MXPA97002345A - Ultrasonic car sealer - Google Patents

Abstract

An ultrasonic sealing apparatus is disclosed which includes at least one anvil (32, 42-54) and at least one transducer (34, 112-116) opposite the anvil, for transmitting the ultrasonic energy to a workpiece (24) embraced between . A deflection element (40) is connected between the anvil or the horn and its actuator (36, 38), to define the sealing pressure developed between the anvil and the horn. The deflection force can be adjusted without stopping the machine, by using an externally applied pneumatic force. The anvil has a backing element (56) with a curved front surface (212) connected to a curved back surface (236) of the anvil. A fastener (226) is provided for selectively securing the anvil and the backrest element together, or for allowing the anvil to travel along the curved surface of the backing element, to align the anvil with respect to the transducer. A cooling fluid may be provided for passage through a passage (240) in an anvil body, for cooling during operation. A method for the alignment of the anvils and the transducers of an ultrasonic sealing apparatus as described above is also described.

Description

ULTRASONIC SEALER OF CARTON BOXES CROSS REFERENCE TO RELATED REQUESTS This application is a continuation in part of North American Series No. 08 / 190,546, filed on February 2, 1994.

TECHNICAL FIELD The present invention relates in general to clamps for securing workpieces, and particularly to configured clamps such as ultrasonic sealants for fastening an inverted V-shaped closure or the like, between an ultrasonic transducer and an anvil, thereby sealing the closing. The invention relates more particularly to the alignment mechanisms and the cooling apparatus for the anvil assemblies of such machines, and to the supporting elements and actuators for the jaw-shaped sealing elements, which embrace, heat or otherwise energize, and then release a seal to seal it.

REF: 24457 BACKGROUND OF THE INVENTION V-shaped inverted top containers or containers are widely used to package milk, juice, and other foods, as well as a variety of other products. Such containers are made from material in the form of a sheet that is heat sealable to itself. The typical material is cardboard coated on both sides with polyethylene or other heat-sealable material. The construction and parts of such containers and the blanks or blanks from which they are formed are described and illustrated, for example, in U.S. Patent No. 4,744,467, issued to Tetra Pa International AB, and Patent North American No. 4,775,096, issued to AB Tetra Pak. These entire patents are incorporated by reference herein. The inverted V-shaped closures are conventionally sealed by folding the carton along the preformed dotted lines, to form an upright fin (or, for a lower closure, a hanging fin) having various thicknesses of sealable material by heat. The fin is captured between an ultrasonic sealing horn and an anvil, and the ultrasonic energy transduced to -a together through the horn causes the heat-sealable material in the fin to fuse, forming a seal. One problem that this sealing apparatus must overcome is the difficulty to reliably apply a uniform sealing pressure, placed precisely on the surfaces of the closure. This problem is particularly detected when the sealing apparatus has multiple commonly driven ultrasonic horns, and anvils to simultaneously seal a corresponding number of cardboard boxes in a sealing stroke. Misalignment or other mis-fitting of a simple sealing horn or its corresponding anvil may result in an unacceptable rejection ratio of the cartons, or bring up the integrity of the seals of the products released for sale. The anvil opposite to a simple ultrasonic transducer has previously been proposed to be mounted on a ball joint, so that the anvil will adjust itself in parallelism with the face of the ultrasonic energy transducer, when the work is embraced between the transducer and the anvil. This arrangement is shown in the North American Patent No. ' 3,661,661.

Another problem to which the cardboard box sealing apparatus must address is the need to adjust the sealing pressure exerted by the apparatus, either when the machine is being reconfigured to seal a different type of container or for accurate tuning of the container. the machine during a run of the product. Still another problem is how to provide a compact sealing station, particularly if both the anvils and the sealing horns are driven, and thus require separate actuators. An independent actuator on each side of the sealing station makes the machine wider than a machine in which only the horns or just the anvils are driven. A more serious problem is thatWhen packaging food or other products that must remain clean, the actuators must be isolated from the hygienic area to which the food is exposed during packaging. If separate actuators are placed for the speakers and anvils on both sides of the sealing area, both actuators should be isolated from the sealing area. The same barriers that maintain hygienic conditions make it difficult to periodically check the cardboard boxes that are sealed. Interconnected actuators for horns and anvils are sometimes difficult to isolate from the hygienic area when the food is sealed. Another problem that must be commonly faced when designing the ultrasonic sealing equipment is how to prevent intentionally separated moving parts of the equipment from welding together, which must be accidentally or intentionally contacted during a sealing operation. Another problem is how to prevent the auxiliary equipment associated with the ultrasonic sealing apparatus, such as the cooling apparatus, from vibrating on its own or otherwise being damaged by scattered ultrasonic vibrations transmitted within the machinery. The anvils for the ultrasonic sealing apparatus have been previously provided with the cooling apparatus to eliminate the heat transmitted during the sealing operation.

BRIEF DESCRIPTION OF THE INVENTION The present machine is a carton sealer for sealing a closure having first and second sides, and placed in a sealing position of the closure. A typical closure that can be sealed by the present machine is an inverted upper V-shaped closure or a lower closure for a food carton. The sealant includes an anvil, an ultrasonic sealing horn, an anvil driver, a horn driver and a deflection member. The anvil is mounted to travel back and forth between an open position, allowing a cardboard box to pass, and a closed position to bear against the first side of a closure placed in the sealing position of the closure. An anvil driver is provided to move the anvil back and forth between its open position and its closed position. The ultrasonic sealing horn is also mounted for travel back and forth between an open position, allowing a cardboard box to pass and a closed position to hold against the second side of a latch located in the sealing position of the closure . A horn actuator is provided to move the horn back and forth between its open position and its closed position.

A feature of the present machine is thus that the anvil and the sealing horn are movable so that a closure located in the center of a cardboard box can be coupled without making any provision to move the carton laterally. A deflection element - which can be thought of as a cushion or spring - is connected between the anvil or the horn and its actuator (or between each of these elements and its actuator, in the alternative mode). The deflection element limits the sealing pressure developed between the anvil and the horn, at a predetermined maximum value. The default value is the pressure exerted by the deflection element. This prevents the anvil and the horn from holding the closure too tightly, and thus damaging the seal or sealing machine, and compensates for slight inaccuracies in the position of the anvil or horn, without increasing or decreasing the sealing force. The force of the deflection can also be adjusted externally, without stopping the machine, by using an externally applied pneumatic force, such as the deflection element.

An ultrasonic sealing apparatus including at least one anvil and at least one transducer opposite the anvil is claimed to transmit the ultrasonic energy to a workpiece clamped therebetween. The anvil has a backing element that supports a pad. The backrest element is adapted to move generally along an axis between an open position and a closed position relative to the transducer. The backing element has a curved front surface opposite the transducer, and which defines an arc of a circle having a center and lying generally in a plane defined by the axis. The seat or anvil pad has a front surface and a back surface. The front surface makes contact with a work piece (such as closing a cardboard box that requires sealing). The back surface of the anvil pad or seat is similarly curved about the same center as the curved front surface of the backing element. The back surface of the anvil is normally held against the curved front surface of the backing element.

A fastener or fastener is provided having an assurance position for securing the anvil seat and the backrest element together, and an adjusting position for allowing the anvil seat to rotate about the center relative to the backrest element, to align the anvil with respect to the transducer. Another aspect of what is claimed is an ultrasonic sealing apparatus that includes a source of cooling fluid, an anvil, and a transducer opposite the anvil. The anvil includes a facing member, a body, and an elastic seat that separates the body from the facing member. A first passage is formed between the facing member to carry a cooling fluid through the facing member. A second passage extends through the body of the anvil and the elastic seat, to bring the fluid from the source of the cooling fluid to the first passage in the anvil. Yet another aspect of what is claimed is a clamp comprising a pair of first and second opposed jaws for holding a work piece. The first jaw includes a backrest element and a seat of the jaw, joined by a fastener.

The backing element of the first jaw is supported and actuated so that it will move back and forth along an axis between an open position and a closed position relative to the second jaw. The backing element has a curved front surface opposite the second jaw and defining an arc of a circle having a center, and lying generally in a plane passing through the axis. The jaw seat of the first jaw has a front surface for contacting a work piece, such as closing a cardboard box that requires sealing. The jaw seat also has a curved back surface which is similarly curved and is normally held against the curved front surface of the backrest element. The fastener has an assurance position to fix the jaw seat and the backrest element together, and an adjustment position to allow the jaw seat to rotate about the center relative to the backrest element, to align the first jaw with respect to the second jaw.

Another aspect of what is claimed is a method for aligning the anvils and transducers of an ultrasonic sealing apparatus, which has more than one anvil and a transducer of the type first described above. The fasteners securing the anvils to a common backrest element are released to their adjustment positions, so that the anvils are free to move. The anvils are then advanced against the transducers. The clamping force between the anvils and the transducers displaces any of the anvil seats that are out of alignment, toward proper alignment around their centers described above. The fasteners are then tightened to fix the anvils on the backrest element, maintaining its alignment. Alternatively, the transducers could be supported by a common backup element and could be adjustable, instead of the anvils, within the scope of what is claimed.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a cardboard box sealing machine.

Figure 2 is a side elevational view of the machine of Figure 1, with some portions shown in section and other portions removed.

Figure 3 is a side elevation view taken from line 3-3 of the Figure 1, with the overlapping structure removed for clarity.

Figure 4 is a fragmentary perspective detail view of the pull rod, pull rod and pneumatic deflection member of the anvil drive assembly, with a portion cut away to reveal the interior details of the biasing element.

Figure 5 is a partial section of the biasing element, taken along line 5-5 of Figure 4.

Figure 6 is a schematic elevational view, taken from the perspective of the sectional line 6-6 of Figure 1, of an anvil and a sealing horn limiting in a sealing position of the closure.

Figure 7 is a view similar to Figure 6, showing the anvil and the sealing horn in their open positions, with an inverted V-shaped closure positioned between them in a closing sealing position.

Figure 8 is a view similar to Figure 7, which shows the anvil and the sealing horn in their closed positions respectively, which are maintained against the closure in the form of an inverted V.

Figure 9 is a section taken along line 9-9 of Figure 1, showing how the hygienic and non-hygienic areas of the present machine are kept separate, where the ultrasonic sealant penetrates the insulation wall.

Figure 10 is a more detailed perspective view, in isolation, of the anvil bar of Figure 1.

Figure 11 is a section, taken parallel to one of its larger side faces, of one of the anvils shown in Figure 10.

Figures 12, 13, and 14 respectively, are graphs of the acceleration, velocity, and position of the cam actuator according to the embodiment of Figures 1-11, each versus time, to seal the upper seal of a cardboard box with the upper part in an inverted V shape.

Figures 15-17 are similar to the Figures 12-14, showing the acceleration, speed, and position of the cam actuator to seal the bottom seal of a cardboard box with an inverted V-shaped bottom.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY While one or more preferred embodiments will be described, it will be understood that the claims are not limited to those embodiments. On the contrary, the claims will be interpreted to include all alternatives, modifications and equivalents within their spirit and scope. With reference first to Figure 1, the carton sealer generally indicated at 20 is a module of a carton filling and sealing machine such as that described in U.S.S.N. 08 / 190,546, filed on February 2, 1994, which is incorporated by reference herein (the other parts of which are not shown). A filling and sealing machine of this type includes two such modules, one for sealing the lower flap 22 (shown in Figure 2) of each carton such as 24, before it is filled, and the other for sealing the upper flap of the carton 24 (which will be placed in the fold line 26 shown in Figure 2, after the top closure is folded). The upper flap 26 is sealed after the carton is filled. Each closure 22, 26 of the carton 24 has a first side 28 which faces the anvils such as 32 and a second side 30, which faces the ultrasonic sealing horns such as 34, when the carton 24, and more particularly a closure such as 22 of the carton 24, is placed in a sealing position of the closure. A typical closure that can be sealed according to the present machine, is a closure with upper or lower part in inverted V shape, for a food carton box. Referring briefly to Figure 2, the carton 24 is sealed according to the following sequence. First, the carton 20, which has been previously folded substantially to its final configuration by the apparatus not illustrated herein, is advanced, moving its lower flap 22 from a position in which it is free of the sealant 20. from cardboard boxes, to the sealing position of the closure. The lower flap is then sealed by closing the anvil 32 and the sealing horn 34 substantially to embrace the closure 22, as also illustrated in Figure 8. The sealing horn heats the lower flap 22, fusing together its heat sealable elements . The closure 22 is then released. After the anvil 32 and the sealing horn 34 are separated, the lower flap 22 is translated in the reverse direction to decouple the carton 24 from the carton sealer 20, allowing the carton 24 to be advanced towards the filler (not shown).

Main Sealing Elements Returning now to Figure 1, the sealer 20 which is an embodiment of the present machine, includes an anvil 32, an ultrasonic sealing horn 34, an anvil actuator generally indicated at 36, a horn actuator generally indicated at 38, and the diverting elements 40 and 41.

Anvil assembly In the illustrated embodiment, a series of eight anvils are provided: 32 and 42-54, so that eight cartons can be sealed at the same time with a simple reciprocal run of the anvils assembled together. The eight anvils 32 and 42-54 are mounted on an anvil bar 56. The bar 56 of the anvil is arranged to travel back and forth alternately, reciprocatingly moving each anvil such as 32 back and forth between an open position (better seen in Figures 1 and 7) allowing a cardboard box to pass, and a closed position (better seen in Figure 8) to limit against the first side 28 of a closure (such as the lower flap 22) placed in the closing sealing position. A frame or structure 58 of the anvil, rectangular, is defined by the bar 56 of the anvil, the driving rods 60 and 62, and the driving rod 64. The driving rods 60 and 62 are rigidly bolted to the legs 66 and 68. from bar 56 of the anvil. The details of the fastening in this embodiment are best observed in Figure 2. The pull rods 60 and 62 are operatively connected to the drawbar 64 by the diverting elements 40 and 41. The details of this connection are provided below. . The pull rod 60 is supported for alternating travel with respect to the frame 70 of the carton sealer 20, by sliding bearings 72 and 74 (which are prominent in Figure 2), while the pull rod 62 is supported for the alternate travel with respect to the frame 70 of the carton sealer 20, by sliding bearings 76 and 78. With reference to Figures 1 and 2, the slide bearings 72 and 76 may be identical.

Each is defined by a bushing or bushing such as 80 which is integral with the frame 70, and has a generally cylindrical bore 82 housed at its respective ends by retaining rings 84 and 86. A slip ring 84 is fixed to the associated pull rod such as 62, and slidable between the boundaries defined by the retaining rings 84 and 86 within the hole 82. The retaining rings 84 and 86 of this embodiment are also sliding seals that help isolate the unhygienic area in general to the right (in Figure 2) of the insulation wall 88, where the drive machinery is located, of the sanitary area in general to the left of the insulation wall 88, where the cartons are being filled and packed . This circumstance is desirable because the pull rods 60 and 62 move alternately through the bushing 80. By providing seals on each end of the bore 82, the successive alternating movements of the rods will not tend to advance the lubricants. other foreign material to or through holes such as 82 from right to left (as shown in Figure 2). It is also important to prevent foreign matter, such as spilled food or waste from cartons, from moving from the left to the right, as shown in Figure 2 toward or through holes such as 82. That goal it is also achieved by the illustrated modality. In this embodiment, the sliding bearings 74 and 78 are placed completely within the unhygienic area to the right of the isolation wall 88 of Figure 2, and a second pair of retaining rings 84 and 86 could be redundant. In this way, the ordinary sliding bearings 74 and 78 which lack the sliding seals, will be sufficient to maintain the travel of the driving rods 60 and 62 correctly axially along the shafts of the driving rods.

Anvil actuator An anvil actuator in general indicated at 36 is provided for moving the draw bar 64, and thus the bar 56 of the anvil and the coupled anvils 32 and 42-54, forwards and backwards between their respective open and closed positions. .

The actuator for advancing the anvil 32 and 42-54 to its closed positions, acts on a side generally facing the horn, of the anvil frame 58, and in this mode acts specifically on the side 90 facing the horn , of the drawbar 64. The side facing the horn, of the drawbar 64, has advancing cam rollers, here the rollers 92 and 93, and the cam rollers for retraction, here the rollers 94 and 95 (95 is shown mainly in dashed lines in Figure 3) coupled thereto, which are actuated by the cams 96 and 98. Since the two cam actuators are identical, only one of them will be described in detail. The cam 98 has a surface 100 for advancing the anvil to move the anvil to its closed position, and an anvil retraction surface 102, best seen in Figures 2 and 3, for the movement of the anvils to their open position. The cams 96 and 98 are respectively rotatably mounted on the pivots. Here, the axes 104 and 106 of the cam (which alternatively can be the respective ends of a single axis) carried in the rotation bearings (not shown), define those pivots. The cam shafts 104 and 106 are driven by a servomotor 108 by means of a gear train located within the gearbox 110 for rotation of the cams 96 and 98 about their pivots. The servomotor or gear train can be used to vary the rotation speed of the cam at various points in its travel, relative to the cam surface profile, so that the required torque amount of the servomotor does not exceed its capacity, particularly where the change in the radius of the cam is gradual. The sealing profile of the cam position, speed, and acceleration can also be changed remotely as desired, by changing the position, speed and servo motor acceleration profile. Typical profiles are discussed below in relation to Figures 12-17. The cam 98 shown in Figures 2 and 3 is in its starting or starting position, in which the anvils 32 and 42-56 are in their fully open positions. The cam 98 is first driven clockwise about 160 degrees by the servomotor 108, so that in general the radius of the portion of the cam surface 100 is supported on the cam roller 94. With reference to Figure 1, that movement of the cam 98 pushes the cam roller 94, and thus the drag bar 64, the driving rods 60 and 62, and the bar 56 of the anvil, with upward direction towards their respective closed positions. Subsequently, when a seal is completed and the anvils 32 and 42-54 are to be retracted to their open position, the cam 98 is operated counterclockwise to its initial position. The retraction surface 102 of the anvil of the cam 98 abuts against the cam roller 95, with the radius of the portion of the cam surface 102 being contacted by the cam roller 95, generally decreasing. This counter-rotation of the cam 98 pulls the draw bar 64, the pull rods 60 and 62, and the bar 56 of the anvil down (as shown in Figure 1) to its open positions.

Ultrasonic Horn Assembly In the illustrated embodiment, a series of four ultrasonic sealing speakers or transducers -34 and 112-116-, each one wide enough to limit against two anvils, is provided, so that eight cartons can be sealed at the same time with a simple reciprocal race of the sealing horns as a whole. The four sealing horns 34 and 112-114 are mounted on a frame or frame 118. The frame 118 is arranged to travel back and forth alternately between an open position (better seen in Figures 1 and 7) allowing a cardboard box pass, and a closed position (better seen in Figure 8) to lean against the second side 30 of a closure (such as the lower flap 22) located in the sealing position of the closure. The frame 118 has integral bushings 120 and 122 slidably received on the driving rods 60 and 62, defining the sliding bearings. This arrangement places the sealing horns and anvils precisely in relation to each other as they move alternately. The ultrasonic stacks ending in the sealing horns 34, 112, 114, and 116 also include ultrasonic converters or transducers and ultrasonic generators, which are not shown.

The ultrasonic stacks are mounted on the frame 118 to place, support and actuate them.

Ultrasonic Horn Operator A cam-operated horn actuator, generally indicated at 38, is provided to move the frame 118 back and forth, between its open position and its closed position. The cams 96 and 98 each have a horn drive cam surface, such as the surface 124 shown in FIG. 2, and a horn retraction cam surface, such as the surface 126 shown in FIG. 2. These cam surfaces are substantially opposite to, but approximately in the same way as, the anvil driving and retracting surfaces, so that the anvils and the sealing horns move in opposition when the cams are rotated. The cams 96 and 98 respectively drive the cam rollers 128 and 130, which are coupled "" to the frame 118, and follow the exterior horn drive surfaces 124, of the cams 96 and 98. In this way, the rotation to With the clockwise of the cams 96 and 98 as described above, generally increases the radius followed by the cam followers 128 and 130, driving the frame 118 and the sealing horns 34 and 112-116 in a downward direction (FIG. as shown in Figure 1) to its closed position. The cams 96 and 98 respectively drive the cam rollers 132 and 134, which are coupled to the frame 118 and follow the internal horn retraction surfaces 126 of the cams. In this way, counterclockwise rotation of the cams 96 and 98 as described above, generally decreases the radius followed by the cam followers 132 and 134, driving the frame 118 and the sealing horns 34 and 112 -116 in an upward direction (as shown in Figure 1) to its open position. A feature of the present machine is in this way that the anvil and the sealing horn are movable in coordination by the same cams, thus using the same acceleration, speed and position profiles, so that a closure located in the center of A cardboard box can be attached without moving the carton laterally. Neither the sealing horn nor the anvil will arrive early or late, since both are operated in cooperation. In this way, the carton can be safely supported in such a way that it is not laterally movable, since the position of the carton need not be adjusted to explain the shifts in the closed position of the speakers and the anvils Another plus advantage of the illustrated arrangement, is that the anvil driver and the horn driver are located on the same side of the sealing area, instead of on opposite sides. Thus, an insulation wall 88 is necessary only on one side of the sealing area, so that the sealing operation can be easily inspected from that side of the machine, while the operation of the non-hygienic part of the machine It can be observed from the other side of the simple insulation wall. The sealing apparatus, which is all located in one area and employing multifunctional cams, also has a minimum width, which is desirable to minimize the width of the sealing line.

Deviation Element The biasing element 40 - which can be thought of as a cushion or spring - is connected either between the anvil or the horn and its actuator (or between each of these elements and its actuator, in an alternative embodiment). The deflection element limits the sealing pressure developed between the anvil and the horn, at a predetermined maximum value. The default value is the pressure exerted by the deflection element. This prevents the anvil and the horn from holding the closure too tightly and thus damaging either the closure or the sealing machine, and compensates for slight inaccuracies in the position of the anvil and the horn, without increasing or decreasing the sealing force. The biasing force can also be adjusted remotely, without stopping the machine, by using an externally applied pneumatic force as the biasing element. In the present embodiment, the diverting elements 40 and 41 operatively connect the anvils such as 32 to their cam actuator. With reference to Figures 4 and 5, the biasing elements 40 and 41 are identical pneumatic unions. Springs or other elastic couplings could also be used, although pneumatic joints have certain advantages that will be described later. For brevity, only the deviation element 40 will be described here. The biasing element 40 comprises a hole 140 which receives a sliding piston 142. The annular cylinder and the surfaces 144 and 146 of the piston and the hole 140 define a substantially closed space 148. The piston 142 is captured on the end of the driving rod 62 by the nuts 150 and 152, screwed onto the extension 154 of the driving rod 62. The hole 140 is formed in an integral part of the driving rod 64. The space 148 is pressurized via a gate 156 and a pressure regulator 158 with a source of pressurized gas 160. A remote control such as 162 can be used to change the desired value of the pressure of regulator 158, thereby changing the pressure within the space 148. The pressure of the gas within the space 148 deflects the surface 146 of the piston to the right in relation to the surface 144 of the cylinder, so that the piston floats above or in front of the surface 144, deviating from this mode the pull rods 62 and the bar 56 of the anvil to their respective closed positions. The degree to which the piston 142 floats above the surface 144 of the cylinder can be controlled by the capture of the piston 142. In the embodiment of Figure 5, the flange 164 of the piston 142 captures the piston 142 within the bore 140 of the piston 142. cylinder When the drag bar 64 and the anvils such as 32 are in their closed positions, the closure of the cardboard box that is sealed is brought against the anvils, keeping the flange 164 out of its stop. At this point, the gas cushion in space 148 is the only force exerted by the anvil against the closure and the opposing sealing horn. This sealing force is the product of the pressure of the gas within the space 148 and the effective area of the surface 144. A specific force of approximately 15,000 N is contemplated in this embodiment, although greater or lesser pressure in given situations may be desirable. . An advantage of the illustrated arrangement is that the sealing force exerted by the anvils 32 is reproducible, despite small differences in the thickness or elasticity of the fins such as 22 (due, for example, to the occasional capture of small amounts. of product inside the fin creases 22). Another advantage is that, being equal to the pressure of the gas within the space 148, the pressure of the anvil can be changed by changing the pressure of the gas. The gas pressure can easily be changed remotely. Yet another advantage of the present arrangement can be realized by allowing communication between the respective spaces 148 of two or more diversion elements such as 40 and 41. This allows deflection pressures to be reliably identical at all times, by means of two elements. of deflection connected to the same driving rods 62 or other elements of the machine. Such communication is systematically illustrated in Figure 1.

Ultrasonic Converter Seal With reference to Figures 1 and 9, there is shown an arrangement for sealing between the ultrasonic release converter 186 and the insulation wall 88 which divides the unhygienic area (to the left of the wall 88 in Figure 9) from the hygienic area (to the right of the wall 88 in Figure 9). This area must be sealed because the converter 186, which is coupled to the sealing horn 112, also moves alternately between the open and closed positions as the frame 118 moves. It is important to prevent foreign material from being pushed into any through the insulation wall 88 by alternating movement and vibration of the converter 186. The necessary barrier is obtained as illustrated in Figure 9. The insulation wall 88 has an opening defined by a marginal edge 188.

An ultrasonic converter 188 is placed in the opening 188, and is reciprocated within the opening 188 along an axis 190 that passes through the opening. The converter 188 is vibrated at an ultrasonic frequency by the machinery placed in the non-hygienic area. The converter 186 has a null area or nodule 92 in which the converter is vibrated substantially minimally. (The ultrasonic waves are standing waves propagated along the axis 190, so that the converter 186 has one or more nodes, each placed substantially in a plane perpendicular to the axis 190, where the local amplitude of the vibrations is very small with relation to its maximum amplitude). A sealing surface 194 generally cylindrical, defined by a jacket or sleeve 196 is fixed with respect to a first member which is one of the marginal edge and the null area. Here, the sleeve 196 is fixed to a skirt or skirt 198 projecting in a forward direction, which depends on the null area 192. The edge or skirt projects effectively forward of the null area, which is important so that the converter does not transmit substantial ultrasonic energy to the sleeve 196, which could damage or melt the seal described below. The sealing surface 194 is facing a second member, which is the other of the marginal edge and the null area (and here is the marginal edge 188 that defines the opening in the wall 88). The web 200 of the sleeve 196 is joined, either by welding, to the skirt or edge 198. The web 200 defines a barrier between the sealing surface 194 and the null area 192, which prevents the foreign material from passing through. the jacket 196. The seal between the converter 186 and the opening 188 is completed by the slide seal 202 mounted to the opening 188, which rubs the sealing surface 194 in general cylindrical, as the converter 186 is moved alternately. It will be appreciated that the parts of the assembly can be rearranged. For example, the seal 202 can be mounted to the null area 192 and the sleeve can be mounted to the opening 188, to obtain the same effect. .

Anvil adjustment Figures 1, 10 and 11 show certain advantageous details of the anvils 32 and 42-54 and their mounting on the bar 56 of the anvil. Each anvil is identically connected, so that only the anvil 32 and its assembly will be described. The anvil 32 is received by a backing member - here, the bar 56 of the anvil extending substantially perpendicular to the axis 210 - which is adapted to move generally along the axis 210 between an open position and a position closed, "in relation to the transducer or the sealing horn 34 (shown in Figure 7), as previously described.The anvil rod has a flat mounting surface 208, to which the anvils such as 32 are bolted. bar 56 of the anvil has a front surface 212 cylindrically curved, which is opposite the corresponding transducer 34 and defines an arc of a circle having a center of curvature 214 and lying generally in a plane (here, the plane of the paper for Figure 11) defined by the axis 210. This plane is chosen because there is a need to pivotally adjust the anvil 32 in this plane. The circle that defines the adjustment plane can also lie in a plane that intersects the paper plane in Figure 11, if adjustments are desired in other planes. Alternatively, the curved surface 212 may be a spherically curved surface, which could allow universal adjustment of the orientation of the anvil 32 about the center 214. The surface 212 is shown as a concave surface, but this could also be a convex surface. With particular reference to Figure 11, the anvil assembly 32 includes an anvil seat 216, a confronting member 218, an elastic seat 220, and the pipe couplers 222 and 224, which are all attached together in an appropriate manner . The clamping screws 226 and 228 are received in the clamping holes 230 and 232 to normally clamp or hold the anvil assembly 32 to the mounting surface 208. The anvil assembly 32 has a complex shaped front surface 234, better seen in FIG. Figures 7 and 8, for contacting a workpiece and a curved back surface 236, which is substantially complementary to and normally rests against the curved front surface 212.

As used in this description, a couple "Complementary" surfaces are a convex surface and a concave surface which have substantially a common center of curvature and define circles that lie in the same plane. The fastening holes 230 and 232 are substantially larger than the pins of the fastening screws 226 and 228 they receive, but smaller than the heads of the fastening screws 226 and 228. The heads may alternatively be smaller, and "Washers" can be inserted between the heads of the clamping screw and the portion of the anvil seat 216, against which the heads of the clamping screws 226 and 228 could otherwise be directly supported. The substantially larger size of the fastening holes 230 and 232 relative to the fastening screws 226 and 228, best seen in Figure 11, allows the anvil 32 to oscillate about the center 214 at least as much as one might wish to adjust the orientation of the anvil 32 relative to the bar 56 of the anvil. The clamping screws 226 and 228 are screwed into corresponding threaded holes in the mounting surface 208. Alternatively, the screws 226 and 228 could pass through the larger holes in the mounting surface 208 and be screwed into the correspondingly threaded holes in the anvil seat 216. The clamping screws 226 and 228 have locking positions for securing the anvil seat 216 and the anvil bar 56, together, which are achieved by screwing the screws 226 and 228 far enough into the mounting surface 208 , for grasping or holding the anvil seat 216 to the mounting surface 208. The fastening screws 226 and 228 have an adjustment position to allow the anvil seat to rotate about the center 214 relative to the bar 56 of the anvil, for aligning the anvil 32 with respect to the sealing horn 34 (Figure 1). The adjustment position is reached by releasing the screws 226 and 228 sufficiently, so that the anvil seat 216 can oscillate with respect to the mounting surface 208. Figure 10 illustrates that the anvils 32 and 42-54 are independently mounted to the mounting surface 208, as previously described, so that these can independently oscillate around their respective centers of curvature, such as the center 214 for the anvil seat 216. Referring now to Figures 6-8 and 11, anvils such as 32 and transducers such as 34 of ultrasonic sealer 20 can be easily aligned before starting a production run. Fasteners such as 226 and 228 for all anvils 32 and 42-54 are first returned to their respective adjustment positions. Next, if desired, the nominal contact positions of the anvils such as the 32 and the sealing horns such as 34 can be established by closing them together with the light pressure, so that they come into contact in the nominal closing position, as illustrated in Figure 6. The contact between the sealing horns such as 34 and the anvils such as 32, causes the anvils such as 32 to move around their centers such as 214, orienting from this the anvils such as 32 to precisely parallel positions relative to the corresponding sealing horns such as 34. The fasteners can then be advanced to their securing positions to maintain the fit. Once the nominal orientation of the anvils has been established, the anvils and transducers can be separated. Subsequently, or instead of, the realization of the adjustment of the anvils such as 32 around their centers such as 214 with the light closing pressure and without any cardboard box present, the gauges representing the workpieces to be embraced (which can simply be the upper fins 26 or the lower fins 28 of the cardboard boxes of the type that will be run immediately) can be inserted between each anvil such as 32 and the transducer such as 34, as in Figure 7. Fasteners such as 226 and 228 may be (or remain) retracted. The calibrators 26 or 28 can be clamped between the anvils such as 32 and the transducers or the sealing horns such as 34, using the full seal pressure which is intended to be exerted during the production run, as shown in the Figure 8. The closing force will push any of the anvil seats such as 216, which are out of alignment to realign themselves by moving around their centers such as 214. The fasteners such as 226 and 228 can then be made forward towards its assurance positions to maintain the adjustment. A wedge or adjustment fitting 237 may be placed between the surfaces 212 and 236 to provide lateral adjustment.

Anvil Cooling Apparatus The anvils receive some of the ultrasonic energy from the transducers or the sealing horns, when the cardboard boxes are sealed. To prevent the anvils from overheating, the anvils can be cooled. For this purpose, cooling water can be directed through the anvils to cool them. By reference to Figures 10 and 11, each anvil such as 32 has an internal passage 240 for water connecting its input and output couplers 222 and 224. Figure 10 illustrates that water is taken from a water supply 242, which can be a municipal water supply. The water can optionally be sanitized so that it can not contaminate the hygienic part of the machine in the event of a leak. The water from the supply 242 is brought to the anvil 54 via a flexible tube 244. The tube 244 is sufficiently long and positioned in such a way that the alternating movement of the bar 56 of the anvil can be accommodated. The tube 244 is fitted on a coupler 246 to pass the cooling water to the internal passages of the anvil 54. The cooling water leaves the output coupler 248 of the anvil 54 via a bridge tube 250, which then directs the water to the input coupler 252 of the next anvil in the line, here the anvil 52. A similar series of bridge tubes 254-264 transmits the cooling water through each of the anvils in turn. outlet 266 transfers the cooling water from the last anvil in line (32) to a drain 268. Exit tube 266 is a flexible tube that is sufficiently long and positioned in such a way that it can be accommodated in the alternating movement of the bar 56 of the anvil .. Of course, the drain 268 can be omitted and the water can be cooled and recycled to the source 242 if that is desired, and particularly if the water has been treated with relatively expensive sanitizing agents. , "which are desirably recycled. In Figure 11 various adaptations of the present cooling system are illustrated. The elastic seat 220, typically made of rubber, ultrasonically and thermally insulates the confronting member 218 from the anvil of the anvil seat 216. Because the confronting member 218 is isolated, the cooling system can be limited to the confronting member 218. Also, to prevent external pipe and fittings from becoming damaged or working loose, they are all mounted on the seats 32 of the anvil behind the elastic seat 220. The pipe and fittings themselves are therefore isolated from the ultrasonic energy. The inner water passage 240 itself has a portion 270 that passes through the elastic seat 220, directing water from an inlet coupler 222 behind the seat 220 to a cooling area in front of the seat 220. The internal water passage 240 it has a further portion 272 which passes through the elastic seat 220 and goes towards the exit coupler 224 behind the seat 220. The elastic seat 220 acts as a packing between the seat 216 and the confronting member 218.

Use of the Apparatus The apparatus described above can be used in a packaging machine such as that described in U.S.S.N. 08 / 190,546, filed on February 2, 1994, which is incorporated by reference herein. The apparatus can be operated using a servo motor and the associated control system, as illustrated in U.S.S.N. 08 / 475,396 (Case of Lawyer No. 10623US01; Corporate Case No.TRX-0126), entitled "Control System for a Packaging Machine", presented on the same date with this, which is likewise incorporated by reference. When the ultrasonic sealant is used to seal the bottom of a cardboard box with an inverted V-shaped upper part in a packaging machine, such as the one described in the patent application x546, it can be controlled using the control system illustrated in USSN 08 / 475,396 (Case of Lawyer No. 10623US01; Corporate Case No. TRX-0126) which may implement the movement profile illustrated in Figures 15-17 of this application. Figures 15-17 illustrate exemplary acceleration, velocity, and position profiles for a simple seal cycle. The movement profile can include two movements. The movement of the first motor, which occurs between 0.2 seconds and 0.6 seconds within the cycle, rotates the cam to close the sealing jaws. The movement of the first motor begins with a sufficient guiding time to ensure that the jaws make contact with the bottoms of the cardboard boxes, just after the bottoms of the cardboard boxes reach the plane of the jaws. In the movement of the second motor, which occurs between about 1.3 and about 1.6 seconds within the cycle, it rotates the cams so that the sealing jaws open. For each movement, 15% of the movement time is accelerated, 70% of the movement is spent at constant speed, and 15% of the movement time is spent decelerating.

The cams are shaped to move the jaws during the constant velocity portion of the movement, thus avoiding the possibility of adding twist, required to move the jaws to the torque required to secure the cams. Each movement of this profile is basically a trapezoidal velocity profile of 15%, 70%, 15%. However, during the time of any acceleration (or deceleration) 20% of the acceleration time is spent raising to constant acceleration, and 20% of the acceleration time is spent decreasing to zero acceleration. The change of accelerations helps prevent the rattle of the mechanism. When the ultrasonic sealing press is used as an upper sealer, it can be moved according to the movement profiles illustrated in Figures 12-14. The movement can proceed according to two movements. The first movement is an atypical movement consisting of three polynomial grooves. The first groove, which operates between about 0.6 and 0.7 seconds within the cycle, rotates the cams so that the jaws contact the upper sealing areas of the carton, generally simultaneously with the arrival of the crates. cardboard in the plane of the jaws. The cams reach that point with a very low speed. The low speed of the cam was desired, so that the speeds of the jaw could be sufficiently small to give refolding mechanisms, such as those illustrated in U.S.S.N. 08 / 315,400 (Case of Lawyer No. 10455US01 -Corporate Case No. TRX-0047), entitled "Apparatus for Sealing the Flap of a Cardboard Box with V-shaped Top Part", filed on the same date herewith, the time to shape the upper parts of the cardboard boxes for proper folding and sealing. At the same time it is desirable to have some velocity greater than zero, so that the subsequent acceleration could be performed without having to overcome the static friction. The second groove of the movement, which acts between approximately 0.7 seconds and 0.8 seconds within the cycle, rotates the cams to the jaws - and thus, the upper parts of the cardboard boxes - are about 5 mm apart. It was desired that this movement last 100 ms to continue allowing time for the action of the refolding mechanisms and allowing excess air to escape from the cardboard box. It is also desired that the speed at the end of the second groove be as low as possible, while at the same time making it possible for the jaws to finish the closing in the next 100 ms via the third groove. The low speed at the end of the second groove (and, thus, at the beginning of the third groove) is desirable to extend the time for exhaust air to proceed as far as possible within the third groove. The third groove, which acts between approximately 0.8 seconds and 0.9 seconds within the cycle, has to decelerate as fast as possible to complete the rotation of the cam and the jaw closure in the 100 ms assigned. The second movement, which acts between about 1.3 and 1.6 seconds within the cycle, opens the upper sealing jaws and is the same as the movement that opens the lower sealing jaws. 15% of the movement time is used by accelerating, 70% of the movement time is used at constant speed, and 15% of the movement time is used by decelerating. During the time of any acceleration (or deceleration) 20% of the time is spent raising to constant acceleration and 20% of the time is spent decreasing to zero acceleration. Again, the acceleration change was implemented to reduce the rattle of the system. The previous figures use units that are in degrees, degrees / second and degrees / sec2 of the rotation of the cam, instead of radius or degrees of rotation of the motor, because the rotation of the motor is directly proportional to the rotation of the motor. cam and because the rotation of the cam is more meaningful for more people than the rotation of the motor.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (32)

1. A cardboard box sealer for sealing a closure having first and second sides, and placed in a sealing position of the closure, said sealant is characterized in that it comprises: A. an anvil mounted for the alternating travel between an open position that allows a cardboard box passes, and a closed position to limit against the first side of a closure located in the closing sealing position; B. an anvil driver for alternating movement of the anvil between its open position and its closed position; C. an ultrasonic sealing horn mounted for the alternate travel between an open position, which allows a cardboard box to pass, and a closed position to limit against the second side of a closure located in the sealing position of the closure; D. a horn actuator for moving the horn between its open position and its closed position; and E. a biasing element operatively connecting one of the anvil and the horn and its driver, to limit the sealing pressure developed between the anvil and the horn, to a predetermined maximum value exerted by the biasing member.

2. The cardboard box sealer according to claim 1, characterized in that the deflection element comprises a pneumatic connection, arranged so that the pressure of the gas in the pneumatic union deflects one from the anvil and the horn towards its closed position.

3. The cardboard box sealant according to claim 2, further characterized in that it comprises a pressure regulator for regulating the gas pressure in the pneumatic union, whereby the sealing pressure exerted through the mechanical union is regulated, consequently .

4. The cardboard box sealer according to claim 3, characterized in that the pressure regulator is remotely controlled, thereby allowing the sealing pressure exerted through the pneumatic union to be controlled remotely.

5. The cardboard box sealer according to claim 1, characterized in that it comprises at least two anvils mounted on an anvil rod, and at least one corresponding ultrasonic horn mounted on a frame or frame.

6. The cardboard box sealer according to claim 5, characterized in that it comprises at least two deflection elements that operatively connect one of the anvil rod and the frame and its actuator.

7. The cardboard box sealer according to claim 6, characterized in that the biasing elements comprise pneumatic joints, arranged so that the pressure of the gas in the pneumatic joints deflects one from the anvil and the horn towards its closed position.

8. The cardboard box sealer according to claim 7, further characterized in that it comprises a pressure regulator for regulating the gas pressure in the pneumatic connections, whereby the sealing pressure exerted through the pneumatic unions is regulated accordingly.

9. The cardboard box sealer according to claim 8, characterized in that the gas in the pneumatic connections is communicated, whereby the gas pressure is maintained equal in each joint.

10. The carton sealer according to claim 1, further characterized in that it comprises a cam having an anvil drive surface for movement of the anvil to its closed position and a horn drive surface for moving the horn towards the closed position.

11. The cardboard box sealer according to claim 10, characterized in that the cam comprises a pivot and an actuator for rotating the cam about said pivot.

12. The cardboard box sealer according to claim 11, characterized in that the "driving surface of the anvil and the operating surface of the horn are substantially opposite with respect to the pivot.

13. The cardboard box sealer according to claim 12, characterized in that the horn is mounted on a frame or horn frame having one side facing the anvil, and one side of the opposite cam roller, and the anvil is mounted on an anvil frame having one side facing the horn and one cam side, opposite.

14. A cardboard box sealer according to claim 13, characterized in that the cam is generally placed between the cam roller sides of the horn frame and the anvil frame.

15. The cardboard box sealer according to claim 11, characterized in that the actuator rotates the cam according to a predetermined speed profile.

16. The cardboard box sealer according to claim 11, characterized in that the cam is rotated reciprocally through an arc around said pivot.

17. The cardboard box sealer according to claim 10, characterized in that the cam further comprises a surface for retracting the anvil to move the anvil to its open position, and a retraction surface for the horn to move the horn to its closed position. .

18. The cardboard box sealer according to claim 1, characterized in that the anvil driver and the driver of the horn are placed on the same side of the sealing area.

19. An ultrasonic sealing apparatus, characterized in that it comprises an anvil and a transducer opposite the anvil; the anvil comprises: A. a backrest element adapted to move generally along an axis between an open position and a closed position relative to the transducer, the backrest element further comprises a curved front surface opposite the transducer, and defines an arc of a circle that has a center and that lies in general in a plane defined by that axis; B. an anvil seat having a front surface for contacting a workpiece, and a curved back surface which is substantially complementary to and normally bounded against the curved front surface of said backing element, and typically defines an arc of the circle that lies in general on the plane; and C. a fastener having an assurance position for securing the anvil seat and the backrest element together, and an adjusting position for allowing the anvil seat to rotate about the center relative to the backrest element, to align the anvil with respect to the transducer.

20. A sealing apparatus according to claim 19, characterized in that the backing element is a bar extending substantially perpendicular to the axis.

21. The sealing apparatus according to claim 20, further characterized in that it comprises a plurality of transducers; a plurality of curved front surfaces positioned along the bar, each lying generally in a plane defined by a line parallel to said axis; and a plurality of anvil seats, respectively having curved back surfaces received by the curved front surfaces, and the front surfaces each opposite one of the transducers.

22. The sealing apparatus according to claim 19, further characterized in that it comprises a second fastener having an assurance position for securing the anvil seat and the backrest element together, and an adjusting position for allowing the anvil seat to rotate about of the center relative to the backing element, to align the first jaw with respect to the transducer.

23. The sealing apparatus according to claim 19, characterized in that the fastener is a threaded fastener reversibly screwed to one of the backing element and the anvil seat, and having a head and a stem, and wherein the other of the backing element and the anvil seat has a hole that receives the fastening pin, said hole has a larger diameter than the pin, said head urging the anvil against the backing element, when the threaded fastener is advanced towards one of the backing element and the anvil seat within which it is screwed.

24. A sealing apparatus according to claim 19, characterized in that the anvil seat has a confronting member and a non-integral body.

25. A sealing apparatus according to claim 6, further characterized in that it comprises an elastic seat that ultrasonically isolates the confronting member and the non-integral body.

26. A sealing apparatus according to claim 25, further characterized in that it comprises a source of cooling fluid and a first passage formed within the confronting member to bring the cooling fluid through the confronting member.

27. A sealing apparatus according to claim 26, characterized in that the source of the cooling fluid is brought to the first passage by a second passage extending through the non-integral body and the elastic seat.

28. A sealing apparatus according to claim 19, characterized in that the curved front surface of the backrest element is concavely curved and the curved rear surface of said anvil seat is convexly curved.

29. An ultrasonic sealing apparatus, characterized in that it comprises: A. a source of cooling fluid; B. an anvil comprising a confronting member, a non-integral body separated from the confronting member by an elastic seat, a first passage formed within the confronting member for carrying a cooling fluid through said confronting member, and a second passage extending through the non-integral body and the elastic seat to carry the fluid from the source of the cooling fluid to the first passage, and C. a transducer opposite the anvil.

30. A clamp comprising a pair of first and second jaws for gripping a workpiece, the first jaw is characterized by comprising: A. an element adapted to move back in turn generally along an axis between an open position and a position closed relative to the second jaw, the backing member further comprises an opposite front surface curved to the second jaw and defining an arc of a circle having a center and lying generally in a plane defined by the axis; B. a jaw seat having a front surface for contacting a workpiece, and a curved back surface that is substantially complementary to and that normally limits against the curved front surface and that normally defines an arc of the circle that lies in general on that plane; and C. a fastener having a securing position for fixing the seat of the jaw and the backing element together and an adjusting position for allowing the seat of the jaw to rotate about the center relative to the backing element for aligning the first jaw with respect to the second jaw.

31. A method for aligning the anvils and transducers of an ultrasonic sealing apparatus, characterized in the method because it comprises the steps of: A. the provision of an ultrasonic sealing apparatus according to claim 3; B. the arrangement of fasteners in their adjustment positions; C. advancing the anvils against the transducers, thereby allowing any anvil seats that are out of alignment, to move themselves toward proper alignment by moving around the centers; and D. the provision of fasteners in their securing positions to maintain said alignment.

32. The method according to claim 31, characterized in that it comprises the additional steps of: A. the placement of calibrators between each anvil and the transducer, which represent the work pieces to be embraced; and B the clamping or clamping of the gauges between the anvils and the transducers. SUMMARY OF THE INVENTION An ultrasonic sealing apparatus is disclosed which includes at least one anvil (32, 42-54) and at least one transducer (34, 112-116) opposite the anvil, for transmitting the ultrasonic energy to a workpiece (24) embraced between these. A deflection element (40) is connected between the anvil or the horn and its actuator (36, 38), to define the sealing pressure developed between the anvil and the horn. The deflection force can be adjusted without stopping the machine, by using an externally applied pneumatic force. The anvil has a backing element (56) with a curved front surface (212) connected to a curved back surface (236) of the anvil. A fastener (226) is provided for selectively securing the anvil and the backrest element together, or for allowing the anvil to travel along the curved surface of the backing element, to align the anvil with respect to the transducer. A cooling fluid may be provided for passage through a passage (240) in an anvil body, for cooling during operation. A method for the alignment of the anvils and transducers of an ultrasonic sealing apparatus as described above is also described.