HK1002355B - Bodymaker - Google Patents

Description

Can making machine

Background

The present invention relates generally to can makers and, more particularly, to an improved construction that minimizes mixing of hydrostatic coolant applied to a tool at the forward end of a longitudinally reciprocating ram with bearing lubrication oil supporting the ram.

U.S. patent No.4,173,138 to r.m. main and e.paramaroff, entitled "can bodymaker with improved punch support and drive", on 11/6/1979, describes a metal working apparatus for forming a shorter cylindrical metal cup into a taller cylinder for a two-piece beverage container. Such can makers utilize hydrostatic bearings to support and guide a punch reciprocating in a horizontal direction. As the punch moves forward in its working stroke, the punch drives the cup through a stationary set of annular dies to reduce the thickness of the cylindrical side wall of the cup and increase its length. Mounted on the front end of the punch is a precision tool element which is inserted into the cup through the open rear end of the cup. To cool this tool element, a cooling fluid is applied near the front end of the punch.

Generally, the cooling fluid is a soluble oil fluid containing about 2% to 4% soluble oil, with the balance being water. The amount of soluble oil must be limited as much as possible because it mixes with hydrostatic bearing lubrication oil of the ram drive system when moving backward. That is, since the soluble oil contains 96% to 98% water, mixing with the hydrostatic bearing lubricating oil in the form of oil causes severe wear of the drive system and leads to failure. At the same time, the amount of hydrostatic bearing oil should be minimized because it moves forward and mixes with the soluble oil to affect the cooling effect of the soluble oil.

One prior art arrangement that minimizes the mixing of the coolant with the hydrostatic bearing lubrication employs an annular seal that includes cylindrical or stationary seals that are pressed against the cylindrical surface of the punch with very high pressure. Due to the high pressure engagement on the interface between the stationary seal and the fast moving punch cylindrical surface, the friction on this interface causes the temperature of the seal to become so high that the seal wears rapidly and must be replaced often. In addition, the high temperature at which the seal is exposed can have a detrimental effect on the trajectory of the punch. Fig. 10 shows here a prior art annular sealing device 11, which is coaxial with the reciprocating punch 12 and surrounds the side wall 13 of the punch. The sealing device 11 comprises a ring 14 and an O-spring 15. In cross-section, the ring 14 is generally rectangular and its rear surface 16 has a groove 17 filled with an O-spring 15. The O-spring is compressed into groove 17 to spread the rear corner portions of ring 14 into inner and outer annular flanges 18, 19. The sealing device 11 rests in an annular groove 21 of a stationary frame 20, the outer edge of the flange 19 resting against the frame 20 and the inner edge of the flange 18 resting against the outer cylindrical surface 13 of the punch 12. The broad interface between flange 18 and surface 13, coupled with the higher pressure between them, results in high friction forces that generate high temperatures when punch 12 reciprocates rapidly. As a result, the sealing device 11 overheats and is thus damaged very quickly.

Summary of The Invention

To overcome the above problems of the prior art, the prior art sealing devices have been replaced by so-called annular oil scrapers, each having a relatively thin inclined annular scraper which is self-biased into contact with the outer surface of the punch at a relatively low pressure. In practice, this pressure is so low that the temperature rise at the contact surface of the annular scraper with the punch is limited to a certain temperature, so that the damage to the annular scraper caused by the temperature rise is negligible. Moreover, at the contact surface of the blade with the punch, the wear of the blade is very slow, so that the effectiveness of the blade as an oil wiper can last several operations of the punch.

It is therefore a primary object of the present invention to provide a can bodymaker with an improved structure for reducing the amount of hydrostatic bearing lubrication oil entering the tool area at the front end of the ram, and also reducing the amount of tool coolant that enters the hydrostatic bearings supporting the ram during reciprocation of the ram.

It is a further object of the present invention to provide a can bodymaker of the type wherein friction between the outer surface of the ram and the elements which limit mixing of hydrostatic bearing oil and coolant is reduced.

It is a further object of the present invention to provide a can bodymaker of the type wherein the annular oil wiper has an annular thin flight in light contact with the ram to limit mixing of the cooling fluid with the hydrostatic bearing oil.

It is a further object of the present invention to provide a can bodymaker of a construction which provides a reduction in operating temperature and wear of the components of the oil scraping device which prevents mixing of the coolant with the hydrostatic bearing lubricating oil.

Brief Description of Drawings

FIG. 1 is a perspective view of a can bodymaker designed in accordance with the teachings of the present invention to limit mixing of tool coolant with hydrostatic bearing lubrication oil.

Fig. 2 and 3 are schematic views of the can bodymaker of fig. 1 shown in the direction of arrows 2-2 in fig. 1. The punch of the can bodymaker is in the last position in fig. 2 in which it has completed its return stroke, the punch is in the foremost position in fig. 3 in which it has completed its working stroke, and the free end of the punch or the tool carrying end of the punch is on the right in fig. 2 and 3.

Fig. 4 is a partial side view of the punch reciprocating mechanism.

Fig. 5 is a partial side sectional view of the punch and its connection to the punch drive mechanism, with the tool carrying end of the punch on the left in fig. 5.

Fig. 6 is an enlarged vertical cross-sectional view of the front hydrostatic bearing and punch oil scraper, with the tool carrying end of the punch in fig. 6 to the left.

Fig. 7 is a rear view of the punch oil scraper shown in the direction of arrows 7-7 in fig. 6.

Fig. 8 is a front view of the punch oil scraper shown in the direction of arrows 8-8 in fig. 6.

FIG. 9 is a partial perspective view of one of the annular oil scrapers used to implement the subject invention.

FIG. 10 is a partial vertical cross-sectional view of a prior art sealing arrangement for limiting hydrostatic bearing lubrication from mixing with cooling fluid for a tool carried by a punch.

Detailed Description

Referring to the drawings and more particularly to FIGS. 1 through 5, the vast majority can also be found in the aforementioned U.S. patent No.4,173,138, the description of which is incorporated herein by reference.

In a manner well known in the art of making two-piece metal beverage containers, a can bodymaker (15) forms a blank 16 (fig. 2) in the form of a shallow metal cup supplied from a feeder 17 into an elongated can body 18 (fig. 3) which drops downwardly into a take-off 19. This is achieved by means of a reciprocating drive 20 which moves a horizontally arranged hollow punch 25 in the working stroke from the rearmost position in fig. 2 in the longitudinal direction to the foremost position in fig. 3. In this foremost position the punch 25 is moved in the reverse direction and the punch 25 is moved in a return stroke to the rearmost position in fig. 2. During the forward stroke of the punch, the tool element 61 at the forward end of the punch 25 enters the cup through the open end of the cup 16 and passes the rear cup 16 through the annular die assembly 22. This operation reduces the diameter of the cup or blank 16 and the thickness of the side walls while simultaneously stretching the side walls to form the can body 18. As the ram 25 moves forward and backward, it is supported by spaced apart fixed rear and front hydrostatic bearings 23 and 24, respectively. For reasons described below, the ram 25 will pass through the oil scraper 60, which is disposed near the front of the front hydrostatic bearing 24.

Drive mechanism 20 is coupled to the rear of ram 25 by a plain bearing assembly 35 (fig. 5). The slide bearing assembly is pivotally coupled at 52 to the forward end of the drive rod 36, while the rearward end of the drive rod 36 is pivotally coupled at 51 to the upper free end of the drive arm 37, while the lower end of the drive arm 37 is fixed to the frame at a pivot center 38 (fig. 4) for oscillation about the pivot center. The arm 37 is driven by an actuator arm 39, one end of the arm 39 being coupled by a pivot 41 to a crank arm 43, and the other end of the arm 39 being pivotally coupled by a pivot 42 to the drive arm 37 at a point intermediate its ends. Pivot 41 is located at the free end of a crank arm 43, and crank arm 43 extends radially outwardly from and is keyed for rotation on a spindle 44. The bull gear 40 is also keyed to the main shaft 44 for rotation therewith and meshes with a pinion gear 46, the pinion gear 46 being keyed to a drive shaft 47, and the drive shaft 47 being driven by an electric motor 48 through a speed change transmission 49.

To ensure that the can 18 does not move rearwardly with the punch 25, compressed air is fed into the interior of the punch 25 through appropriate passages of the coupling 35 at the rear end of the punch 25 and the compressed air is vented into the interior of the can 18 through a front opening 152 (fig. 5) of the tool element 61 to facilitate removal of the can from the front end of the punch 25. For this purpose, the coupling device 35 is provided with a passage having a coupled axial portion 56 and a transverse portion 57 with a stub 58 extending therefrom. An elastic hose 59 extending from the short tube 58 is operatively coupled to a canister dump control valve (not shown).

The purpose of the scraper 60 shown in fig. 6-8 is to prevent the hydrostatic bearing oil 62 of the hydrostatic bearing units 23, 24 from flowing in front of the front hydrostatic bearing unit 24 to the region of the punch 25 where the coolant 63 is added to the punch 25 to cool the tool element 61. The oil scraper 60 also serves to prevent the coolant 63 from flowing to the rear and mixing with the hydrostatic bearing oil 62 in the hydrostatic bearing device 24.

More specifically, bearing assembly 24 includes an inner cylinder 64 that fits closely within a bore 66 of an outer bracket 65. The ram 25 passes axially through the inner cylinder 64 with a narrow gap 67 formed therebetween to provide a passage for hydrostatic bearing lubrication oil 62, which oil 62 is supplied to the bearing assembly 24 at high pressure through four inlets 68. Each inlet is coupled by a separate channel 69 in the bracket 65 to a separate chamber 71, the chamber 71 passing laterally through the cylinder 64. There are four cavities 71 equally spaced around the outer surface 70 of the punch 25 and communicating with the gap 67. Four axial passages 72 at the rear of the bearing assembly 24 provide a direct return path for the hydrostatic bearing lubrication oil 62 from the rear of the gap 67 to an oil sump (not shown). At a point just after the front end of the cylinder 64, the interior of the cylinder 64 is provided with a circular relief groove 73 which is connected to the passage 72 by a separate oil return 74, the oil return 74 extending axially within the wall of the cylinder 64.

The oil scraper 60 arranged immediately before the bearing arrangement 24 comprises a main ring 75 which is fastened to a stationary bracket part 76 with four bolts 77. The rear ring 78 is secured to the rear of the main ring 75 with four bolts 79, while the front ring 81 is secured to the front of the main ring 75 with four bolts 82. The main ring 75 supports oil scrapers 84,85 and the rear ring 78 supports oil scraper 83, the oil scraper 84 being located between the oil scrapers 83, 85. The circular inner surface 111 forms a shallow concave opening in the rear of the primary ring 75 which receives the forward end of the outer carrier 65 and thereby axially centers the bearing 24 and the central open portion of the oil scraper 60.

Each of the oil scrapers 83 to 85 has generally the same size and shape, and the shape thereof is shown with reference to FIGS. 6 and 9, and the oil scraper 85 includes a metal shell 86 and an elastic annular oil scraper 87 bonded to the shell 86. The shell 86 is L-shaped in cross-section and is pressed into an operative position against the annular shoulder 112 in front of the primary ring 75. The annular oil wiper 87a includes a generally rectangular main section 87 and a relatively thin flexible annular flight 89 extending radially inwardly from a corner 91 of the main section 87, the corner 91 being diagonally opposite the intersection 88 between the annular oil wiper surfaces 88a, 88b, the surfaces 88a and 88b abutting the shell 86. The scraper 89 of the oil scraper 85 is inclined radially inward and forward from the corner 91. The thickness of the blade 89 gradually tapers from the root of its thick end or corner 91 to the free edge 90. The scrapers 89 of the oil scrapers 83 and 84 are each inclined radially inward and rearward.

The coolant 63 is supplied to the inlet 92 of the main ring 75 and flows through the connecting passage portion 94 of the rings 75 and 81 into the annular groove 93 on the inner surface of the front ring 81. The radially inner recess 93 is open and faces the punch surface 70, thus allowing the coolant 63 to impinge on the punch surface 70. The coolant 63 flowing forward along the surface 70 to the front of the ring 81 is returned to another oil sump (not shown). The coolant 63 flowing backwards along the surface 70 is scraped off here by the free edge 90 of the oil scraper 85, flows through the annular space 96 and the passages 97 in the ring 81 to the front of the ring 81 and into the last mentioned oil sump.

The hydraulic oil 62 flows along the punch surface 70 and before the ridge 98 at the rear end of the inner surface of the cylinder 64 (fig. 6), then through a portion of the labyrinth seal 99 including the nine through holes of the rear ring 78 and the axial passage 101 of the outer housing 65, and into the same reservoir that also receives the hydraulic oil 62 from the passage 74. The ridge 98 is relatively short in a direction parallel to the longitudinal axis of the punch 25 and is closely spaced to the outer surface 70 of the punch 25. This narrow spacing between ridge 98 and surface 70 allows a majority of the hydraulic oil 62 to flow forward from chamber 71 into overflow channel 73.

The annular space 102 between the back-to-back annular oil scrapers 84,85 is part of the relief passage which serves to contain any leaking hydraulic oil 62 before flowing to the annular oil scrapers 84 and also to contain any leaking cooling liquid 63 after flowing to the annular oil scrapers 85. The leaking part of the hydraulic oil 62 and/or the cooling liquid 63 is discharged as waste through the outlet channel 103. This process is facilitated by the introduction of compressed air through the inlet passage 104. Both passages 103 and 104 extend radially from the outer edge of the primary ring 75 to the space 102.

The annular scraper 89 is extremely flexible so that the free edge 90 scrapes liquid from the punch surface 70 when the punch surface 70 moves towards the surface of the scraper 89 at an obtuse angle thereto. The scraper 89 is self-biased against the punch surface 70 with minimal temperature rise due to minimal pressure on the contact surface between the scraper 89 and the surface 70 to reduce friction on the contact surface. The life of the annular oil wiper 87 is thus extended, so that an unstable movement path along the punch centerline is avoided. For a 2.50 inch diameter punch, the temperature rise at the punch/wiper interface is limited to 4 ° F when the punch is operated at 400 rpm. The desired improvement is achieved by limiting the pressure at the interface between each free edge 90 and the punch surface 70 to a level that reduces the friction between the free edge 90 and the punch surface 70 by about 85% as compared to the prior art arrangement shown in figure 10.

When the ram 25 is moved forward, scraping hydraulic oil 62 from the surface 70 with two rearwardly inclined scrapers 83, 84, it has been found that satisfactory operation can be achieved over an extended period of time even with only one of the scrapers 83, 84. Another oil scraper 85 scrapes the coolant 63 from the surface 70 when the ram 25 moves backward.

While the invention has been described with respect to specific embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.

Claims (18)

1. A bodymaker for forming a metal cup into an elongated can body, said bodymaker comprising:

an elongated punch having a front end and a cylindrical outer surface and a tool at said front end of said punch;

a hydrostatic bearing surrounding said punch and including pressurized hydraulic oil supporting said punch for horizontal longitudinal reciprocation, said hydraulic oil being applied at high pressure to said cylindrical outer surface of said punch;

first and second ring scrapers having aligned first and second bores, respectively, through which the punch projects;

a drive operatively engaged with said punch for imparting said reciprocating motion to said punch to cause said punch to move forward in a power stroke and then move backward in a return stroke;

a die set located in front of said bearing, said cups being driven through said die set one by said tool as said punch moves through a working stroke to form said cups into said cans;

a coolant impinging on the outer surface of the punch before the bearing; the method is characterized in that:

a groove arranged along the direction of a circular ring and positioned at the front end of the bearing, so as to relieve the high pressure of the hydraulic oil at the front end of the bearing;

and a ridge disposed in a circumferential direction, adjacent to the outer surface of the cylinder and in front of the groove, for limiting a thickness of the hydraulic oil remaining on the outer surface of the cylinder after the hydraulic oil passes through the groove and the ridge;

said first and second annular oil scrapers being self-biased into engagement with said cylindrical outer surface and including respective first and second flexible annular scrapers defining respective first and second bores, respectively;

said first and second flights having respective first and second radially inward free edges biased radially inward into engagement with said outer surface at low pressure;

the first flight is located before the second flight and both flights are located before the bearing;

the first scraper blade is inclined rearwardly and radially outwardly from the first free edge to facilitate scraping of coolant ahead of the first scraper blade from the outer surface in a forward direction as the ram moves rearwardly;

the second scraper is inclined forwardly and radially outwardly from the second free edge to facilitate scraping hydraulic fluid located behind the second scraper in a rearward direction from the outer surface as the ram moves forwardly.

2. A bodymaker as defined in claim 1, further including:

an overflow passage between said first and second flights for receiving and diverting from said second ring wiper any of said cooling fluid that may flow after said first flight;

the relief passage is also arranged to receive and divert away from the first annular oil wiper any hydraulic oil that may flow before the second scraper.

3. A can bodymaker as defined in claim 1 in which said first and second flights engage said cylindrical outer surface at a sufficiently low pressure to limit the temperature rise of said cylindrical outer surface engaged by said first and second flights to 4 ° F when said punch has an outside diameter of about 2.50 inches and is producing can bodies at a speed of about 400 pieces/minute with a working stroke of about 24 inches.

4. The can bodymaker as defined in claim 1 in which said first and second ring scrapers further include respective first and second ring bodies, each having a generally rectangular cross-section;

the first flight extends radially inward from a corner of the first ring and the second flight extends radially inward from a corner of the second ring.

5. The can bodymaker as defined in claim 1 in which said first and second annular oil scrapers are part of respective first and second oil scraping means which include respective first and second annular bodies;

the first and second oil scraping devices further comprise respective first and second annular frames, each generally L-shaped in cross-section;

the first and second annular bodies are bonded to the respective first and second annular frames;

the mounting ring has a central opening through which the punch passes;

said mounting ring having a front face and a rear face and cylindrical first and second inner surfaces, said first inner surface being located at said front face and said second inner surface being located at said rear face;

the first and second annular shelves frictionally engage the respective first and second inner surfaces to facilitate mounting of the oil wiper device to the mounting ring.

6. The can bodymaker as defined in claim 1 in which said first and second ring scrapers further include respective first and second ring bodies;

the first flight extending radially inward from the first annular body and the second flight extending radially inward from the second annular body;

the first and second scrapers and the corresponding first and second annular bodies form a whole; and

the first and second annular oil wipers are self-biased into engagement with the cylindrical outer surface.

7. A bodymaker as defined in claim 6 in which each of said first and second toroids is generally rectangular in cross-section; and

the first flight extends radially inward from a corner of the first ring and the second flight extends radially inward from a corner of the second ring.

8. The can bodymaker as defined in claim 7 in which said first and second ring oil scrapers are part of respective first and second oil scraping means;

the first and second oil scraping devices further comprise respective first and second annular frames, each generally L-shaped in cross-section;

the first and second annular bodies are bonded to the respective first and second annular frames;

the mounting ring has a central opening through which the punch passes;

said mounting ring having a front face and a rear face and cylindrical first and second inner surfaces, said first inner surface being located on said first face and said second inner surface being located on said rear face;

the first and second annular shelves frictionally engage the respective first and second inner surfaces to facilitate mounting the oil scraping device to the mounting ring.

9. The can bodymaker as defined in claim 6 in which the pressure between each of said first and second flights and said cylindrical outer surface is limited to a value such that the temperature rise of said outer surface engaged by said flights is about 4 ° F.

10. A bodymaker as defined in claim 1, further including a third annular oil wiper of substantially the same construction as said second annular oil wiper;

said third annular oil wiper comprises a third flexible annular scraper having a radially inward third free edge engaging said outer surface of said punch under low pressure;

the third scraper is inclined forwardly and radially outwardly from the third free edge to scrape hydraulic oil located behind the third scraper from the outer surface when the ram is moved forwardly.

11. A bodymaker as defined in claim 1 in which said hydrostatic bearing includes a plurality of aligned cavities around and facing said cylindrical outer surface, said pressurized hydraulic oil being discharged from said cavities to impinge upon said cylindrical outer surface and thereby support said ram;

an axially extending relatively short ridge surrounding and closely spaced from said cylindrical outer surface;

an overflow channel in front of said chamber and around said outer surface of said cylinder to receive a portion of said pressurized hydraulic oil flowing to the front of said chamber and to direct said pressurized hydraulic oil into an overflow passage; the short ridge is located behind the second flight and is disposed between the overflow trough and the second flight to affect pressurized hydraulic oil impinging on the second flight in front of the overflow trough.

12. A bodymaker as defined in claim 1 in which said first and second flighting plates are each tapered in thickness from their root radially outwardly to their said first and second free edges; the first and second free edges are defined by intersecting surfaces of the flights that form acute angles at the first and second free edges.

13. A bodymaker as defined in claim 3 in which said first and second flighting plates are each tapered in thickness from their root radially outwardly to their said first and second free edges; the first and second free edges are defined by intersecting surfaces of the flights that form acute angles at the first and second free edges.

14. A bodymaker as defined in claim 10 in which said first and second flighting plates are each tapered in thickness from their root radially outwardly to their said first and second free edges; the first and second free edges are defined by intersecting surfaces of the flights that form acute angles at the first and second free edges.

15. The can bodymaker as defined in claim 12 in which said first and second ring scrapers further include respective first and second ring bodies;

the first flight extending radially inward from the first annular body and the second flight extending radially inward from the second annular body;

the first and second scrapers and the corresponding first and second annular bodies form a whole;

each of said first and second toroids being generally rectangular in cross-section, said first flighting extending radially inwardly from a corner of said first toroids and said second flighting extending radially inwardly from a corner of said second toroids;

said first and second ring oil scrapers being part of respective first and second oil scraping means which also include respective first and second ring frames of generally L-shaped cross-section, said first and second rings being secured to the respective first and second ring frames;

the first annular shelf and the first annular flight are at diagonally opposite corners of the first annular body, and the second annular shelf and the second flight are at diagonally opposite corners of the second annular body.

16. A bodymaker as defined in claim 15, further including a mounting ring having a central opening through which said punch passes;

said mounting ring having a front face and a rear face and cylindrical first and second inner surfaces, said first inner surface being located at said front face and said second inner surface being located at said rear face;

the first and second annular shelves frictionally engage the respective first and second inner surfaces to facilitate mounting the oil scraping device to the mounting ring.

17. The can bodymaker as defined in claim 1 in which said first and second flights are biased radially inwardly in the absence of high pressure fluid and no high pressure fluid impinges on said first and second flights.

18. A bodymaker as defined in claim 1 in which no high pressure seal is disposed between said hydrostatic bearing and coolant.