USRE27137E - Differential pressure forming machine - Google Patents
Differential pressure forming machine Download PDFInfo
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- USRE27137E USRE27137E US27137DE USRE27137E US RE27137 E USRE27137 E US RE27137E US 27137D E US27137D E US 27137DE US RE27137 E USRE27137 E US RE27137E
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- machines
- die
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
- B29C51/04—Combined thermoforming and prestretching, e.g. biaxial stretching
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
- B29C51/10—Forming by pressure difference, e.g. vacuum
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
- B29C51/18—Thermoforming apparatus
Definitions
- ABSTRACT OF THE DISCLOSURE This disclosure relates to dilferential pressure forming machines for molding articles in thermoplastic material
- the invention is concerned with a machine of the type which can be placed in position for in-line operation with an extruder issuing a continuous sheet of thermoplastic material, or which may be adapted to mold sheets of thermoplastic material which are drawn from a roll. Accordingly, such machines usually include banks of heaters, mounted above and below the level of the sheet which is brought into the machine, to bring the plastic to the forming temperature.
- forming machines of this character usually employ a pair of platens, one above and one below the sheet or web of material, for mounting male and female die members which cooperate to form products in the preheated sheet of material in accordance with the configuration of the molds.
- Such machines may be deep draw machines such as are suitable for forming cups and the like or shallow draw machines for forming articles such as cup lids and like articles.
- the male dies are plug assists which aid in moving portions of the plastic sheet into the female cavities, and a vacuum pump is connected to the female cavities to draw the material into engagement with the walls thereof at an appropriate time.
- Nesting chains are conventionally employed to clamp the sides of the sheet material and at intervals to draw successive lengths of it from the heating zone to a position between the forming dies.
- One of the prime objects of the present invention is to provide a machine to form products in a plastic web which can be brought between the forming dies and formed at a lower temperature than heretofore possible, without losing the detail of the dies in the formation process.
- a corollary object of the invention is to also provide a machine in which the molds can be used at lower temperatures than the molds of conventional machines, so that the less hot web virtually sets instantaneously when it is brought into intimate contact with the molds and it is not necessary to wait a certain time for the material to cool and set prior to stripping the molds and commencing the next cycle.
- the deep draw machine which will presently be described can process a sheet which is nearer to setting temperature and can employ a mold which is substantially at room temperature, because air under pressure is employed in conjunction with the suction forces to insure 100% contact of the sheet with the female mold cavities and accordingly l% heat transfer between the mold surfaces and sheet.
- the present invention provides means which load the vacuum and air box die frames in a direction to take up the slack in the machine frame, so to speak, and effect a positive seal which permits uniformity to be achieved.
- a further object of the invention is to provide a machine which applies the air pressure to the sheet in a manner which does not create cold spots on the sheet which would not be formed with the full detail of the molds.
- FIGURE 1 is a side elevational view of the portion of the machine with which the invention is concerned;
- FIGURE 2 is a front end elevational view thereof
- FIGURE 3 is an enlarged, fragmentary, side elevational view illustrating particularly the toggle mechanism for loading the upper platen of the machine, the chain lines illustrating the open or force applying position of the toggle mechanism;
- FIGURE 4 is a fragmentary, top plan view thereof with parts of the frame broken away to more clearly illustrate elements of the mechanism which otherwise would be obscured;
- FIGURE 5 is an enlarged, transverse, sectional view with the die boxes shown in confronting relationship with the plastic web;
- FIGURE 6 is a top plan view of the lower die box and the plug assist members which it carries;
- FIGURE 7 is a still more enlarged, fragmentary view illustrating one of the baifies used to deflect one of the air streams which are released to pressurize the lower die box at a designated time in the forming operation and prevent the air stream for forming a cold spot on the plastic sheet which would prevent proper molding of the plastic with the necessary detail;
- FIGURE 8 is a view illustrating a typical electropneumatic circuit which may be used to control the operation of the various elements of the machine.
- FIGURE 9 is a schematic view of the pressure responsive valve which is employed to limit the pressure of the air in the lower die box.
- a web 10 of a suitable thermoplastic material such as polystyrene, is shown in FIGURES 2 and S disposed between a female die box assembly designated 11 and a male die box assembly generally designated 12.
- the female die box assembly 11 is shown as having spaced apart cavities 13 of a size to form a truncated, coneshaped, thin walled cups in the plastic web suitable for use as drinking cups when separated from the web, and it will be noted that the male die box assembly 12 includes spaced apart, plug assist members 14 in vertical axial alignment with the cavities [14] 13.
- the cups, which are formed in the plastic web 10, are formed in inverted position and the formed web is then fed through a separate trim press which severs the cups from the web.
- the frame of the forming machine which is generally designated F, is shown, for the sake of convenience, as comprising upper and lower longitudinal sill members and 16, respectively, which are connected at both ends by vertical members 17 and upper and lower end cross members 18. Only the front end of the machine is shown in FIGS. 1 and 2. However, it is to be understood that the frame F is oblong in shape and that the left end also includes suitable end connecting members. Mounted intermediate the ends of the frame are vertical columns 19 which are joined to the lower sill members 16 at their lower ends and are connected by a header channel member 20 at their upper ends. It is the function of the columns 19 to support the female die box assembly 11 and the male die box assembly 12 for vertical travel.
- Vertical rails 19a are secured on the inner walls of the columns 19 to furnish guide surfaces for a vertically traveling upper platen 21 which carries the female die box assembly 11, angle members 22 supporting the assembly 11 on the platen 21, as shown. It will be seen that transversely extending angle brackets 23 on the platen 21 support follower roller members 24 and 25 which guide on the inner and side faces of the guide rails 19a, as shown, during vertical travel of the platen 21.
- a pressure fluid cylinder 26 ineluding a piston rod 26a which is coupled to the platen 21 by a member [24] 24 and clearly, when a suitable fluid under pressure, such as air, is introduced to the upper end of the double-acting cylinder 26, the platen 21 will be lowered toward the plastic web 10.
- a lower platen 27 is also mounted for vertical travel on the guide 19a, there being angle brackets 27a provided on the sides of the platen 27 which mount follower rollers 28 and 29 and angle members 27b which connect the platen 27 and die box assembly 12.
- a sill channel member 30 connects the lower ends of the columns 19 and houses a double-acting, lower platen, pressure fluid cylinder 31 which has a piston rod 32 coupled, by a member 33, to the lower platen 27.
- the plastic web 10 is fed intermittently between the upper and lower die assemblies 11 and 12 in the usual manner by pairs of superposed, nesting, upper and lower endless chains 34 and 35, respectively, which are intermittently powered to advance the plastic web 10 from a heating station generally designated 36 (see FIG. 1).
- the heating station 36 comprises banks of electrically powered heaters 37 mounted on crossbars 38 supported on a frame 39. While only a few of the heaters 37 are shown, it is to be understood that to the left of the portion of the machine shown in FIG. 1 are banks of heaters above and below the level of the plastic sheet 10 which bring the plastic to the forming temperature.
- the upper die unit 11 includes a vacuum manifold chamber 47 which connects to the cavities 13 by means of passages 48, and a line member 49 is employed to connect the vacuum manifold chamber 47 with a conventional rotary pump and surge tank.
- the vacuum pump which has been found suitable for the purpose is that manufactured by Gast Manufacturing Co. of Benton Harbor, Mich., which is a 1 horsepower, 21.6 cubic feet per minute pump.
- the plug assist box assembly 12 includes a member 50 mounting the plug assist member 14 in spaced apart relation and a surrounding clamp frame 51. It is to be understood that there is a clearance of about /a inch between the clamp frame 51 and the member 50, and that the member 50 includes a rim 52 mounting a resilient seal 53 which maintains a sealed airtight relationship between the web 10 and plug assist mounting member 50.
- the member 50 may be electrically heated by thermostat incorporating resistance heating elements 50a of the chromalox type. Air under a pressure of about 80 p.s.i. and traveling at about 20 cubic feet per minute is supplied to the assembly 12 via a line 55 which connects with pipes 56 leading from the air supply hose 55 to bored openings 57 in the member 50 and, as shown in FIG.
- baffie plates 58 are supported over each of the openings 57 on spaced apart pins 59 so that the air stream passing through openings 57 is deflected laterally and does not impinge directly on the plastic web 10. This prevents cold spots from being formed on the plastic sheet 10 which would not be moldable to take the detail of the die cavities 13.
- a pressure of about 80 p.s.i. is maintained in the cylinders 60, which are connected through lines 60a at their lower ends to a suitable source of air under pressure.
- toggle mechanism is provided for forcing the platens 21 and 27 toward one another and locking them in position.
- Toggle mechanism is provided in association with both the upper platen 21 and the lower platen 27, and is particularly illustrated in FIGS. 3 and 4.
- Mounted at each side of the platen 21 and connected to the channel member 20 and platen 21 are a pair of spaced apart blocks 63a and 63b and it will be seen that pairs of links 64 and 65 at each side of the platen 21 connect the upper and lower blocks 63a and 63b, respectively, with the outer end of horizontally disposed pressure fiuid cylinder 66 which has a piston rod 67.
- the blocks 63a are connected to the channel 20 by threaded members 68 which are secured by nuts 68a.
- the relatively expandable and contractable links 64 and 65 are pivotally connected to the upper and lower blocks 63a and 63b, at each end of the platen 21, as with pins 69 and 69a, and are pivotally connected to the end of each cylinder 65 by a pin 70.
- the front end of each piston rod 67 is pivotally connected to the upper and lower blocks 63a and 63b by pairs of links 71 and 72.
- the links 71 and 72 are connected to the blocks 63a and 63b by the pins 69 and 69a and to the piston rod 67 in each case by a pin 73.
- the piston rods 67' of the cylinders 66 are actuated at the same time as the piston rod 32 and function both to aid in raising the platen 27 and to preload the platen 27 in a direction toward the plastic web and lock it in position. Inasmuch as the cylinders 66 and 66 are not in any way mounted on the frame of the machine, the preloading movement is not in any way restricted.
- the down position of the linkage is indicated in the chain lines in FIG.
- the sheet advancing chains 34 and 35 are operated after the forming operation has taken place and the platens 21 and 27 have been retracted vertically, as shown in FIG. 2.
- shafts 42 and 43 Mounted on the opposite ends of shafts 42 and 43 are sprockets and 76 around which are trained chains 77 which are also trained around sprockets 78 provided on the shaft 46.
- the mechanism for driving shaft 46 is illustrated in applicants Pat. No. 3,217,852 and will only be briefly described.
- a pinion 79 mounted on a shaft 46a revolves the shaft 46 when the air operated clutch 80 is engaged, there being a diaphragm housing 81 which engages the clutch 80 when air under pressure is supplied to the diaphragm housing 81 through a line 82 in the manner described in the said application.
- Cylinder 83 includes a rack 84 connected with its piston rod which is in mesh with the pinion 79 and, as the aforementioned application discloses, when the rack member 84 is moved downwardly air is supplied through the line 82 to the air operated diaphragm housing 81 to engage the clutch 80 and transmit the rotation of pinion 79 to the advancing chains 34 and 35.
- the cylinder 83 is mounted on a frame column member 85 and mounted on the upper end thereof is a stop bar 86 provided with an adjustable stop bolt 86a, as shown.
- the control system in FIG. 8 is shown a typical circuit diagram including line wires L-l and L-2 and conventional electric and pneumatic components which may be used in the operation of the machine. It is to be understood that other sys terns may also be used and the instant control arrangement is intended only as exemplary of one system which may be used.
- the vacuum pump 89 is shown connected by a line 90 to a main vacuum valve 91 and by a branch line 92 to a vacuum bleed valve 93.
- the valves 91 and 93 may be normally closed Johnson valves of the type manufactured by Johnson Corporation of Three Rivers, Mich., the valve 91 having an attached valve actuator Model AV114CM such as manufactured by Automatic Valve Co. of Farmington, Mich., and the valve 93 having a similar valve actuator.
- Valve 91 connects with the flexible vacuum line 49 via a line 94 and includes a solenoid 95 connected in a circuit line a with switch contacts 96.
- the valve 93 is connected with vacuum line 49 via a line 97 and includes a solenoid 98 connected in circuit line b in series with switch contacts 99.
- a normally closed valve 100 connected by means of line 101 with the flexible air supply line 55 leading to the plug box assembly 12.
- the valve 100 is preferably a normally closed Mac air valve Model No. 4084, such as manufactured by Mechanical Air Controls Inc. of Detroit, Mich., and includes a solenoid 102 connected in series in circuit line c with switch contacts 103. Also connected in circuit line c are the normally closed contacts 104 of a conventional pressure actuated switch 105, the contacts being opened when a predetermined pressure, such as, for example, 40 p.s.i. is reached in the plug box 12.
- the pressure switch 105 may be the Model 836-T manufactured by Allen Bradley Company of Milwaukee, Wis.
- FIG. 8 A schematic representation of a suitable switch is shown in FIG. 8 and comprises a cylinder 105b within which is a diaphragm 105e having a contact 104 on its stern 105d which is forced normally into engagement with a fixed contact 104 by a spring 105e of predetermined strength.
- the contacts 104 are suitably insulated from the cylinder and an opening 105f is provided in the cylinder to admit the pressure fluid thereto
- a normally open air valve 106 also communicates with the air line 55 via a line 107 and has a solenoid 108 connected in a circuit line d in series with normally open contacts 109.
- the valve 106 may also be a Mac valve No. 4086 which exhausts to atmosphere out a port 110.
- the lines L-l and L-2 power a timer motor T which is disposed in circuit line e.
- the timer can be an Eagle Multiflex timer of the type manufactured by Eagle Signal Co. of Moline, Ill.
- the double-acting air cylinders 66 for locking the toggle links 64, 65. 71. and 72. which preload the upper platen 21, are shown as having advance solenoids 111 connected in a series line f with normally open switch contacts 112 and retract solenoids 113 connected in a circuit line g with normally open switch contacts 114.
- the double-acting air cylinders 66' which preload the lower platen 27 are shown as having advance solenoids 115 connected in a circuit line h with normally open switch contacts 116 and retract solenoids 117 connected in a circuit line i with normally open switch contacts 118.
- the doubleacting air cylinder [22] 26 for powering the upper platen 21 includes an advance solenoid 119 connected in a circuit line i with normally open switch contacts 120 and a retract solenoid 121 connected in the circuit line k with normally open switch contacts 122.
- the double-acting air cylinder 31 for powering the lower platen 27 includes an advancing solenoid 123 connected in a circuit line I with normally open switch contacts 124 and a retract solenoid 125 connected in a circuit line in with normally open switch contacts 126, as shown.
- Each of the air cylinders 66, 66, [22] 26 and 31 may be of the type manufactured by The Bellows Co. of Akron, Ohio.
- a valve 127 which is operated by a solenoid 128 and opens to atmosphere as at 129, is connected with line 49 as shown via line 127a.
- the valve may be a Skinner solenoid valve Model L2DB4-l50 of the type manufactured by Skinner Chuck Co. of New England, Conn. and is operated by switch contacts 130 in circuit line b It may be assumed for the sake of simplicity and convenience that the normally open contacts 96, 99, 103. 109.
- switch contacts 120 and 112 could be additional contacts of the limit switch 88
- the contacts 124 and 116 could be limit switch contacts located in the path of platen 21
- the contacts 99 could be limit switch contacts located in the path of platen 27
- the contacts 103 and 96 could be limit switch contacts located in the path of the pistons of cylinders 66
- the contacts 122 could be limit switch contacts located in the path of the clamp frame 50.
- the contacts 124 in circuit line 1 are closed and energize the advance solenoid 123 of the air cylinder 31 so that the lower platen 27 commences to move upwardly toward the plastic sheet 10.
- the clamp frame 51 will engage the plastic web to clamp the sheet firmly between itself and the upper die box 11 and thereafter further upward movement of the piston rod 32 and platen 27 will cause the plug assist members 14 to deform the heated plastic as the plug assists 14 commence to enter the cavities 13.
- the contacts 99 in circuit line b are closed and the solenoid 98 is energized to open the normally closed vacuum bleed valve 93 and bleed the air out of the cavities 13 at a controlled rate corresponding to the displacement of air within the cavities 13 which is caused by the plug assists and plastic entering the cavities 13.
- the contacts 116 in circuit line h are closed to energize the advance solenoids 115 of the cylinders 66' and, when the piston rod 32 reaches the limit of its upward travel, the links 64', 65' and 71', 72' are spread a final increment, which may be about of an inch, to lock the die members 11 and in sealed relation.
- the plastic sets immediately upon contact with metal of the die 11 and the set is uniform over all of the area of the plastic displaced within the cavities 13 because the plastic comes into intimate contact 'Wllh all of the area of the die surface. For this reason it is only necessary for the die boxes 11 and 12 to remain closed for an instant.
- a predetermined value such as 40 p.s.i.
- the pressure switch is actuated to open normally closed contacts 104 in circuit line c and, of course, deenergize solenoid 102 so that normally closed valve 100 closes immediately.
- the pressure is prevented from building to a point where it would separate the mold boxes and, of course, with the pressure streams being deflected by baflles 58, cold spots are not created by the air stream which would cause local hardening of the plastic during the forming operation.
- the male members 14 are maintained at a suitable temperature so that they also do not cause local hardening of the plastic when they engage it.
- normally open contacts 109 in circuit line :1 can be opened to deenergize the solenoid 108 of the exhaust valve 106 and open the valve 106 to bleed air from the plug assist box assembly 12 to atmosphere.
- the contacts 96 in circuit line a, and 99 in circuit line b are opened, and normally closed valves 91 and 93 are closed and release the vacuum forces in line 49 and vacuum box assembly 11.
- the normally open contacts in line b are closed and the solenoid 128 of valve 127 is energized so that the normally closed valve 127 is opened to furnish the vacuum box 11 with air.
- the contacts 118 in circuit line i and 126 in circuit line m are closed to energize solenoids 117 and 125, respectively, and first retract the piston rods of cylinders 66' so that the preloading forces are removed from the platen 21 and thence retract the platen 27.
- the clamp frame 51 will remain in engagement with the plastic web 10 as the plug assists 14 are retracted during the initial part of the retracting stroke because of the pressure developed in the cylinders 60. However, during the remainder of the stroke the pressure in cylinders 60 will be relieved with downward movement of the platen 27 and the clamp frame 51 will also be retracted from engagement with the plastic web 10.
- the cycle requires only about two seconds to complete, and thus it should be clear that the machine operates much faster than conventional machines and is a considerable improvement in the art.
- the cavity die box of conventional machines has been maintained at a temperature of about 130 F., it now can operate at room temperature.
- the cylinders 66 and 66' which lock the die boxes 11 and 12 in assembled relation positively prevent any separation of the boxes 11 and 12 at the crucial moment when the air pressure within the plug assist box assembly 12 has reached a maximum and there is no need for a cooling period once the cups have been formed in the web 10 because the plastic virtually sets immediately over the whole surface of the plastic formed.
- a differential pressure forming machine for molding articles in a sheet of thermoplastic material: a pair of oppositely disposed die support box frames mounted for relative movement toward and away from one another; aligned male and female die means for said frames; fluid pressure actuated means connected with one of said frames for moving it toward the other frame; means for supporting a web of plastic between said frames; means for sealing both frames at a time when they are brought into engagement with said web; means for applying a vacuum to one of said box frames; means for substantially simultaneously introducing air under pressure through a line into the other box frame at a line pressure; and pressure responsive means downstream from said line and in said other box frame continuously sensitive to the actual pressure of the air in said other box frame for disabling said means for introducing air under pressure and limiting the pressure of the air in said other box frame to a maximum designated pressure less than said line pressure.
- a differential pressure forming machine for molding articles in a sheet of thermoplastic material; stationary frame means; a pair of oppositely disposed die support frames thereon mounted for relative movement; means for supporting a plastic web therebetween; cooperating male and female die members arranged in aligned, spaced relation on said frames; fluid pressure operated motor means for moving at least one of said frames toward the other to engage said web; expandable togQe link means carried by one of said frame means and connected to react between said frame means and at least one of said die support frames and lock said one of said die support frames in position on said web; means actuatable to expand said link means and exert a loading force on said one frame in a direction toward the other frame; and means operable for only thereafter [for introducing] providing a fiuid under a pressure which would otherwise spread said die frames in [to] one of said die frames to form the web to the configuration of the female die means.
- said means actuatable to expand said link means comprises a fluid pressure cylinder and a piston rod therein; and said link means comprises: a block connected to said stationary frame means, a block connected to said one of said die support frames, links connected to the rear of said cylinder and to each of said blocks, and links connected to said piston rod and to each of said blocks.
- a differential pressure forming machine for forming articles in thermoplastic material; frame means; a pair of oppositely disposed die support platens mounted in spaced relation thereon for movement toward and away from one another; a female die box on one of said platens and a plug assist die box on the other with the plug assists in alignment with the cavities of the female die means; means for supporting a web of formable plastic between said die boxes against which said boxes seal when they are brought together; means for moving said female die box into engagement with the web; means for thereafter moving said plug assist die box into engagement with said web and deforming said web into said cavities with said plug assists; means for introducing air through a line under pressure into said plug assist die box after said plug assist die box has traveled to its extended position; means for substantially simultaneously evacuating the air from said female die box; and means sensitive to the pressure in said plug assist die box in said plug assist die box and for terminating the introducion of air under pressure to said plug assist die box when a predetermined pressure less than said line pressure has been reached therein.
- a differential pressure forming machine for forming articles in a sheet of thermoplastic material; frame means; a pair of oppositely disposed, vertically spaced, die support platens mounted in spaced relation thereon for movement toward and away from one another; a female die means with ca-vity means on one of said platens and a plug assist die means with at least one air admitting opening and plug assist means on the other, the plug assist means being in alignment with the cavity means of the female die means; means for supporting a web of formable plastic between said die means against which said die means seal when they are brought together; an electrical control circuit; first fluid pressure operated motor means connected in said circuit for moving said female die means into engagement with the web; second fluid pressure operated motor means connected in said circuit for moving said plug assist die means into engagement with said web and deforming said web into said cavity means with said plug assist means; expandable toggle linkage means carried by said platens and reactable between said frame means and said platens for preloading said platens and locking them against said web; means connected in said circuit and operable
- a differential pressure forming machine for forming articles in thermoplastic material; frame means; a pair of oppositely disposed die support platens mounted in spaced relation thereon for movement toward and away from one another; a female die box on one of said platens and a plug assist die box on the other with the plug assists in alignment with the cavities of the female die means; said plug assist die box including a clamp frame and a plug assist plate mounted therein for relative movement therewith; yieldable means connecting said clamp frame and plug assist plate; means for supporting a web of formable plastic between said die boxes against which said boxes seal when they are brought together; means for moving said female die box into engagement with the web; means for moving said plug assist die box toward said web with said clamp frame first engaging said web and said plug assist plate continuing to move to deform said web into said cavities with said plug assists; means for introducing air under pressure into said plug assist die box after said plug assist die box has traveled to its extended position; means for simultaneously evacuating the air from said female die box; and means in said plug assist die box and sensitive to the plug
- said yieldable means comprises fiuid cylinders mounted to one of said clamp frame and plug assist plate with the piston rods thereof mounted to the other.
- a differential pressure forming machine for molding articles in thermoplastic material: frame means; a pair of oppositely disposed mold frames mounted thereon; one of said frames including cavity means and the other comprising an air box frame; means connected with at least one of said frames for moving it toward the other frame; means for supporting a web of plastic between said frames; means for applying a vacuum to said cavity means; line means for introducing fluid under pressure into the air box frame at a line pressure greater than that desired in said air box frame; and pressure responsive means, downstream from said line means and sensitive to the pressure in said air box frame, disabling the fluid pressure introducing means when a designated pressure less than said line pressure is reached in said air box frame.
- a differential pressure forming machine for forming articles in a sheet of thermoplastic material; frame means; a pair of oppositely disposed, vertically spaced, die support platens mounted in spaced relation thereon; one of said platens having a female die with cavity means and the other having an air box having at least one air admitting opening therein; means for supporting a web of formable plastic between said platens; an electrical control circuit; motor means connected in said circuit for moving one of said platens to the other and into engagement with the web; expandable toggle linkage means reactable between said frame means and said movable platen for locking said platen against said web; means connected in said circuit communicating with said opening and operable to expand said linkage means; means connected in said circuit for [introducing] providing air undot a forming pressure which otherwise would spread said platens in [into] said air box only after said linkage means has been expanded; means for substantially simultaneously evacuating air from said cavity means; means connected in said circuit for thereafter retracting said motor means and moving said movable platen
- a differential pressure forming machine for forming articles in thermoplastic material: frame means; a pair of oppositely disposed die support platens mounted in spaced relation thereon for movement toward and away from one another; a female die box on one of said platens and a plug assist die box on the other with the plug assists in alignment with the cavities of the female die means; means for supporting a web of formable plastic between said die boxes against which said boxes seal when they are brought together; means for moving said female die box into engagement with the web; means for thereafter moving said plug assist die box into engagement with said web and deforming said web into said cavities with said plug assists; means for introducing air under pressure into said plug assist die box after said plug assist die box has traveled to its extended position; means for substantially simultaneously evacuating air from said female die box; and means for terminating the introduction of air under pressure to said plug assist die box when a predetermined pressure has been reached therein; said means actuatable to expand said link means comprising an air cylinder with a piston rod therein; and said link means comprising:
- frame means In a differential pressure forming machine for molding articles in thermoplastic material: frame means; a
- pair of oppositely disposed mold frames mounted there- 2 on; one of said frames including mold cavity means and the other comprising an air box frame communicating therewith; means connected with at least one of said frames for moving it toward the other frame; means for supporting a web of plastic between said frames; means i for applying a vacuum to said cavity means; toggle linkage means reactable between said frame means and movable frame movable substantially to a dead center position to positively lock said movable frame against the plastic web; motor means independent of said frame moving means for moving said toggle linkage means to and from substantially dead center position; and means operable substantially only after said toggle linkage has been moved to substantially dead center position for introducing air under pressure to said air box frame to aid the differential pressure molding operation.
- expandable toggle linkage means is reactable between said movable frame and frame means to substantially a dead center position to lock said frame against said web prior to the time said means for introducing fluid under pressure is operated.
- a frame for deforming a sheet of thermoplastic synthetic plastic material: a frame; a pair of opposed die parts mounted thereon; means for supporting a web of plastic between said die parts; drive means, connected with at least one of said die parts, for moving it toward the other die part, through a path of travel to substantially engage one side of said web of plastic and for returning it to a remote position; toggle linkage means, reactable between said frame and said movable die part, and movable, after said die part has moved to substantially engage said web, to a substantially dead center position to lock the movable die part against the plastic web; motor means supported by said toggle linkage means independently of said die part moving means for moving said toggle linkage means to and from substantially dead center position; and control means for cyclically operating said drive means and motor means.
- said toggle linkage means includes first and second toggle link sets connected between said one die part and said frame, said motor means being reactable between said first toggle link set and said second toggle link set to move one of said toggle link sets to substantially dead center position.
- said first toggle link set comprises a firstt pair of pivotally connected links pivotally connected by a first connecting pin, one of the links of said first pair of pivotally connected links being pivotally connected with said frame and the other of the links of said first pair of pivotally connected links being pivotally connected with said die part;
- said second toggle link set comprises a second pair of pivotally connected links pivotally connected by a second connecting pin, one of the links of said second pair of links being plvotally connected to said frame and the other of the links, of said second pair of links being pivotally connected to said die part;
- said motor means comprises a pressure fluid operated device, including a cylinder pivotally connected with said first connecting pin, and a piston rod pivotally connected with said second connecting pin.
- stationary frame means for molding articles in a sheet of thermoplastic material: stationary frame means; a pair of oppositely disposed die support frames thereon mounted for relative movement; said die support frames including cooperating male and female die members arranged in aligned, spaced relation on said die support frames; means for supporting a plastic web between said die members; fluid pressure operated motor means for moving at least one of said die support frames toward the other to engage said web; expandable toggle link means carried by one of said die support frames and connected to react between said frame means and at least one of said die support frames and lock said one of said die support frames in position on said web; means actuatable to expand said link means and exert a loading force on said one die support frame in a direction toward the other die support frame,- and means operable only thereafter for introducing a fluid under pressure to one of said die members to form the web to the configuration of the female die member.
Abstract
DIES ARE PLUG ASSISTS WHICH AID IN MOVING PORTIONS OF THE PLASTIC SHEET INTO THE FEMALE CAVITIES, AND A VACUUM PUMP IS CONNECTED TO THE FEMALE CAVITIED, AND A VACUUM PUMP IS CONNECTED TO THE FEMALE CAVITIES TO DRAW THE MATERIAL INTO ENGAGEMENT WITH THE WALLS THEROF AT AN APPROPRIATE TIME. NESTING CHAINS ARE CONVENTIONALLY EMPLOYED TO CLAMP THE SIDES OF THE SHEET MATERIAL AND AT INTERVALS TO DRAW SUCCESSIVE LENGTHS OF IT FROM THE HEATING ZONE TO A POSITION BETWEEN THE FORMING DIES.
Description
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US293959A US3346923A (en) | 1963-07-10 | 1963-07-10 | Differential pressure forming machine |
DE1779901*CA DE1779901B2 (en) | 1963-07-10 | 1964-07-03 | Device for sealing the two molding tools of a machine for deep drawing hollow bodies open on one side |
US87791269A | 1969-10-17 | 1969-10-17 |
Publications (1)
Publication Number | Publication Date |
---|---|
USRE27137E true USRE27137E (en) | 1971-06-08 |
Family
ID=27181391
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US27137D Expired USRE27137E (en) | 1963-07-10 | 1969-10-17 | Differential pressure forming machine |
Country Status (1)
Country | Link |
---|---|
US (1) | USRE27137E (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5002479A (en) * | 1989-05-30 | 1991-03-26 | John Brown Inc. | Apparatus for adjusting the shut height of a mold in a differential pressure forming machine |
US5263839A (en) * | 1991-11-05 | 1993-11-23 | Trafalgar House Inc. | Apparatus for sensing the temperature of a thermoplastic sheet in a differential pressure forming machine |
US20130049242A1 (en) * | 2011-08-31 | 2013-02-28 | Dale L. Vantrease | Thermoforming Machine, Plug Assist Drive Assembly and Method |
-
1969
- 1969-10-17 US US27137D patent/USRE27137E/en not_active Expired
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5002479A (en) * | 1989-05-30 | 1991-03-26 | John Brown Inc. | Apparatus for adjusting the shut height of a mold in a differential pressure forming machine |
US5263839A (en) * | 1991-11-05 | 1993-11-23 | Trafalgar House Inc. | Apparatus for sensing the temperature of a thermoplastic sheet in a differential pressure forming machine |
US20130049242A1 (en) * | 2011-08-31 | 2013-02-28 | Dale L. Vantrease | Thermoforming Machine, Plug Assist Drive Assembly and Method |
US9238325B2 (en) * | 2011-08-31 | 2016-01-19 | Irwin Research And Development, Inc. | Thermoforming machine, plug assist drive assembly and method |
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