Abstract:
A packaging device includes a film fitting mechanism, a film shrinking mechanism and a controller. The film fitting mechanism fits a tubular heat shrinkage film over a film cylinder and moves the film a distance along the cylinder and cuts a length of the film off. The length of the film is then conveyed to the film shrinking mechanism. The film shrinking mechanism is arranged next to the film fitting mechanism and includes a base for supporting an article to be packed with the film that is cut by the film fitting mechanism and heating units for supplying high temperature air flows to the film thereby making the film shrink and tightly wrap over the article. The controller controls and coordinates the operations between the film fitting mechanism and the film shrinking mechanism.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to the field of heat-shrinking film packaging, and in particular to a device for both fitting a heat-shrinking film over an article to be packed and heating and shrinking the packaging film with a simplified structure. 
   2. The Related Art 
   Plastic packaging films have been widely used to wrap and pack consumer products, such as foods, books, video/audio compact disks for protecting the products from contamination and damage. The film is fit over an article to be packaged and then heated to shrink and thus tightly wrap over the article. 
   Conventionally, in a large-scale packaging system that employs heat-shrinking film to pack commercial or industrial products, two separate stations are arranged, respectively for fitting a length of a tubular packaging film over each of the products to be packed and for heating and thus shrinking the film tightly over the product. This is because the film fitting and film shrinking operations must be organized in accordance with the a number of parameters, such as the products to be packed, the quantity of the products to be packed in unit time of manufacturing and the manufacturing process of the products. Thus, integration of the fitting and shrinking operations in a single device is not available heretofore, especially for small businesses having limited work space and/or small quantity packaging operation. 
   Further, the conventional packaging system also suffers the complication of the parts and structure thereof. This makes it hard, and even impossible, to operate the system with a single operator. The packaging system is comprised of at least two stations, respectively for film fitting and film shrinking, requiring separate operators. This increases the overall costs of labor and time consumed in wrapping products. This is anther reason that the conventional packaging system does not fit the need of small-sized businesses and small-scale packaging. 
   Thus, the present invention is aimed to provide a unitary packaging device that overcomes the drawbacks of the conventional packaging systems. 
   SUMMARY OF THE INVENTION 
   A primary objective of the present invention is to provide a packaging device having a simplified structure in which both fitting and shrinking are combined as a unitary device whereby costs and the amount of space occupied by the device are reduced. 
   Another objective of the present invention is to provide a packaging device capable to perform both film fitting and film shrinking with a simplified structure whereby labor of operator for controlling a packaging process with the packaging device is substantially reduced. 
   A further objective of the present invention is to provide a packaging device in which film fitting mechanism and film shrinking mechanism are integrated as a unitary device whereby the whole device can be controlled by a single operator and is thus particularly fit for the needs of small business and small quantity packaging purposes. 
   To achieve the above objectives, in accordance with the present invention, there is provided a packaging device comprises a film fitting mechanism, a film shrinking mechanism and a controller. The film fitting mechanism fits a tubular heat shrinkage film over a film cylinder and moves the film a distance along the cylinder and cuts a length of the film off. The length of the film is then conveyed to the film shrinking mechanism. The film shrinking mechanism is arranged next to the film fitting mechanism and comprises a base for supporting an article to be packed with the film that is cut by the film fitting mechanism and heating units for supplying high temperature air flows to the film thereby making the film shrink and tightly wrap over the article. The controller controls and coordinates the operations between the film fitting mechanism and the film shrinking mechanism. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be apparent to those skilled in the art by reading the following description of preferred embodiments thereof, with reference to the attached drawings, in which: 
       FIG. 1  is a perspective view of a packaging device constructed in accordance with a first embodiment of the present invention; 
       FIG. 2  is a front view of the packaging device illustrated in  FIG. 1 ; 
       FIG. 3  is a perspective view of a film fitting mechanism of the packaging device, including a film cylinder, a film feeding device, and a film cutting device; 
       FIG. 4  is a perspective view similar to  FIG. 3 , with the film cylinder removed to show a film cutter of the film cutting device; 
       FIG. 5  is a top view of the filming fitting mechanism of the packaging device of the present invention; 
       FIG. 6  is a front view of a packaging device constructed in accordance with a second embodiment of the present invention; and 
       FIG. 7  is a front view of a packaging device constructed in accordance with a third embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to the drawings and in particular to  FIGS. 1 and 2 , a packaging device constructed in accordance with the present invention, generally designated with reference numeral  100 , comprises a film fitting mechanism  10 , a film shrinking mechanism  20 , and a controller  30 . The film fitting mechanism  10  includes a film cylinder  11 , a film feeding device  12 , and a film cutting device  13 , all arranged in a casing  15 , and a film discharge device  14  arranged below the casing  15 . 
   Also referring to  FIGS. 3–5 , the film cylinder  11  of the film fitting mechanism  10  is arranged on a center portion of a bottom  151  of the casing  15 . In operation, a length of tubular packaging film  300  is fit over the film cylinder  11 , either manually or by an automatic film supply device (not shown). 
   The film feeding device  12  comprises a motor  121 , a worm  122 , a clutch  123 , a pair of retention blocks  124 , a shaft  125 , a retention bar  126 , and roller axles  127 . The motor  121 , such as an electric motor, the worm  122 , and the clutch  123  constitute a power generation system, in which the worm  122  and the clutch  123  are driven by the motor  121  to separately supply mechanical power from the motor  121  to the moving parts of the packaging device  100 . The coupling between the motor  121  and the worm  122  and the clutch  123  can be of any known devices, such as a gear system and a belt based transmission system. 
   The retention blocks  124  are arranged on opposite sides of the bottom  151  of the casing  15 . The shaft  125  and the retention bar  126  extend, in parallel to each other, between the retention blocks  124  and rotatably supported thereby. The shaft  125  has an inner end, substantially located between the retention blocks  124 , to which two first bevel gears  125 C are mounted, and an outer end extending beyond one of the retention blocks  124  with a worm gear  125 A mounted thereon. The worm gear  125 A mates the worm  122  of the power generation system thereby allowing mechanical power to be transmitted from the motor  121  to the shaft  125 . The outer end of the shaft  125  is supported by a bearing  125 B fixed to the casing  15 . 
   Upper and lower pairs of lug  124 A are formed on each retention block  124  and spaced from each other in a vertical direction. Each lug pair comprises two lugs  124 A aligned in a front-rear direction to support a roller axle  127 . Each roller axle  127  has an outer end extending beyond the lug  124 A to support a roller  127 B that is engageable with the film cylinder  11 . The roller axle  127  associated with each lower pair of lugs  124 A has an inner end extending beyond another lug  124 A to support a second bevel gear  127 A that mates each first bevel gear  125 C thereby transmitting the mechanical power to the rollers  127 B. 
   With the tubular heat shrinking film  300  fit over the film cylinder  11  and the rollers  127  engaging the film cylinder  11  to tightly interpose the film  300  between the rollers  127  and the film cylinder  11 , the rotation of the lower rollers  127 B that is driven by the bevel gears  125 C,  127 A causes the film  300  to slide along the film cylinder  11  in a downward direction. The upper rollers  127  help guide the movement of the film  300  along the film cylinder  11 . 
   The film cutting device  13  is arranged in a front portion of the casing  15 , comprising a rotating disc  131  and a plurality of cutters  132 . The rotating disc  131  forms a central bore  131 A through which a lower section of the film cylinder  11  extends. A coupling portion  131 B is formed on an underside of the rotating disc  131  and is coupled to the clutch  123  by a belt  131 C whereby mechanical power is transmitted from the motor  121  to the rotating disc  131  and thus rotating the disc  131  about the film cylinder  11 . Idle rollers  131 A are provided on the casing  15  to engage the coupling portion  131 B and thus guide the rotation of the disc  131 . 
   Each cutter  132  is pivoted to the underside of the disc  131  whereby when the disc  131  rotates, the cutter  132  is forced toward the film  300  fit over the film cylinder  11  by the centrifugal force acting on the cutter  132  and thereby cutting through the film  300 . In practice, the cutting operation is performed only after the film  300  is driven downward a predetermined distance by the rollers  127  of the film feeding device  12  and thus the film  300  can be cut off at any desired length. 
   The film discharge device  14  includes a motor  141  and a roller  142 . The motor  141  is mounted to the casing  15  and comprises a spindle  141 A having an end located below the lower section of the film cylinder  11 . The roller  142  is mounted to the end of the spindle  141 A and physically engaging the film  300  fit over the film cylinder  11 . The roller  142  is driven by the spindle  141 A to move the predetermined length of the film  300  that is cut off by the cutters  132  in a downward direction toward a product to be packed. 
   Although the fitting mechanism  11  has been described with great detail, it is apparent to those having ordinary skills to replace one or more parts of the fitting mechanism  11  just described. Thus, the above described structure of the fitting mechanism  11  is only a preferred embodiment of the present invention and can be replaced by any equivalent mechanisms, within the scope of the present invention defined in the appended claims, that are capable to feed, cut and discharge a packaging film  300 . 
   The film shrinking mechanism  20  is arranged below the film fitting mechanism  11 , comprising a base  21  and at least one pair of hot air supply units  22 . The base  21  is located substantially below the film cylinder  11  of the film fitting mechanism  10  to support a product  200  to be packed thereon whereby the length of the film  300  cut off by the cutters  132  is supplied by the film discharge device  14  toward and fitting over the product  200 . The hot air supply units  22  can be of any known devices that heat and conduct air streams toward the product  200  and thus induce shrinkage of the film  300  around the product  200  due to the high temperature of the heated air streams. The heated air streams are started and guided toward the product  200  only after the cut film  300  is fit over the product  200  in order to ensure packaging quality. 
   The controller  30  is provided to control the operation of the packaging device  100 , including film feeding, film cutting, discharge and fitting the film  300  over the product  200 , and heating and thus shrinking the film  300 . The controller  30  comprises a keypad  31  comprised of a number of operation keys, a control knob or pushbutton  32 , and indicators  33 , which allow for entry of instruction, starting/stopping the operation and display operation conditions to the operator. 
   Also referring to  FIG. 6 , a second embodiment of the packaging device in accordance with the present invention is shown, also designated with reference numeral  100  for simplicity. The packaging device  100  of the second embodiment comprises a sensor  40  arranged on the base  21  of the film shrinking mechanism  20  to detect if the product  200  to be packed is properly placed on the base  21 . The sensor  40  can be of any known type, such as photoelectrical sensor and micro-switch. Based on the detection, the sensor  40  issues a signal to the controller  30 , which in turn starts the operation of the film fitting mechanism  10  and the film shrinking mechanism  20  when the product  200  is properly placed on the base  21 . This ensures operation safety of the packaging device  100 . 
   Also referring to  FIG. 7 , a third embodiment of the packaging device in accordance with the present invention is shown, also designated with reference numeral  100  for simplicity. The packaging device  100  of the third embodiment comprises a front panel  23  mounted in the front side of the film shrinking mechanism  20 . An opening  231  is formed on the panel  23 , at a position corresponding to the base  21  and the product  200  placed on the base  21 , in order to provide easy visual inspection and access of the product  200  y the operator. The panel  23  helps concentrating the heated air around the product  200  to be packed and thus enhancing the operation efficiency of film shrinking. 
   Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.