A HIGH-SPEED ROTARY TRANSFER DEVICE

Abstract: This invention provides a rotary transfer device (10) for transferring a material from one point to another point using a conjugate cam vehicle (21) and a transfer drive mechanism (28) therein to provide transfer speed ratios of between about 1x10<4>:1, about 1:1, and/or about 1:1x10<4>, and also from a stationary position to a specified speed and vice versa.

Description: A HIGH-SPEED ROTARY TRANSFER DEVICE FIELD OF INVENTION This invention provides a rotary transfer device for transferring a material from one point to another point using a conjugate cam vehicle and a transfer drive mechanism therein to provide transfer speed ratios of between about lxl 0 4 : 1, about 1: 1, and/or about l : lxl0 4 , and also from a stationary position to a specified speed and vice versa. BACKGROUND OF INVENTION Articles, such as disposable diapers, generally have been manufactured by a process where discrete parts or components of different materials, such as leg elastic, waist elastic, tapes, and other fasteners such as hook and loop materials or snaps, have been applied to a continuously moving product web of interconnected articles. Often, the speed at which the parts are fed into the process is not the same as the speed of the product web itself. Thus, the speed of the parts must be changed to match the speed of the product web to properly apply the parts without adversely affecting the process or the finished articles. Several different conventional methods for changing the speed of a part or component of material such that it can be applied to a continuously moving web have been known to those skilled in the art. For example, one method has been known as the slip gap or slip cut method. A web of material, which is traveling at a slower speed than the moving web, is fed into a knife and anvil roll having a surface speed equal to the speed of the moving web. As the material is cut into discrete parts, vacuum in the anvil roll is activated to draw the parts of material to the surface of the anvil roll. The anvil roll then carries the parts to the moving web where the vacuum is released and the parts are applied to the moving web while both the parts and the moving web are traveling at the same speed. Another method has utilized festoons to reduce the speed of the moving web to match the speed of the discrete parts of material to be applied to the web. The moving web is temporarily slowed down to the speed of the parts with the excess portion of the moving web gathering in festoons. The parts of material are then applied to the moving web while both the parts and the web are traveling at the same speed. The festoons are then released allowing the moving web to return to its original speed. Another method has utilized a slider-crank mechanism to accomplish the speed change. The slider-crank mechanism utilizes concentrically mounted arms or linkages to receive the discrete parts of material, increase the speed of the parts to match the speed of the moving web and apply the parts to the moving web. The slider-crank mechanism is a special case of a four bar linkage system. Another such method to change the speed of a discrete part before it is applied to a moving web has utilized a cam actuated crank-follower mechanism. The cam actuated crank-follower mechanism comprises crank levers that are mounted on a rotatable driving plate. Each crank lever includes a cam follower on one end and a follower lever connected to the other end. The other end of the follower lever is connected to an applicator device which is mounted concentric with the driving plate's center of rotation. The cam follower remains in contact with a fixed cam that is also mounted concentric with the driving plate's center of rotation. As the driving plate rotates, the crank levers pivot as their cam followers follow the cam shape. As the crank levers pivot, the follower levers cause the applicator devices to speed up or slow down. An example of this method is described in U.S. Pat. No. 4,610,751 issued September 9, 1986, to Eschler. Finally, another such method to change the speed of a discrete part before it is applied to a moving web utilizes an offset crank motion of a drive ring and the pivoting of coupler arms to vary the effective drive radius of a material transfer segment to provide variable speeds. More specifically, as the transfer segments rotate about their drive ring, they are movable along their radial arm to effect changes in their speeds at pick-up and transfer of elastic materials. An example of this method is described in U.S. Patent No. 5,716,478 issued February 10, 1998 to Boothe, et al. Conventional methods, such as those described above, have exhibited several drawbacks. For example, as the discrete parts of material are transferred, they are often subjected to a tugging action because the surface speed of the transfer means used to transfer the parts is greater than the speed of the parts. The tugging action may result in an undesirable elongation or tear of the parts. Also, few, if any, of the conventional methods have the ability to achieve the high speed ratios claimed by the invention herein; e.g., the cut & slip method is one such conventional method and also, it cannot provide irregular shapes taken from one web to another. Finally, several of the conventional methods can be very expensive and time consuming to change as the size and speed of the discrete parts and the speed of the moving web change to coincide with various finished product sizes. Consequently, an inexpensive and adaptable apparatus for receiving discrete parts traveling at a speed and applying the parts to a web traveling at a different speed is desirable. Moreover, it is desirable that the receiving and applying of the parts occurs while the respective surface speeds are maintained substantially constant for a fixed duration. For example, it is desirable to apply the parts to the substrate web while the parts and substrate web are traveling at substantially the same surface speed or at match speed. Such a substantially constant speed dwell allows precise control of the length and placement of the part on the substrate web especially if the part is fragile and/or elastic. In addition, it is desired herein that the radius between the transfer shafts and the center of the rotatable drum remains constant. SUMMARY OF THE INVENTION Accordingly, the present invention provides a transfer device comprising a conjugate cam vehicle for achieving a speed ratio ranging from about lxl0 4 :l, about 1 :1, and/or about l :lxl0 4 at pick-up or stationary at some speed and transfer of materials about the device. This speed ratio range is achieved about a pair of points of pick-up and transfer spaced at least 10° and preferably at least 90° apart on the conjugate cam vehicle. The conjugate cam vehicle comprises a first cam having a center point, an outer perimeter, an inner perimeter, and irregularly shaped teeth faced inwardly toward the center point. The conjugate cam also comprises a second cam having a center point, an outer perimeter, an inner perimeter, and irregularly shaped teeth faced inwardly toward the center point. The first cam and the second cam are positioned adjacent to one- another to form a conjugate cam vehicle having a center, an outer perimeter, an inner perimeter and irregularly shaped teeth faced inwardly toward the center. The conjugate cam vehicle is configured to provide substantially inconstant acceleration about the irregularly shaped teeth such that the conjugate cam vehicle provides acceleration from between about 0° to about 180° of the outer perimeter and a deceleration from between about 180° to about 360° of the outer perimeter. The transfer device also comprises a rotary transfer drive mechanism or transfer drive that picks up and transfers material. The transfer drive is positioned within the conjugate cam and operates partially therein. The transfer drive comprises a main drive shaft for driving the transfer drive mechanism which extends through the center of the conjugate cam. Further, the transfer drive comprises a rotatable drum having a perimeter, a center, a first side, and a second side opposed to the first side. The rotatable drum is attached to the main drive shaft at its center and rotates thereabout as the drive shaft rotates. At least one transfer shaft is placed onto and through the rotatable drum adjacent to or near the drum perimeter. Each transfer shaft comprises a first end and a second end. The first end of each transfer shaft is positioned above the first side of the rotatable drum and the second end of each rotatable shaft is positioned below the second side of the rotatable drum. Also, at least one transfer head is positioned about the first end of each transfer shaft above the first side of the rotatable drum, each transfer head preferably but not necessarily being rotatable about each transfer shaft. A cam follower mechanism is positioned about the second end of each transfer shaft below the second side of the rotatable drum. Each cam follower mechanism comprises a cam follower plate having a perimeter, a first side and a second side opposed to the first side, and at least two cam followers attached to each cam follower plate. At least one cam follower is attached to the first side of the cam follower plate with the other cam followers being attached to the second side of the cam follower plate. Each cam follower mechanism is rotatable about one transfer shaft. The transfer drive mechanism fits at least partially within the conjugate cam vehicle whereby the cam followers move about the irregularly shaped teeth of the conjugate cam as the rotary transfer drive mechanism is rotated by the main drive shaft within the conjugate cam.. BRIEF DESCRIPTION OF THE FIGURES While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as forming the present invention, it is believed that the invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a perspective view of the high-speed rotary transfer device; Fig. 2 is a side view of the high-speed rotary transfer device; Fig. 3 is a plan view of the conjugate cam vehicle; Fig. 4 is a plan view of the conjugate cam vehicle; Fig. 5 is a plan view of the conjugate cam vehicle; Fig. 6 is a plan view of the conjugate cam vehicle; Fig. 7 is a plan view of the conjugate cam vehicle; Fig. 8 is a plan view of the conjugate cam vehicle; Fig. 9 is a plan view of the conjugate cam vehicle; Fig. 10 is a plan view of the conjugate cam vehicle; Fig. 11 is a graph relating the planet or cam followers displacement, velocity, and acceleration as compared to the drum angle; and Fig. 12 is . DETAILED DISCLOSURE OF THE INVENTION The present invention provides a transfer device that comprises a conjugate cam vehicle for achieving a speed ratio ranging from about lxl0 4 :l, about 1:1, and/or about lxlO 4 at pick-up and transfer of materials about the device. This speed ratio range is achieved about a pair of points of pick-up and transfer spaced at least 10° and preferably at least 45° apart on the conjugate cam vehicle from the center of the vehicle. As shown in Fig. 1, the conjugate cam vehicle 20 comprises a first cam 21 having a center point, an outer perimeter, an inner perimeter, and irregularly shaped teeth 25 faced inwardly toward the center point. The conjugate cam vehicle 20 also comprises a second cam 22 having a center point, an outer perimeter, an inner perimeter, and irregularly shaped teeth faced inwardly toward the center point. The first cam 21 and the second cam 22 are positioned adjacent to one-another to form a conjugate cam vehicle 20 having a shared and common center, outer perimeter, inner perimeter and irregularly shaped teeth faced inwardly toward the center. The conjugate cam vehicle 20 is configured to provide substantially inconstant acceleration about the irregularly shaped teeth 25 such that the conjugate cam vehicle 20 provides accelerations through the conjugate cam vehicle 20 ranging from between about 0° to about 180° of the outer perimeter and decelerations ranging from between about 180° to about 360° of the outer perimeter. The transfer device 10 also comprises a rotary transfer drive mechanism 28 or transfer drive 28 that picks up and transfers material about the device 10. The transfer drive 28 is positioned within the conjugate cam vehicle 20 and operates partially therein. The transfer drive 28 comprises a main drive shaft 32 for driving the transfer drive 28 which extends through the center of the conjugate cam vehicle 20. Further, the transfer drive 28 comprises a rotatable drum 30 having a perimeter, a center, a first side, and a second side opposed to the first side. The rotatable drum 30 is attached to the main drive shaft 32 through its center and rotates thereabout as the drive shaft 32 rotates. At least one transfer shaft 35 is placed onto and through the rotatable drum 30 adjacent to or near the drum perimeter. Each transfer shaft 35 comprises a first end 35 A (not shown) and a second end 35B (not shown). The first end 35 A of each transfer shaft is positioned above the first side 30A of the rotatable drum 30 and the second end 35B of each rotatable shaft 35 is positioned below the second side 30B of the rotatable drum 30. Also, at least one transfer head 40 is positioned about the first end 35 A of each transfer shaft 35 above the first side 30A of the rotatable drum 30, each transfer head 40, preferably but not necessarily, being rotatable about each transfer shaft 35 to accommodate product size changes. A cam follower mechanism 34 is positioned about the first end 35A of each transfer shaft 35 above the first side 30a of the rotatable drum 30. Each cam follower mechanism 34 comprises a cam follower plate 38 having a perimeter, a first side 38' and a second side 38" opposed to the first side 38', and at least four cam followers 36 attached to each cam follower plate 38. At least two cam follower 36 are attached to the first side 38' of the cam follower plate 38 and at least two cam followers 36 are attached to the second side 38" of the cam follower plate 38. For every one cam follower 36 on one side (either first or second) of the cam follower plate 38 there is another cam follower 36 positioned on the opposite side (either first or second) of the cam follower plate 38 Each cam follower mechanism 34 is rotatable on one transfer shaft 35. The transfer drive mechanism 28 fits at least partially within the conjugate cam vehicle 20 whereby the cam followers 36 move about the irregularly shaped teeth 25 of the conjugate cam vehicle 20 as the transfer drive mechanism 28 is rotated by the main drive shaft 32 within the conjugate cam vehicle 20. In practice the first and second cams each comprise a minor cam diameter ranging from about 3.0 inches to about 200 inches. Preferably, the minor cam diameters range from about 22 inches to about 28 inches. Also, the first and second cams each comprise a major cam diameter ranging from about 4.0 inches to about 260.0 inches. Preferably, the major cam diameters of the first and second cams range from about 30 inches to about 34 inches. The minor cam diameter is that diameter measured from the inner perimeter of the conjugate cam (i.e., from the tips of the cam teeth) to the center of the conjugate cam vehicle 20. The major cam diameter is that diameter measured from the deepest points of the irregularly shaped teeth (i.e., the bottom of the teeth) to the center of the conjugate cam vehicle 20. Additionally, the conjugate cam comprises 20 an outer diameter ranging from about 4.5 inches to about 180 inches. Preferably, the outer diameters of the conjugate cam vehicle 20 range from about 35 inches to about 37 inches. The first and second cams each comprise a cam width ranging from about 0. 25 inches to about 8 inches. Preferably, the cam widths range from about 0.3125 inches to about 2.0 inches. The first cam 21 and second cam 22, and thus the conjugate cam vehicle 20, also each comprise a harmonic deviation ranging from about 0° to about 10,000°. As used herein, the term "harmonic deviation" refers to the maximum rotational deviation of the planet per rotatable drum 30 cycle, or 360° rotation, due to the harmonic change in position. The rotatable drum 30 of the transfer device 10 comprise a diameter ranging from about 2.5 inches to about 160 inches, preferably from about 15 inches to about 35 inches. The thickness of the rotatable drum 30 may range from about 0.25 inches to about 20 inches. Figure 1 provides a perspective view of the high-speed rotary transfer device or transfer device 10 taken at an angle behind the conjugate cam vehicle 20, the cam followers 36, the cam follower plates 38 and the rotatable drum 30. Also shown is the main drive shaft 32 extending through the transfer device 10 and the conjugate cam vehicle 20. Recall that the conjugate cam vehicle 20 is comprised of a first cam 21 and a second cam 22. Also shown are the transfer shafts 35 attached to the cam follower plates 38 at one end and attached to the transfer heads 40 at the other end. Fig. 1 shows a preferred embodiment wherein the transfer shafts 35 are attached to a rotatable guide plate 42 such that the transfer shafts 35 are stabilized at each of their respective ends. The preferred motion of the transfer shafts 35 is that first, they rotate about the main drive shaft 32 as the cam followers 36 move along the conjugate cam's irregularly shaped teeth 25 of the first and second cams within and without of the conjugate cam vehicle 20 and second, the transfer shafts 35 themselves rotate such that the transfer heads 40 rotate about the transfer shafts 35. Figure 2 provides a side view of the transfer device 10. In an alternative embodiment, holding plates 15 (not shown) may secure the device 10 to the ground or to some other structure while the transfer device 10 is in operation. As is shown in Fig. 1, the main drive shaft 32 is shown herein extending through the device 10 and being connected to the rotatable drum 30 and the rotatable guide plate 42. Transfer shafts 35 are shown in spaced relationship to the main drive shaft 32. Figures 3-5 provide top plan views of the conjugate cam vehicle 20, the rotatable drum 30, one end of the main drive shaft 32 the cam follower plates 38 and the cam followers 36 attached thereto and moving about the irregularly-shaped teeth 25 of the conjugate cam vehicle 20. In these views, the front most cam is the second cam 22 and the first cam 21, although not shown here, would be positioned behind the second cam 22. Fig. 3 provides an embodiment wherein three cam followers 36 are positioned on either side of the cam follower plate 38 giving a total of six cam followers 36 positioned onto each cam follower plate, three of which are not seen in this view. The shape and form of the cam teeth 25 in Fig. 3 provide a suitable cam profile through which the followers may travel (by rotation) throughout the conjugate cams to meet the designed transfer speed and pick-up speed requirements. It is noted herein that the cam followers 36 freely rotate about either a rotatable or stationary shaft 52 (not shown) connecting each cam follower to its resident cam follower plate. By the term "cam profile" it is meant herein the structure and shape of the cam teeth 25 of each cam in the conjugate cam vehicle 20. In another embodiment herein, Fig. 4 shows four cam followers 36 on the second side 38" of the cam follower plate 38. Therefore, four other cam followers 36 (not shown herein) are also attached to the first side 38' (not shown) of the cam follower plate 38 making a total of eight cam followers positioned onto each cam follower plate. As in the embodiment for Fig. 3, the cam profile shown in Fig. 4 was constructed to meet the design criteria (e.g., speed) of the transfer device 10 operating within the conjugate cam vehicle 20. Figure 5 provides an additional component to that of Figure 4, the transfer head 40. The transfer heads 40 herein are used to transfer a material from one source to another. For example, in Fig. 5 the transfer head 40 is shown to be contacting a source A, conceivably for either transfer or pick-up of a material. In practice, the transfer heads 40 will always be aligned with the source A as they are rotated about transfer shafts 35 which in turn rotate about the main drive shaft 32. Preferably, each transfer head 40 is independently rotatable about its transfer shaft 35. Figure 6 provides a plan view of the conjugate cam which shows the first cam 21 and the second cam 22. Also, four cam follower plates 38 with the cam followers 36 thereon are shown. The shaded cam followers 36 represent those cam followers which are positioned on the second side 38" of the cam follower plate 38. The unshaded cam followers 36 are positioned on the first side 38' of the cam follower plate 38. Eight cam followers 36 for each cam follower plate 38 are shown. Additionally, each cam follower plate 38 has a rotatable transfer head 40 positioned thereon. As shown, each transfer head 40 will follow the path of rotation 50 shown by the heads 40 located on each transfer shaft 35. As is also shown, the path 50 for the transfer heads 40 develops from the design of the conjugate cam vehicle 20 and the speed requirements for the pick-up and transfer of a material about the conjugate cam vehicle 20 from one point about the vehicle 20 to another point about the vehicle 20. At the flattened out or bulbous portion of the "teardrop" path formed, the transfer heads 40 are moving at their slowest rotation about the conjugate cam vehicle 20. As the transfer heads 40 make their way back up to transfer/pick-up area A, they are beginning to travel with greater rotational speed until they reach transfer/pick-up area A, the point or area of their greatest speed. Note, all of these speeds will correspond to the speeds of material to be picked up and transferred; i.e., when the transfer heads 40 pick-up and deliver materials, the heads surface will be moving at substantially the same speed as the pick-up and transfer sources. Also note that the closer that the irregularly-shaped teeth 25 are, the faster the transfer heads 40 will travel. Correspondingly, the more spread-out the teeth 25 are, the slower the heads will travel. Generally, the speed of the main drive shaft 32 remains constant. Fig. 7 shows a plan view of a "cloverleaf configuration; i.e., the path of the transfer heads 40 about the conjugate cam and at a look at the conjugate cam vehicle 20 from behind the second cam 22. Where the teeth of the conjugate cam 25 are smallest and closest together, the transfer heads 40 are moving at their fastest. Correspondingly, where the teeth of the conjugate cam vehicle 20 are at its widest and most spaced apart, the transfer heads 40 are moving at their slowest. The "cloverleaf path of the transfer heads 40, as in the "teardrop" path configuration, results from calculations determining the number of transfer head revolutions per drum revolutions. The "cloverleaf path relates to the speed, and the orientation of the pick-up and transfer of materials from one point to another point. It is noted herein that one skilled in the art can construct various types of transfer head paths 50 to suit her design criteria. Any such path design therefore falls within the scope of the invention herein. The transfer device may achieve times of transfer ranging from less than one millisecond to about 10 seconds between a point or points of pick-up. In one embodiment herein, one pair of cam followers are attached to the first side of the cam follower plate and another pair of cam followers is attached to the second side of the cam follower plate. Preferably, each cam follower is positioned equidistant or proportionately from the other cam followers on the cam follower plate. In another embodiment herein, each cam follower mechanism comprises at least three cam followers placed equidistant apart about the cam follower plate perimeter on the first side of the cam follower plate and also at least three cam followers placed equidistant on the second side of the cam follower plate. The rotatable drum may take-on any number of shapes per the designer's preferences and needs. For example, the rotatable drum may be in the shape of a circle, cross, star, bar, triangle or whatever shape might be useful for the operation of the device described herein. Rotational Displacement & Harmonic Deviation Rotational displacement is the amount of rotation of the top dead center (t.d.c.) point on the transfer head relative to the radius of the drum which passes through the center of the head (Fig. 6). By top dead center point it is meant herein that point (or area) on a transfer head that contacts material along or adjacent to the transfer or pick-up points adjacent to the conjugate cam. Rotational displacement is measured by the angular rotation of the top dead center point from the radius of the drum passing through the center of the transfer head 40. The cam profile is driven by the harmonic deviation required. The higher the harmonic deviation, the greater the speeds will be at various points about the conjugate cam vehicle 20, and specifically at the pick-up and/or transfer points about the conjugate cam vehicle 20. Harmonic deviation is the amount of rotational displacement of top dead center point over one-half revolution about the conjugate cam, i.e., 180° from a point midway between the transfer and pick-up points to a point 180° from that point 90° to 270° on the cam. Furthermore, harmonic deviation dictates how slowly or quickly the transfer head will spin about the transfer shafts 35 at the pick-up and transfer points about the conjugate cam vehicle 20. In this way harmonic deviation is said to drive the cam profile or determine the shape, height and contour of the teeth 25 of the conjugate cam vehicle 20. As is shown in Fig. 6, the 180° revolution about the conjugate cam begins from 0° (a point of pick-up or transfer) and goes to 180° ( another point of transfer or pick-up). Obviously if the pick-up point is set at 180°, then the transfer point for the particular profile shown in Fig. 6 will be located at the 180° point. It is noted herein that the points of pick-up and transfer do not have to be 180° apart. More specifically, depending upon the size of a material to be picked-up, the transfer point may be less than or greater than 180°. For example, a discrete component pitch length and an interconnected article pitch length at about 20 inches at about 1 inch, respectively, will, in one embodiment herein, have a range between transfer points at about 166° ± 5°. In one alternative embodiment herein, a material having a length at about 1 inch which is transferred to a product having a length at about 15 inches will have transfer points about the conjugate cam vehicle ranging from about 131° ± 5°. Likewise, a material having a length at about 3 inches which is transferred to a product having a length at about 15 inches will have range between transfer points of about 130° ± 5. In practice, the cam followers will move about the conjugate cams in certain prescribed configurations. Each of these configurations is created based upon various criteria specific to each transfer device design. For example, Fig. 6 shows a conjugate cam vehicle 20 and cam followers 36 moving about the conjugate cam in a "teardrop" configuration. This prescribed configuration is determined by various factors which include the speed of the transfer device moving within the cam, the number of cam followers used, and the teeth profile of the conjugate cam vehicle 20. In designing the transfer device, all of these factors combine to produce the "teardrop" configuration or path of travel of the transfer heads 40. Fig. 7 shows another configuration called the "cloverleaf. Like the "teardrop", the "cloverleaf is determined by the speed of the transfer device moving within the cam, the number of cam followers used, and the teeth profile of conjugate cam. In one example, the fewer the number of head revolutions per 360° revolutions of the drum produces less motion of the cam followers about the conjugate cam. In the "teardrop" configuration, the transfer head rotates fewer times within one 360° revolution of the rotatable drum. Generally, fewer transfer head revolutions within one 360° drum revolution results in fewer teeth being built, machined or carved into the conjugate cam. Such a design would generally result in less contact stress being applied to the conjugate cam as a whole and on the teeth specifically. Also, less forces would be placed on the cam followers. This can result in greater product reliability in pick-up and transfer of materials about the conjugate cam. Figures 8, 9, and 10 provide illustrations regarding use of the invention for a range of sizes of interconnected articles 202, 206 and a range of sizes of discrete components 201, 205. Interconnected articles 202, 206 may be, for example, uncut or unreleased articles within a web. In one example, this web could be a diaper web or that of any of the known absorbent articles. The discrete components 201, 205 may be component parts like tape tabs, waist features and other types of known elements commonly applied to sanitary napkins. The range of pitch lengths of discrete components 201, 205 which the transfer device 10 is capable of applying and the range of pitch lengths of interconnected articles 202, 206 on which the discrete components will be applied is determined by the conjugate cam vehicle 200. The maximum discrete component pitch length and maximum interconnected article pitch length have been set forth prior to the design of the conjugate cam vehicle 200. The transfer device 10 is able to apply discrete components having a pitch length equal to or less than the maximum discrete component pitch length and is able to apply the discrete components onto interconnected articles having a pitch length equal to or less than the maximum interconnected article pitch length. Referring now to Figures 8, 9, and 10, in practice, when it becomes necessary either to apply a discrete component of which its size is not equal to the maximum discrete component pitch length or to apply a discrete component to an interconnected article of which its size is not equal to the maximum interconnected article pitch length, or the distance between similar points of adjacent product parts, adjustments should be made to the transfer device 10. Specifically, cam shift, the fixed rotational position of the conjugate cam vehicle 200 must be adjusted. The pick up heads 208 (Fig. 8) must be replaced with new pick up heads 210 matching the shape of the new discrete components 205 and having a new top dead center head radius. By the term "top dead center head radius" it is meant herein the distance between the top dead center of the pick-up head surface and the center of the pick-up head shaft. The new pick-up heads must be phase rotationally aligned to match their placement with the interconnected articles 202, 206. Anvil roll 203 must be adjusted in position and rotational phase to align with the pick-up heads 208. The vertical position and machine direction phasing of the interconnected articles 202, 206 must be adjusted to be aligned with the pick-up heads 208. It is usually desirable that the supply rate of interconnected articles is equal to the number of heads on the drum 209 per every one revolution of said drum. By the term "supply rate" it is meant herein the rate at which one interconnected article 202, 206 is delivered to the point of transfer, i.e., pick-up head 208. It is also usually desirable that the rotational speed of the anvil roll is such that the discrete components 205 are supplied at a rate of one discrete component per one interconnected article. To create a cam which produces rotary motion of a planet that is attached to a drum rotating at a fixed speed, it is necessary only to describe the paths of the centers of the cam followers that ride along the cam. Each cam follower of the planet will have its own unique path that it will travel through once for every revolution of the drum. By using a cutting device with the same diameter as the cam followers, these same paths can be used to fabricate the cam. Therefore, the task of defining the cam profile becomes a matter of mathematically describing the paths of the followers and hence the cam cutters that will create the profile. A pair of equations for each follower path should be found and a list of coordinates for each path should be created, these being the outputs of said equations given some incremental step of drum rotation. To aid in describing the mathematics involved with the invention, the description can be broken down into several concepts that can be understood individually more easily. The invention can be thought of as two wheels in space that spin in opposite directions. One is the main drum. The other is one of the planets. The total number of planets is not of concern here because if one planet can be modeled correctly then modeling the others is simply a matter of copying the first. The following three examples explain the two essential concepts to the design of the cam, Planet Speed Factor and Harmonic Deviation. EXAMPLES Example One: The drum spins at constant velocity. The planet spins at constant velocity and at twice the rotational velocity of the drum in the opposite direction. In this example, Planet Speed Factor is 2. Harmonic Deviation is 0 because there is no change in planet velocity. Example Two: Again the drum spins at constant velocity. The planet has no initial rotational velocity, but begins accelerating up to some rotational speed, slows back to zero velocity, accelerates in the opposite direction up to the same rotational speed in the opposite direction, and then slows back to zero velocity. This cycle repeats for every revolution of the drum. In this example, the Planet Speed Factor is 0 because the planet makes no cumulative revolutions. The Harmonic Deviation is at some value, not zero. This example illustrates that Harmonic Deviation is the amount of rotation the planet experiences from rotational stopping point to rotational stopping point. Example Three: Combine Example One and Example Two. The drum spins at constant velocity. The planet begins at twice the rotational velocity of the drum in the opposite direction. It accelerates to some speed and then returns to the two times speed, then decelerates to some slower speed (without reversing), and returns to the two times speed. Speed Factor is 2 and Harmonic Deviation is some value. Fig. 11 shows a graph of planet rotational displacement, velocity, and acceleration. The planet is placed on the edge of and in the same plane as the drum. At this point in the discussion the drum and planet motion have been described. The next step is to track a point on the edge of the planet, representing the center of a cam follower. The total number of cam followers is not of concern here because if one follower can be modeled correctly then modeling the others is simply a matter of copying the first as with the planets. The path that this point will trace will be one of the cam follower paths. The pair of equations that gives the position of the cam follower, namely the angle and distance from the center of the drum, for any given Drum Angle is dependent on a set of five fixed variables. The names and definitions for these variables follows: Drum Radius - Distance from center of drum to center of planet. Planet Radius - Distance from center of planet to center of cam follower. Planet Speed Factor - Average rotational speed of planet divided by the speed of drum. Harmonic Deviation - Mathematically, the greatest amount of rotational displacement that planet will experience from constant rotation defined by the Planet Speed Factor. Qualitatively, the amount of change in rotational speed of planet as drum makes constant rotation. Follower Shift - Position of each follower on its planet. On a four follower planet configuration, follower shift equals 0° for follower one, 90° for follower two, 180° for follower three, and 270° for follower four. For the conjugate cam, follower shift equals 45° for follower one, 135° for follower two, 225° for follower three, and 315° for follower four. Fig. 12 shows the cam paths 55 (four) which can be used to fabricate the cam itself. Note that this is only one of two cams, a conjugate pair. In fact, second cam 22 is showing. The first cam 21 is created by shifting the four followers 36 by 45°, half the spacing of the followers 36 to create four new paths 55. For a four follower per cam design, adding 45° to each of the follower shift values 0°, 90°, 180°, & 270°, will give new values of 45°, 135°, 225°, & 315° which will yield four new pairs of equations. While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention.

Claims: What is claimed is: 1. A transfer device for transferring items, characterized in that: a conjugate cam vehicle for achieving a speed ratio ranging from about 1 : 1 to about L 1X10 10 about a pair of points spaced at least 45° apart on the conjugate cam vehicle, the conjugate cam vehicle comprising a first cam having a central point, an outer perimeter, an inner perimeter, and irregularly shaped teeth faced inwardly toward the central point, a second cam having a central point, an outer perimeter, an inner perimeter, and irregularly shaped teeth faced inwardly toward the central point, the first cam and the second cam being positioned adjacent to one-another to form a conjugate cam vehicle having a central point, an outer perimeter, an inner perimeter and irregularly shaped teeth faced inwardly toward the central point, the conjugate cam vehicle being configured to provide substantially discontinuous acceleration about the irregularly shaped teeth such that the conjugate cam vehicle is configured to provide an acceleration from between about 0° to about 180° of the outer perimeter and a deceleration from between about 180° to about 360° of the outer perimeter, a transfer drive mechanism providing multiple points of contact at the pick-up and transfer of material and operating with the conjugate cam vehicle comprises a main drive shaft for driving the transfer drive mechanism, a rotatable drum having a perimeter, a center, a first side, and a second side opposed to the first side, the rotatable drum being attached to the main drive shaft through the center and rotating thereabout, at least two transfer shafts being placed oppositely onto and through the rotatable drum adjacent to the drum perimeter, each the transfer shaft comprising a first end and a second end, the first end of each the transfer shaft being positioned above the first side of the rotatable drum and the second end of each the rotatable shaft being positioned below the second side of the rotatable drum, at least one transfer head being positioned about the first end of each the transfer shaft above the first side of the rotatable drum, each the transfer head being rotatable about each the transfer shaft, and a cam follower mechanism positioned about the second end of each the transfer shaft below the second side of the rotatable drum, each the cam follower mechanism comprising a cam follower plate having a perimeter, a first side and a second side opposed to the first side, at least two cam followers attached to each the cam follower plate, at least one the cam follower being attached to the first side of the cam follower plate and at least the other cam follower being attached to the second side of the cam follower plate, each the cam follower mechanism being rotatable about one the transfer shaft, the transfer drive mechanism fitting at least partially within the conjugate cam vehicle such that the cam followers fit within and move about the irregularly shaped teeth of the conjugate cam. 2. The transfer device of Claim 1 wherein the first cam and the second cam each comprise a minor cam diameter ranging from about 6.0 inches to about 50 inches and preferably from about 22 inches to about 28 inches. 3. The transfer device of Claim 1 wherein the first cam and the second cam each comprise a major cam diameter ranging from about 8.0 inches to about 64.0 inches and preferably from about 30 inches to about 34 inches. 4. The transfer device of Claim 1 wherein the first cam and the second cam each comprise an outer diameter ranging from about 9 inches to about 72 inches and preferably from about 35 inches to about 37 inches. 5. The transfer device of Claim 1 wherein the first cam and the second cam each comprise a cam width ranging from about 0.3125 inches to about 2.5 inches and preferably from about 0.25 inches to about 2.0 inches. 6. The transfer device of Claim 1 wherein the first cam and the second cam each comprise a harmonic deviation ranging from about 100° to about 230°. 7. The transfer device of claim 1 wherein the speed ratio ranges from about 1 : 1 to about 35:1. 8. The transfer device of Claim 1 wherein the rotatable drum comprises a diameter ranging from about 25 inches to about 28 inches. 9. The transfer device of Claim 1 wherein the rotatable drum comprises a thickness ranging from about 2 inches to about 5 inches. 10. The transfer device of Claim 1 wherein the transfer drive mechanism achieves a time of transfer ranging from about 0 milliseconds to about 10 seconds. 11. The transfer drive mechanism of Claim 1 wherein a pair of the cam followers are attached to the first side and side second side of the cam follower plate, each the cam follower of each the pair being positioned 180° from the other cam follower in the pair. 12. The transfer device of Claim 1 wherein each the cam follower mechanism comprises at least three cam followers placed equidistant apart about the cam follower plate perimeter on the first side of the cam follower plate and at least three cam followers placed equidistant about the cam follower plate perimeter on the second side of the cam follower plate. 13. The transfer device of Claim 1 wherein the rotatable drum comprises a circular shape, a cross shape, a star shape, or a bar shape.

Inventors: BRIDGES RUSSELL PEARCE, DROSTE JOHN FREDERICK, HAMILTON JAMES YU, HELTON RONALD HERBERT, IRAOLAGOITIA MAITE, BRIDGES, RUSSELL, PEARCE, DROSTE, JOHN, FREDERICK, HAMILTON, JAMES, YU, HELTON, RONALD, HERBERT, IRAOLAGOITIA, MAITE
Applicants: PROCTER & GAMBLE, THE PROCTER & GAMBLE COMPANY
Application year: 1999
Main classification: B65H5
IPC codes: B65H3, B65H5, B65H29