cam follower secured thereto at 12a and 13a respectively, as best seen in FIG. 2. The followers 12a and 13a cooperate with cam grooves 14 and 15 formed in the barrel cam 16. The barrel cam is mounted on the main shaft 17 and is driven through gearing generally indicated at 18 by an electric motor 19. The motor 19 drives the barrel cam continuously and at a constant speed. The grooves 14 and 15 are continuous and are configured to provide the desired movement of the rams 12 and 13 as will be described in more detail hereinafter.

A cam 20 having a groove 21 is mounted on the shaft 17 and it actuates the cup feeding and re-rounding mechanism which will be described in more detail hereinafter. Furthermore, by means of a sprocket 21 on the shaft 17 and a chain 22 the motor 19 also drives the shaft 23 which drives the conveyor 24 to be described hereinafter, and the trimmer 11 through suitable gearing.

The ram 12 carries the ironing punch 25 best seen in FIG. 4 and the ram 13 carries the stripper punch 26. The punches 25 and 26 occupy the condition of FIG. 4 during the working stroke of the ram. It will be seen that the stripper punch at its end carries the doming punch 27 and that it makes an air seal at the inner face 28 with the ironing punch. Air is admitted to the axial bore 29 at constant pressure and this air through the lateral passage 30 has access to the annular space 31. When the punches 25 and 26 separate for the stripping operation, the air seal at 28 is broken and the air pressure in the chamber 31 is now placed in communication with the interior of the formed can so that as the ironing punch is withdrawn, the ambient air pressure does not produce a collapse of the can as a result of a vacuum pulled by the withdrawal of the ironing punch. The ironing punch is cooled by coolant entering the passage 32 and through the passage 33 passing into the annular cylindrical space 34 whence it returns in the passage 35.

From the consideration of FIG. 4 it will be seen that the ironing punch and the stripper punch are coaxial and have telescoping engagement. Thus the stripper punch is connected by means of the tube 36 to the ram 13 while the ironing punch 25 is connected to the ram 12.

The configurations of the grooves 12a and 13a is such that at the extreme retracted position of the punches with the punches in the condition shown in FIG. 4, there is a dwell period to permit bringing a succeeding cup into position for wall-ironing and doming. Thereupon the two punches driven by the rams 12 and 13 move forward in a working stroke as a unit and enter a preformed cup and force the cup through a wall ironing tool pack indicated at 37 in FIG. 1. Immediately after forcing the preformed cup through the wall-ironing tool pack whereby the cup in wall-ironed into a can body, the combined punches 25 and 26 force the formed can against the female doming die 38 to produce the proper can end configuration. At this point, the working stroke of the two punches is complete. The cam groove 15 is then configured to provide a dwell for the doming punch 27 while the groove 14 is configured to provide a quick return for the wall ironing punch. Thus the wall ironing punch 25 is withdrawn while the doming punch 27 holds the can in position against the female doming die. As soon as the wall-ironing punch has cleared the can body, the groove 15 is configured to then provide a quick return for the stripper and doming punch to return it also to its finished position, whereupon the two punches will again assume the configuration of FIG. 4 and will dwell briefly while another can comes into position. It should be noted that while cam grooves have been shown and described, the cam tracks could as well be constituted by cam lobes.

In order to prevent damage to the apparatus in the event of a jam, the ironing punch is connected to the ram by means of a shear pin at 39 so that the pin will shear and permit the ram to pursue its movement without exerting further force on the punch.

A cup chute for preformed cups is indicated generally at 40 in FIG. 1, and the operation of the cup feeding mechanism will now be described in more detail with reference to FIG. 3. The feeding mechanism comprises a bell crank lever arrangement indicated generally at 41 and pivoted at 42. An ear 43 is pivotally connected to a plunger 44 on the end of which is a cam follower 45 riding in the cam groove 21. It will be understood that the groove 21 provides a dwell over a major portion of the rotation of the shaft 17 and then a relatively rapid movement of the bell crank lever 41 from its solid line position to its dotted line position. It will be noted that the member 41 has a substantially semi-circular concavity at 46 and a cup aligning element is provided at 47 having a semi-circular cavity 48. Thus the lowermost cup in the chute 40 rests on the bell crank 41 until the cam rocks the bell crank, whereupon the cup is moved from its solid line position to its broken line position and is in effect clamped between the semi-circular surfaces 46 and 48 and during this operation, if a cup is slightly oval or noncircular, it is re-rounded, so as to facilitate entry of the punches thereinto. In FIG. 2 a cup ready for entry of the punches thereinto is indicated at 49.

After a cup has been wall ironed and domed and the punches have been retracted, the cup falls into one of the pockets of the conveyor 24. This conveyor is driven as heretofore described through a step by step drive (not described) in timed relation to the action of the punches and carries the formed cans individually one step at a time from the forming position to the triming position. The reason for this individualized conveyor is that after wall-ironing, the formed cans will be of unequal length as a result of normal variations in basic material gauge. If such cans are collected in a chute or gravity runway, the differences in length can create trackage jams and line stoppages. By having the indexing pocket conveyor carrying individual containers one at a time from the wall ironer to the trimmer such stoppages are avoided. After the can bodies have been trimmed, they will all be of the same length and can be discharged into a conventional gravity chute. The trimmer per se does not form a part of this invention and is conventional in all respects.

From the foregoing description, it will be clear that by the present invention the advantage of speed of operation of a mechanical press is achieved while at the same time the advantage of constant speed of punches through the wall ironing tool pack which are characteristic of a hydraulic press is also obtained.

It will be clear that numerous modifications may be made without departing from the spirit of the invention. No limitations not specifically set forth in the claims to follow is intended nor should be implied.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A can body making machine having a primary ram carrying an ironing punch, and a secondary ram carrying a stripper punch, said stripper punch being telescopingly arranged within said ironing punch, the ends of said punches being complementary, and the end of said stripper punch constituting a male doming die, said punches being adapted, as a unit, to enter a preformed cup and force it through a wall ironing tool pack and into a female doming die, said rams operating in common guides and each ram having a cam follower, a barrel cam and power means to rotate said barrel cam continuously at constant speed, said barrel cam having a primary and a secondary cam track for engagement by said cam followers respectively, said tracks providing a dwell period at the fully retracted position of said rams, said cam tracks then providing a constant speed advance of both rams as a unit in a working stroke, said secondary cam track then providing a dwell for said stripper punch at the end of said working stroke, and said primary cam track providing a quick return for said ironing punch to fully retracted position, and said secondary cam track also providing a quick return to fully retracted position for said stripper punch starting as soon as said ironing punch has cleared the formed can body.

2. A machine according to claim 1, wherein said stripper punch has an internal bore subjected to a constant air pressure, and said stripper punch and ironing punch ends have cooperating surfaces providing an air seal, whereby when said ironing punch starts its return stroke said air seal is broken and said air pressure is applied to the interior of the formed can to avoid collapse thereof during stripping.

3. A machine according to claim 1, having a gravity chute for feeding pre-formed cups to the punches, said chute being laterally offset from the path of said punches, a cup transfer receiver, having a substantially semicircular cavity for a cup, disposed at the bottom of said chute, said receiver being mounted for oscillating movement toward the path of said punches, a cup locating member having a semicircular concave portion and positioned such that when said receiver oscillates to carry a cup thereto, the axis of said cup is aligned with said path, the complementary concavities of said receiver and member cooperating to re-round a cup prior to entry thereinto of said puches, and means to oscillate said receiver in timed relation to the stroke of said rams.

4. A machine according to claim 1 in combination with a trimmer, a conveyor disposed to carry formed cans from the path of said punches to said trimmer, said conveyor having a series of semi-cylindrical pockets, and means to advance said conveyor in a step-by-step manner in timed relation to the stroke of said rams, whereby to bring formed cans to said trimmer one at a time without jamming due to varying lengths thereof.

5. A machine according to claim 1 wherein said ironing punch is secured to said primary ram by means of a break-away connection, whereby to prevent damage to the machine in the event of a jam in front of the punch.