Depth control of seal line penetration for rotary ultrasonic horn / anvil welding without mechanical stops

Abstract

A device 200 for joining a first film portion and a second film portion along a sealing line is disclosed. The device includes a welding head 208 and an anvil 220. The anvil is positioned proximate to the welding head. The welding head or anvil has a surface 216, 226 that is rotatable about an axis of rotation. The surface has a raised profile, and the height of the raised profile relative to the surface is sized to correspond to 50% to 150% of the thickness of the first film portion or the second film portion. Alternatively, the raised profile has a tapered side having a radius between 0.5 and 5 degrees relative to the uppermost surface of the raised profile, the surface being positioned so that the raised profile extends along the circumference, providing continuous running contact between the raised profile and the other of the welding head and the anvil when rotated about the axis of rotation, thereby forming a sealing line without any external structure to control the distance between the welding head / anvil while providing continuous running contact. Pulling patterns, cutting, and sealing features are also disclosed.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Patent Application No. 17 / 399,429, filed on August 11, 2021, entitled “Depth Control of Seal Line Penetration For Rotary Ultrasonic Horn / Anvil Welding Without Mechanical Stop,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates generally to ultrasonic welding systems and, more particularly, to depth control of seal line penetration for rotary ultrasonic horn / anvil welding without mechanical stops. Background Art

[0004] When bonding thin films (thickness less than 150 μm), achieving consistent penetration with air-loading systems can be challenging. This is particularly true for single-layer and single-material films. In some ultrasonic welding applications, it is advantageous to use a disc-shaped horn and anvil, known as a rotary horn or rotary anvil. When the application requires forming a seal or joint between two substrates or layers to be joined in a final product (e.g., a pouch or container), some conventional rotary ultrasonic technologies employ mechanical stops to control the depth of the joint or seal by stopping the advancing ultrasonic horn. However, mechanical stops have very severe limitations for thin film processing. Mechanical stops require near-perfect concentricity and overall concentricity of the rotating elements (rotary horn and rotary anvil), particularly for film applications with thicknesses around 0.002 inches (50 μm). They also experience mechanical wear and tear over time, which adversely affects consistent joint or seal depth control. Mechanical stops also require designers to account for thermal expansion and contraction, and operators will need a high level of accumulated skill to fine-tune them to accommodate varying film thicknesses. Mechanical stops are comprised of multiple components, such as bearings, shafts, and other parts, and manufacturing tolerances in these components can introduce a small but significant element of rotational runout. If this runout occurs, the bond consistency from end-to-end product will be lost due to the very small gap dimensions required between the rotating elements.

[0005] Other conventional rotary applications using ultrasonic energy have a pattern of ridges formed on the surface of the rotary angle and / or rotary anvil, such as those disclosed in U.S. Patent No. 10,889,066, owned by the same assignee as the present disclosure, which are particularly suitable for bonding nonwoven fabrics by trapping elastic strands in a permanent state of tension. These applications are not particularly suitable for fusing plastics together to form an airtight or airtight seal between two plastic parts. In addition, the ridge pattern tends to be much taller than the thickness of the fabric being bonded together by the ultrasonic energy. The patterned profile also does not create an airtight seal, which is desirable in some applications, such as small bags or containers to be filled with liquids.

[0006] Additionally, conventional rotary ultrasonic welding applications incorporate raised profiles on the horn or anvil. However, similar to patterned profiles, the overall height of these raised profiles is greater (often many orders of magnitude greater) than the thickness of the parts being joined, making them unsuitable for controlling the depth of the seal line and poorly suited for sealing thin films together. Highly raised profiles like these result in a weakened bond or seal due to the high forces / pressures applied, making them undesirable for sealing (plastic) films.

[0007] Figure 1A FIG. 1 is a cross-section of a cutaway portion of a prior art anvil 100 having a raised, patterned profile 102. The height H1 of the patterned profile 102 is several orders of magnitude greater than the thickness of the layers sandwiched between the anvil 100 and a conventional horn receiving ultrasonic energy. Due to the magnitude of the height H1, significant forces or pressures are applied to the layers sandwiched between the horn and the anvil 100. This can result in undesirable weakening (e.g., excessive thinning) of the seal line or bond formed at the interface between the patterned profile 102 and the horn, particularly in the case of films such as plastic films, when mechanical stops are insufficient to limit the weld force and distance due to lack of concentricity, thermal expansion, or operator misadjustment.

[0008] Figure 1B FIG. 1 is a cross-section of a cut-away portion of another prior art anvil 110, which also has a raised profile 112, but the raised profile 112 has a similar shape to that of FIG. Figure 1A A smooth surface opposite the patterned surface shown. Similar to anvil 100, Figure 1B The raised profile 112 of the anvil 110 is shown to have a height H2 of 0.063 inches, which is much greater than the thickness of the layer of the part sandwiched between the anvil 112 and a conventional welding head (typically more than twice). Figure 1A Similar to the general outline shown in Figure 1B The conventional profile of will operate to weaken the bond or seal formed between the film layers. Figure 1BThe raised profile 112 shown in , forms a continuous seal, but the raised profile 112 can disadvantageously over-thin the material being welded, thereby weakening the material being welded and the package being sealed when mechanical stops are insufficient to limit weld force and distance due to lack of concentricity, thermal expansion, or operator misadjustment.

[0009] Therefore, there is a need for a rotary ultrasonic welding technique that does not use mechanical stops and can accurately and repeatably join two thin parts (e.g., portions of a film) together and accommodate parts of varying thicknesses. Aspects of the present disclosure are directed to meeting this need and other needs. Summary of the Invention

[0010] The key features of the present invention are the height of the profile and the absence of any mechanical stops to control the depth of the seal using the ultrasonic energy applied by the rotating horn and anvil. The height of the profile is very small, such as between 50% and 150% or 100% of the thickness of the films or parts being joined. The very low height of the profile on the horn or anvil (which may be present on one or both) provides a "dynamic mechanical stop" effect without any actual external mechanical stops by squeezing the two layers of film with enough force or pressure to achieve mechanical support, but not too hard to melt the plastic in the film layers. The combination of the height of the profile and the absence of any mechanical stop structure to control the depth of seal penetration is a key differentiator over the prior art.

[0011] The profile may extend continuously around the entire circumferential outer surface of the rotary horn or rotary anvil. The continuous circumferential profile maintains a constant and continuous force / pressure on the membrane while sealing, while the height of the profile is no greater than the thickness of the membrane.

[0012] The profile height depends on the thickness of the membrane being sealed, but in some embodiments, the profile height can start as low as 0.00" (inch) high and then increase in very small 0.0005" increments, demonstrating the high precision required from an alternative design that utilizes a traditional mechanical stop as opposed to the depth control anvil design of the present invention.

[0013] According to one aspect of the present disclosure, a device is disclosed for joining a first membrane portion and a second membrane portion together along a sealing line using ultrasonic energy. The device includes: a horn configured to receive ultrasonic energy; and an anvil that can be positioned adjacent to the horn, the horn advancing toward the anvil, wherein at least one of the horn and the anvil has a surface having a width dimension and a circumference and rotatable about an axis of rotation. The surface has a raised profile having a height dimension corresponding to 50% to 150% of the thickness of the first membrane portion or the second membrane portion. The surface is positioned so that the raised profile extends along the circumference. When rotating about the axis of rotation, continuous running contact is provided between the raised profile and the other of the horn and the anvil, thereby forming a sealing line without any external structure to control the distance between the horn and the anvil. The thickness of the first membrane portion and the second membrane portion can be between 10 μm and 150 μm.

[0014] The height dimension of convex profile can correspond to 100% of the thickness of the first film portion or the second film portion. The height dimension of convex profile can correspond to between 50% and 125% of the thickness of the second film portion or the first film portion. The first film portion and / or the second film portion can be made of plastics. The first film portion or the second film portion can be multilayer film, recyclable film, biodegradable film, decomposable film, monolayer film, paper base film or single material film.

[0015] The raised profile may further include a scoring element configured to score or cut along the sealing line when the anvil rotates about the rotation axis. The surface may have a second raised profile having a height corresponding to 50% to 150% of the thickness of the first film portion or the second film portion. The second raised profile may extend along a circumference and provide continuous running contact between the second raised profile and the other of the horn or the anvil when rotated about the rotation axis.

[0016] The height dimension of the second raised profile may correspond to 100% of the thickness of the first or second film portion. The raised profile may be part of the anvil and further in combination with the second anvil may have a second raised profile having a height dimension that exceeds the height dimension of the raised profile by 0.0005 inches.

[0017] The present invention discloses a product comprising a first film portion and a second film portion and a seal line formed by any of the apparatus disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1A is a cross-section of a cut-away portion of a prior art anvil having a raised patterned profile;

[0019] Figure 1Bis a cross-sectional view of a cutaway portion of another prior art anvil 110 having a smooth convex profile 112;

[0020] Figure 2 is a perspective view of a rotary ultrasonic welding apparatus adapted for use with a raised profile on an anvil or horn to produce a dynamic stopping effect;

[0021] Figure 3 is an enlarged cross-sectional view of a portion of a horn or anvil having a convex profile according to an aspect of the present invention;

[0022] Figure 4 is an isometric cross-sectional view of a horn or anvil according to another aspect of the present invention having two raised profiles thereon to produce a dynamic stop effect;

[0023] Figure 5 yes Figure 4 An isometric cross-sectional view of a welding head or anvil having two raised profiles is shown;

[0024] Figure 6 yes Figure 5 a cross-sectional view of a portion of the horn or anvil shown;

[0025] Figure 7 is a cross-sectional view of a portion of a horn and anvil and a raised profile, wherein two membranes pass between the horn and anvil during application of ultrasonic energy;

[0026] Figure 8 is a functional diagram of a depth control configuration in which the horn and anvil each have a raised profile to achieve equal or intentionally unequal penetration from both sides of the film being bonded;

[0027] Figure 9A is a functional diagram of a sealing and scoring arrangement wherein the raised profile includes scoring elements to impart a score to the sealing layer after the sealing layers have been bonded;

[0028] Figure 9B is a functional diagram of an inclined sealing profile configuration, wherein the raised profile is inclined to facilitate sealing of the layers to be joined;

[0029] Figure 10A is a cross-sectional view of a portion of a horn or anvil having a tapered bond profile and an exemplary pulling pattern taken along line 10B-10B;

[0030] Figure 10B yes Figure 10A a top cross-sectional view of a portion of the exemplary traction pattern shown;

[0031] Figure 10C is a cross-sectional view of a portion of the pulling pattern taken along line 10C-10C;

[0032] Figure 11A is a side view of a horn or anvil having cutting and sealing features; and

[0033] Figure 11B yes Figure 11A An enlarged view of the cutting and sealing features is shown, with the inset showing an enlarged view of the cutting features.

[0034] Figure 12 A tapered bond profile is shown on the horn or anvil, which may have different profiles on either side of the horn or anvil. DETAILED DESCRIPTION

[0035] Figure 2 is a general illustration of a rotary ultrasonic bonding apparatus 200, the general operation and components of which are well known to those skilled in the art of ultrasonic welding, and particularly rotary ultrasonic welding techniques. Apparatus 200 has an anvil module 202 and a horn module 204 that cooperate to perform a joining or sealing operation on a plurality of parts, such as two or more film layers, as described in greater detail below.

[0036] The weld head module 204 includes a frame 206 on which is mounted a disc-shaped rotating weld head 208, a motor 210 for driving the weld head 208 in rotation via a suitable drive train 212, and a housing 214 that houses at least a portion of a vibration control unit (not shown) that vibrates the weld head 208. The weld head 208 has an exposed outer surface 216 having a substantially continuous contour (i.e., the weld head surface 216 has a contour that is substantially smooth (or uninterrupted) across its entire surface area). In other embodiments, the weld head surface 216 may have any suitable contour that facilitates the functioning of the weld head 208 as described herein.

[0037] In some embodiments, the vibration control unit (although not shown) includes a conventional booster (e.g., a drive booster and an integral booster) mechanically connected to a converter, which can be electrically connected to a generator. The converter is capable of converting high-frequency electrical energy provided by the generator into mechanical energy (or vibration), which is selectively transmitted across one or more boosters to the horn 208. The one or more boosters are capable of modifying (i.e., increasing or decreasing) the vibration transmitted from the converter to the horn 208, causing the horn 208 (particularly the face 216 of the horn 208) to vibrate while rotating during the bonding operation, as described in greater detail below. It is contemplated that the horn module 204 can have any suitable operating components arranged in any suitable manner to facilitate the operation of the horn 208 as described herein. Details not shown will be apparent to anyone familiar with rotary ultrasonic bonding systems.

[0038] In the illustrated embodiment, the anvil module 202 includes a frame 218 on which is mounted a disc-shaped rotating anvil 220 and a motor 222 for driving the anvil 220 in rotation via a suitable drive train. The anvil 220 has an exposed outer surface 226 having a substantially continuous profile (i.e., the anvil surface 226 has a profile that is substantially smooth or uninterrupted over its entire surface area). The anvil module 202 is positioned relative to the horn module 204 so that the anvil surface 226 can rotate about an axis of rotation R (see FIG. Figure 4 ) is rotated in close proximity to the horn surface 216, and vice versa, to facilitate ultrasonic bonding of the parts as the parts are held under tension through the apparatus 200, as described in more detail below. As used herein, the term "in close proximity" refers to being minimally spaced apart from the horn surface 216 when the anvil surface 226 is in contact with the horn surface 216, or when the horn 208 is not ultrasonically vibrating.

[0039] In some embodiments, the apparatus 200 may be configured such that at least one of the anvil module 202 and the horn module 204 may be displaced relative to the other via a suitable displacement mechanism, the displacement mechanism being operable: (A) when the system 100 is offline and the horn 208 is stationary (i.e., when the horn 208 is not rotating or vibrating); and (B) when the system 100 is online and the horn 208 is active (i.e., when the horn 208 is rotating and vibrating).

[0040] In particular, refer to Figure 2In the illustrated embodiment, apparatus 200 can be configured as a continuous clamping apparatus, wherein horn module 204 is: (a) fixed in position relative to anvil module 202 when system 100 is online and horn 208 is active; and (b) displaceable relative to anvil module 202 when system 100 is offline and horn 208 is stationary. This displacement is facilitated by a selectively actuatable pneumatic cylinder 228 (or other suitable linear actuator) connecting frames 206 and 218 to one another. In this manner, the spacing between horn surface 216 and anvil surface 226 can be adjusted while system 100 is offline, primarily for servicing apparatus 200.

[0041] Figure 3 A cross-sectional view of a portion of a horn 208 or anvil 220 is shown, the horn or anvil having an outer surface 302 having a substantially continuous profile (i.e., the outer surface 302 has a profile that is substantially smooth or uninterrupted across its entire surface area) and a raised profile 312 having a height H3 that is between 50% and 150% (e.g., 100%) of the thickness of the parts to be joined between the horn 208 and the anvil 220. It should be emphasized that the raised profile 312 can be present on the horn 208 or the anvil 220, or both, and that the principles discussed herein apply equally to both the horn 208 and the anvil 220. In most applications, the raised profile 312 is present on the anvil 220. More than one raised profile 312 can be present, e.g., Figure 4 . Multiple raised profiles, such as raised profile 312, may be present on the horn 208, on the anvil 220, or distributed between the horn 208 and the anvil 220 (e.g., a raised profile may be present on the horn 208 and a raised profile may be present on the anvil 220) for joining a pair of parts together or for joining multiple pairs of parts together. Raised profile 312 may be referred to herein as a "depth control" profile because the raised profile is used to control the depth of weld penetration in the parts to be joined together by sealing or bonding.

[0042] Figure 3The raised profile 312 shown in has a substantially flat and continuous raised surface having a width of 0.040 inches and transitioning on both sides by curved surfaces with a radius of R = 0.015 inches. The width of the raised profile 312 is also much narrower than the non-patterned profiles of the prior art and, for example, spans less than 10% or less than 7% or less than 5% of the entire width of the horn 208 or anvil 220. The radius size is exemplary but serves to impart a dynamic stop function to the rotary system without the need for mechanical stops present in prior art rotary ultrasonic welding systems. The radius size is also a function of the height H3 of the raised profile 312, but the height H3 is limited to not exceed the thickness of the part, such as a film, to be joined between the horn 208 and the anvil 220, where the horn 208 and the anvil 220 rotate about the axis of rotation R (see Figure 4 ) are rotated relative to each other, the parts are joined by applying ultrasonic energy to the welding head 208. In this example, the raised profile 312 has a height H3 of, for example, approximately 0.0035 inches (within typical tolerances). However, the height H3 can be as low as 0.002 inches to accommodate films of this thickness.

[0043] The horn 208 or anvil 220 can be easily swapped out for another horn 208 or anvil 220 having a raised profile of different dimensions (e.g., height and / or width). The height H3 of each raised profile can be machined to increments of only 0.0005 inches between profiles. For example, if the smallest height profile has a height of 0.0020 inches, the next profile can have a height of 0.0025 inches, followed by 0.0030 inches, and so on. Figure 3 In the example shown, the raised profile 312 on one anvil 220 may have a height of approximately 0.003 inches, and another anvil may have a raised profile with a height of 0.0035 inches, followed by a raised profile of 0.0040 inches, and so on. Depending on the thickness of the parts (e.g., films) being joined together, the anvil 220 or welding head 208 can be easily swapped out to match the height of the raised profile to the thickness of the parts. It should be emphasized that the dimensions or tolerances provided herein are merely exemplary and are used to illustrate the relative height of the profile relative to the thickness of one or more parts layers being welded or joined together.

[0044] The raised profile 312 may be formed around the entire circumference of the horn 208 or anvil 220, such as Figure 4 The partially cutaway perspective view shown in Figure 5 and Figure 6 As shown in more detail in FIG. Since the height of the raised profiles 312a, 312b is very low, Figure 5 and Figure 6 Raised profiles 312a, 312b are shown ( Figure 5 (two are shown in an enlarged view). Energy is provided for sufficient bonding at profile 312. It should be noted that the raised profiles 312a and 312b can have different heights. This can be useful, for example, when the raised profiles 312a and 312b are located on the horn 208 and the anvil 220 has a narrower width than the horn 208. This allows the operator or end user to weld different part thicknesses using the same horn 208 by simply flipping the horn 208 so that the appropriate raised profile (312a or 312b) contacts the anvil 220. For example, if raised profile 312a has a height X and raised profile 312b has a height Y, where Y > X, then when welding thicker parts, the horn 208 can be flipped so that raised profile 312b contacts the anvil 208. Conversely, when welding thinner parts, the horn 208 can be flipped so that raised profile 312a contacts the anvil 208. It should be emphasized that the respective widths of the horn 208 and the anvil 220 may be the same or different (eg, the anvil 208 may be thinner or narrower than the horn 220 when the raised profiles 312a, 312b are present on the horn 220).

[0045] Figure 7 An exemplary cross section of two parts is shown, which in this example are two layers of film, including a lower film 400 and an upper film 402. When the films 400, 402 are pulled between the horn 208 and the anvil 220, the films 400, 402 begin to melt due to the application of ultrasonic energy to the horn 208. When the films 400, 402 are pulled along the anvil 220 by force or pressure, the films 400, 402 begin to melt. Figure 7 When the films 400 and 402 are moved in the direction of arrow G shown in FIG or into a space having a height corresponding to the thickness of only one of the films 400 and 402 (because the height of the raised profile 312 does not exceed the thickness of one of the films 400 and 402), the films 400 and 402 are squeezed by the raised profile 312. It is assumed that the thicknesses of the films 400 and 402 are the same, but the thicknesses of the films 400 and 402 are not necessarily the same. The height H3 of the raised profile can be sized to accommodate the thicker of the two films 400 and 402.

[0046] An important aspect of the height dimension of raised profile 312 is that it creates a dynamic stopping effect, eliminating the need for an external mechanical stop device. When films 400, 402 enter the gap between horn 208 and anvil 220, the clamping force and the amplitude of the ultrasonic energy generated at raised profile 312 provide sufficient energy for bonding along raised profile 312. Because the welding force is distributed over an increased surface area after profile penetration is achieved, there is insufficient energy for bonding in the areas between horn 208 and anvil 220 beyond the raised profile. In these areas, unbonded films 400, 402 prevent contact between horn 208 and anvil 220. Consequently, this eliminates the need for external physical mechanical stops, which would otherwise be required to maintain the thickness and consistency of the seal line. The unbonded layer between horn 208 and anvil 220 becomes the physical stop typically provided by a mechanical stop, but mechanical stops are eliminated through various aspects of the present disclosure.

[0047] In prior art systems, when the height of the raised profile is much greater than the thickness of the film present between the horn and the anvil, an external mechanical stop device is required to inform the system when to stop the forward motion of the horn. Otherwise, excessive or insufficient force or pressure is applied to the film and an insufficient or poor bond is formed at the sealing interface. In contrast, a depth controlled profile such as profile 312 has a shallower profile and is also narrower. This continuous profile (see Figure 4 ) The films 400, 402 can be welded by inducing melting on the contoured surface 312 until the contour 312 penetrates to the depth of the adjacent shoulder. Once the shoulder meets the film 400, 402, the much larger surface area bottoms out on the shoulder, and melting and penetration cease (referred to herein as the dynamic stop effect).

[0048] The gap between the horn 208 and the anvil 220 and the resulting seal line thickness is determined by the profile height as a percentage of the thickness of the individual material layers. For example, if the material thickness = x, then the profile height is a predetermined percentage of x, typically 50% to 150%, depending on the materials being bonded and the desired bonding result (e.g., a hermetic seal).

[0049] Compared to prior art rotary systems, the benefits of welds produced using the apparatus and methods of the present disclosure are that the continuous weld is stronger and forms a hermetic seal. The raised profiles according to aspects of the present disclosure can be applied to multi-layer films, recyclable films, biodegradable films, decomposable films, single-layer films, paper-based films, or single-material films. According to aspects of the present disclosure, full control over the seal line thickness can be achieved for material thicknesses ranging from 10 μm to 150 μm.

[0050] As mentioned above, the raised profiles on both the horn 208 and the anvil 220 may be of the same height or unequal heights. Figure 8 An exemplary depth control configuration 800 is shown in which one of the horn 208 and anvil 220 has a first raised profile 812a and the other of the anvil 220 or horn 208 has a second raised profile 812b, both of which are exaggerated in size and profile for ease of illustration and discussion. A product 802, such as a pouch or container to be filled with a liquid and thus requiring an airtight seal, has a first layer 400 and a second layer 402. When the profiles have the same height, each raised profile 812a, 812b must have a height less than 100% of x (where x is the thickness of the film 400, 402). When the profiles have different heights or unequal penetration is required, one element may exceed 100% of x, but the other element must be proportionally reduced. Although in Figure 8 The horn 208 and anvil 220 are both shown having the raised profiles 812a, 812b, but in alternative embodiments, only one of the horn 208 and anvil 220 may have the raised profile while the other of the horn 208 and anvil 220 does not have the raised profile.

[0051] For example, if the thickness of films 400, 402 is 100 μm (x = 100), and a seal thickness of 25 μm is desired at interface 830, and seal 830 is offset, a profile height of 125% of x on one element 812a (horn 208 or anvil 220) and a profile of 50% of x on a second element 812b (anvil or horn) will result in a 25 μm thick offset seal line. If equal penetration is desired, the horn 208 and anvil 220 will have raised profiles 812a, 812b with a height corresponding to 87.5% of x. Unbonded films 400, 402 in region 832 downstream of sealing interface 830 prevent contact between the horn 208 and anvil 220. As a result, the need for external physical and mechanical stops, which would otherwise be required to maintain seal line thickness and consistency, is eliminated. The unbonded film 400 , 402 in the region 832 between the horn 208 and the anvil 220 becomes a physical stop.

[0052] Figure 9A A "seal and score" configuration 900 is shown in which a raised profile 912 on the horn 208 or anvil 220 includes a scoring element 916 to score or cut the sealing interface 930 of the bonded film 400, 402 just at one of the shoulders distal (relative to the product 902) to the raised profile 912. The unbonded film 400, 402 in area 932 is scored or cut from the sealing interface 930, enabling the sealing and scoring operations to be performed in one step. Figure 8For ease of illustration and discussion, the configuration 800 shown in FIG. Figure 9A The raised profile 912 and scoring element 916 shown in FIG are greatly exaggerated. Scoring element 916 may have a wedge shape to score other materials, such as in shrink wrap applications. The unbonded film in region 932 maintains the bond and score depth, thereby eliminating the possibility of anvil 220 damaging horn 208 (assuming scoring element 916 is part of raised profile 912 of anvil 220).

[0053] Figure 9B A "slanted sealing profile" configuration 950 is shown, wherein a raised profile 952 on the horn 208 or anvil 220 includes a sloped profile to facilitate sealing or bonding the bonded films 400, 402 at a sealing interface 930. A product package or container 902 (e.g., containing contents 960 such as liquids, powders, gels, food, etc. within a sealed enclosure) has a sealing interface 930 formed in part by the sloped profile of the raised profile 952. Figure 9B As shown, the seal line of the raised profile 952 is angled across the interface 930, with its shallow edge adjacent to or closest to the product 902. As the distance from the product 902 increases along the interface 930, the angle increases or tapers away from the product 902. The angled profile of the raised profile 952 improves speed and increases seal strength while diverting more molten material 400, 402 toward the product side.

[0054] Will combine Figures 10A to 11B Discussion of additional features that may be combined with any of the raised profiles disclosed herein. Three features broadly summarized as "pull," "tapered bond profile," and "cut and seal" are described below. Some of these features may be combined, such as a pull feature may be combined with a tapered bond profile feature, such as Figure 10A shown.

[0055] Figure 10A A horn 208 or anvil 220, such as described above, is shown incorporated into a rotary ultrasonic welding apparatus 1000 having the same basic structure as the rotary ultrasonic welding apparatus 200 described above, except that a pulling component 1020 is shown downstream of a raised profile 1012, and a tapered weld profile component 1014 is shown upstream of the raised profile 1012 and leads into the raised profile 1012.

[0056] Figure 10A Example dimensions for the features shown are summarized in the table below.

[0057]

[0058] exist Figure 10AIn the exemplary raised bond profile 1012 shown, the height H4 of the raised bond profile relative to the surface of the horn / anvil 208, 220 is 0.0035 inches or approximately 0.1 mm. Leading into the raised bond profile 1012 is a leading tapered bond profile 1014 having a taper angle of angle α1 across the surface of the horn / anvil 108, 220. Angle α1 can be between 0.5 degrees and 5 degrees and, in this example, is shown as having an angle of approximately 1.15 degrees. Following the raised bond profile 1012 is a trailing tapered bond profile 1016, followed by a pulling or pattern feature 1020.

[0059] Pull feature 1020 provides a feature to pull the material through the ultrasonic nip, so the ultrasonic nip needs to provide its own drive. Vertical Form Fill and Seal Packaging (FFS) systems are particularly suitable for pull feature 1020 because these systems lack a way to pull the material. Figure 10B An example pattern 1020 can be seen in the , where an array or pattern of raised nubs or protrusions 1004 are distributed in a grid-like pattern on the surface of the horn / anvil 208, 220. The pattern 1020 is designed to avoid excessive, localized heat buildup, particularly in the presence of a single layer of film, and thus the pattern 1020 should not detract from the drive required for the material to pass through the FFS system. The pattern 1020 is exemplary only, and while it has been shown as a pattern extending parallel to the edge of the horn 208 or anvil 220, the pattern 1020 may be tilted at an angle relative to the edge, such as between 1 and 15 degrees, to provide the desired drive characteristics without generating excessive heat buildup. Likewise, the shape and form of the nubs or protrusions 1004 shown may be modified to provide pulling or grabbing friction to the passing material. For example, the nubs 1004 may have a tooth-like shape. In the Figure 10C In the example shown (along Figure 10B 10C-10C), it can be seen that the small piece 1004 has a tapered profile with an angle α2 as shown in the figure. Figure 10B Example values ​​for the dimensions shown are shown in the table below.

[0060]

[0061] Horizontal applications can also benefit from the pulling feature 1020. For example, in an application that includes a zipper, there is material that is preheated just before bonding, and there is slack along the edge caused by the laser scoring of the film. The edge slack and preheating caused by the laser scoring create control issues, i.e., the material is difficult to maintain in the nip of the welding head / anvil 208, 220. The pulling pattern 1020 avoids these problems.

[0062] Back to Figure 10A , a tapered bonding profile or feature 1014 can be seen on the front side of the raised bonding profile 1012. The taper shown by angle α1 can be in the range of 0.5 to 5 degrees, and in the example shown, the angle is 1.15 degrees. The product side of the bond will be Figure 10A on the left side (for example, in the case of a pillow bag with a zipper, the zipper will be on the Figure 10A and the product or contents within the pillow-shaped package will be on the left side of the tapered joining profile 1014.

[0063] The tapered joining profile 1014 has several advantages. First, the melt flow is directed toward the product side, which provides an improved seal. A flat profile (e.g., Figure 3 ) can move material equally but in an uncontrolled manner on both sides of the joint, while the tapered joining profile 1014 will direct the melt toward the product in a more controlled manner, resulting in a thicker, stronger seal on that side of the joint. Additionally, the tapered design is resilient to material thickness variations (for example, some materials have up to 40% variation in material thickness). In other words, if the maximum combined thickness (2 layers) is 180 μm, but can be as low as 108 μm, a depth-controlled anvil with an 88 μm profile will over-penetrate at its highest point; however, the transverse taper 1014 will mean that the ideal joining point will shift from the highest point of the horn / anvil 208, 220 to its lowest point, ensuring that ideal joining conditions will be met at some point along the profile of the horn / anvil 208, 220, even with material thickness variations. The tapered design 1014 also allows for a wider range of film thicknesses to be used on the same anvil or horn 208, 220.

[0064] It should be noted that the tapered joining profile will not work on an anvil / weld head that does not use depth control because over-penetration will quickly occur and the anvil will become a cutting tool rather than a joining tool. The tapered joining profile 1014 disclosed herein works with depth control profiles 312, 1012, such as Figure 3 、 Figures 10A-10C As shown, it is not suitable for conventional anvils that do not have a raised depth control profile such as disclosed herein 312, 1012. The tapered profile design also provides speed improvements because the tapered profile design penetrates the material more easily during the bonding process.

[0065] Typically, thinner materials require a smaller taper angle in the tapered joining profile 1014. This allows for higher speeds and improved sealing compared to a non-tapered raised profile. The taper of the tapered joining profile 1014 can be determined by a radius (e.g., a curve) or an angle (e.g., Figure 10A The inclined plane or α1) shown in FIG.

[0066] Conventional rounded (non-depth-controlled) profiles can be problematic for certain packaging films because they produce a "porpoising effect." This occurs when the rounded anvil initially penetrates the material, but as penetration depth increases, the surface contact between the anvil profile and the material being bonded increases exponentially. This leads to a situation where the amplitude and pressure are insufficient to maintain the anvil's penetration depth, forcing the anvil to retract against the pressure exerted by the material. In doing so, the contact area then decreases exponentially, resulting in excessive pressure and amplitude for the decreasing bond depth, and thus increased anvil penetration, leading to a cyclical "porpoise" effect.

[0067] In contrast, using an inclined profile 1014 such as Figure 10A ) shown in is less sensitive to these effects because the angle of attack of the tapered bond profile 1014 joining the profile bond height (H4) of the flat convex profile 1012 is determined based on the range of film thicknesses.

[0068] Other advantages of the tapered joining profile 1014 include:

[0069] Increased speed due to easier penetration of the material

[0070] Improved seal, with the sloped profile 1014 towards the shallow side of the product helps improve seal strength by controlling and directing the melt flow to the product side of the seal. This also improves vacuum pot test performance and reduces the likelihood of fault lines being created in the film by the bonding process.

[0071] The reduced particle spread, shallow angle of the taper (α1) in the tapered profile 1014 will trap and attach the particles within the bond line, so instead of bonding at the shallow side of the seal line, a firm contact pressure will be applied, trapping the particles.

[0072] Simultaneous sealing / cutting possibilities, utilizing an angle (e.g., α1) allows for reliable cutting / sealing in both depth controlled and non-depth controlled applications. The depth of the cut can be precisely controlled by adjusting the applied pressure and / or amplitude. The system will utilize unbonded material below the shallow edge of the anvil profile 1012 as the blade side (1130, Figure 11B ) penetration-related compressible depth stop. This engagement occurs when the tip 1130 meets the shallower edge of the profile (e.g., Figure 10A 1014).

[0073] Next, we will combine Figure 11A and Figure 11Bto describe the "cut and seal" feature. In some applications, it is desirable to simultaneously seal and cut or score shrink wrap or other materials to provide a zero fin seal height and a virtually invisible seal. Figures 11A-11B A horn 208 or anvil 220 is shown which utilizes depth control that will penetrate the film material at a combined two-layer thickness of, for example, 30 μm and leave 4 μm uncut, which can then be easily separated by a conventional vacuum removal system (not shown), a step that will be readily familiar to those skilled in the art to which the present disclosure pertains.

[0074] Example dimensions are summarized in the table below.

[0075]

[0076] The angle of the profile (which is critical to achieving the desired result) ensures that the force bonding conditions are met within a narrow area, resulting in a very narrow bond, but at least on the film, a very strong bond that can withstand activation of the shrink wrap after bonding. Figure 11A As shown, the anvil 208 / horn 220 has two bonding profiles, one on each edge, which can be used in applications where the width of the sonotrode is smaller than the width of the anvils 208, 220. Figure 11A In the illustrated anvil 208 or horn 220, the depth control contour 1112 is the entire center portion between the two contours. Figure 11B , an enlarged view of the cutting portion is shown, wherein a cutting feature 1130 having a height H9 provides a cutting feature to a film (e.g., shrink wrap) present at its surface or interface. Cutting feature 1130 has a height H9 that is slightly raised compared to the height of raised profile 1112. Cutting feature 1130 forms a generally sharp 90-degree angle relative to the surface of raised profile 1112, and this abrupt transition provides a cutting action to the film or material passing through anvil 208 / weld head 220. Height H9 of cutting feature 1130 may be between 1% and 20% of height H4 of raised profiles 1012, 1112. Cutting feature 1030 forms the distal end of raised profile 1112 and is therefore located adjacent to or at the end of raised profile 1112.

[0077] Figure 12 A tapered bond profile is shown having two different profiles on either side of the horn 208 / anvil 220. Due to the relatively small size of the profiles, only one side of the horn 208 / anvil 220 is shown here for ease of illustration. Figure 12Example values ​​for the dimensions indicated in are shown in the table below. The profile includes an inclined profile 1214 having an angle α3, a depth control profile 1212, followed by a trailing profile 1016, which may be angled or inclined.

[0078]

[0079] According to other aspects of the present disclosure, enhanced depth control (and anvil geometry details) can be coupled to the generator output. For example, adding specific depth control and anvil details results in higher ultrasonic power (and thus allows for better sealing and faster speeds). Limits and power adjustments can be set around these parameters.

[0080] The present disclosure produces more consistent power consumption, stability not seen in rounded anvils through non-depth control. In fact, lower power consumption is achieved using the sloped profile 1014 compared to rounded anvils, which results in higher speed capabilities.

Claims

1. An apparatus for joining a first film portion and a second film portion together along a sealing line using ultrasonic energy, the apparatus comprising: a welding head (208) configured to receive ultrasonic energy; as well as an anvil (220) positionable proximate to the horn (208), the horn (208) advancing toward the anvil, wherein at least one of the horn (208) or the anvil (220) includes a surface (216, 226) having a width dimension and a circumference and is rotatable about an axis of rotation, The surfaces (216, 226) have a raised profile (312a), the surfaces (216, 226) being positioned such that the raised profile (312a) extends along the circumference and provides continuous running contact between the raised profile (312a) of one of the horn (208) or the anvil (220) and the other of the horn (208) or the anvil (220) when rotated about the rotation axis, thereby forming a sealing line without any external structure to control the distance between the horn (208) and the anvil (220) while providing continuous running contact, The raised profile (312a) is part of the welding head (208) and is also combined with a second anvil, and the welding head (208) has a second raised profile (312b) whose height dimension exceeds the height dimension of the raised profile (312a) to seal different film thicknesses.

2. The device according to claim 1, wherein The thickness of the first membrane portion and the second membrane portion is between 10 μm and 150 μm.

3. The device according to claim 1, wherein The height dimension of the raised profile corresponds to 100% of the thickness of the first membrane portion or the second membrane portion.

4. The device according to claim 1, wherein The height dimension of the raised profile corresponds to 87.5% of the thickness of the second membrane portion or the first membrane portion.

5. The apparatus of claim 1, the raised profile further comprising a scoring element configured to score or cut along the sealing line as the anvil rotates about the rotation axis.

6. The apparatus according to claim 1, wherein The second raised profile (312b) has a height corresponding to 50% to 150% of the thickness of the first or second membrane portion, extends along the circumference, and provides continuous running contact between the second raised profile and the anvil when rotating about the rotation axis.

7. The apparatus according to claim 6, wherein The height dimension of the second raised profile corresponds to 100% of the thickness of the first membrane portion or the second membrane portion.

8. The apparatus according to claim 1, wherein The first membrane part and the second membrane part are composed of plastic.

9. The apparatus according to claim 1, wherein The first film portion or the second film portion is a multilayer film, a recyclable film, a biodegradable film, a decomposable film, a monolayer film, a paper-based film, or a single-material film.

10. A product comprising a seal line formed by the apparatus of claim 1, a first film portion, and a second film portion.

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