Thermoforming Apparatus Having Adjustable Length Load Shafts and Method
A thermoforming machine is provided having a load shaft end adjustment apparatus. The thermoforming machine load shaft end adjustment apparatus includes a load shaft, a backlash nut, a height adjustment nut, a collar, and at least one fastener. The load shaft has a threaded end segment and an axially extending key slot. The backlash nut is threaded onto the end segment. The height adjustment nut is threaded onto the end segment adjacent the backlash nut. The collar is configured to receive the height adjustment nut for rotation, having a key configured to be received within the key slot, and is configured to be mounted onto a platen of the thermoforming machine. At least one fastener extends between the backlash nut and the collar and is configured to secure together the backlash nut and collar with the height adjustment nut interposed there between. A method is also provided.
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This application claims priority to U.S. Provisional Patent Application Ser. No. 61/559,212 which was filed on Nov. 14, 2011, the entirety of which is incorporated by reference herein.
TECHNICAL FIELDThe disclosure pertains generally to thermoforming apparatus. More particularly, this disclosure relates to thermoforming machines having adjustable length load shafts for securing together opposed platens and dies of a thermoforming apparatus.
BACKGROUND OF THE INVENTIONThe use of large tonnage thermoforming frames and drive mechanisms is known where pneumatic pressure is being applied to a heated sheet of thermoformable material during an article forming operation. Where large arrays of articles are provided on die plates on a platen, the surface area subject to pneumatic pressure and/or vacuum generates very large loads on the kinematic drive linkages and frame of a thermoforming machine. Improvements are needed in order to enable forming using very large loads without requiring further increases in the size and strength of traditional frames and linkages of a thermoforming machine, particularly when forming newer plastic sheet materials and/or article geometries that require greater forming pressures and loads.
SUMMARY OF THE INVENTIONA thermoforming machine is provided with a plurality of load shaft end adjustment assemblies. Each load shaft is adjustable in length using the respective load shaft end adjustment assemblies to enable alignment of the mating mold surfaces on respective platens of a thermoforming machine when in a locked, closed position, providing for the capability of handling increased thermoforming pressures on the thermoforming machine during a thermoforming operation. A preload can be applied to the end adjustment assemblies in order to prevent damage to mating threaded assembly components due to platen forming loads.
According to one aspect, a thermoforming machine load shaft length adjustment apparatus is provided. The apparatus includes a load shaft, a structural support, a length adjustment nut, a collar, and at least one fastener. The load shaft has a threaded segment, and is configured to engage between a pair of thermoforming platens of a thermoforming machine and carry forming loads between the pair of platens during a thermoforming operation. The structural support is provided on the load shaft proximate the threaded segment. The length adjustment nut is threaded onto the threaded segment of the load shaft proximate the structural support and is movable to effect length adjustment of the load shaft as engaged between the pair of platens. The collar is mounted onto a platen of the thermoforming machine and is configured to receive the length adjustment nut for relative rotation. At least one fastener extends between the structural support and the collar and is configured to secure together the structural support and the collar with the length adjustment nut interposed there between and engaged in threaded relationship to impart a preload that urges the height adjustment nut against the collar that is greater than a load received by the load shaft as thermoforming pressure is applied between the platens.
According to another aspect, a length-adjustable thermoforming machine load shaft apparatus is provided having a load shaft, a load-bearing support, an adjustment nut, a collar, and a preload fastener. The load shaft has a threaded segment and spaced-apart engagement portions for releasably engaging together a pair of thermoforming platens of a thermoforming machine and is operative to carry pneumatically-induced thermoforming loads imparted between forming dies on the pair of platens during a thermoforming operation. The load-bearing support is provided on the load shaft proximate the threaded segment. The adjustment nut is threaded onto the threaded segment proximate the load-bearing support and is movable to effect length adjustment of the load shaft as engaged between the pair of platens. The collar is mounted onto a platen of the thermoforming machine and is configured to mate in engagement with the adjustment nut. The preload fastener extends between the structural support and the collar and is configured to draw together the structural support and the collar so as to urge the collar into engagement with the adjustment nut so as to preload threads on the adjustment nut with complementary threads on the load shaft such that the resulting preload is greater than a load received by the load shaft as forming pressure is applied between the platens.
According to yet another aspect, a method is provided for adjusting lengths of load shafts on a platen of a thermoforming apparatus. The method includes providing: a first platen with a first die mold, a second platen with a second die mold, a drive linkage for moving together and apart the first platen and the second platen, and a plurality of load shafts extending between the first platen and the second platen operative to secure together under thermoforming loads the first die mold and the second die mold during a thermoforming operation; urging together the first platen and the second platen such that the first die mold and the second die mold are held together in engagement; ascertaining any loose fit-up along respective die surfaces between the first die mold and the second die mold; and adjusting length on one of the load shafts to eliminate the ascertained loose fit-up between the first die mold and the second die mold when the die molds are held together in engagement.
Preferred embodiments of the disclosure are described below with reference to the following accompanying drawings.
This disclosure is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).
Attention is now directed towards embodiments of the device.
A set of platen load shafts 48-51 and 52-55 are provided on either side of mold plates, or die plates 44 and 46, extending between upper platen 24 and lower platen 26. More particularly, platen lock assembly 12 comprises set of shafts 48-51 attached to platen 24 along a top end and lock plate assemblies 70 and 71 (see
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More particularly, kinematic linkages 34 and 36 of
More particularly, each drive system, including the motor and associated drive controller, forms the motor of an associated rotary press. This rotary press attaches to a rotating crank arm assembly that moves the associated four-bar linkage. The linkage causes the attached platen to move up and down in response to rotation of the drive. Accordingly, a single revolution of shafts 56 and 58 caused by drive motors 38 and 40 and gearboxes 39 and 41 will produce a corresponding complete press cycle of both the upper and lower platens 24 and 26, respectively. Hence, a complete cycle of each drive will return the press to a starting, or closed position. For example, when lower drive motor 40 is at an initial rotated position of zero degrees, the lower platen 26 is closed, or upwardly raised against the thermoformable sheet, or web. Similarly, when lower driven motor 40 is rotated to 180 degrees, the lower platen 26 is lowered, or completely opened. Likewise, the same holds true for upper drive motor 38 and upper platen 24.
A control system is configured to move upper platen 24, lower platen 26, and third motion, or plug assist platen 27 via respective servo motors, such as servo motors 38, 40. According to one construction, upper platen 24 and lower platen 26 are each drive platens, and plug assist platen 27 is also a moving platen. The control system includes a controller comprising processing circuitry and memory configured to precisely regulate motion of platens 24, 26 and 27 in desired, timed synchronization such that individual plugs, or male dies 47 are driven upwardly with a greater combination of speed and force than would be capable by merely moving platens 24 and 26 together. In operation, platens 24 and 26 are driven together into a heated web of thermoformable material that is captured between upper platen 24 and lower platen 26 during a thermoforming operation.
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Preferably, a modern rotary electric servo drive motor, or actuating device, is used for drive motors 15 and 17 (see
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One or more of load shafts 54 can be adjusted in length in order to eliminate any pneumatic leakage between die plates during thermoforming. A visual inspection with feeler gauges can detect a local gap requiring one or more load shafts to be adjusted in length, when die plates are engaged together and a pneumatic source and/or vacuum are applied across the web (while engaged between the die plates and locked together with load shafts 54). An audible inspection can also be used in order to identify where pressurized air, or gas is leaking through a seal between engaged die plates, then adjacent load shafts can be adjusted in length so as to reduce or eliminate any leakage of pneumatic air/vacuum during a thermoforming operation.
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According to one implementation, a method is provided for adjusting lengths of load shafts on a platen of a thermoforming apparatus. The method includes providing: a first platen with a first die mold, a second platen with a second die mold, a drive linkage for moving together and apart the first platen and the second platen, and a plurality of load shafts extending between the first platen and the second platen operative to secure together under thermoforming loads the first die mold and the second die mold during a thermoforming operation; urging together the first platen and the second platen such that the first die mold and the second die mold are held together in engagement; ascertaining any loose fit-up along respective die surfaces between the first die mold and the second die mold; and adjusting length on one of the load shafts to eliminate the ascertained loose fit-up between the first die mold and the second die mold when the die molds are held together in engagement.
According to another implementation, a method is further provided for adjusting lengths of load shafts on a platen of a thermoforming apparatus, or machine. A first load shaft is adjusted in length while molds on dies of a thermoforming machine are held together in engagement. A second load shaft, spaced apart from the first load shaft is also adjusted in length while the molds are held together in engagement. Subsequent load shafts are also adjusted in length so as to ensure sealing fit-up of a seal that is interposed between the mating molds on each of a pair of platens on the thermoforming machine.
In compliance with the statute, embodiments of the invention have been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the entire invention is not limited to the specific features and/or embodiments shown and/or described, since the disclosed embodiments comprise forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.
Claims
1-20. (canceled)
21. A thermoforming machine load shaft apparatus, comprising:
- a load shaft configured to engage between a pair of thermoforming platens of a thermoforming machine to carry forming loads between the pair of platens during a thermoforming operation;
- a first structural support provided on the load shaft at a first location configured to mate with a first platen of the pair of platens;
- a second structural support provided on the load shaft at a second location configured to mate with a second platen of the pair of platens and spaced from the first location with the length adjustment segment provided between the first location and the second location; and
- a length adjustment mechanism carried by one of the load shaft and one of the pair of platens movable to effect length adjustment of mating fitment between the pair of platens as engaged together along the load shaft during application of forming loads.
22. The thermoforming machine load shaft apparatus of claim 21, wherein the length adjustment mechanism is carried by the load shaft.
23. The thermoforming machine load shaft apparatus of claim 22, wherein the length adjustment mechanism comprises a preloaded compression mechanism.
24. The thermoforming machine load shaft apparatus of claim 23, wherein the length adjustment mechanism comprises a threaded segment provided on the load shaft and a length adjustment nut threaded onto the threaded segment of the load shaft proximate the first structural support and movable to effect length adjustment of the load shaft proximate the first structural support and movable to effect length adjustment of the load shaft as engaged between the pair of platens.
25. The thermoforming machine load shaft apparatus of claim 24, wherein the length adjustment mechanism comprises at least one fastener extending between the first structural support and the first platen and configured to secure together the first structural support and the first platen and further comprising a length adjustment nut interposed there between and engaged in threaded relationship to impart a preload that urges the length adjustment nut against the collar that is greater than a load received by the load shaft as thermoforming pressure is applied between the platens.
26. The thermoforming machine load shaft apparatus of claim 21, wherein the first structural support comprises a mechanical coupling system configured between the load shaft and the first platen.
27. The thermoforming machine load shaft apparatus of claim 26, wherein the second structural support comprises a mechanical coupling system configured between the load shaft and the second platen.
28. The thermoforming machine load shaft apparatus of claim 27, wherein the first structural support and the second structural support each comprise a mechanical coupling system having an array of dog legs provided on the load shaft and a complementary locking collar provided on the respective platen.
29. A thermoforming machine, comprising:
- a frame;
- a first thermoforming platen;
- a second thermoforming platen;
- a drive mechanism configured to move the first platen relative to the second platen in reciprocation;
- a load shaft configured to engage between the platens to carry forming loads between the pair of platens during a thermoforming operation;
- a first structural support provided on the load shaft at a first location configured to mate with a first platen of the pair of platens;
- a second structural support provided on the load shaft at a second location configured to mate with a second platen of the pair of platens and spaced from the first location with the length adjustment segment provided between the first location and the second location; and
- a length adjustment mechanism carried by one of the load shaft and one of the pair of platens movable to effect length adjustment of mating fitment between the pair of platens as engaged together along the load shaft during application of forming loads.
Type: Application
Filed: Dec 5, 2016
Publication Date: Mar 23, 2017
Applicant:
Inventor: Dale L. Vantrease (Naches, WA)
Application Number: 15/369,345