CA1079020A - Apparatus for simultaneously cutting, sealing and stitching thermoplastic material - Google Patents
Apparatus for simultaneously cutting, sealing and stitching thermoplastic materialInfo
- Publication number
- CA1079020A CA1079020A CA252,375A CA252375A CA1079020A CA 1079020 A CA1079020 A CA 1079020A CA 252375 A CA252375 A CA 252375A CA 1079020 A CA1079020 A CA 1079020A
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- CA
- Canada
- Prior art keywords
- cutting
- wheels
- wheel
- stitching
- pulley
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Lining Or Joining Of Plastics Or The Like (AREA)
- Treatment Of Fiber Materials (AREA)
- Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
Abstract
Abstract of the Disclosure An ultrasonic horn cooperates with a cutting wheel and two stitching wheels to simultaneously cut, seal and stitch thermoplastic material. The cutting and stitching wheels are urged towards the ultrasonic horn by a spring biased pivot arm upon which the wheels are rotatably mounted. The combination of ultrasonic horn, wheels and pivot arm define a cutting assembly.
The entire cutting assembly is connected to the reciprocating rod of a piston which alternately lowers the cutting assembly into a cutting position wherein the material to be cut is located be-tween the horn tip and the wheels, and raises the cutting assembly into a return position wherein the material to be cut is below and out of contact with the cutting assembly.
The entire cutting assembly is connected to the reciprocating rod of a piston which alternately lowers the cutting assembly into a cutting position wherein the material to be cut is located be-tween the horn tip and the wheels, and raises the cutting assembly into a return position wherein the material to be cut is below and out of contact with the cutting assembly.
Description
1~79~0 Background of the_Invention 1 The present invention relates to the field of ultra-sonics. More specifically, this invention relates to an apparatus for simultaneously cutting, sealing and stitching thermoplastic material using an ultrasonic horn assembly.
Ultrasonic energy has long been employed to both melt and cut metallic or non-metallic thermoplastic materials. In a typical application, high frequency currents are applied to a trans-ducer which converts electrical energy into mechanical energy in the form of vibrations in the ultrasonic horn. The exact orientation of these vibrations will depend on the particular shape and struc-tural characteristics of the horn. The most preva'ent horn used for cutting takes the shape of a tapered cone. Such a horn will insure a concentration of longitudinal vibrations at the horn tip.
When the tip of the horn is biased against a rigid material such as metal, the longitudinal vibrations at the horn tip will transfer vibrational energy to the metal at the point of contact. Frictional forces induced within the metal work pieces will then heat the metal and thereby produce the desired cut.
This procedure will not be successful when the ma-terial to be cut is a flexible thermoplastic. In such a case thevibrations transferred from the tip of the horn to the thermo-plastic material will be widely distributed throughout the ma-terial. As such, the friction induced in any one section of the material will not be sufficient to produce adequate heating. In order to overcome this problem, a rigid anvil may be utilized to concentrate the transferred mechanical energy in a small swatch .~ .
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1 of the thermoplastic material. In a typical application, a flat faced anvil having a surface area smaller than that of the horn tip will be used to firmly press the flexible thermoplastic ma-terial against the face of the horn tip. In this way, substan-tially all of the vibrational energy transferred to the material will be concentrated in the area defined by the face of the anvil.
The internal frictional forces between the fibers of the thermo-plastic material will thereby melt the material along the sur-face defined by ~he face of the anvil. If the area of concentra-tion is sufficiently small, the heat will be sufficiently intenseto actually cut the material being worked on.
The above characteristics of ultrasonic horns are well-known in the art and have been employed to provide stitch seams in thermoplastic sheet-like elements. One such application can be found in U.S. patent 3,666,599 issued to Edward ~. Obeda.
The present invention exceeds the level of the prior art by provid-ing a fully automatic apparatus which can simultaneously cut, seal and stitch thermoplastic material.
Brief Summary of the Invention : Apparatus is provided for simultaneously cutting, sealing and stitching thermoplastic material. A plurality of wheels are biased against the flat cutting head of an ultrasonic . . _~ .
horn. Reciprocating means are provided for alternately j placing the cutting head and the wheels in a first ~ position wherein the material ' ' _ ,~
:B
~079020 is situated between the cutting head and the wheels, and a second position wherein the cutting head and the wheels are disposed from and out of contact with the material.
In accordance with one broad aspect, the invention relates to a machine for simultaneously cutting, sealing and stitching thermoplastic material, comprising: a frame assembly;
means mounted on said frame assembly for advancing the material through the machine and for positioning the section of material to be cut along a predetermined cutting plane;
a frame member mounted on said frame assemblv transversely to the direction in which said material is advanced and in a plane parallel to said cutting plane; a cutting assembly including a sonic horn having a flat cutting head, a plurality ~
of wheels for pressing the material against said cutting head, ~-and wheel support means biasing the working edges of said wheels against said cutting head; reciprocating means slidably mounted on said frame member for alternatively placing said cutting assembly in a first position wherein said cutting plane i5 situated between said cutting head and said wheels, and a second position wherein said cutting head and said wheels are disposed from said cutting plane in a direction perpendicular to said cutting plane; and means for moving said reciprocating means and said cutting assembly along said frame member.
-~ For the purpose of illustrating the invention, there -is shown in the drawings a form which is presently preferred;
it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.
Brief Description of the Drawings .
Figure 1 is a front view partially broken away, of the apparatus comprising the herein disclosed invention.
Figure 2 is an elevated side view, partially broken ~3-..
.
away, taken along line 2-2 of Figure 1.
Figure 3 is an elevated side view, partially in cross section, taken along line 3-3 of Figure 1.
Figure 4 is an enlarged top view of the cutting wheels and pivot arm taken along line 4-4 of Figure 1.
Figure 5 is a simplified expanded perspective view showing the relative positioning of the horn tip, thermoplastic material and cutting wheels.
Detailed Description of the Preferred Embodiment Referring to the drawing, wherein like numerals indicate like elements, there is shown in Figure 1 the cutting, sealing and stitching machine in accordance with the herein disclosed invention designated 10. The cutting assembly 12, as well as the roller assembly 14, is mounted upon the frame assembly 16.
The frame assembly 16 consists of base members 18, horizontal support members 20, vertical support members 22, and transversing support member 24. In the preferred embodiment, the ' "
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1 base members 18 are I-beams, while the remaining support members 20, 22, and 24 are channel beams. The various support members 18, 20, 22, and 24 are metallurgically or mechanically coupled to one another so as to provide a rigid support for cutting assembly 12 and roller assembly 14.
As can best be seen in Figures 2 and 3, roller assembly 14 consists of motor driven feed roller 26, motor driven exit roller 28 and idler rollers 30 and 32. Rollers 26 and 28 are rotatably mounted on vertical support members 22. Idler rollers 30 and 32 are rotatably mounted on brackets 34. Brackets 34 are, in turn, mounted on slide guides 36 of vertical support members 22.
Air cylinders 38 are coupled to each end of idler rollers 30, 32 and lift these rollers so as to provide a gap for threading the thermoplastic material 40 which is ~o be cut by the machine 10.
Idler rollers 30 and 32 are positioned above rollers 26 and 28 so that when pistons 38 are extended, idler rollers 3a and 32 are urged against rollers 26 and 28 respectively. In this way, idler rollers 30 and 32 provide a pressurized nip section for grasping the material 40 which is to be cut by the machine 10. Each roller 26, 28, 30 and 32 is provided with a high friction covering ~- 42 such as rubber or high friction tape to increase its gripping capabilities.
The thermoplastic material 40 enters the machine 10 at the interface of rollers 26 and 30 and exits at the interface of rollers 28 and 32. Rollers 26 and 28 are provided with adjust-able speed drive motors (not shown) which will both pull the ma-terial through the machine and apply a slight holding force so as ~-to create tension in the material located between the feed roller .
,~ . .
.
1~79020 1 26 and exit roller 28. For purposes of reference, the thermo-plastic material 40 located between rollers 26 and 28 define what may be referred to as a cutting plane. The speed of each drive motor can be set to apply the proper tension required by differ-ent types of thermoplastic material 40. An air brake (not shown) is associated with each roller 26, 28 to maintain material tension after the rollers 26, 28 have stopped.
Referring again to Figure 1, the cutting assembly 12 consists of an ultrasonic horn 44, a cutting wheel assembly 46, and a support bar 48. In the preferred embodiment, the ultrasonic horn 44 is a standard catenoidal horn with replaceable tips, -booster and converter. Typically, such a horn will convert a 20,000 hertz input signal into mechanical force in the form of a vertical vibration in the horn tip or cutting head 50. However, it should be recognized that other types of horns operating at various frequencies may be employed without deviating from the spirit of the invention.
The construction of cutting wheel assembly 46 can best be understood with reference to Figures 1 and 4. A spring loaded pivot arm 54 is pivotally mounted on support bar 48 by pin 56.
Shafts 58 and 59 extend through the forward end of spring loaded pivot arm 54 and are rotatably mounted thereon. At least one stitching wheel 62 is rigidly mounted on each shaft 58, 59. The placement of stitching wheels 62 is such that in the absence of any material both wheels come into contact with horn tip 50 when spring loaded pivot arm 54 biases the shafts 58 and 59 towards the horn tip 50.
As can be seen in Figure 4, the front end of pivot arm 54 is biased towards the horn tip 50 by torsion spring 57. One end of torsion spring 57 is attached to support bar 48 and the other end is attached to pivot arm 54. It should be noted that the use of a torsion spring to bias the front of the pivot arm in the direction of horn tip 50 is merely exemplary and any equivalent means for effectuating this result may be used without exceeding the spirit or the scope of the herein disclosed invention. The only critical limitation in this respect is that the stitching wheels 62 must be biased against the horn tip 50 at such a pressure that the material 40 located between the working edges 63 of the stitching wheels 62 and the horn tip 50 is melted but not actually cut. This limitation is discussed in further detail below.
Cutting wheel 60 is rigidly connected to cutting wheel support member 51 by bolt 53. Bolt 53 prevents the cutting wheel 60 from rotating as the cutting assembly 12 traverses the material 40. However, if the beveled working edge 61 flattens from use, the bolt 53 may be loosened and the cutting wheel 60 rotated to ex-pose a new surface to horn tip 50. Cutting wheel support member 51 is rigidly connected to support bar 48 and depends horizontally therefrom. The positioning of support member 51 is such that cut-ting wheel 60 will be firmly biased against horn tip 50 at a -; pressure sufficient to cause the material 40 passing between the working edge 61 of the cutting wheel 60 and the horn tip 50 to be cut. This action is described in greater detail below.
In the preferred embodiment, support bar 48 is adjust-able up and down to allow for proper placement of wheels 60 and 62. :~
The spring loaded pivot arm 54 is spring loaded to provide an ~:, , j ,-, . . , . . , .. ~ . ...... ..
16)790Z0 l adjustment for wear or size change. Additional pressure adjust-ment may be provided by a "knee" type linkage located on support bar 48 by adjusting a pressure screw. Such "knee'' type linkages are well-known and conventional in the mechanical arts and there-fore need not be illustrated.
The pressure at which the cutting and stitching wheels 60, 62 are biased against the horn tip 50 is critical in determin-ing whether each wheel will cut or stitch the thermoplastic ma-terial 40. This is due to the fact that the intensity of the heat energy induced in the material 40 is directly proportional to the pressure at which the cutting wheel 60 presses the material 40 against the horn tip 50. As noted above, the wheels 60, 62 act as rigid anvils which concentrate the transferred vibrational energy in a smallswatch of the flexible thermoplastic material 40.
Exactly how concentrated this energy will be is dependent upon the pressure at which the wheels 60, 62 press the material 40 against the horn tip 50. The greater the pressure, the more concentrated the transferred vibrational energy and therefore the greater the intensity of the heat induced in the material 40.
As can best be seen in Figure 5, cutting wheel 60 has a sharp beveled working edge 61 which presses the thermoplastic material 40 against the horn tip 50. As the thermoplastic material 40 passes between the horn tip 50 and cutting wheel 60, the vibra-tional energy in the horn tip 50 is converted to frictional energy in the form of heat in thermoplastic material 40. As noted above, the cutting wheel 60 is firmly biased against the cutting head 50 at a pressure sufficient to cut the material at the point of con-tact between the working edge 61 and the horn tip 50. In addition :
10790~0 l to cutting the material 40, the heat produced by the translation of vibrational energy into the material 40 will be sufficient to melt and seal the freshly cut edges on either side of the cutting wheel 60.
Stitching wheels 62 have flat intermittently protuding working edges 63 which press thermoplastic material 40 against horn tip 50 and thereby cause frictional energy at the point of contact.
However, since the two outer stitching wheels 62 are spring biased at a lesser pressure than the cutting wheel 60 against the horn tip 50, the heat produced at these points will not be as great and the material will fuse together without actually being cut. In the preferred embodiment, the working edges 63 of stitching wheels 62 are such that they will imprint a dashed pattern along a line re-cessed from the cut edges of the thermoplastic material 40. In one embodiment, the cutting wheels 60 are positioned such that the dashed pattern is recessed one-quarter inch from the cut edge.
However, any distance can be chosen within the limits of the radius of the horn tip 50. This stitching effect not only makes the ma-terial more attractive, but adds strength to the cut and sealed 20 edge. While in the preferred embodiment the working edges of -stitching wheel 62 were rectangular in shape, other designs such as dots, small circles, or any other desired configuration may be used.
During the operation of the machine 10 (described be-low), it becomes necessary to rotate stitching wheels 62 while the cutting assembly 12 traverses the thermoplastic material 40. For this reason, rotational energy is transferred from auxiliary drive wheels 64 to shafts 58, 59 via pulleys 66 and belts 68. The auxil-iary drive wheels 64 are mounted on shaf~ 69 which extends through ~079020 1 spring loaded plvOt arm 54. Auxiliary drive wheels 64 are in turn powered by drive belt 72 and center pulley 70 which is located on the center of shaft 69. Drive belt 72 is driven by drive wheel 74 which will be described in greater detail below. It should be noted at this time that pulley 66 and drive wheels 64 are mounted on first and second en~s of pivot arm 54 which extend in opposite directions, respectively,from support bar 48.
As best seen in Figures 1 and 2, piston 52 supports the cutting assembly 12. Its function is to lower the cutting assembly 12 into a cutting position wherein the thermoplastic material 40 lies between the horn tip 50 and wheels 60 and 62. The hGrn ti.p 50 and wheels 60 and 62 will be sustained in this position unti~ the cut is completed, whereupon the piston 52 will raise the cutting assembly 12 above the thermoplastic material 40 so that the cutting - assembly 12 may be returned to its initial position while new- thermoplastic material 40 is fed into the machine 10. In the preferred embodiment, the piston 52 is a pneumatic piston. How-ever, any other means for alternately raising and lowering the cutting assembly 12 may be utilized.
. Referring to Figures 1 and 3, the piston 52 is bolted - to perpendicular support member 76 of transversing frame assembly 78. Transversing frame assembly 78 consists of two side plate members 80 rigidly displaced by perpendicular support member 76.
Side plate members 80 are disposed adjacent to and inside of transversing support members 24 and are slidably mounted thereupon by castors 82. Castors 82 are positioned as shown in Figure 1 and permit transversing frame assembly 78 to move along transvers-~- ing support member 24.
, ' _g_ ~ ' 1~790~0 : 1 A roller chain 84 connects the transversing frame assembly 78 to a variable speed gear head motor 86 positioned on the top of one of vertical support members 22. As noted above, the drive wheels 74 supply rotational energy to drive belt 72. As can best be seen in Figures 1 and 3, drive wheel 74 cooperates with two castors 82 to rotate shaft 88. Shaft 88 is rotatably mounted on perpendicular support member 76 by brackets 90. A pulley locat-ed on the center of shaft 88 cooperates with drive belt 72 to sup-ply rotational energy to cutting wheel assembly 46. It should be noted at this time that drive belt 72 must be positioned directly behind support member 51 so that it will not interfere with thermo-plastic material 40 during the cutting process. It will also be -.
noted that when the cutting assembly 12 is raised into the return position the drive belt 72 is slack and will not transmit power :
to auxiliary drive wheels 64. -. Having described the structure of the machine 10, I
~ will now describe its operation. When the cutting process is to : begin, the idler rollers 30 and 32 are pneumatically lifted by theoperation of air cylinders 38. The thermoplastic material 40 will then be placed o,ver both feed roller 26 and exit roller 28. At :
~ this time, the idler rollers 30 and 32 will be returned to their .. normal posi~ion wherein the thermoplastic material 40 is securely retained between each pair of rollers. The adjustable speed drive motors will then rotate feed roller 26 and exit roller 28 thereby advancing thermoplastic material 40 through the machine 10.
- When a predetermined length of material has been drawn through the machine, power to rollers 26 and 28 will be cut off. The motor powering feed roller 26 stops a fraction of a second before the ~, 107~0~0 1 motor powering exit roller 28. In this manner, proper cutting tension in the material 40 located between rollers 26 and 28 is assured. At this point, the cutting assembly 12 is lowered into the cutting position. The cutting assembly 12 is positioned above the extreme right-hand edge (viewed from Figure 1) of rol-lers 28 and 32 immediately prior to the beginning of the cutting cycle. Since the thermoplastic material 40 does not extend across the entire length of rollers 26 and 28, cutting wheel assembly 46 will be free to extend below the cutting plane of the thermoplastic material 40 at this time. When the piston 52 has lowered the cut-ting assembly 12 into the proper cutting position, variable speed gear head motor 86 will begin operation, causing roller chain 84 to pull transversing frame assembly 78 across the length of trans-versing support member 24. In this way, the thermoplastic material 40 will pass between the horn tip 50 and cutting and stitching wheels 60 and 62, wherein the material will be simultaneously cut, sealed and stitched by the frictional energy imparted from the horn tip 50 to material 40 as described in greater detail above.
When the entire width of the material has been tra-versed, piston 52 will raise the cutting assembly 12 into a re-turn position wherein the cutting assembly 12 may be returned to its starting position above the extreme right-hand edge of rollers 26 and 28 without interfering with the thermoplastic material 40.
It should be noted that the variable speed gear head motor 86 operates at full speed when returning the cutting assembly 12 to its starting position.
While the cutting assembly 12 is being returned to the starting position, the air brakes on rollers 26 and 28 are re-.1~ ' 1 leased and rollers 26 and 28 are actuated. The motor powering feed roller 26 is provided with a very slight delay to allow exit rol-ler 28 to create a gap between the cut edges of thermoplastic ma-terial 40. Again, a predetermined length of material is fed into the machine 10 across rollers 26 and 28. When the proper length of material is detected, ~he power to the rollers will stop and the entire process is repeated.
The present invention may be embodied in other speci-fic forms without departing from the spirit or essential attri-butes thereof and, accordingly, reference should be made to theappended claims, rather than to the foregoing specification as indicating the scope of the invention.
.~
Ultrasonic energy has long been employed to both melt and cut metallic or non-metallic thermoplastic materials. In a typical application, high frequency currents are applied to a trans-ducer which converts electrical energy into mechanical energy in the form of vibrations in the ultrasonic horn. The exact orientation of these vibrations will depend on the particular shape and struc-tural characteristics of the horn. The most preva'ent horn used for cutting takes the shape of a tapered cone. Such a horn will insure a concentration of longitudinal vibrations at the horn tip.
When the tip of the horn is biased against a rigid material such as metal, the longitudinal vibrations at the horn tip will transfer vibrational energy to the metal at the point of contact. Frictional forces induced within the metal work pieces will then heat the metal and thereby produce the desired cut.
This procedure will not be successful when the ma-terial to be cut is a flexible thermoplastic. In such a case thevibrations transferred from the tip of the horn to the thermo-plastic material will be widely distributed throughout the ma-terial. As such, the friction induced in any one section of the material will not be sufficient to produce adequate heating. In order to overcome this problem, a rigid anvil may be utilized to concentrate the transferred mechanical energy in a small swatch .~ .
~ Ç D
~r'~ ..
1~790Zo V ~
1 of the thermoplastic material. In a typical application, a flat faced anvil having a surface area smaller than that of the horn tip will be used to firmly press the flexible thermoplastic ma-terial against the face of the horn tip. In this way, substan-tially all of the vibrational energy transferred to the material will be concentrated in the area defined by the face of the anvil.
The internal frictional forces between the fibers of the thermo-plastic material will thereby melt the material along the sur-face defined by ~he face of the anvil. If the area of concentra-tion is sufficiently small, the heat will be sufficiently intenseto actually cut the material being worked on.
The above characteristics of ultrasonic horns are well-known in the art and have been employed to provide stitch seams in thermoplastic sheet-like elements. One such application can be found in U.S. patent 3,666,599 issued to Edward ~. Obeda.
The present invention exceeds the level of the prior art by provid-ing a fully automatic apparatus which can simultaneously cut, seal and stitch thermoplastic material.
Brief Summary of the Invention : Apparatus is provided for simultaneously cutting, sealing and stitching thermoplastic material. A plurality of wheels are biased against the flat cutting head of an ultrasonic . . _~ .
horn. Reciprocating means are provided for alternately j placing the cutting head and the wheels in a first ~ position wherein the material ' ' _ ,~
:B
~079020 is situated between the cutting head and the wheels, and a second position wherein the cutting head and the wheels are disposed from and out of contact with the material.
In accordance with one broad aspect, the invention relates to a machine for simultaneously cutting, sealing and stitching thermoplastic material, comprising: a frame assembly;
means mounted on said frame assembly for advancing the material through the machine and for positioning the section of material to be cut along a predetermined cutting plane;
a frame member mounted on said frame assemblv transversely to the direction in which said material is advanced and in a plane parallel to said cutting plane; a cutting assembly including a sonic horn having a flat cutting head, a plurality ~
of wheels for pressing the material against said cutting head, ~-and wheel support means biasing the working edges of said wheels against said cutting head; reciprocating means slidably mounted on said frame member for alternatively placing said cutting assembly in a first position wherein said cutting plane i5 situated between said cutting head and said wheels, and a second position wherein said cutting head and said wheels are disposed from said cutting plane in a direction perpendicular to said cutting plane; and means for moving said reciprocating means and said cutting assembly along said frame member.
-~ For the purpose of illustrating the invention, there -is shown in the drawings a form which is presently preferred;
it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.
Brief Description of the Drawings .
Figure 1 is a front view partially broken away, of the apparatus comprising the herein disclosed invention.
Figure 2 is an elevated side view, partially broken ~3-..
.
away, taken along line 2-2 of Figure 1.
Figure 3 is an elevated side view, partially in cross section, taken along line 3-3 of Figure 1.
Figure 4 is an enlarged top view of the cutting wheels and pivot arm taken along line 4-4 of Figure 1.
Figure 5 is a simplified expanded perspective view showing the relative positioning of the horn tip, thermoplastic material and cutting wheels.
Detailed Description of the Preferred Embodiment Referring to the drawing, wherein like numerals indicate like elements, there is shown in Figure 1 the cutting, sealing and stitching machine in accordance with the herein disclosed invention designated 10. The cutting assembly 12, as well as the roller assembly 14, is mounted upon the frame assembly 16.
The frame assembly 16 consists of base members 18, horizontal support members 20, vertical support members 22, and transversing support member 24. In the preferred embodiment, the ' "
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; - - - - .. . - - . - . .
- . . : - .: : ;
, ~
107902~
1 base members 18 are I-beams, while the remaining support members 20, 22, and 24 are channel beams. The various support members 18, 20, 22, and 24 are metallurgically or mechanically coupled to one another so as to provide a rigid support for cutting assembly 12 and roller assembly 14.
As can best be seen in Figures 2 and 3, roller assembly 14 consists of motor driven feed roller 26, motor driven exit roller 28 and idler rollers 30 and 32. Rollers 26 and 28 are rotatably mounted on vertical support members 22. Idler rollers 30 and 32 are rotatably mounted on brackets 34. Brackets 34 are, in turn, mounted on slide guides 36 of vertical support members 22.
Air cylinders 38 are coupled to each end of idler rollers 30, 32 and lift these rollers so as to provide a gap for threading the thermoplastic material 40 which is ~o be cut by the machine 10.
Idler rollers 30 and 32 are positioned above rollers 26 and 28 so that when pistons 38 are extended, idler rollers 3a and 32 are urged against rollers 26 and 28 respectively. In this way, idler rollers 30 and 32 provide a pressurized nip section for grasping the material 40 which is to be cut by the machine 10. Each roller 26, 28, 30 and 32 is provided with a high friction covering ~- 42 such as rubber or high friction tape to increase its gripping capabilities.
The thermoplastic material 40 enters the machine 10 at the interface of rollers 26 and 30 and exits at the interface of rollers 28 and 32. Rollers 26 and 28 are provided with adjust-able speed drive motors (not shown) which will both pull the ma-terial through the machine and apply a slight holding force so as ~-to create tension in the material located between the feed roller .
,~ . .
.
1~79020 1 26 and exit roller 28. For purposes of reference, the thermo-plastic material 40 located between rollers 26 and 28 define what may be referred to as a cutting plane. The speed of each drive motor can be set to apply the proper tension required by differ-ent types of thermoplastic material 40. An air brake (not shown) is associated with each roller 26, 28 to maintain material tension after the rollers 26, 28 have stopped.
Referring again to Figure 1, the cutting assembly 12 consists of an ultrasonic horn 44, a cutting wheel assembly 46, and a support bar 48. In the preferred embodiment, the ultrasonic horn 44 is a standard catenoidal horn with replaceable tips, -booster and converter. Typically, such a horn will convert a 20,000 hertz input signal into mechanical force in the form of a vertical vibration in the horn tip or cutting head 50. However, it should be recognized that other types of horns operating at various frequencies may be employed without deviating from the spirit of the invention.
The construction of cutting wheel assembly 46 can best be understood with reference to Figures 1 and 4. A spring loaded pivot arm 54 is pivotally mounted on support bar 48 by pin 56.
Shafts 58 and 59 extend through the forward end of spring loaded pivot arm 54 and are rotatably mounted thereon. At least one stitching wheel 62 is rigidly mounted on each shaft 58, 59. The placement of stitching wheels 62 is such that in the absence of any material both wheels come into contact with horn tip 50 when spring loaded pivot arm 54 biases the shafts 58 and 59 towards the horn tip 50.
As can be seen in Figure 4, the front end of pivot arm 54 is biased towards the horn tip 50 by torsion spring 57. One end of torsion spring 57 is attached to support bar 48 and the other end is attached to pivot arm 54. It should be noted that the use of a torsion spring to bias the front of the pivot arm in the direction of horn tip 50 is merely exemplary and any equivalent means for effectuating this result may be used without exceeding the spirit or the scope of the herein disclosed invention. The only critical limitation in this respect is that the stitching wheels 62 must be biased against the horn tip 50 at such a pressure that the material 40 located between the working edges 63 of the stitching wheels 62 and the horn tip 50 is melted but not actually cut. This limitation is discussed in further detail below.
Cutting wheel 60 is rigidly connected to cutting wheel support member 51 by bolt 53. Bolt 53 prevents the cutting wheel 60 from rotating as the cutting assembly 12 traverses the material 40. However, if the beveled working edge 61 flattens from use, the bolt 53 may be loosened and the cutting wheel 60 rotated to ex-pose a new surface to horn tip 50. Cutting wheel support member 51 is rigidly connected to support bar 48 and depends horizontally therefrom. The positioning of support member 51 is such that cut-ting wheel 60 will be firmly biased against horn tip 50 at a -; pressure sufficient to cause the material 40 passing between the working edge 61 of the cutting wheel 60 and the horn tip 50 to be cut. This action is described in greater detail below.
In the preferred embodiment, support bar 48 is adjust-able up and down to allow for proper placement of wheels 60 and 62. :~
The spring loaded pivot arm 54 is spring loaded to provide an ~:, , j ,-, . . , . . , .. ~ . ...... ..
16)790Z0 l adjustment for wear or size change. Additional pressure adjust-ment may be provided by a "knee" type linkage located on support bar 48 by adjusting a pressure screw. Such "knee'' type linkages are well-known and conventional in the mechanical arts and there-fore need not be illustrated.
The pressure at which the cutting and stitching wheels 60, 62 are biased against the horn tip 50 is critical in determin-ing whether each wheel will cut or stitch the thermoplastic ma-terial 40. This is due to the fact that the intensity of the heat energy induced in the material 40 is directly proportional to the pressure at which the cutting wheel 60 presses the material 40 against the horn tip 50. As noted above, the wheels 60, 62 act as rigid anvils which concentrate the transferred vibrational energy in a smallswatch of the flexible thermoplastic material 40.
Exactly how concentrated this energy will be is dependent upon the pressure at which the wheels 60, 62 press the material 40 against the horn tip 50. The greater the pressure, the more concentrated the transferred vibrational energy and therefore the greater the intensity of the heat induced in the material 40.
As can best be seen in Figure 5, cutting wheel 60 has a sharp beveled working edge 61 which presses the thermoplastic material 40 against the horn tip 50. As the thermoplastic material 40 passes between the horn tip 50 and cutting wheel 60, the vibra-tional energy in the horn tip 50 is converted to frictional energy in the form of heat in thermoplastic material 40. As noted above, the cutting wheel 60 is firmly biased against the cutting head 50 at a pressure sufficient to cut the material at the point of con-tact between the working edge 61 and the horn tip 50. In addition :
10790~0 l to cutting the material 40, the heat produced by the translation of vibrational energy into the material 40 will be sufficient to melt and seal the freshly cut edges on either side of the cutting wheel 60.
Stitching wheels 62 have flat intermittently protuding working edges 63 which press thermoplastic material 40 against horn tip 50 and thereby cause frictional energy at the point of contact.
However, since the two outer stitching wheels 62 are spring biased at a lesser pressure than the cutting wheel 60 against the horn tip 50, the heat produced at these points will not be as great and the material will fuse together without actually being cut. In the preferred embodiment, the working edges 63 of stitching wheels 62 are such that they will imprint a dashed pattern along a line re-cessed from the cut edges of the thermoplastic material 40. In one embodiment, the cutting wheels 60 are positioned such that the dashed pattern is recessed one-quarter inch from the cut edge.
However, any distance can be chosen within the limits of the radius of the horn tip 50. This stitching effect not only makes the ma-terial more attractive, but adds strength to the cut and sealed 20 edge. While in the preferred embodiment the working edges of -stitching wheel 62 were rectangular in shape, other designs such as dots, small circles, or any other desired configuration may be used.
During the operation of the machine 10 (described be-low), it becomes necessary to rotate stitching wheels 62 while the cutting assembly 12 traverses the thermoplastic material 40. For this reason, rotational energy is transferred from auxiliary drive wheels 64 to shafts 58, 59 via pulleys 66 and belts 68. The auxil-iary drive wheels 64 are mounted on shaf~ 69 which extends through ~079020 1 spring loaded plvOt arm 54. Auxiliary drive wheels 64 are in turn powered by drive belt 72 and center pulley 70 which is located on the center of shaft 69. Drive belt 72 is driven by drive wheel 74 which will be described in greater detail below. It should be noted at this time that pulley 66 and drive wheels 64 are mounted on first and second en~s of pivot arm 54 which extend in opposite directions, respectively,from support bar 48.
As best seen in Figures 1 and 2, piston 52 supports the cutting assembly 12. Its function is to lower the cutting assembly 12 into a cutting position wherein the thermoplastic material 40 lies between the horn tip 50 and wheels 60 and 62. The hGrn ti.p 50 and wheels 60 and 62 will be sustained in this position unti~ the cut is completed, whereupon the piston 52 will raise the cutting assembly 12 above the thermoplastic material 40 so that the cutting - assembly 12 may be returned to its initial position while new- thermoplastic material 40 is fed into the machine 10. In the preferred embodiment, the piston 52 is a pneumatic piston. How-ever, any other means for alternately raising and lowering the cutting assembly 12 may be utilized.
. Referring to Figures 1 and 3, the piston 52 is bolted - to perpendicular support member 76 of transversing frame assembly 78. Transversing frame assembly 78 consists of two side plate members 80 rigidly displaced by perpendicular support member 76.
Side plate members 80 are disposed adjacent to and inside of transversing support members 24 and are slidably mounted thereupon by castors 82. Castors 82 are positioned as shown in Figure 1 and permit transversing frame assembly 78 to move along transvers-~- ing support member 24.
, ' _g_ ~ ' 1~790~0 : 1 A roller chain 84 connects the transversing frame assembly 78 to a variable speed gear head motor 86 positioned on the top of one of vertical support members 22. As noted above, the drive wheels 74 supply rotational energy to drive belt 72. As can best be seen in Figures 1 and 3, drive wheel 74 cooperates with two castors 82 to rotate shaft 88. Shaft 88 is rotatably mounted on perpendicular support member 76 by brackets 90. A pulley locat-ed on the center of shaft 88 cooperates with drive belt 72 to sup-ply rotational energy to cutting wheel assembly 46. It should be noted at this time that drive belt 72 must be positioned directly behind support member 51 so that it will not interfere with thermo-plastic material 40 during the cutting process. It will also be -.
noted that when the cutting assembly 12 is raised into the return position the drive belt 72 is slack and will not transmit power :
to auxiliary drive wheels 64. -. Having described the structure of the machine 10, I
~ will now describe its operation. When the cutting process is to : begin, the idler rollers 30 and 32 are pneumatically lifted by theoperation of air cylinders 38. The thermoplastic material 40 will then be placed o,ver both feed roller 26 and exit roller 28. At :
~ this time, the idler rollers 30 and 32 will be returned to their .. normal posi~ion wherein the thermoplastic material 40 is securely retained between each pair of rollers. The adjustable speed drive motors will then rotate feed roller 26 and exit roller 28 thereby advancing thermoplastic material 40 through the machine 10.
- When a predetermined length of material has been drawn through the machine, power to rollers 26 and 28 will be cut off. The motor powering feed roller 26 stops a fraction of a second before the ~, 107~0~0 1 motor powering exit roller 28. In this manner, proper cutting tension in the material 40 located between rollers 26 and 28 is assured. At this point, the cutting assembly 12 is lowered into the cutting position. The cutting assembly 12 is positioned above the extreme right-hand edge (viewed from Figure 1) of rol-lers 28 and 32 immediately prior to the beginning of the cutting cycle. Since the thermoplastic material 40 does not extend across the entire length of rollers 26 and 28, cutting wheel assembly 46 will be free to extend below the cutting plane of the thermoplastic material 40 at this time. When the piston 52 has lowered the cut-ting assembly 12 into the proper cutting position, variable speed gear head motor 86 will begin operation, causing roller chain 84 to pull transversing frame assembly 78 across the length of trans-versing support member 24. In this way, the thermoplastic material 40 will pass between the horn tip 50 and cutting and stitching wheels 60 and 62, wherein the material will be simultaneously cut, sealed and stitched by the frictional energy imparted from the horn tip 50 to material 40 as described in greater detail above.
When the entire width of the material has been tra-versed, piston 52 will raise the cutting assembly 12 into a re-turn position wherein the cutting assembly 12 may be returned to its starting position above the extreme right-hand edge of rollers 26 and 28 without interfering with the thermoplastic material 40.
It should be noted that the variable speed gear head motor 86 operates at full speed when returning the cutting assembly 12 to its starting position.
While the cutting assembly 12 is being returned to the starting position, the air brakes on rollers 26 and 28 are re-.1~ ' 1 leased and rollers 26 and 28 are actuated. The motor powering feed roller 26 is provided with a very slight delay to allow exit rol-ler 28 to create a gap between the cut edges of thermoplastic ma-terial 40. Again, a predetermined length of material is fed into the machine 10 across rollers 26 and 28. When the proper length of material is detected, ~he power to the rollers will stop and the entire process is repeated.
The present invention may be embodied in other speci-fic forms without departing from the spirit or essential attri-butes thereof and, accordingly, reference should be made to theappended claims, rather than to the foregoing specification as indicating the scope of the invention.
.~
Claims (4)
1. A machine for simultaneously cutting, sealing and stitching thermoplastic material, comprising:
a frame assembly;
means mounted on said frame assembly for ad-vancing the material through the machine and for positioning the section of material to be cut along a predetermined cutting plane;
a frame member mounted on said frame assembly transversely to the direction in which said material is advanced and in a plane parallel to said cutting plane;
a cutting assembly including a sonic horn hav-ing a flat cutting head, a plurality of wheels for pressing the material against said cutting head, and wheel support means biasing the working edges of said wheels against said cutting head;
reciprocating means slidably mounted on said frame member for alternatively placing said cutting assembly in a first position wherein said cutting plane is situated between said cutting head and said wheels, and a second position wherein said cutting head and said wheels are disposed from said cutting plane in a direction perpendicular to said cutting plane; and means for moving said reciprocating means and said cutting assembly along said frame member.
a frame assembly;
means mounted on said frame assembly for ad-vancing the material through the machine and for positioning the section of material to be cut along a predetermined cutting plane;
a frame member mounted on said frame assembly transversely to the direction in which said material is advanced and in a plane parallel to said cutting plane;
a cutting assembly including a sonic horn hav-ing a flat cutting head, a plurality of wheels for pressing the material against said cutting head, and wheel support means biasing the working edges of said wheels against said cutting head;
reciprocating means slidably mounted on said frame member for alternatively placing said cutting assembly in a first position wherein said cutting plane is situated between said cutting head and said wheels, and a second position wherein said cutting head and said wheels are disposed from said cutting plane in a direction perpendicular to said cutting plane; and means for moving said reciprocating means and said cutting assembly along said frame member.
2. A machine as claimed in Claim 1 wherein said plurality of wheels includes a cutting wheel and a stitching wheel and wherein said wheel support means comprises:
a support bar connected to said reciprocating means;
a pivot arm pivotally connected to said support bar, said pivot arm having first and second ends extending in opposite directions, respectively, from said support bar;
said stitching wheel rotatably mounted on said first end of said pivot arm for concurrent rotation with a first pulley;
a second pulley rotatably mounted on said second end of said pivot arm;
a belt connecting said first pulley to said second pulley whereby rotation of said second pulley causes rota-tion of said first pulley;
means for rotating said second pulley so as to cause rotation of said stitching wheel; and means for biasing said first end of said pivot arm towards said sonic horn.
a support bar connected to said reciprocating means;
a pivot arm pivotally connected to said support bar, said pivot arm having first and second ends extending in opposite directions, respectively, from said support bar;
said stitching wheel rotatably mounted on said first end of said pivot arm for concurrent rotation with a first pulley;
a second pulley rotatably mounted on said second end of said pivot arm;
a belt connecting said first pulley to said second pulley whereby rotation of said second pulley causes rota-tion of said first pulley;
means for rotating said second pulley so as to cause rotation of said stitching wheel; and means for biasing said first end of said pivot arm towards said sonic horn.
3. A machine as claimed in Claim 2 wherein said reciprocating means includes a pneumatic piston.
4. A machine in accordance with claim 2 wherein said cutting wheel is rigidly supported for non-rotation by said wheel support means, said stitching wheel being supported for rotation by said wheel support means, and means for biasing said stitching wheel against said cutting head so that material there between is melted but not cut.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA252,375A CA1079020A (en) | 1976-05-12 | 1976-05-12 | Apparatus for simultaneously cutting, sealing and stitching thermoplastic material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA252,375A CA1079020A (en) | 1976-05-12 | 1976-05-12 | Apparatus for simultaneously cutting, sealing and stitching thermoplastic material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1079020A true CA1079020A (en) | 1980-06-10 |
Family
ID=4105946
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA252,375A Expired CA1079020A (en) | 1976-05-12 | 1976-05-12 | Apparatus for simultaneously cutting, sealing and stitching thermoplastic material |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1079020A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114713921A (en) * | 2021-01-05 | 2022-07-08 | 中国航发商用航空发动机有限责任公司 | Support removing tool and support removing method |
-
1976
- 1976-05-12 CA CA252,375A patent/CA1079020A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114713921A (en) * | 2021-01-05 | 2022-07-08 | 中国航发商用航空发动机有限责任公司 | Support removing tool and support removing method |
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