US 3800578 A
Our disclosure relates to an apparatus for the vibratory forming of a sheet of material into a die. More specifically, this invention relates to a new and improved forming of metal sheet material by ultrasonic means.
Description (OCR text may contain errors)
United States Patent [1 Brennan 'et al.
[451 Apr. 2, 1974 1 SONIC STYLIZING APPARATUS  Inventors: James Norton Brennam'Americus Mitchell, both of Chicago, Ill.
 Assignee: Continental Can Company, Inc.,-
' New York, NY.
 Filed: June 1, 1972  Appl. No.: 258,597
 US. Cl 72/56, 72/63, 29/421  Int. Cl B2ld 26/06  Field of Search 72/56, 63; 29/421 l  References Cited UNITED STATES PATENTS 2,385,083 9/1945 Kemerer 72/56 3,222,902 Brejcha et al 72/56 3,557,590 l/l97l Erlandson 72/56 3,529,457 9/1970 Butler et al. 72/56 3,225,578 l2/l965 Krieger 72/56 Primary 1 Examiner Richard J. Herbst Attorney, Agent, or 'FirmAmericus Mitchell; Joseph E. Kerwin; William A. Dittmann 57 I ABSTRACT Our disclosure relates to an apparatus for the vibratory forming of a sheet of material into a die. More specifically, this invention relates to a new and improved forming of metal sheet material by ultrasonic means.
12 Claims, 5 Drawing Figures E PRESSURE SOURCE PATENIEBAPR 2 i874 SHEU 1 BF 3 5 PRESSURE SOURCE PRESSURE PAIENIEUAPR 2am I $800,578 sum 2 or 3 PRESLSURE SOURCE l SONIC S TYLIZING APPARATUS Prior to this time, a great deal of work has been done in the forming of metal sheets into female dies. In most of this forming machinery, a male die is made which is'an approximate fit into a female die. A sheet of metal is inserted between these dies and the male die is forced into the female die. When the male die is lifted away from the female die, the sheet-of metal has been formed approximately into the shape of the dies. Another apparatus is used with thin metal, paper and plastic. In this apparatus, a male die has been forced in a similar way into a rubberized universal female die. The male die is released and the sheet of formed material is removed. These methods are subject to certain disadvantages such as the fact that it is a one shot operation which produces thin spots, tears and wrinkles in the sheet of metal.
Hydraulic forming of cylindrical metal objects such formed into the female die. This method is subject to the same difficulties as mentioned above plus the fact that where the can body is electrohydraulically formed, the pressure is generated by a spark gap within the pressure transmitting medium. Then the bag must be emptied each time that a spark or are is formed. Such an apparatus is shown in the patent to R. W. Norin et al., U.S. Pat. No. 3,566,648 granted Mar. 2, 1971. This shows the speed of operation.
It is an object of this invention to provide a forming machine providing a simple, fast and efficient operation.
It is another object of this invention to provide a machine having a relatively simple design.
It is a final object of this invention to provide a machine which forms by means of a hydraulic static pressure with a dynamic pressure component added to the static pressure. I
In brief, our invention is to a method and means for forming sheet material. A sheet material is placed adjacent. a thin elastomeric membrane and on the other side of the elastomericmembrane is a liquid such as mineral oil or water inside a casing. Means are provided to supply a pressure which is composed of two components, a constant static average part on which is superposed an oscillatory pressure such as sonic waves. The pressure is applied to the mineral oil or water so that the latter provides in turn pressure against the sheet material. The static pressure alone is less than the forming pressure of the sheet of material. A transducer or horn is located in the liquid and'pressure is exerted against the rubber membrane which falls against'the' sheet of material. The transducer is started and it causes compressional waves in the liquid. These waves impinge against the elastomeric membrane which moves the sheet of material by small increments 1 into the female die to form the material into the female die. The horn or transducer is then stopped. The steady pressure source is cut off and at the same time,
a relief valve is opened so that the elastomeric mem- I sheet of material inserted and the operation may be performed again. An elastomeric membrane is desirable but the apparatus will operate using direct application of liquid to the sheet of mateiral. Metal, plastic and paper material may be formed using the principles of this invention.
Other objects, aspects and advantages in the present invention will be more fully understood by one skilled in the art when the following detailed description is considered in conjunction with the accompanying drawings, as follows:
FIG. 1 shows an elementary form of our invention being a device for forming sheet material into a die.
FIG. 2 shows an embodiment of the invention for more evenly exerting dynamic pressure against the sheet material to be formed.
FIG. 3 shows an embodiment of our invention for deep forming sheet material.
FIG. 4 shows an embodiment of our invention for forming a cylindrical tube into a female die by lateral pressure waves, and
.FIG. 5 shows a form of our invention for forming a cylindrical tube into a female die using longitudinal pressure waves.
A simple embodiment of our invention is shown in FIG. 1 where a pressure vessel 1 shown as a hollow cupshaped member 2 has two ports 3 and 4 into it. One port 3 is connected to a constant pressure source 5 by a conduit 6 and is adapted to supply the mineral oil, water or some other pressure transmitting means 7 to the interior of cup-shaped member 2.v The other port 4 is connected by a second conduit 8 to a pressure relief valve 9 and both valves 9 and 10 are operated by a single motor 11 which opens one of the valves at the same time that it closes the other. Across the open face of the cup is thin elastomeric membrane 12. At some point inside the metal cup 2, a transducer 13 (phantom lines) or horn 14 is inserted so that undulations or vibrations of a sonic or ultrasonic nature may be imparted to the liquid material 7 inside cup 2. Underneath cup 2 is shown a sheet-of material 15 which is to be formed and underneath the sheet of material is a female die 16. The cup-shaped member 2 may be pressed against the sheet of material 15 so that the edges of the sheet of material are not drawn into the die as the material is formed.
In operation, the sheet of material 15 on the female die 16 is pressed up against the pressure vessel 1 while the valve 10 into the source of constant pressure is open. A constant pressure which is less than the pressure necessary for forming the sheet of metal into the die isnot applied into the interior of the cup. After this pressure is applied, the transducer 13 or sonic horn 14 is turned on and dynamic undulating pressure is now applied against the elastomeric membrane 12 lying next to the sheet 15 of metal. This dynamic pressure gradually drives the sheet 15 of metal into the female die 16 to make a high fidelity imprint of the female die on the sheet of metal. A sonic absorber 17 is placed in theconduit 6 between the interior of the cup and the constant pressure source. The transducer is now turned off. The pressure source valve 10 is closed and the pressure relief valve 9 is opened allowing the elastomeric membrane to withdraw from the metal. The sheet of material and die are now moved away. The formed sheet is picked out of the die and a new sheet of metal is returned to the top of the die and the metal sheet and die are placed against the cup. The pressure relief valve 9 is closed and the constant pressure valve 10 is opened. The whole operation may now be repeated for a fresh uncoined sheet of metal.
The pressure waves from the horn are not appreciably reflected into the constant static pressure source and do not appreciably lower the steady pressure being applied to the rubber membrane and to the sheet of material but rather add to this pressure. The sonic absorber 17 is added in the conduit between the constant pressure source and the pressure vessel to avoid fluctuating changes of pressure from being reflected inside the constant pressure source. In any case, the pressure waves which till the pressure vessel when the transducer is turned on do notdiminish the pressure from the constant source but are additive onto this pressure inside the vessel or cup. Thus, there is a pulsating pressure against the elastomeric member and this pulsating pressure is applied to the sheet of material and tends to form it into the female die in a series ofsmall movements. As the sheet of material forms into the female die, the size of the actual cavity formed by the elastomeric membrane and the cup-shaped member increases in volume. However, this volume is taken up by more liquid coming in from the constant pressure source and there is no limit to the depth of forming into the female die.
In the preceding embodiment (FIG. 1) the horn, if used, may be a quarter wave length. The interior dimensions of the pressure vessel are usually a fraction of the wave length.
The liquid used as the pressure transmitting medium may be mineral oil, sorbotal, water or any other pressure transmitting material.
The embodiment shown in FIG. 2 operates on the same principle as the embodiment shown .in FIG. 1. However, the pressure vessel or cup 18 is made in the shape of a parabola. The waves which are reflected from the walls 19 forming the interior of the parabola proceed generally in a straight direction to be applied normal to thesurface of the rubber membrane 12 and to the sheet of material. This embodiment works best where the waves are short in relation to the dimensions of the interior ofthe pressure vessel.
Alternatively, the pressure vessel may be mounted below the sheet of material and all the pressure exerted through the liquid upwardly to force the sheet of material into the interstices of the female die. After forming, the transducer and steady pressure source are turned off and the formed sheet is removed. Another sheet may then be inserted between the pressure vessel and the female die.
The embodiment shown in FIG. 3 is designed particularly for deep drawing of sheet material and particularly for plastic material. The pressure vessel 1 is mounted substantially as shown in FIGS. 1 and 2. The
variation contemplated in this embodiment is that it is modified for deep drawing in that the female die 20 is a deep die and the elastomeric membrane 21 may be either flat as in FIGS. 1 and 2 or it may be shaped so as to be somewhat thicker in the middle than near its edges as shown in FIG. 3. This modification is particularly adapted for use with plastic materials and paper. The rate of drawing is controlled more nearly by the thickness of the elastomeric membrane rather than the plastic or paper material itself. Since the elastomeric membrane 21 is thicker in the middle, the middle is the last part to be drawn and the plastic sheet 22, for example, against which elastomeric membrane 21 is pressed elongates first around the edge 23 and then after an elongation is reached in this area, it elongates toward the center also. The elastomeric material, for example rubber, may be shaped to control the rate of the drawing. Further, by the use of an elastomeric material which is being vibrated, the plastic heats up under the impact of the vibratory force. This heating allows the plastic to flow. However, when the flow comes into contact with the metal of the deep die, then at that point, heat is drawn from the plastic and the plastic will solidify. Because elastomeric, materials as a class have a low constant of heat conductivity [rubber C=0.00045 calories/(sec) (cm (c/cm) and steel C=0.l l5 calories/(sec) (cm (c/cm)], the plastic tends to remain yielding and in a condition of plastic flow until such time as it finally presses and is stilled against the sides or bottom of the deep draw die. That is to say, when the plastic contacts the metal side of the deep draw die, friction between plastic and metal keeps the plastic from extending further and the heat from the plastic is transmitted to the side of the metal deep draw die and the plastic, at least that part which is adjacent to the deep draw die itself, does not flow further. However, the plastic sheet which is adjacent to the rubber only continues to be in a flowing state until it has been cooled by conduction to the metallic deep draw die.
The force of the steady state pressure is lateral as well as vertical and for this reason, the plastic which is cooled against the metal die tends to stay in place against the metal die. The elastomeric membrane 21 which is associated with the plastic is not forced to move further because it lies against the side of the deep die and the force from the vibratory energy source or transducer is applied in a vertical direction. When the elastomeric membrane is pressed against the vertical lateral wall of deep die 20, then most of the vibratory force passes by and is applied in the main against such elastomeric material as is still in a horizontal nonvertical orientation. Further, materials may be formed into a female die having deep undercuts as well as the shallow undercuts shown in FIGS. 3-5. This is because the plastic against the die hardens and does not work further but the rest of the material continues to work until it contacts the die, hardens and stops working. This working and cooling mechanism operates to a greater or less degree in all embodiments of our invention.
In this way, the rate of draw and the thickness of the plastic sides may be controlled by the contour of the elastomeric member. The elastomeric member 21 is under constant pressure from the steady state pressure in the pressure vessel and superimposed upon that is the vibratory pressure coming from the transducer. This vibratory pressure may be of any frequency suitable for the work at hand. An example of the variety of possible contours using a variable thickness elastomeric membrane is the case where the elastomeric For normal drawing, a smoothly variable thickness elastomeric membrane having a somewhat thickened center portion would be preferable. In any case, it is readily appreciated that the varying thickness of the elastomeric membrane varies the rate of draw of either plastic or paper which may be underneath. The elastomeric membrane may be contoured in most shapes. The general principle is that the thicker portions of the elastomer are the last to be formed as the plastic, paper or metal is forced into the deep die.
'FIG. 4 shows an ultrasonic stylizing device for forming cylindrical tubes, such as hollow tubular body blanks 25 for cans, into a cylindrical female die 26. This device has an elastomeric bag 27 filled with water, sorbotal or some other pressure transmitting medium 28. Because of a possibility of cavitation, this device may operate on the compression wave which is applied against the side of the can to form it into a female die having the design which is desired for stylizing; Because of the steady state pressure and because of the pulsating waves, the forming is gradual and in small steps.
The bag is filled with a liquid pressure transmitting medium 28 and located approximately centrally of the fresh can body for the stylized can body which has bag is an ultrasonic transducer 29 or horn. As shown in FIG. 4, this transducer may bearranged so that on vibrating, it gives out longitudinal waves i.e. waves which travel to right and left as shown in H0. 4. This transducer may be mounted by suitable rod means 30 on a base 31. The base 31 is shaped approximately as shown and has in its face at least two ports 32 and 33. One port 32 is used for admitting pressure transmitting material and the other port 33 is used for relief purposes. Underneath the bag (as shown in its assembled form) is a carrier 34 bywhich' the can body is moved.
- In operation, the carrier 34 is moved to a point underneath the bag 27 which is loosely dangling suspended from base 31. As the carrier 34 moves upward, it places the can body 25 about the bag 27 and has the upper edge of the can body against the circular jog 35 of the base. Thebag 27 slips easily into the can body and as the carriercomes to its uppermost position, the bag fits fairly tightly inside the can body. Now the female die 26 is moved from a withdrawn position (a matter of 1 or 2 centimeters) to the tight position against the can body 25. Under this pressure, quite probably the can body will start. However, if the can body does not start, then start pressure is exerted through one of the two ports 32 and 33 in the base 31. This start pressure eliminates any air between the female die and bag and also gives a rough form to the can as it penetrates into the female die.
The ultrasonic tranducer is then turned on and the stylized can is now formed and coined. If the transducer output is horizontal, then a transducer frequency of approximately 20,000 cycles per second is in order for a can 12 cm. long. A much lower frequency may be used so that the horn or transducer is coupled directly to the can wall. Each vibration imparts a small hammer blow to the sheet material of the wall. After coining takes place, a standing wave is set up to impart force to the can wall 25. The transducer is now stopped and the starting pressure is released. The female die 26 is now withdrawn a centimeter or two. The carrier '34 is removed and replaced with a been removed. a l V Alternatively, in FIGS. .4 and 5, the transducer may be turned laterally, or, in any case, the transducer or horn output is lateral so that its waves are set up between the top and bottom surfaces of the base and the carrier. In this case, the frequency will be lower, prabably on the order of 5,500 cycles per second if the can is about 6 /2 cm. in diameter. A lower frequency may be used to give a hammer effect.
A horn such as that shown in the patent to A. Balamuth, US. Pat. No. 3,088,343, ganted May 7, 1963 could be used in this embodiment.
Some of the advantages of our apparatus are stepwise forming, simplicity of apparatus, a dynamic pressure placedon a static liquid pressure and controllable forming of plastic, paper or metal materials.
The foregoing is a description of an illustrative embodiment of the invention, and it is applicants intention in the appended claims to cover all forms which fall within the scope of the invention.-
1. A forming head mechanism for shaping a body comprising: v
a substantially closed pressure vessel having a cavity and a port in the wall of said cavity;
an opening in the wall of said cavity for placing adjacent said body; I l
a pressure transmitting liquid filling said pressure vessel;
means for generating sonic pressure waves mounted inside of said pressure vessel;
a constant pressure source;
conduit means connecting said port to said constant pressure source; and
a sonic absorber in said conduit means for inhibiting the progress of sonic pressure waves from said pressure vessel to said constant pressure source through said conduit means and allowing the free flow of fluid through said conduit means.
2. A forming head mechanism for shaping a body as set forth in claim 1 in which said substantially closed pressure vessel comprises:
a cavity having walls in the shape of a parabola, and
means mounting said-pressure wave source at the focus of said parabola whereby most pressure waves from said pressure wave source are reflected from said walls in a direction such that their force impinges directly onto the body.
3. A forming head mechanism for shaping a body as set forth in claim 1 in which said means for generating pressure waves comprises:
4. A forming head mechanismfor shaping a body as set forth in claim 1 in which said means for generating pressure-waves comprise:
a horn which projects through the wall of said cavity.
5. A forming head mechanism for shaping a body as set forth in claim 1 in which said constant pressure source comprises:
a hydraulic accumulator having an output and an ina pressure generating means for developing constant pressure having an output; and
8. Apparatus for the pressure forming of a workpiece into a deep die comprising in combination:
a deep draw female die having a first opening in the face of said die with a deep cavity in said die, and
a forming device comprising;
a substantially closed pressure vessel having a cavity and a port in the wall of said cavity;
a second opening in the wall of said cavity of about the same size as said first opening for placing against said first opening of said die;
a pressure transmitting liquid filling said pressure vessel;
means for generating sonic pressure waves mounted inside of said pressure vessel;
a source of liquid under constant pressure;
conduit means connecting said port in said cavity to said source of constant liquid pressure;
a sonic absorber in said conduit means for inhibiting the progress of sonic pressure waves from said pressure vessel to said source of constant liquid pressure through said conduit means while allowing the free flow of liquid through said conduit means;
an elastomeric sheet of varying thickness fastened across said second opening in the wall of said substantially closed pressure vessel whereby a workpiece may be mounted across said first opening in said female die and constant liquid pressure supplemented by vibratory pressure applied to the liquid in said cavity of said pressure vessel and said workpiece formed into said deep draw die with a rate of draw determined in part by the thickness of said elastomeric sheet when said second opening of said forming device is pressed against said first opening in the face of said die. 9. A forming head mechanism for sonic-hydraulically forming hollow tubular container body blanks comprising:
a female die member having a cavity with an opening at one end; a forming member comprising a tubular impermeable elastomeric diaphragm contoured for insertion into the interior of a tubular container body blank;
a pressure transmitting liquid contained within said diaphragm;
constant pressure supplying means for supplying pressurized liquid;
means for imparting a vibratory pressure to said pressure transmitting liquid in said forming member whereby said liquid presses said diaphragm against said tubular container body blank and forms it into the female die;
a conduit connecting said constant pressure supply means to the interior of said forming member; and
a sonic absorber in said conduit for inhibiting the progress of sonic pressure waves from said vibratory pressure imparting means up said conduit to said-constant pressure supply means.
10. A forming head mechanism for sonichydraulically forming hollow tubular container body blanks as set forth in claim 9 in which said female die member comprises:
a female die having a generally tubular shaped interior with embossing on said interior of said die.
11. A forming head mechanism for sonichydraulically forming hollow tubular container body blanks as set forth in claim 9 in which said means for supplying a vibratory pressure comprises:
a transducer mounted in said liquid at about the center of said forming member.
12. A forming head mechanism for sonichydraulically forming hollow tubular container body blanks as set forth in claim 9 in which said means for supplying a vibratory pressure comprises:
a horn having a transducer attached to the horn and mounted on the forming member at a node in the horn when it is vibrating and said horn extending into said pressure transmitting liquid whereby vibratory energy is passed from said horn to said tubular blank.