Abstract:
A tool changing device for a cutting head of a machine for cutting flat glass sheets, the tool changing device comprising: a bridge; a carriage for supporting the cutting head, the carriage being slidingly attached to the bridge for translation along the bridge; an electric motor that provides for translational motion of the carriage with respect to the bridge; and a tool supporting slider, which is configured to support a plurality of tools such that the tools can be automatically exchanged between the tool supporting slider and the cutting head, the tool supporting slider coupled, by way of reversible fixing elements to the cutting head supporting carriage during work by the cutting head, and wherein the tool supporting slider is uncoupled from the cutting head supporting carriage during tool changing operations.

Description:
TECHNICAL FIELD 
     The present invention relates to a tool changing device for a cutting head of a machine for cutting flat glass sheets. 
     BRIEF DISCUSSION OF RELATED ART 
     Currently known machines for cutting flat glass sheets generally have a resting surface for a glass sheet to be worked, and associated with such resting surface is a bridge, which is motorized in order to travel its length, and which carries a cutting head, which in its turn is motorized for translational motion on such bridge. 
     The cutting head has a wheel tool at its end, such tool comprising a body, to which the cutting wheel, which in the sector jargon is called “clip” is hinged, such body being shaped so as to reversibly engage in a corresponding seat on the end of the cutting head. 
     Depending on the type and thickness of the glass sheet, the use of a dedicated and specific cutting wheel is in fact necessary, so that for each type of sheet the most correct cutting of the glass will be performed. 
     Since, on the work surface, sheets of different thicknesses and types can follow each other, it is necessary that the substitution of the cutting wheels can be rapid, and indeed the clip tool is easy to remove and apply, even if it is done manually. 
     Some of the current glass cutting machines known today are provided with tool changing devices, which however limit the tool changing position to a specific region of the cutting area, thus forcing the dimensions of the machine and the paths of the working axes to be increased, as well as lengthy tool changing operations, even if these are automatic, and which in the end are not very functional, given that the tool changing position is arrived at electronically with the interpolation of two axes without mechanical alignment. 
     Moreover, these machines with tool changing devices have been shown to be difficult to maintain and economically disadvantageous, while limiting the productivity of the machine itself owing to a cycle time that is too long. 
     BRIEF SUMMARY 
     The aim of the present invention is to provide a tool changing device for a cutting head of a machine for cutting flat glass sheets, which is capable of overcoming the drawbacks in known types of tool changing devices. 
     Within this aim, the invention provides a tool changing device that makes it possible to eliminate fruitless idle excursions to arrive at the tool changing region, so improving the production rates of the cutting machine of which it is a part. 
     The invention further provides a tool changing device with which clip tools of a per se known type can be associated. 
     The invention also is intended to devise a tool changing device that is rapid, exact and has a low cost. 
     The invention further provides a tool changing device for a cutting head of a machine for cutting flat glass sheets, which can be produced using known technologies and equipment. 
     This is achieved by a tool changing device for a cutting head of a machine for cutting flat glass sheets, characterized in that it comprises, so that they can slide in a parallel arrangement with means for sliding on a bridge that supports the cutting head,
         a carriage for supporting a cutting head, with motorization means for translational motion on said bridge,   a tool supporting slider, which is normally coupled, by way of reversible fixing means, to said head supporting carriage during the work of said cutting head and which can be uncoupled, for tool changing operations, in order to allow the movement of said carriage with respect to said slider, which is stationary, to select a tool to be used.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further characteristics and advantages of the invention will become better apparent from the following detailed description of a preferred, but not exclusive, embodiment of the tool changing device according to the invention, illustrated, by way of non-limiting example, in the accompanying drawings, wherein: 
         FIG. 1  is a partially sectional side view of the device according to the invention; 
         FIG. 2  is an exploded perspective view of the device according to the invention; 
         FIG. 3  is a top view of a detail of the device according to the invention; 
         FIG. 4  is a partially sectional front elevation view of a part of the tool supporting slider. 
         FIGS. 5 to 14  each schematically show a step in the tool changing operation. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to the figures, a tool changing device for a cutting head of a machine for cutting flat glass sheets is generally designated by the reference numeral  10 . 
     The device  10  comprises, so that they can slide in a parallel arrangement with sliding means on a bridge  11  that supports a cutting head  12 ,
         a carriage  13  for supporting the cutting head  12 , provided with motorization means  14  for translational motion on the bridge  11 ,   and a tool supporting slider  15 , which is normally coupled, by way of reversible fixing means  16  for detachably fixing the tool supporting slider  15  to the carriage  13 , to the carriage  13  during the work of the cutting head  12  and which can be uncoupled, for tool changing operations, in order to allow the movement of the carriage with respect to the slider, which is stationary, to select a tool to be used.       

     The bridge  11  is understood to be laterally supported by abutments  17  which are associated with a worktable  18 . 
     The means for the sliding of the carriage  13  on the bridge  11  are constituted by an electric motor  19 , which is supported by a bracket  23  that is jointly connected to the carriage  13 , with a pinion  20  engaged with a rack  21  which is fixed to the bridge  11 . 
     The carriage  13  for supporting the head  12  is constituted by a supporting plate  22 , which is substantially perpendicular with respect to the worktable  18 , which is normally horizontal, the cutting head  12  with the respective means for moving the tool being fixed to the plate  22  at one end, i.e. an actuator  24  for the vertical translational movement of the end  30   a  to which the tool is fixed, and a motor  25  for the rotation of such end, and at the opposite side, on the bridge side, at least four sliders  26  for sliding on corresponding rails  27  and  28  associated with the bridge  11 , as well as stroke limiting means  29  for the vertical actuator  24 , which are designed to measure the lowering of the end  30   a  of the stem  30  of the cutting head for tool changing operations, described in more detail hereinbelow. 
     The tool supporting slider  15  is constituted by a bracket  31  which is L-shaped, the vertical section of which has two second sliders  32 , which are arranged so as to slide on the rails  27  and  28 , each interposed between two first sliders  26  of the carriage  13  which can slide on the same rail. 
     The horizontal portion  33  of the L-shaped bracket  31  carries a rack  34  for supporting tools  35 , which is moved in a sliding fashion by means of an actuator  36  which is fixed below the horizontal portion  33 . 
     The tool supporting rack  34  is moved by a stem  36   a  of the actuator  36 , and is supported by means of a frame  37  to which it is fixed, the frame  37  being provided with sliding wheels  38  which are associated with corresponding guides  39  which are fixed to the actuator  36  and are therefore jointly connected to the bracket  31 . 
     The reversible fixing means  16  for detachably fixing the tool supporting slider  15  to the carriage  13 , are constituted by an actuator which is fixed to the vertical portion of the bracket  31 , with a tip  40  which can be extracted and retracted for engagement or disengagement with respect to a hole  41  chosen among a series of holes formed in the face of the supporting plate  22  that is directed toward the bridge  11 . 
     There are at least as many holes  41  as the number of tools carried by the tool supporting rack  34 . 
     The tools  35 , which are understood to be known per se, with clip bodies for quick and reversible engagement in a corresponding seat formed in the end  30   a  of the cutting head  12 , and since they are known they are not shown for simplicity, have two lateral symmetric hollows  44 , which are extended at right angles with respect to the vertical direction of movement of the stem  30  of the cutting head and are designed to slide on complementary shaped protrusions  45  which protrude laterally from teeth  47  in compartments  46  of the rack  34 . 
     The stroke limit means  29  for the vertical actuator  24 , which are designed to measure the lowering of the end  30   a  of the stem  30  of the cutting head for tool changing operations, are constituted by a fluid-operated actuator designed to produce the translational motion of a piston  19   a.    
     When the stem  30  needs to be lowered for the tool to be changed, the fluid-operated actuator is commanded to extract the piston  19   a  to protrude from the plate  22  until it affects the downward stroke of the motor  25 , to which the stem  30  is fixed. 
     When the stem  30  needs to be lowered until the tool is brought to the worktable  18 , then the fluid-operated actuator is actuated to retract, so freeing the vertical motion of the motor  25  to which the stem  30  is fixed. 
     The operation of the tool changing device  10  according to the invention is as follows, and is illustrated in the Figures from  5  to  14 . 
     A first step of the tool changing operations is shown in  FIGS. 5 and 6 . 
     In this first, illustrative, step, the slider  15  is jointly connected to the carriage  13 , and therefore the tip  40 , which is jointly connected to the slider  15 , is inserted into a first hole  41   a  formed in the plate  22  of the carriage  13 . 
     The slider  15  is fixed in a first relative position with respect to the carriage  13 . 
     It is assumed that the cutting head  12  has a first tool  35   a  in use and that it needs to uncouple it. 
     In  FIG. 7  the piston  29   a  can be seen extracted so as to interfere with the downward stroke of the motor  25 . The position of the piston  29   a  on the plate  22  determines a stroke of the motor  25  which is such as to lower the tool  35   a  to the height of the tool supporting rack  34 . 
       FIG. 8  shows the sliding movement of the tool supporting rack  34 , and this sliding movement ensures that the corresponding prearranged compartment, which is designated by the reference numeral  46   a  in order to identify it by way of example with respect to the other similar compartments  46  of the rack  34  shifts until the protrusions  45  protruding on it couple with the corresponding hollows  44  of the tool  35   a , the compartment  46   a , the protrusions  45  and the hollows  44  being shown in  FIGS. 3 and 4 . 
     The subsequent operation of lifting the stem  30  determines the rapid detachment of the first tool  35   a  from the end  30   a , as in  FIG. 9 . 
     Also in  FIG. 9  the tip  40  is shown retracted from the hole  41 . This configuration of the tip frees the slider  15  from the carriage  13 , allowing the latter to move with respect to the slider itself as shown in  FIG. 10 . 
     With the slider  15  stationary, the carriage  13 , now freed from the slider, moves to a second position, for example to load the second tool  35   b , which is arranged at the other end of the rack  34  with respect to the first tool  35   a , as shown in  FIG. 10 , the first tool  35   a  and the rack  34  being shown for example in  FIGS. 7 and 8 , and the second tool  35   b  being shown by way of example in  FIGS. 11 to 14 . 
     The end  30   a  remains lifted and the piston  29   a  remains extracted, as shown in  FIG. 11 . 
       FIG. 12  shows the end  30   a  lowered to engage the second tool  35   b , with the motor  25 , shown for example in  FIG. 7 , which is in abutment at its stroke limit against the piston  29   a , already shown in  FIG. 11 . 
       FIG. 13  shows the rack  34  which retracts, the stem  30  with the new tool  35   b  which raises and the piston  29   a  which retracts in order to permit the lowering to the level of the worktable  18 , such situation being shown in  FIG. 14 . 
     In practice it has been found that the invention fully achieves the intended aim and objects. 
     In particular, with the invention a tool changing device has been developed which makes it possible to eliminate fruitless idle excursions to arrive at the tool changing region, since the slider  15  with the tool supporting rack  34  travels with the carriage  13  that carries the cutting head  12 , and long excursions are not necessary for the cutting head to reach magazines which are fixed at the edges of the worktable. This improves the production rates of the cutting machine of which the device is a part. 
     Moreover, with the invention a tool changing device has been developed in which the translational movement of the slider with the tool supporting rack with respect to the cutting head supporting carriage to change the tool is executed by the same motor that moves the cutting head with respect to the bridge, without the addition of other motors. 
     Further, the tip  40  of the reversible fixing means  16  is controlled by position sensors which enable a correct mechanical alignment between the tool supporting rack and the cutting head before and during every tool change. 
     The device according to the invention makes it possible to resolve all the above-mentioned problems concerning current, fixed-position tool changing systems. 
     The tool change is thus extremely simple, precise, i.e. always mechanically aligned, and extremely rapid. 
     The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other, technically equivalent elements. 
     In practice the materials employed, as well as the dimensions and the contingent shapes, may be any according to requirements and to the state of the art. 
     The disclosures in Italian Patent Application No. PD2009A000315 from which this application claims priority are incorporated herein by reference.