Abstract:
The present invention provides a molding machine and a mold assembly having a quick change volume control insert. The volume control insert can be changed without disassembly of the mold or use of special tools. The molding machine includes a mold, a mold insert, a locking member, and a release member. The mold insert is received in one of the mold halves and further includes a mold detail defining a portion of the mold cavity, and a retention member. A locking member engages the retention member when the mold detail is received within the mold half. The release member, accessible from the exterior of the mold half, and is adapted to disengage the locking member from the retention member, allowing the mold detail to be removed.

Description:
BACKGROUND  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to molding machines. More specifically, the invention relates to quick change inserts provided in the cavity of a mold.  
         [0003]     2. Description of the Related Art  
         [0004]     The process of blow molding plastic containers is susceptible to many environmental and process variables, such as temperature, moisture, and pressure. These variables will affect the apparent volume of the container once filled with liquid. If the volume of the container is slightly larger than designed, the container may not appear full when the specified amount of liquid is dispensed into the container. For example, if the volume of a milk container is larger than one gallon, when the container is properly filled with one gallon of milk, the container will appear to be less than full, and a consumer might assume that the container has less than a full gallon of milk and not purchase that container. Therefore it is commercially undesirable for containers to appear less than full.  
         [0005]     One method developed to adjust the apparent volume of the container locates an insert in the mold to change the volume of the mold cavity. In the past, this was accomplished by bolting a simple mechanical insert into the cavity of the mold. This had the disadvantage that the bolt fastening the insert would often be accessible only from the back of the mold, requiring complete removal of the mold from the machine in order to change the mold insert.  
         [0006]     Another method that emerged for adjusting the volume of blow molded containers is to have the position of the insert adjusted by a pneumatic control. Using this method, pneumatic pressure is adjusted to extend or retract the insert relative to the surface of the mold cavity. The disadvantage of the pneumatic method is that the installation and removal of the insert requires a complex procedure and special tools, including a pneumatic pump. Additionally, there is a risk that the insert can fall out of the mold if the insert is not correctly installed or if the pneumatic system loses pressure, since a continuous vacuum draw is not provided.  
         [0007]     In view of the above, there exists in the industry a need for volume control inserts that are readily accessible, can be quickly changed and do not require specific tools for changing them.  
       SUMMARY  
       [0008]     In satisfying the above need, as well as overcoming the enumerated and other limitations of the prior art, the current invention provides a molding machine and a mold assembly having a quick change volume control insert. The volume control insert can be changed without disassembly of the mold or use of special tools.  
         [0009]     In an embodiment of the present invention, a molding machine for blow molding a plastic article is provided. The molding machine is adapted to quickly adjust the volume of the plastic article and includes a mold, a mold insert, a locking member, and a release member. Located in the molding machine, the mold has two mold halves which form a cavity in the shape of the plastic article. The mold insert is located in one of the mold halves and further includes a body and a retention member. The insert body includes one or more surfaces that define a portion of the mold cavity while the retention member is interiorly received in the same mold half. Also located in the mold half, the locking member engages the retention member when the mold insert is received within the mold half. The release member is accessible from the exterior of the mold half without removing the mold from the machine and is adapted to disengage the locking member from the retention member allowing the mold insert to be removed.  
         [0010]     In one embodiment, the release member is movable between a retracted position and an extended position. During the movement into the extended position the release member engages the retention member causing the locking member to disengage from the retention member. With the retention member disengaged, the mold insert is removable. To aid with removal, the insert may be biased away from the mold half when the locking member is disengaged from the retention member.  
         [0011]     Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims appended to and forming a part of this specification. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a diagrammatic top plan view of a molding machine embodying the principles of the present invention;  
         [0013]      FIG. 2  is cut away view illustrating a volume control insert fully seated and locked in place within a mold half;  
         [0014]      FIG. 3  is cut away view illustrating the volume control insert released from the mold half;  
         [0015]      FIG. 4  is a cut away view of a second embodiment with the volume control insert fully seated and locked in place; and  
         [0016]      FIG. 5  is a cut away view of the second embodiment illustrating the volume control insert released from the mold half. 
     
    
     DETAILED DESCRIPTION  
       [0017]     Referring now to the drawings, a molding machine  10  embodying the principles of the present invention is diagrammatically illustrated therein and designated at  10 . As its primary components, the molding machine  10  includes a controller  11 , a frame  12 , actuators  14 , platens  15  and a mold  16 .  
         [0018]     The actuators  14  are supported by the frame  12 . Upon receiving appropriate signals from the controller  11 , the actuators  14  cause the platens  15 , which carry the mold  16 , to move between open and closed positions during various stages of the molding process. The mold  16  itself is made up of two mold halves  18 , having surfaces  19  which cooperate to form a mold cavity  20 . Each mold half  18  is attached to a platen  15  coupled to an actuator  14  which closes the mold  16  during molding and separates the mold halves  18  to enable removal the molded container. The molding machine  10  is only diagrammatically shown in  FIG. 1  since one skilled in this field will readily understand that the machine may take many forms and have features that are not essential for an understanding of the present invention. As seen in  FIG. 1 a  volume control insert  22  is incorporated into one or both mold halves  18 .  
         [0019]     Referring now to  FIG. 2 , the volume control insert  22  includes a body or mold detail  24  with a surface  25  defining a portion of the cavity  20  and, therefore, the article to be molded. As further discussed below, the mold detail  24  can be exchanged with another mold detail  24  whose shape protrudes farther into the mold cavity  20  thereby changing the volume of the molded container. The mold detail  24  is received into an appropriately shaped recess  31  formed in the mold cavity surface  34 .  
         [0020]     A boss  35 , on the rear surface of the mold detail  24 , supports a retention member  26  that extends away from the mold detail  24 . Both the retention member  26  and the boss  35  are received in a stepped bore  36  formed in the recess  31  in the mold cavity surface  34 . The retention member  26  is engaged by a locking member  30  to retain the mold detail  24  within the mold half  18 .  
         [0021]     In  FIGS. 2-3 , the retention member  26  is illustrated as a shoulder bolt  26 . The shoulder bolt  26  has a threaded end  27 , a rounded end  29  opposite the threaded end  27 , and a circumferential groove  28  located generally adjacent to the distal end  29 . The threaded end  27  of the shoulder bolt  26  is received into a tapped bore in the boss  35  of the mold detail  24 .  
         [0022]     As seen in  FIGS. 2-3 , the locking member  30  is illustrated as a spring plunger  30  including a tip  38  on one end and a spring  40  on the other. The spring plunger  30  is received in a bore  37  in the mold  16  oriented transversely to and intersecting with the stepped mounting bore  36 . The spring plunger  30  is positioned such that the plunger tip  38  protrudes into the stepped mounting bore  36  at a location that aligns with the groove  28  on the shoulder bolt  26  when the mold detail  24  is fully inserted into the stepped mounting bore  36 . Being spring biased, when the rounded edge of the shoulder bolt  26  contacts the plunger tip  38 , the plunger tip  38  is pushed back compressing the spring  28 , as the shoulder bolt  26  is inserted into the mounting bore  36 . The spring  28 , being seated against the mold  16 , will force the plunger tip  38  into the groove  28 , locking the mold detail  24  into place, once the mold detail  24  is fully inserted and the groove  28  becomes properly aligned with the plunger tip  38 .  
         [0023]     After initial set up and running of the molding machine  10 , it may be necessary to adjust the volume of the containers being molded so that the apparent volume of the material or fluid therein will be perceived by an end consumer as being proper for the amount of material or fluid stated on the container. This is achieved by changing the mold detail  24  in favor of one protruding more or less into the mold cavity  20  as the situation dictates. With the present invention, this is easily done through incorporation of a release member  32 .  
         [0024]     As seen in  FIGS. 2-3 , the release member  32  is illustrated as a jackscrew  32 . The jackscrew  32 , is located within the mold  16  and oriented transversely to the stepped mounting bore  36  in a threaded bore the mold  16 . The location of the jackscrew  32  is aligned with the shoulder bolt  26  so that as the jackscrew  32  is turned, its chamfered tip  33  will be advanced into the stepped mounting bore  36  and engage the distal end  29  of the shoulder bolt  26 . Engagement with the shoulder bolt  26  forces the shoulder bolt  26  in a direction out of the mounting bore  36 . This movement of the shoulder bolt  26  forces back the plunger tip  38 , compressing the plunger spring  40 , moving the plunger tip  38  out of the groove  28 . As the shoulder bolt  26  is pushed further out of the mounting bore  36 , the tip  38  of the spring plunger  30  completely disengages the groove  28 .  
         [0025]     To cause advancement of the jackscrew  32 , drive head  39  of the jackscrew  32 , located opposite of the tip  33 , is accessible through an opening  41  in a side face  43  of the mold half  18 . The head  39  maybe provided with various shapes or means to enable it to be driven by an appropriate tool such as a screwdriver, hex driver, wrench or other tool.  
         [0026]     Alternately, the jackscrew  32  can be replaced with other constructions for the release member  32  not requiring threading in order to advance the release member. For example, the release member  32  may be manually slid forward to extend and engage the retention member  26  and normally biased into retracted position out of engagement. Similarly, the locking member and the retention member may take alternative forms. For example the retention member could be a pin or recess in the body of the volume control insert engaged by a movable hook or member located in the mold.  
         [0027]     Now referring to  FIGS. 4 and 5  another embodiment of the invention provides for volume control insert  22  including a mold detail  24  and a retention member  26 . In this embodiment the shoulder bolt  26  has a threaded end attached to the boss  35  of the mold detail  24 , a circumferential recess  28  and a distal end  54  adapted to seat against a compression spring  44 .  
         [0028]     The locking member  42  is illustrated in this embodiment as a plunger rod  42 . The plunger rod  42  includes a shaft with a shoulder  46  and a tip  50  on one end. A stepped bore  45 , is located in the mold  16  oriented transversely to and intersecting the mounting bore  36 . The plunger rod  42  is received by the stepped bore  45 , the tip  50  of the plunger rod  42  protrudes into the mounting bore  36 . A plunger spring  40 , located and compressed between the shoulder  46  of the plunger rod  42  and a surface  49  of the mold  16 , is provided such that the shaft of the plunger rod  42  extends through the plunger spring  40 . Being compressed between the shoulder  46  of the plunger rod  42  and the surface  49  of the mold  16 , the plunger spring  40  biases the plunger tip  50  into the mounting bore  36 . The plunger tip  50  is aligned with the shoulder bolt  26  such that the plunger tip  50  will engage with the groove  28  on the shoulder bolt  26  when the mold detail  24  is fully seated in the recess  31  of the mold surface  34 , locking the mold detail  24  into place.  
         [0029]     The release member  47  is illustrated in this embodiment as an extension of the plunger rod  42  providing a bore  51  in a side face  43  of the mold  16 . A ring  34  is attached to the end of the plunger rod  42 . The ring  34  maybe pulled with one hand, retracting the plunger tip  50  from the groove  28  in the shoulder bolt  26 , while the mold detail  24  is held with the other hand.  
         [0030]     To aid in removal of the mold detail  24 , a compression spring  44  is seated in the end of the mounting bore  36  against a surface  52  of the mold  16 . The compression spring  44  is aligned to interface with the distal end  54  of the shoulder bolt  26 . Biasing the volume control insert  26  away from the mold cavity surface  34 , the spring  44  is compressed when the shoulder bolt  26  is inserted into the mounting bore  36 . The volume control insert  26  is ejected from the mounting bore  36 , when the plunger tip  35  is disengaged from the groove  28  in the shoulder bolt  26 .  
         [0031]     As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles depicted in this invention. The description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from the spirit of this invention, as defined in the following claims.