Abstract:
An apparatus for transferring articles such as absorbent cores or disposable diaper chassis components from a rotary mechanism, such as a pad turner, to a linear mechanism, such as a conveyor for further processing. The invention provides a device for picking an article from the outside of a toroidal surface, thence extending transversely under tension the article to be transferred so that at the point of deposition the article is held flat and at full length. The device is of particular benefit where an article to be transferred is subject to internally biasing elastic forces.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to apparatus for transferring articles such as absorbent pads in the manufacture of disposable absorbent articles such as diapers, incontinence control garments or female sanitary pads as they advance along a production line. 
     In the production and manufacture of disposable products such as sanitary napkins or pants-type diapers, it frequently becomes necessary to manufacture a component of the product in one orientation, and then to rotate that component part 90° so that it is suitably oriented for use in another step in the production process. Various devices have been developed for this purpose and are known to those experienced in the industry. Examples of such apparatus are those described in U.S. Pat. Nos. 4,726,876, 4,880,102 and 5,025,910. 
     One common method for reorienting such product parts, such as absorbent pads, is to transfer them to a large rotating device, where each part is retained by vacuum on an individual head. The heads each successively pick up one of the parts, are caused to rotate 90° by means of cams or gears, and then caused to deposit the part, after 90° reorientation, onto the next downstream conveyor. 
     In most applications of this type, the amount of convexity of the vacuum head (i.e., the arc segment angle) is kept to a minimum so as to create the least amount of chord height. This becomes less practical as product length increases, as the required diameter of the turning drum becomes unreasonably large. As the chord height becomes larger, the machine designer must find a compromise between the need for maintaining control of the ends of the product and the need for achieving a firm placement of the product&#39;s center section. 
     Additionally, the product being transferred may possess certain contractile forces which tend to cause unwanted retraction of the ends of the pads during the transfer process. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to solve the aforementioned problems typically associated with transfer devices. In accord with an important aspect of the invention, the product is picked up from a toroidal or convex surface and placed on a flat surface while being, in the process, stretched to a fully extended condition. Additionally, it is an object of this invention to provide these capabilities with apparatus requiring a minimum of moving parts. The apparatus of this invention is of particular benefit where an article to be transferred is subject to internally biasing elastic forces, for example, various types of disposable diapers and, especially, absorbent pads used in the manufacture of such diapers, which pads may contain elastic materials. 
     The invention includes a coordinated set of three aligned vacuum wheels, which pick the products up from the surface of an upstream product turner or conveyor and place the product onto a destination conveyor later in their rotation. The two outermost wheels (outboard wheels) are truncated cones, with their inboard diameters smaller than their outboard diameters. The center, or inboard wheel is cylindrical in shape. In a preferred embodiment, each wheel is provided with a vacuum pattern arranged to positively attract and hold the individual products. 
     The outboard wheels are canted with respect to the central wheel so that their faces are approximately parallel to the product surfaces at the point of acquisition or picking up of the product. This angle of cant also places the faces of the outboard wheels, when viewed at the deposition point, in a aligned straight line, parallel to and generally in the same tangental plane as the center wheel. At this point, approximately 180° from the acquisition point, the product is deposited onto a traveling destination conveyor where it may be secured by mechanical means, vacuum or adhesive. 
     As the outboard canted wheels or drums rotate, their vacuum faces move away from the product centerline. This effect serves to stretch the product and pull it to its fully extended length. Inasmuch as the amount of extension of the wheels may exceed the actual maximum length of the product, the intention is that the ends of the product are able to slip across the face of the canted wheels in the event that the extension tensile force exceeds the force required to overcome the effects of friction. As a means of preventing the body of the transferred product from being pulled off of the centerline, the surface materials selected for the center wheel or drum preferably have a higher coefficient of friction with the product than do the surfaces of the canted outboard drums. Alternatively, a higher vacuum level or a more advantageous pattern of vacuum holes may serve to hold the product more securely to the center wheel. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary side elevational view, shown in somewhat diagrammatic form, of a pad transferring assembly of this invention; 
     FIG. 2 is a top plan view of the apparatus shown in FIG. 1; 
     FIG. 3 is a perspective fragmentary, diagrammatic view, showing the related apparatus by means of phantom lines and illustrating the path of movement of pads moving in accordance with the invention; 
     FIG. 4 is a bottom view showing a commercial embodiment of the invention with the pad transfer wheels in the canted position at which pads are picked-up; 
     FIG. 5 is a side elevational view of the apparatus of FIG. 4 viewed from an upstream position; 
     FIG. 6 is an end view of the apparatus of FIG. 4; 
     FIG. 7 is a perspective view of the turning drum assembly in accordance with a somewhat modified embodiment of the invention; 
     FIG. 8 is a perspective view of the turning drum assembly shown in FIG. 7 with parts removed to reveal the drive system of the assembly and, 
     FIG. 9 is a perspective view of another modified embodiment of the apparatus of this invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring more particularly to the drawings, there is seen in FIG. 1 a transfer device  10  of this invention. Transfer device  10  is adapted to receive a series of articles  14  from a pad turning device  12 , which includes a plurality of radially extending transfer heads  16 . Device  12 , for example, may be a rotary pad turner of the type more fully described in U.S. Pat. No. 5,025,910. Articles  14 , such as absorbent pads, may be any elongated articles which need to be rotated 90 degrees during the course of a manufacturing operation. Such pad turning devices are especially needed and are suited for use in connection with the manufacture and packaging of sanitary napkins as well as absorbent pads which are used in the assembly of disposable garments such as adult incontinence garments or children&#39;s′ training pants. 
     Also, as seen in FIG. 1, pads  14  are successively and individually picked-up by the transfer heads  16  of pad transfer device  12 . In the illustrated embodiment, the pads are picked up from a vacuum drum  20  of which is provided for use, in the nature of an anvil, for cutting a web  22  of absorbent material into individual pads  14  utilizing a rotary cutting device  24  of a type well known in the art. Various conventional conveying and direction changing devices such as rollers  23  may be employed in the feeding of web  22  and do not form a part of this invention. 
     After the pads  14  have been rotated 90 degrees, they are picked-up by the transfer device  10  of this invention which stretches the articles  14  to their maximum length and deposits them in that condition onto another conveyor  30  as it travels around the outer surface of a drum  29 . Conveyor  30  transports the pads for further processing or to a packaging device, as required by a particular application. 
     Referring to FIG. 3, there is seen a diagrammatic depiction of the travel path of the web  22  and the resultant pads  14  which are formed therefrom. In this depiction the apparatus has been eliminated but is partially illustrated by means of phantom lines. 
     The pad transfer device  10  of this invention is more fully shown in FIGS. 4-8. In FIG. 4 the transfer device  10  is shown, from beneath, in the orientation at which it receives a pad  14  from pad transfer head  16 , the pad pickup position also being depicted in FIGS. 2,  7  and  9 . Pad transfer device  10  includes a central vacuum drum section  39  which is rotatable about a central axis. A drive shaft  52  rotated by any available power supply system is provided for operation of the apparatus. As illustrated, the central drum section  39  is in the form of a partial segment  40  of a full cylinder wherein those portions of the full cylindrical drum surface which are not necessary for the pad transfer function are omitted. 
     Also best seen in FIG. 4, are a pair of canted outboard vacuum drum sections  41  and  43 . The sections  41  and  43  are in the form of truncated cones, which have their central rotational axis disposed at an oblique angle relative to the central drum section  39 . Due to this oblique angle, the faces  42  and  44 , of the outboard drum sections  41  and  43 , respectively, slope toward the central drum section  39 , at the pad acquisition point. Each of the drum section faces  40 ,  42 , and  44  are connected, internally, to a source of vacuum and are provided on their surfaces with openings  46  which, due to the internal vacuum utilized, tend to draw pads  14  toward the partial cylindrical surfaces  40 ,  42  and  44 . 
     As also seen in FIG.  4  and FIG. 2, the peripheral surfaces  40 ,  42 , and  44  of the drum sections  39 ,  41  and  43  come into approximate linear alignment with each other at the opposite side of the device, ie., the pad-drop off position, as illustrated. Thus, it will be appreciated that as the transfer device  10  rotates from the position adjacent the transfer heads  16 , wherein the drum sections  42 ,  40 , and  44 , are in their most concave configuration, to their linear orientation at the drop-off point, the pads  14  which are being transported are, successively, pulled to their maximum linear length. 
     As also already indicated, the central drum section  40  is provided with a surface having a greater co-efficient friction relative to the pads  14  than the surfaces  42  and  44  of the outer sections. Thus the ends of the products  14  are able to slip across the faces  42  and  44  of the canted wheels when the pad-extending tensile forces exceed the force required to overcome the effects of friction. Thus, as a means of preventing the body of the transferred product  14  from being pulled off of the centerline of the device  10 , the surface materials selected for the center wheel or drum preferably have a higher coefficient of friction relative to the product than that of the surfaces of the canted outboard drums. In an exemplary embodiment, the surface of the center section  40  may be formed of a low durometer silicone rubber, while the end sections  42  and  44  may be formed of stainless steel. 
     In the modified embodiment of FIGS. 7 and 8 curved plates  62  are attached to the drum surface  42   a  in an axially extending direction. Similar plates  64  are attached to the outer surface of section  40   a  and plates  66  are secured to the outer surface of section  44   a . Parts which are similar to those of the earlier described embodiment are given the same identifying numerals and are not referred to in detail again in connection with the modified embodiments. 
     The addition of these axially extending thickened plates  62 ,  64  and  66  assists in preventing the slippage of transferred articles around the circumference of the drum sections  44   a ,  42   a , and  44   a  when the sections are rotated. The addition of such thickened sections which preferably have angular corners is of particular assistance if the articles are of a fleecy or low density nature. In the illustrated embodiment these thickened sections are mechanically secured to the drum surfaces, however it will be appreciated that the drum surfaces can be manufactured with the thickened sections,  62 ,  64  and  66  formed integrally with the drum sections. 
     Vacuum can be maintained within the interior of the drum sections by means of vacuum drawn through conduits  54  and plenum chamber  55  which is connected via conduit  57  to an available source of vacuum. As seen in FIG. 6, a sheet metal end cover  60  is provided for safety purposes. 
     Also more fully depicted in FIGS. 7 and 8 are the drive systems for rotation of the drum sections. Section  41 ,  42   a  is removed in FIG. 8 to more fully show the drive system. As seen, a rotatable shaft  52  would be driven so as to rotate with the product-making process. A pulley  70  on shaft  52  is used to drive a pulley  72  connected to drum section  41  by means of a conventional drive belt  73 . Similarly the middle drum section  39 ,  40   a  is driven by the rotatable shaft  52  which is provided with a pulley  74  used to drive pulley  76  by means of drive belt  75 . Also in similar fashion, the drum section  43 ,  44 a is driven by a belt  81  which is journaled on pulley  80  and drives a driven pulley (not visible) connected to the drum section  43 . The movement of various components of the device described herein are driven in coordination with the related assembly line components depicted in FIGS. 1 and 2, as will be understood by those skilled in the art. In the modified embodiment depicted in FIG. 9, slippage of the articles in an axial direction is minimized by means of a modified array of vacuum openings  46   b . As shown, the central drum section  40   b  and its associated plates  64   b  are provided with a significantly greater density of openings  46   b  than are the end sections  42   b  and  44   b  and their associated plates  62   b  and  66   b , respecively. In this fashion the force of vacuum applied to the central portion of the assembly  10   b  is greater than that applied to each end. Hence any tendency of the articles  14  to slip endwise during transfer is minimized. 
     Although the forgoing illustrative embodiments have been described in detail, the description is intended to be illustrative rather than limiting. Thus the invention may be variously embodied and is to be limited only by the interpretation of the following claims.