Abstract:
A mold for a tire includes a device for easily releasing a pocket plate from a recess in a side wall ring. The device includes a rod movably disposed in a hole in the mold part that extends from an outer surface to adjacent the recess. The distal end of the rod includes a cam surface wherein movement of the rod causes the cam to press on the pocket plate to urge it from the recess.

Description:
BACKGROUND AND SUMMARY 
     The invention relates to molds for manufacturing new tires and molds for retreading tires. More particularly, the invention relates to a device for easily releasing a removable plate from a hot mold. 
     Such pocket plates are inserts for a mold side wall ring that are used to mold information onto a tire sidewall, for example, tire brand information or a bar code for inventory identification. A mold side wall ring may be used over a relatively long period of time, and for molding different versions of a single tire model. The removable plates are changed when the information on the plate needs to be changed for different tire molding requirements. 
     In conventional molds, pocket plates are held in place in a mold by magnets, by screws fastened from the front of the plate, or by screws fastening the plates from the back of the side wall ring. In the case of magnets, when the mold is heated, the side wall ring and plate expand, which provides friction to help hold the plate in place. 
     The conventional means of holding pocket plates in side wall rings present drawbacks. In molds in which the plates are fastened with front attaching screws, the screw heads leave a mark on the molded tire. When the screws are fastened from the back of the plate, the mold must be first removed from the press to gain access to the screws. Once the plate is changed, the mold must be reinstalled and realigned in the press, which involves time and effort. The magnet fastened plates must be allowed to cool before they can be removed, which causes delay, and additionally are difficult to grasp for removal because of the lack of an edge or grip on the surface of the plate. 
     The present invention provides a device for quickly and easily removing pocket plates from a mold. According to the invention, a mold half has a recess to receive a pocket plate. A rod inserted in a hole in a mold half part, a first end of the rod being disposed at an accessible outer surface of the mold half part, a second end of the rod disposed in a position adjacent to the pocket plate recess. The rod is movable in the hole and includes a cam surface that is selectably moved into the recess to push on the pocket plate by movement of the rod. 
     According to another aspect of the invention, the rod is rotatable in the hole and the cam is radially arranged on the rod for movement upon rotation. In addition, the second end include a hook radially opposite the cam surface for engaging a catch on the back surface of the pocket plate to secure the pocket plate in the recess. 
     According to an alternative embodiment of the invention, the rod is slidable in the hole, and the cam is linearly arranged on the second end of the rod. The rod includes a tab that engages a slot in the pocket plate to selectably secure the pocket plate in the recess. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top view of a tire mold part showing in partial section a quick release device in accordance with the invention; 
     FIG. 2 is a section view of the mold part taken along the lines  2 — 2  in FIG. 1; 
     FIG. 3 is a section view of the mold part taken along the lines  3 — 3  in FIG. 2; and 
     FIG. 4 is a section view according to lines  2 — 2  of FIG. 1 showing an alternative embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 is a top view of tire mold part  10 . As will be understood by those skilled in the art, the tire mold part  10  will contact and form one sidewall of a tire. A second mold part (not illustrated) forms the opposite sidewall, and tread forming segments (also not illustrated) are positioned in the radial direction to the two mold parts. The assembled mold parts and tread segments are placed in a press that holds the assembled parts together as they are heated to cure the tire. The drawings are not to scale, and the dimensions of various features have been exaggerated or reduced to improve the clarity of the figures. 
     The tire mold part  10 , and the opposite mold part, include aspects that mold information and ornamental features into the tire sidewall. For example, the brand name and model of the tire, the tire size, load, and pressure specifications may be molded onto the sidewall. Some information for a given tire mold may require occasional change. For example, when the mold is used to make tires for a private label customer, the brand name will change. For such information, the mold part typically includes a removable plate (not illustrated in FIG. 1) that is inserted in a recess  20  in the mold part  10 . 
     The invention is directed to a device to allow the quick and easy removal of such plates. In conventional molds, such plates are held in the mold by screws, either mounting from the front or rear of the plate, or by magnets. Removal of plates held by either means is awkward and time consuming. 
     According to the invention, a rod  30  is inserted in a hole  22  in the mold part  10 . The hole  22  extends from an outer surface  12  of the mold part  10  to a position adjacent the recess  20 . A first end  32  of the rod  30  is disposed at the outer surface  12  so that it may be manipulated to move the rod, as described below. A second end  34  of the rod  30  is disposed adjacent the recess  20 . 
     The rod  30  is movable in the hole  22  to effect release of a plate in the recess  20 . 
     FIG. 2 is a section view of the mold part of FIG. 1 taken along the lines  2 — 2  in FIG. 1. A plate  50  is inserted the recess  20  in the mold part  10 . In the illustrated view, the recess  20  is formed in a side wall ring  14  of the mold part  10 . As may be seen, the rod  30  extends to a position adjacent the recess  20 . In the embodiment illustrated in FIG. 2, the rod  30  is rotatable in the hole  22 . The first end  32  of the rod  30  includes tool engaging means, a hex head hole, a slot, or other suitable structure. The second end  34  includes a cam  36 , shown in FIG.  3 . Turning the rod  30  causes the cam surface  36  to contact and press against the plate  50 . The cam surface  36  is shaped so that it will push the plate  50  sufficiently free of the recess  20  to be removed by an operator. 
     According to another aspect of the invention illustrated in FIG. 3, the second end  34  of the rod  30  includes a hook  38  oppositely disposed from the cam surface  36 . The plate  50  includes a catch  52  that couples with the hook  38  when the rod  30  is rotated appropriately. The hook  38  and catch  52  serve to secure the plate in the recess  20 . 
     An alternative embodiment is illustrated in FIG.  4 . The rod  31  is slidable in the hole in the mold part  10 , and includes a linear cam  37  formed on the second end  35 . By pulling the rod in the left direction in the figure, the linear cam  37  will contact and press on the bottom face  53  of the plate  51 , causing it to raise out of the recess  20 . The rod  31  could, of course, be arranged so that pushing, rather than pulling, causes the linear cam  37  to engage the plate  51 . A spring or other device could be installed in the hole  22  to bias the rod  31  to a neutral position. 
     The slidable rod  31  includes a tab  39  spaced from the linear cam  35  that engages a slot  55  formed in the plate  51  when the rod is moved to a forward position to secure the plate in the recess  20 . 
     A mold part can have as many removable plates and release devices as needed. The present invention is not limited to a particular mold type, and those skilled in the art will understand how to apply the principles of the invention to various molds. The described structures and embodiments are meant to be illustrative and not limiting, and those skilled in the art will appreciate that substitutions of equivalents may be made without departing from the scope of the inventions as defined by the following claims.