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. Further, the invention allows for apparatus to match the velocity of both the first and second transfer points, even if these velocities are not the same. The device is of particular benefit where an article to be transferred is subject to internally biasing elastic forces.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention related to an 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.  
         [0002]     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.  
         [0003]     As discussed above, a typical article to be reoriented by the apparatus of this invention is an absorbent pad. Because absorbent pads are typically comprised of several webs, an absorbent core and several elastic members, there is a tendency of these assemblies to contract and become distorted during transfer operations.  
         [0004]     An example of a device developed for this purpose is described in U.S. Pat. No. 6,648,122. In this patent, an apparatus is described which receives inserts at an infeed point, stretched them in the cross-direction to what is a more normal length, and then places them onto a receiving web. However this apparatus has the limitation of receiving and placing the inserts at similar product pitches, or web velocities. Additionally, as stated above, this apparatus is only able to stretch the inserts in a cross-direction.  
         [0005]     It is desirable to have an apparatus which is capable of receiving items at one pitch, while placing them onto a receiving conveyor at a second pitch in order to provide more flexibility in the range of product configurations. It is also desirable to have an apparatus which is capable of stretching an item in both the cross direction and the machine direction.  
       SUMMARY OF THE INVENTION  
       [0006]     The apparatus of the presenting invention is provided with the capability of receiving inserts at one pitch, while placing them onto a receiving conveyor at a second pitch. This allows for the placement of very short inserts onto relatively wide products, or long inserts onto relatively narrow products. This flexibility provides the user with the option of designing a wide range of product configurations in response to market demands.  
         [0007]     The apparatus uses servo-motor electronic cam profiling to match web velocities at the pick-up and lay-down points. An additional benefit of this new design lies in the fact that you can manipulate the exact motion profiles to optimize transfers. This is a particularly useful tool in that inserts can be manipulates to stretch them nominally in both the cross and machine directions, thereby reducing the amount of wrinkling which might occur as the stretched elastic members are handed off from one device to the next. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a fragmentary side elevation view, shown in somewhat diagrammatic form, of a pad transferring assembly of this invention.  
         [0009]      FIG. 2  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.  
         [0010]      FIG. 3  is a bottom view of the apparatus of the invention.  
         [0011]      FIG. 4  is a side elevation view of the apparatus of the invention.  
         [0012]      FIG. 5  is a simplified cross sectional view of the apparatus of the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.  
         [0014]     Referring more particularly to the drawings, there is seen in  FIG. 1 a  transfer device  10  of the present invention. The transfer device  10  is adapted to receive a series of articles from a pad turning device  12  which includes a plurality of radially extending transfer heads  16 . The pad turning device  12  may be, for example, a rotary pad turner of the type more fully described in U.S. Pat. No. 5,025,910. The articles  14 , such as absorbent pads, may be any elongated articles which need to be rotated 90° during the course of a manufacturing operation. Such pad turning devices  12  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.  
         [0015]     Also seen in  FIG. 1 , articles  14  are successively and individually picked-up by the transfer heads  16  of the pad transfer device  12 . In the illustrated embodiment, the pads  14  are picked up from a vacuum drum  20  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 may be employed in the feeding of the web and do not form a part of this invention.  
         [0016]     After the articles  14  have been rotated 90 degrees, they are picked-up by the transfer device  10  of this invention. In this sense, a canted pitch changer  43  is provided which stretches the articles  14 , as will be described below, and deposits them in that condition onto another conveyor  28  as it travels around the outer surface of a drum  26 . A conveyor  28  transports the articles  14  for further processing or to a packaging device, as required by a particular application.  
         [0017]     Referring to  FIG. 2 , 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 various apparatus have been eliminated but are partially illustrated by means of phantom lines.  
         [0018]     The article transfer device  10 , and particularly the canted pitch changer  43  of this invention is more fully shown in  FIGS. 3-4 .  
         [0019]     As shown in  FIG. 3 , the transfer device  10 , and canted pitch changer  43  includes a central cylindrical section  30  and a pair of canted outboard sections  32 ,  34 . The center cylindrical section  30  is adapted to hold and transfer the center of the article  14 . The canted outboard sections  32 ,  34  are in the form of truncated cones which have their central rotational axis at an oblique angle relative to the central cylindrical section  30 . Due to this oblique angle the surfaces of the outboard sections  32 ,  34  slope toward the center cylindrical section  30  at the pad acquisition point. However, the surfaces of the outboard sections  32 ,  34  and the central section  30  come into approximate alignment with each other at the opposite side of the device, i.e. the pad drop off point. This configuration causes the pads  14  to be stretched in a lengthwise direction as the pad  14  is rotated from the pad acquisition point to the pad drop off point.  
         [0020]     Further, as is best shown in  FIG. 5 , each of the center section  30  and the outboard sections  32 ,  34  is comprised of two separately driven segments. The separately driven segments have two advantages. First, a velocity differential between the center section  30  and outboard sections  32 ,  34  can be utilized to stretch the pads  14  in the cross-machine direction. Second, each segment of each section can be driven at a different velocity, such that the transfer device can be placing a first pad  14  at a first velocity at the same time a second pad  14  is being acquired at a second velocity.  
         [0021]     In use, the transfer apparatus  10  rotates from the position adjacent the transfer heads  16  wherein the surfaces of the outboard sections  32 ,  34  and the center section  30  are in their most concave position, to their linear orientation at the drop-off point, the pads  14  which are being transported are each successively stretched and pulled to their maximum length. If the outboard sections  32 ,  34  are driven at a different velocity than the center section  30 , the pads  14  will also be stretched in the cross-machine direction.  
         [0022]     As is well known in the art, each of the segments is connected internally to a source of vacuum. A pattern of holes is provided on the surface of each segment through which the internal vacuum acts to draw the pads  14  towards the surface. The center section  30  may be provided with a surface having a greater coefficient of friction than the surfaces of the outboard sections  32 ,  34 . Therefore, the ends of the articles  14  are able to slip across the faces of the outboard sections  32 ,  34  when the pad-extending tensile forces exceed the force required to overcome the effects of friction. The higher coefficient of friction of the center section  30  prevents the transferred article  14  from being pulled off the centerline of the device  10 . For example, the surface of the center section  30  may be formed of a low durometer silicone rubber while the surface of the outboard sections  32 ,  34  may be formed of stainless steel.  
         [0023]     Referring again to  FIG. 5 , the left outboard  32  section is comprised of an inner segment  42  and an outer segment  44 . The right outboard section  34  is also comprised of an inner segment  46  and an outer segment  48 . Each segment is separately movable and driven by a servo motor. Referring first to the left outboard section  32 , the outer segment  44  is driven by a first servo motor  54  which is connected directly to the outer segment  44  by a first drive shaft  66 . The inner segment  42  is connected to a second servo motor  56  by a first set of sprockets  86  and a first belt  78 . Likewise, referring to the right outboard section  34 , the outer segment  48  is driven by a third servo motor  58  which is directly connected to the outer segment  48  by a third drive shaft  70 , while the inner segment  46  is connected to its fourth servo motor  60  by a second set of sprockets  88  and a second belt  80 .  
         [0024]     The center section  30  is comprised of a first center segment  50  and a second center segment  52 . Each segment  50 ,  52  is separately movable and driven by a servo motor  62 ,  64  which is connected to the segment  50 ,  52  by a belt and a set of sprockets  90 ,  92 . The first center segment  50  is driven by a fifth servo motor  62  via a third set of sprockets  88  and a third belt  82 . The second center segment  52  is driven by a sixth servo motor  64  via a fourth set of sprockets  92  and a fourth belt  84 .  
         [0025]     The two segments which makes up each section could be driven by a single servo motor, but preferably, each of the segments is be separately driven so that one can be picking up articles at one velocity, while the other is depositing the articles at a different velocity. Having each outboard section  32 ,  34  and the center section  30  being separately driven allows the outboard sections  32 ,  34  and the center section  30  to be driven at different velocities. This velocity differential will allow for stretching the article  14  in the cross-machine direction. This is significant in that stretching the product reduces the amount of wrinkling which may occur as the stretched member are handed off from one device to the next.  
         [0026]     Likewise, each segment could be driven by a mechanical drive means capable of producing the velocity changes. Eccentric or other non-circular gears could produce such a velocity changing source of power. However, servo motors are the preferred means, as they provide programmability, flexibility, and isolation of torque disturbances. A preferred embodiment of this invention uses separate drives for each of the six segments. Additional embodiments might use more than three sections, or any reasonable number of segments.  
         [0027]     It is clear that this technology can be applied to the transfer and placement of many different types of articles in the disposable goods industry and other industries as well.  
         [0028]     The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.