Abstract:
An automatic high-speed wrapping system for wrapping packages in heat sealable thermoplastic film includes a film delivery unit wherein the film is dispensed and wrapped around the packages at a high rate of speed as the packages travel through the system. The packages travel continuously in a straight line through the system and are delivered at the input end of the system by a feed conveyor into a wrapping station where the packages are surrounded by the film, thence to the side sealing mechanism which forms a seal while severing the salvage from the packages, then into an end sealing mechanism where both ends of the packages are sealed and the film web connecting succeeding packages is severed. The system has a variety of components which are adjustable to efficiently accommodate a variety of product dimensions. The spacings of the various components are represented one calibrated scales for efficient and accurate set up and operation of the system.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to the art of film wrapping systems for use in wrapping objects with shrink wrap film and, more particularly, to improvements directed to preparing the film wrapping system for wrapping products of differing dimensions. 
     A wide variety of systems are known for wrapping packages in thermoplastic film. Some of these machines are known as L-sealers because they form “trim seals” utilizing a web of center folded film. More recent machines utilize a continuous longitudinal sealer and a cross sealer which moves at approximately the velocity of the packages as they travel through the machine so that the packages are not stopped while the machine performs the end sealing operation. One example of a shrink wrap packaging system is disclosed in U.S. patent application Ser. No. 10/286,523, filed Nov. 1, 2002, assigned to the Assignee of this invention and hereby incorporated by reference in its entirety. 
     Most known shrink wrap packaging systems utilize film which is provided on a roll in two plies with each ply being joined together by a longitudinal fold line. The two-ply film is dispensed from a supply roll and delivered to a wrapping station of the shrink wrap packaging system. The film is commonly inverted and reoriented to provide an opening for convenient access and entry of the products between the dual plies of the film. The film is reoriented in many shrink wrap packaging systems by an upper and a lower film inverting rod or plow system. The upper and lower film inverting rods are positioned above and below, respectively, a feed conveyor which is advancing the products to be wrapped. 
     Shrink wrap packaging systems of these types process and wrap a variety of different products. Commonly, such products are of differing shapes, sizes and dimensions. For example, shrink wrap packaging systems may process and wrap a single compact disc (CD) package which is very thin and other consumer retail items which have a significantly greater height and a larger width dimension. One problem associated with many known shrink wrap packaging systems is the difficulty in efficiently processing and wrapping a wide variety of packages and products, especially those having distinctly different dimensions, heights and widths. 
     Recent advancements in the art of shrink wrap packaging systems have included adjustable film inverter rods in which a spacing between the rods is adjustable to accommodate a variety of differing height products being wrapped. The film inverter rods are only one of many pairs of components in typical film wrapping systems which must be adjusted depending upon the dimensions of the product being wrapped. Moreover, the spacing between the various pairs of associated components of the shrink wrap packaging systems is not always the same as the product dimension. For example, while the spacing between the film inverter rods is roughly equal to the height of the product being wrapped, the position of a side seal mechanism for joining the free edges of the shrink wrap film and enclosing the product is roughly half the height of the product. Generally, the side seal should be located approximately at the equator of the product and the side seal mechanism should be centered at that location above the platform or conveyor supporting the product. 
     Many other components of the shrink wrap packaging system likewise must be adjusted and appropriately positioned for a given product and associated product dimensions. In one shrink wrap packaging system commercially available from the assignee of this invention, five different height adjustments and three different width adjustments must be made to the system to properly set it up for wrapping a given product. An operator of a shrink wrap packaging system typically must initially measure the product and perform the required calculations to determine the spacing between each of the eight or so pairs of components required for proper wrapping of the product. The set up procedure for the shrink wrap packaging system requiring these operations can take anywhere from eight to 19 or more minutes. This has proven to be an inefficient and often troublesome procedure minimizing the productivity of the shrink wrap packaging system, wasting time and materials and providing poor packaging results if not completed accurately and correctly. 
     Therefore, a need exists in the shrink wrap packaging industry for a packaging system which can readily accommodate a wide variety of product configurations, heights and widths without the above-described problems associated with known shrink wrap packaging systems, set up operations and procedures. 
     SUMMARY OF THE INVENTION 
     These and other objectives have been achieved with this invention, which in one embodiment is a shrink wrap packaging system with calibrated scales for efficient and accurate set up and operation of the system. The film wrapping system according to one embodiment of this invention includes a number of stations or sub-systems for wrapping products of differing dimensions in film. The film wrapping system includes a feed conveyor to deliver a series of products to a wrapping station. The wrapping station includes a pair of film inverter rods and an adjustment mechanism for changing the spacing from one another to correspond to the height of the product being wrapped. A film delivery unit dispenses a supply of film in a direction generally perpendicular to the feed direction of the products. The film is inverted by the inverter rods at the wrapping station where the products are inserted between the plies of the film. 
     The system also includes in one embodiment a film delivery unit adjustment mechanism to adjust a position of the film delivery unit and the film being delivered to the wrapping station as a function of the spacing between the film inverter rods and, consequently, the height of the product being wrapped. The film delivery unit adjustment mechanism is described in more detail in the aforementioned U.S. patent application Ser. No. 10/286,523 filed Nov. 1, 2002, assigned to the assignee of this invention and hereby incorporated by reference in its entirety. 
     Additionally, the system in one embodiment includes an adjustable roller positioned between the film delivery unit and the wrapping station to deliver film to the wrapping station at a desired height relative to the position of the film inverter rods and the height of the product being wrapped. A side seal mechanism and an end seal mechanism are each located downstream in the feed direction from the wrapping station to join the first and second plies together and enclose each of the products in individually wrapped packages. A heat shrink tunnel in one embodiment is located downstream from the sealing mechanisms to heat the film and thereby shrink it around the product. 
     The various components of this system which require adjustment based upon a height, width or other dimension of the product being wrapped each include a display or scale which indicates a spacing between the associated components. Adjustment mechanisms are available for an operator to positionally adjust the various components relative to the complementary component. 
     One important advantage of this invention is that the various scales and displays are calibrated so that the operator more efficiently and effectively adjusts the position of the various components for a given product dimension. For example, a product having a three inch height might require the operator to positionally adjust the various height components relative to each other for appropriate wrapping so that each scale displays a “3” even though specific pairs of components represented by one or more of the scales do not actually have a three inch spacing there between. The machine components, adjustment mechanisms and associated scales are calibrated so that for a given product dimension each scale is to be set at the same number for the entire shrink wrap packaging system even though given components in the system may not have an actual spacing of that value. As a result, an operator of the system simply sets each adjustment mechanism so that the associated scale reads the same number as the other scales thereby avoiding the need for complicated calculations and other decisions associated with properly setting up known shrink wrap packaging systems. 
     Generally, this invention is a film wrapping system in which the relative positions of a first pair of adjustably spaced components are adjusted by a first adjustment mechanism adapted to selectively change the spacing of the first pair of components. A first scale indicates the spacing of the first pair of components and the indicated spacing is correlated to a product dimension in a first manner. Moreover, the wrapping system includes a second pair of adjustably spaced components in which their relative positions are changed by a second adjustment mechanism and a second scale indicates the spacing of the second pair of components. The indicated spacing of the second pair of components is correlated to the product dimension in a second manner different than the first manner. The first and second scales are adapted to the manners of correlation such that differences in the spacing of the first pair of components and the spacing of the second pair of components for the product dimension result in the indicated spacing from the first and second scales being substantially the same. 
     As a result of the film wrapping system and associated method according to this invention, a variety of product configurations, heights and widths can be conveniently and efficiently accommodated with adjusting the spacing between the various components of the system while avoiding the associated problems and disadvantages of shrink wrap packaging systems in the prior art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objectives and features of the invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a top view of a film wrapping system according to one embodiment of this invention; 
         FIG. 1A  is a perspective view of an exemplary product to be wrapped in the system of  FIG. 1 ; 
         FIG. 2  is a perspective view of a film delivery unit and a product wrapping station as well as other portions of the system of  FIG. 1 ; 
         FIG. 3  is a view of exemplary calibrated scales to display spacings between associated components related to a height dimension of the product being wrapped in the system of  FIG. 1 ; and 
         FIG. 4  is a view similar to  FIG. 3  of exemplary calibrated scales to display a width dimension of the product to be wrapped. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIG. 1 , a top view of an exemplary automatic high-speed film packaging system  10  according to one embodiment of this invention is shown. The system  10  generally includes a feed conveyor  12 , a film delivery unit  14 , a wrapping station  16 , an intermediate conveyor  18 , a side sealer  20 , an end sealer  22 , a downstream conveyor  24  and a heat shrink tunnel  26 . Products P to be wrapped in film  28  enter the system  10  via the feed conveyor  12 . The feed conveyor of  FIG. 1  includes a number of spaced flight lugs  30  which move continuously in the feed direction to advance the products P. The products P are centered laterally on the feed conveyor  12  by a pair of spaced, adjustable guides  32 . 
     The conveyor  12  delivers the spaced-apart and aligned products P to the wrapping station  16  where a folded film  28  from a film roll  34  in the film delivery unit  14  surrounds each product P. The folded film  28  enveloping each product P is sealed at its free edges  36 ,  36  by the side sealer  20  to form a tube of film  28  enclosing the spaced products P. The film  28  between the adjacent products P is sealed and severed at the end sealer  22  to produce individual sealed packages of the product P. 
     The system  10  wraps a product P in a flexible plastic film  28  in which the travel of the product P is essentially continuous through the system  10  in a feed direction indicated by arrow A. The film  28  may be any one of a variety of films well known in the art (i.e., commercial grade polyolefin, PVC, LDPE, etc.) and is supplied to the system  10  as a folded web in the direction of arrow B and at right angles to the feed direction of the product P (shown in  FIGS. 1 and 2 ). The film  28  is folded about a longitudinal fold  38  thereby forming upper and lower plies  40 ,  40  in which each ply has a free edge  36  opposite from the fold line  38 . Commonly, the two-ply folded film  28  is provided on the supply roll  34 . Alternatively, single ply film may be provided on a supply roll and subsequently folded into the described two-ply configuration as is well known in the art. The film  28  is provided to upper and lower inverter rods  42 ,  42  of the wrapping station  16  where the film  28  is redirected and turned inside out to travel in the feed direction with the products P delivered by the feed conveyor  12 . 
     The feed conveyor  12  pushes products P into the wrapping station  16  to cause them to be enclosed by the folded film  28  supplied by film delivery unit  14  on the top, bottom, and one side of the product P with the other side of the product P adjacent to the free edges  36 ,  36  of the folded film  28  being open initially. The product P thus enclosed in the web of film  28  travels on the intermediate conveyor  18  with the film  28  past the side sealing mechanism  20  in  FIG. 1  which seals the two free edges  36 ,  36  of the folded film  28  together to form a continuous tube of film which envelops the succession of products P which are being fed into the system  10 . The side sealer  20  also severs the excess width of film  28  from the tube and this salvage (not shown) is removed by a salvage accumulator (not shown), such as a vacuum or other take-up mechanism. 
     As the product P progresses further through the system  10 , the end sealing mechanism  22  seals the trailing edge  44  of each package while simultaneously sealing the leading edge  46  of the succeeding package P in the system  10  and it also severs one package P from the other while the packages are traveling without stopping through the system  10 . The end seal mechanism  22  is so designed that it travels a short distance with the product P at substantially the same velocity while the seals  44 ,  46  are being made. After the seals  44 ,  46  have been made, the sealing mechanism  22  releases from the film  28  and returns to its original position to repeat the transverse seals  44 ,  46  for the next products. The wrapped product P may then be conveyed on the downstream conveyor  24  through the shrink tunnel  26  for shrinking of the film  28  around the product P. 
     The system  10  shown and described herein is representative of a Lantech.com model SW-3000 Continuous Motion, Flighted Infeed, Side-Seal Shrink Wrapper. Additional details of the system  10  are found in U.S. patent application Ser. No. 10/286,523, filed Nov. 1, 2002 and hereby incorporated by reference. While exemplary embodiments of the system  10 , and associated components, are shown and described herein to describe the invention, specific models or embodiments of the system or these components could readily be varied, deleted or changed as known by one of ordinary skill in this art without departing from the scope of this invention. 
     The system  10  is designed to accommodate a variety of product P heights, widths and dimensions. Accordingly, selected pairs of components are positionally adjustable relative to each other to properly wrap the film  28  around products P of different widths, heights or dimensions. Examples of such components will now be described. 
     As shown particularly in  FIGS. 1 and 2 , the two-ply film  28  is delivered from the supply roll  34  by the film delivery unit  14  in a direction indicated by arrow B generally perpendicular to the feed direction (arrow A) of the products P. As the film  28  enters the wrapping station  16 , each ply  40  is guided around one of the film inverter rods  42  and thereby redirected approximately 90° to travel in the feed direction of arrow A. The film inverter rods  42  are oriented approximately 45° with respect to the feed direction. In addition to being redirected, the film  28  is inverted by the film inverter rods  42  such that confronting inner first faces of the film  28  provided by the film delivery unit  14  are inverted so that previously outer second faces of the plies  40  of the film  28  are juxtaposed to each other and around the product P downstream from the film inverter rods  42 . 
     As shown particularly in  FIG. 2 , each film inverter rod  42  is joined to a pair of mounting rods  48 ,  50  to form a generally triangular configuration. Mounting rod  48  is oriented generally parallel to the feed direction; whereas, mounting rod  50  is oriented generally perpendicular to the feed direction. An inclined guide tab  52  is mounted proximate the intersection of each film inverter rod  42  and the associated mounting rod  48 . 
     Each film inverter rod  42  and the associated mounting rods  48 ,  50  are mounted to a hub  54 , respectively. The hub  54  for the lower film inverter rod  42  is fixed beneath the conveyor  18 . The hub  54  for the upper film inverter rod  42  is mounted on a film inverter rod adjustment mechanism  56  to adjust a spacing H 1  between the upper and lower film inverter rods  42  in a direction generally perpendicular to the feed direction (i.e., vertically) to accommodate products P of differing heights. The film inverter rod adjustment mechanism  56  in one embodiment includes an operator hand wheel  58  mounted atop a threaded rod  60  to rotate the rod  60 . The hub  54  includes a threaded aperture  62  engaged with the threaded rod  60  as well as two additional apertures  64 ,  64  through which guide rods  66 ,  66  project. In operation of the system  10 , the operator rotates the hand wheel  58  in the appropriate direction to raise or lower the upper film inverter rod  42  so that the upper ply  40  of the film  28  is positioned slightly above the top upper surface of the product P being wrapped. The adjustment mechanism includes a scale  68  and the spacing H 1  between the film inverter rods  42  is displayed by a pointer  68   a  on scale of  FIG. 3 . 
     The film delivery unit  14 , as shown generally in  FIGS. 1–2 , is mounted adjacent to the wrapping station  16  in a direction generally perpendicular to the feed direction. The film delivery unit  14  supplies film  28  from the supply roll  34  to the wrapping station  16 . The supply roll  34  is supported by a cradle assembly  70  of the film delivery unit  14 . The supply roll  34  is positioned atop the cradle assembly  70  and between a pair of film roll retainer posts  72 ,  72 . In one embodiment, the downstream film roll retainer post  72  is joined to a bracket  74  that is secured by a set screw  76  in a slot  78  of front frame member  80  in the cradle assembly  70 . To adjust the spacing between the film roll retainer posts  72 ,  72  for different width supply rolls  34 , the operator would loosen the set screw  76  and slide the bracket  74  and associated film roll retainer post  72  along the slot  78  to the appropriate position to capture the supply roll  34  between the film roll retainer post  72 . The spacing W 3  between the posts  72 ,  72  is displayed on scale  82  of  FIG. 4  by set screw  76 . The spacing W 3  is a geometry correction for different width products P in certain embodiments of this invention. 
     Referring to  FIG. 2 , the path of the film  28  from the supply roll  34  through the delivery unit  14  and to the wrapping station  16  is shown. The supply roll  34  rotates on a pair of cradle rollers  84 ,  84  and the film  28  is fed around a series of rollers toward a film delivery height adjustment roller  86  positioned between the film delivery unit  14  and the wrapping station  16 . The roller  86  is mounted between a pair of arms  88 ,  88  which are coupled to corresponding links  90  mounted to the frame  92  of the system  10 . Advantageously, the position of the arms  88  and subsequently the height H 3  of the roller  86  relative to the upper surface of the feed conveyor  12  is adjustable to deliver the film  28  to the wrapping station  16  at an appropriate height H 3  relative to the position of the film inverter rods  42 . Preferably, the height H 3  of the roller  86  is equal distance between the upper and lower film inverter rods  42 . Since the spacing H 1  between the film inverter rods  42  is adjustable, the height H 3  of the film delivery roller  86  is likewise adjustable to provide for proper positioning relative to the film inverter rods  42 . Generally, the spacing H 1  of the film inverter rods  42  is about twice the height H 3  of the roller  86  above the feed conveyor  12  surface. 
     The arm  88  supporting the roller  86  includes a set screw  94  which is captured within an arcuate slot  96  in a scale plate  98 . Adjustment of the roller  86  height is accomplished by the operator loosening the set screw  94  and pivoting the arms  88  coupled to the roller  86  upwardly or downwardly as desired and then resecuring the set screw  94  with the roller  86  in the appropriate position approximately midway between the upper and lower film inverter rods  42 . As the film  28  passes around the roller  86 , the two plies  40  are separated and guided by the respective film inverter rod  42  to surround the product P on the conveyor  12 . The height H 3  is displayed on scale  98  by pointer  98   a  of  FIG. 3 . 
     As the spacing H 1  between the upper and lower film inverter rods  42  is adjusted to accommodate different height products P, movement of the film delivery unit  14  in a direction generally parallel to the feed direction is required to maintain proper film delivery geometry. Spacing H 2  is displayed on scale  100  of  FIG. 3  by pointer  100   a  and is indicative of the position of the film delivery unit  14  relative to the wrapping station  16 . For products P which are extremely thin and having little or no height such as a CD lying generally flat on the feed conveyor  12 , a reference point R at the intersection of the film inverter rods  42  and the mounting rod  50  is generally aligned with the upstream edge  102  of the supply roll  34  on the film delivery unit  14 . However, the film delivery unit  14  must be moved in a direction generally parallel to the feed direction as the spacing H 1  between the film inverter rods  42  is adjusted to accommodate different height products P. 
     In operation, the spacing H 1  between the film inverter rods  42  is adjusted to accommodate the product P height. Once the film inverter rods  42  are so adjusted, the position H 3  of the film delivery height adjustment roller  86  is likewise set by the operator to be approximately equal distance between the film inverter rods  42 . The position H 2  of the film delivery unit  14  is then adjusted relative to the film inverter rods  42  to provide for proper alignment, geometry and delivery of the film  28  to the wrapping station  16 . According to one embodiment of this invention, the film delivery unit  14  is moved via the adjustment knob  104  along the rails  106  one-half inch to adjust for each inch in package P height to establish the correct film delivery geometry. The film inverter rods  42  at the wrapping station  16  should remain stationary as the film delivery unit  14  position is adjusted. For each inch increase in product P height, the position H 2  of the film delivery unit  14  is adjusted one-half inch in the upstream direction. Conversely, for each inch decrease in product P height or spacing between the film inverter rods  42  a half-inch movement of the film delivery unit  14  in the downstream feed direction is required for correct film geometry. 
     As previously described, the position of the film roll  34  in relation to the film inverter rods  42  must be adjusted depending on the product P height. Preferably, the downstream edge  108  of the film roll  34  must be aligned with the film  28  position on the inverting rods  42 . H 2  represents the offset of the position of the film roll  34  relative to the film inverting rods  42 . If a product P has a theoretical height dimension of zero, the upstream edge  102  of the film roll  34  will align with the apex  110  of the film inverting rods  42  and the downstream edge  108  of the film  28  is by default aligned. When the product P height changes, for example to four inches, the opening movement of the film inverter rods  42  pulls two inches from the top ply  40  of the film  28  and two inches from the bottom ply  40  of the film  28 . As a result, the right side edge of the inverting rods  42  is no longer in alignment and is offset by two inches. The H 2  height adjustment allows the operator to move the film roll  34  in its cradle  70  two inches to the left or upstream in the product flow direction so that the downstream edge  108  of the film roll  34  is properly aligned relative to the film inverter rod  42  position based upon the product P height dimension. The position of the film delivery unit  14  is indicated by the scale  100  and pointer  100   a  in  FIG. 3 . 
     In addition to the spacing H 1  between the film inverter rods  42  and the height H 3  of the roller  86  delivering the film  28  to the wrapping station  16 , a variety of other spacings of various components of the system  10  must be adjusted depending on the product P dimensions. H 4  is a height of the side sealer  20  relative to the upper surface of the conveyor  24 . Preferably, H 4  is approximately half the product P height dimension so that the side seal is located at approximately the equator of the wrapped product. The position of the side sealer is represented on scale  112  by pointer  112   a . The final height adjustment shown in  FIGS. 1–2  is H 5  which is the seal bar jaw  114  opening for the end sealer  22  and is represented by scale  116  in  FIG. 3  by pointer  116   a . The spacing H 5  of the seal bar  114  provides clearance for the product P exiting the side sealer  20  on the conveyor. 
     In addition to the adjustments for spacings H 1 –H 5  required for product P height, adjustments for various components of the system  10  are required depending on the product P width dimension. For example, W 1  represents an adjustment for the width of the product P to move the intermediate conveyor  18  relative to the center line CL of the system  10  and is shown on digital scale  118 . W 2  represents a width dimension adjustment for the inverting rod  42  width to adjust to the center line CL of the system  10  and is shown in scale  120  by pointer  102   a . W 3  represents an adjustment that applies to the Lantech Model SW-3000 which includes adjustment of the inverting rod  42  width adjustments which are made in 45° increments rather than parallel to the film roll  34  as in other shrink wrap film systems. When making adjustment in parallel mode, the apex  116  of the inverter rods  42  always stays in line with the film roll  34 . For example, if the upstream left edge  102  of the film roll  34  is offset by one inch for a width of two inches, any width adjustment parallel (up to the maximum of 15 inches width) will keep the upstream left side edge  102  of the film roll  34  at the one inch marker. On the system  10  shown in  FIGS. 1 and 2 , the inverting rods  42  move at 45° and if the upstream edge  102  of the film roll  34  is offset by one inch for a width of two inches, the offset will increase as the width adjustment increases. Therefore, running two different width products P of the same height requires correction to the position of the upstream edge  102  of the film roll  34  and that adjustment is independent of the adjustment required for the H 2 . The proportion of the W 3  scale  82  shown in  FIG. 4  is made by running the inverting rod  42  width from zero to a maximum of 15 inches dividing it into equal increments. 
     Referring to  FIGS. 3 and 4 , on various scales  68 ,  100 ,  98 ,  112 ,  116  for H 1  through H 5 , respectively, and scales  118 ,  120 ,  82  for W 1  through W 3 , respectively, representing the spacing of the associated components previously described are shown. The scales  68 ,  100 ,  98 ,  112 ,  116  for H 1  through H 5  and scales  120 ,  82  for W 2  through W 3  are analog scales and each include a pointer in one form or another to indicate a spacing of the associated components. Scale  118  for W 1  includes a digital display to indicate the associated spacing. An important feature of this invention is that for a product P dimension, height, width or otherwise, the associated scales for H 1  through H 5  or for W 1  through W 3  will be set to the same numbers even though the spacings for the components associated with that scale may not be equal. 
     For example, for a product P height of approximately four inches, the spacing H 1  of the inverter rods  42  is roughly four inches and the scale  68  will indicate four. However, the scale  98  for spacing H 3  will likewise indicate four as will the scales  100 ,  112 ,  116  for H 2 , H 4  and H 5  even though the spacing between the components associated with H 2  through H 5  may not be four inches. In fact, the spacing for the components associated with H 3 , the roller  86  and the supper surface of the conveyor  12 , will be roughly two inches even though the associated scale  98  reads four. Having all of the H 1  though H 5  scales reading the same value for a given product P height greatly simplifies the operator&#39;s time and effort in setting up the system  10  for wrapping a given product P. In fact, it has been estimated that the set-up time for the system  10  is reduced from eight to 19 minutes in prior art machines down to two minutes with systems according to this invention, even for new users of the system. 
     While the various adjustment mechanisms to position various components of the system  10  are shown and described herein as being manual and independent from each other, alternative embodiments of this invention include automatic adjustment of the positions. 
     From the above disclosure of the general principles of this invention and the preceding detailed description of at least one preferred embodiment, those skilled in the art will readily comprehend the various modifications to which this invention is susceptible. Therefore, we desire to be limited only by the scope of the following claims and equivalents thereof.